Surfactants in Cosmetics, edited by Martin M. Rieger see Volume 68 Miller and P. Neogi Swisher Detergency: Theory and Technology, edited by W. Gale Cutler and Erik Kissa Parfitt Schick Microemulsion Systems, edited by Henri L. Rosano and Marc Clausse Biosurfactants and Biotechnology, edited by Naim Kosaric, W. Cairns, and Neil C. Gray Surfactants in Emerging Technologies, edited by Milton J. Rosen Reagents in Mineral Technology, edited by P.
Somasundaran and Brij M. Moudgil Wasan, Martin E. Ginn, and Dinesh O. Shah Thin Liquid Films, edited by I. Ivanov Schechter Botsaris and Yuli M. Scamehorn and Jeffrey H. Harwell Richmond Alkylene Oxides and Their Polymers, F. Bailey, Jr. Koleske Morrow Rubingh and Paul M.
Holland Kinetics and Catalysis in Microheterogeneous Systems, edited by M. Grtzel and K. Kalyanasundaram Analysis of Surfactants, Thomas M. Schmitt see Volume 96 Polymeric Surfactants, Irja Piirma Anionic Surfactants: Biochemistry, Toxicology, Dermatology. Friberg and Bjrn Lindman Defoaming: Theory and Industrial Applications, edited by P. Garrett Wettability, edited by John C. Berg Pugh and Lennart Bergstrm Technological Applications of Dispersions, edited by Robert B. McKay Singer Surfactants in Agrochemicals, Tharwat F. Tadros Solubilization in Surfactant Aggregates, edited by Sherril D.
Christian and John F. Scamehorn Stache Prudhomme and Saad A. Khan The Preparation of Dispersions in Liquids, H. Stein Lomax Nace Emulsions and Emulsion Stability, edited by Johan Sjblom Vesicles, edited by Morton Rosoff Applied Surface Thermodynamics, edited by A. Neumann and Jan K. Spelt Surfactants in Solution, edited by Arun K. Chattopadhyay and K. Mittal Detergents in the Environment, edited by Milan Johann Schwuger Liquid Detergents, edited by Kuo-Yann Lai Rieger and Linda D. Enzymes in Detergency, edited by Jan H. Baas Powdered Detergents, edited by Michael S.
Showell Biopolymers at Interfaces, edited by Martin Malmsten Polymer-Surfactant Systems, edited by Jan C. Kwak Schwarz and Cristian I. Contescu Interfacial Phenomena in Chromatography, edited by Emile Pefferkorn Binks Silicone Surfactants, edited by Randal M. Hill Milling Interfacial Dynamics, edited by Nikola Kallay Adsorption on Silica Surfaces, edited by Eugne Papirer Pastore and Paul Kiekens Volkov Schmitt Detergency of Specialty Surfactants, edited by Floyd E. Friedli Physical Chemistry of Polyelectrolytes, edited by Tsetska Radeva. Nnanna and Jiding Xia Oxide Surfaces, edited by James A.
Wingrave Hackley, P. Somasundaran, and Jennifer A. Lewis Giese and Carel J. Interfacial Electrokinetics and Electrophoresis, edited by ngel V. Delgado Keane Adsorption and Aggregation of Surfactants in Solution, edited by K. Mittal and Dinesh O. Rusling Birikh, Vladimir A. Briskman, Manuel G. Velarde, and Jean-Claude Legros Colloidal Science of Flotation, Anh V. Nguyen and Hans Joachim Schulze Although great care has been taken to provide accurate and current information, neither the author s nor the publisher, nor anyone else associated with this publication, shall be liable for any loss, damage, or liability directly or indirectly caused or alleged to be caused by this book.
The material contained herein is not intended to provide specic advice or recommendations for any specic situation. Trademark notice: Product or corporate names may be trademarks or registered trademarks and are used only for identication and explanation without intent to infringe.
ISBN: This book is printed on acid-free paper. Copyright n by Marcel Dekker. All Rights Reserved. Neither this book nor any part may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, microlming, and recording, or by any information storage and retrieval system, without permission in writing from the publisher. The battle cry for sustainable development is persistent in all circles, gaining acceptance, worldwide, as the guiding rationale for activities or processes in the science technologyenvironmenteconomysociety interfaces targeting improvement and growth.
Such activities are expected to result in higher standards of living, leading eventually to a better quality of life for our increasingly technology-dependent modern society. Interestingly, it is not surprising, despite the overall maturity of the consumer market, that detergents continue to advance more rapidly than population growth. The soap and detergent industry has seen great change in recent years, responding to the shifts in consumer preferences, environmental pressures, the availability and cost of raw materials and energy, demographic and social trends, and the overall economic and political situation worldwide.
Currently, detergent product design is examined against the unifying focus of delivering to the consumer performance and value, given the constraints of the economy, technological advancements, and environmental imperatives. The detergent industry is thus expected to continue steady growth in the near future. For the detergent industry, the last decade of the twentieth century has been one of transformation, evolution, and even some surprises e. On both the supplier and consumer market sides both remain intensely competitive , the detergent industry has undergone dramatic changes, with players expanding their oerings, restructuring iii Copyright by Marcel Dekker.
This has resulted in the consolidation of the market, especially in the last several years, and this trend appears to be gaining momentum. This may suggest that the supply of solutions to most cleaning problems confronted by consumers in view of the increasing global demand for a full range of synergistic, multifunctional detergent formulations having high performance and relatively low cost, and the need for compliance with environmentally oriented green regulation, may be based on modications of existing technologies. What does all this mean for the future of the detergent enterprise?
How will advances in research and development aect future development in detergent production, formulation, applications, marketing, consumption, and relevant human behavior as well as short- and long-term impacts on the quality of life and the environment? Since new ndings and emerging technologies are generating new issues and questions, not everything that can be done should be done; that is, there should be more response to real needs rather than wants.
Are all the questions discussed above reected in the available professional literature for those who are directly involved or interested engineers, scientists, technicians, developers, producers, formulators, managers, marketing people, regulators, and policy makers? The Handbook of Detergents is an upto-date compilation of works written by experts each of whom is heavily engaged in his or her area of expertise, emphasizing the practical and guided by a common systemic approach.
The aim of this six-volume handbook Properties, Environmental Impact, Analysis, Formulation, Applications, and Production is to reect the above and to provide readers who are interested in any aspect of detergents a state-of-the-art comprehensive treatise, written by expert practitioners mainly from industry in the eld. Thus, various aspects involvedraw materials, production, economics, properties, formulations, analysis and test methods, applications, marketing, environmental considerations, and related research problemsare dealt with, emphasizing the practical in a shift from the traditional or mostly theoretical focus of most of the related literature currently available.
The philosophy and rationale of the Handbook of Detergents series are reected in its title, its plan, and the order of volumes and ow of the chapters within each volume. The various chapters are not intended to be and should not necessarily be considered mutually exclusive or conclusive. Some overlapping facilitates the presentation of the same issue or topic from dierent perspectives, emphasizing dierent points of view, thus enriching and complementing various perspectives and value judgments.
There are many whose help, capability, and dedication made this project possible. The volume editors, contributors, and reviewers are in the front line in this respect. Many others deserve special thanks, including Mr. Russell Dekker and Mr. Joseph Stubenrauch, of Marcel Dekker, Inc. My hope is that the nal result will complement the tremendous eort invested by all those who contributed; you the reader, will be the ultimate judge.
Uri Zoller Editor-in-Chief. Regardless of the state-of-the-art and aairs in the detergent industry worldwide, with respect to scientic, technological, economic, safety, and regulatory aspects of detergent production, formulation, application, and consequently consumption, their environmental impact constitutes and will continue to be an issue of major concern.
This is particularly so given the operating global free-market economy, which is supposed to, and is expected to, ensure sustainable development. This volume is a comprehensive treatise on the multidimensional issues involved, and represents an international industryacademia collaborative eort of over 50 experts and authorities worldwide.
The fate, eects, safety, survival, distribution, biodegradability, biodegradation, ecology, and toxicology of anionic, cationic, and nonionic surfactants Environmental impact and ramications of inorganic detergent builders, chelating agents, bleaching activators, perborates, and other components of detergent formulations Toxicology and ecotoxicology of minor components in personal care detergent formulations Biodegradation of surfactants in sewage treatment plants and in the natural environment Science versus politics in the environment-related regulatory process.
All the above are accompanied and supported by extensive research-based data, occasionally accompanied by a specic representative case study, the derived conclusions of which are transferable. I thank all the contributors who made the realization of this volume possible. Uri Zoller. Rodriguez and D. Holt and K. Thorpe and Charles R. Tarchitzky and Y. Mogensen, and Karl V. Baker, C. Drummond, D. Furlong, and F. Harald P. Jose Luis Berna. Furlong Australia Ester Gorelik F. Grieser Australia. Louis Ho Tan Tai. Kristine A. Betty B. Rodriguez Alicante, Spain. Susan E. John Solbe.
Karen L. Karl V. Peter White Kingdom. The role of science and technology in meeting the sustainable development challenge is obvious and is recognized worldwide by all stake holders. In this context, environmental sciences are emerging as a new multidimensional, crossinterdisciplinary scientic discipline and beyond. They draw on all the basic sciences to explain the working of the entire complex and dynamic earth systemthe environmentwhich is constantly changing by natural causes and under human impact .
At present, they are in a process of moving from a specialized, compartmentalized, sub- disciplinary, unidimensional enterprise into a multidimensional, cross-boundary endeavor in the context of the sciencetechnologyenvironmentsociety STES interfaces . This poses new challenges with respect to both the intrinsic science and technology organization and performance and the way the relevant generated and 1 Copyright by Marcel Dekker.
Ultimately, this would require all involved to operate within an open-ended ideas-oriented culture . In view of the fact that the public, many policymakers, some scientists and engineers, and even some environmental professionals believe that science and technology can solve most pollution problems, prevent future environmental impact, and should pave the way for sustainable development, it is of the utmost importance to recognize the limits of environmental science and technology alone to meet the challenge of sustainable development .
This is because science and technology are useful in establishing what we can do. However, neither of them, or both, can tell us what we should do [1,6,7]. The latter requires the application of evaluative thinking [7,10] by socially responsible, reective, and active individual, group, and organizational participants in the STES-economic-political decision-making process [12,6 7,10], particularly in the context of the contemporary stressed ecology imperative.
The detergent industry is deliberate, steady, and mature, so its pattern of change is evolutionary, avoiding drastic step changes. In spite of gloomy economic forecasts, detergent sales are expected to continue increasing, both in dollar and physical volume, in the rst decade of the new millennium, as new formulations providing better convenience for customers improve the value-added component of the products. Anionic surfactants still dominate world output and consumption, accounting in the United States for about two-thirds of the total, compared with about one-fourth of the nonionic detergents.
Although some dierencesas far as market share is concernedare apparent, the general pattern is quite similar worldwide. Additionally, they contain builders: sequestrants such as carbonates, phosphates, silicates, as well as oxidants and other ingredients. Compared to other industries, the detergent industry recognized rather early the ecological challenge. Its voluntary for the most part switch, in the s from the nonbiodegradable hard anionic, branched-chain dodecylbenzene sulfonate DDBS or ABS: alkyl-benzene sulfonate to the substituting biodegradable linear alkylben-.
The subsequent large-scale preregulation switch from polyphosphates to, mainly, zeolites in laundry and dishwashing formulations is no less impressive. Since then, the detergent industry worldwide has been constantly confronted by one demand, the minimization commandment: that detergent formulation be the very best that yields the desired eect with the least amount.
This demand is quite obvious in view of the fact that surfactants and other components of detergent formulations constitute a signicant portion of municipal sewage water proles. Ultimately, positive feedbacktype relationships have been developed between environmental concerns and detergent formulation: The higher the public awareness of the former, the higher the environmental acceptability of the latter. Indeed, the current reformulation of detergent products reects the response of the detergent industry to environmental regulatory as well as economic-technological and demographic social factors in an attempt to cope with the increased awareness of environmental concerns, the upswing in action against phosphate builders and the unclear future of other builder systems, the tight sewage treatment requirements, the higher demand for cost performance and added-value compositions associated with lowering of washing temperatures, the increasing share of washload held by synthetic textiles, the increasing demand for liquid formulations, supereective or powdery concentrates, and the pressure of the change in customer habits requiring ecient and convenient multipurpose time-saving processes.
The appropriate response of the detergent industry to these pressures required 1 an overall increase of surfactants at the expense of builders in formulations, with the nonionics gaining most of the increased share; 2 substitution of polyphosphates mainly by zeolites as well as other eective sequestering agents; and 3 higher concentrations of active components in multifunctional formulations eective in low-temperature processes . A major outcome of the foregoing was a three-fold development: 1.
A substantial reduction in the use of polyphosphates in detergent formulations, with concomitant replacement, partially or totally, by zeolites 3. Currently, concern about the environment is leading the detergent industry to develop environmentally friendly products, which are increasingly being sold in recycled packaging material to meet regulatory requirements and satisfy customer demand.
A case in point: the concentrated detergent formulations that are both more powerful and require less packaging material. Thus, in the nal analysis, the new products and modications made within the basic formulations did make a dierence as far as the environment is concerned. This implies the importance of inter- and transdisciplinarity in environmental research [5,15,16], appropriate research methodologies [16,17], as well as strategies for technology assessment in the context of sustainable action.
In-depth systematic examination of these shifts reveals their pertinence and relevance to the systemic challenge of maintaining sustainable relationships as far as detergents and their environmental impact are concerned. What are the implications with respect to sustainable detergent production and consumptionenvironmental relationships? Ensuring sustainable development requires, to begin with, a radical change in the environmental behavior as well as thinking Environment of individuals, institutions, industry, social organizations, politicians, and governments.
This, in turn, requires reconceptualization of long-accepted relevant concepts and beliefs [9,13,14,18]. Thus, for example, the shift from the acceptance of new technologies to facilitating sustainable technologies in responding to society needs is substantially dependent on the shift from peoples or customers wants to peoples needs.
On the other hand, the technological feasibility of the economically and socially healthy shift may carry the seeds of contradiction with the shift from peoples wants to peoples needs if economics is the governing criteria. Similarly, a shift from the conceptualization of environmental science and technology as omnipotent to a recognition of their limits in solving pollution problems, preventing future environmental impact, and paving the way for sustainable development through appropriate design  has its clear implications and consequences as far as detergents and their environmental impact are concerned.
If the foregoing imperative paradigm shifts are about to be realized, then dierent quality criteria for research and practice in the sustainable development environmental context become necessary. This is because not only do methodological disciplinary aspects have to be rethought and reevaluated, but critical questions or issues arise, such as societal and practical relevance as well as external validity, particularly with respect to the risks and potentials of only partly controllable.
Sustainable developmentenvironment interrelationship. Technological, economic, and social Sustainable development growth at all cost. Peoples wants Peoples needs. Selection from among available alternatives Generation of alternatives. Environmental ethics Environmental sustainability-oriented pragmatism B. Scientic and technological research and development.
Corrective Preventive. Reductionism, i. Compartmentalization Comprehensiveness, holism. Technological feasibility Economic-social feasibility. Scientic inquiry per se Social accountability and responsible and environmental soundness. Technological development per se Integrated technological development and assessment. Clearly, the application of the identied paradigm shifts in the context of the environmental impact of detergents requires a corresponding paradigm shift in the related conceptualization. Raising the standard of living equals raising the quality of life?
Relying on disciplinary or transdisciplinary science researchbased technology for rational management of the environment and sustainable development. A case in point, to serve as an example: We are committed to meet our customers needs is a currently dominant central concept. A clear distinction between customers wants and customers needs has to be made. The rst led to overconsumption, which is not necessarily benecial to the consumer and, in fact, is perpetually and aggressively being promoted an industry motivated by growth and prots at all cost, with all the uncontrolled socioenvironmental consequences involved.
The latter, however, should be targeted and responded to by a responsible, environmentally concerned detergent industry. Only an orientation to peoples needs has the chance albeit not guaranteed to meaningfully contribute to sustainable development, not only in developing countries emerging markets but also in highly developed Western countries.
A needs orientation is, mainly, a promoter of quality of life, with a consumption-limiting potential. In contrast, a wants orientation is a promoter of standard of living, which is not only inconsistent with the existing trend of ever-increasing overconsumption, but in most cases further accelerates the pace of this trend. The environmental consequences of overconsumption are apparent [1,14,18]. With respect to science and technology, virtually any discussion concerning the current and future states of scientic and technological research and problem solving is typied by statements about the importance of enabling researchers and engineers to work seamlessly across disciplinary boundaries and by declarations that some of the most exciting problems, particularly the complex systemic environmental ones, span the disciplines.
Moreover, transdisciplinary applied research evolves from real, complex problems in the interdisciplinary STES context, which are relevant to societies living in dierent environments. Such problems have no disciplinary algorithmic solutions or even resolutions. It is growing increasingly dicult to establish the transdisciplinary basis necessary for addressing complex environmental problems [1,13,17]. Therefore, the challenge for this kind of target-oriented research and technology development is to develop problem-solving methodologies that not only integrate dierent qualities and types of knowledge, but also envision researchers and engineers as an integral nonobjective insiders part of the investigated, or to be remediated corrected , system.
Sustainable development via appropriate environmental management and industrial production, formulation, marketing, and business policies is, thus, highly dependent on transdisciplinary research and development in the STES context. This will facilitate transfer beyond the specic subject s or discipline s and, consequently hopefully , a higher success in coping with previously unencountered complex problem situations [13,17].
However, the prevention approach to ensure environmental quality and restoration of ecosystems requires, most of all, appropriate and responsible environmental behavior and action on the part of both producers and customers, which, in turn, is contingent on an adequate environmental education . This implies an urgent need for strengthening the social and educational components within the corrective-to-preventive paradigm shift process concerning the sustainable management of, and maintaining system-sustainable relationships in, our environment.
The expected resultant critical thinking and interdisciplinary transfer capabilities mean rational, logical, reective, and evaluative thinking in terms of what to accept or reject and what to believe in, followed by a decisionwhat to do or not to do about it and responsible action-taking. Thus, any meaningful response to meet the challenge of sustainable development requires transdisciplinarity, essentially by denition, that is, the development and implementation of policies and cross-disciplinary methodologies, which can lead to the changes in behaviorof individuals, industries, organizations, and governmentsthat will allow development and growth to take place within the limits set by ecological imperatives.
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The educational challenge is rather clear. It is a precondition for the required reconceptualization, which, in turn, will ensure sustainable development and growth. The detergent industry is a representative case in point; e. The sociobehavioral consumption economics and environmental links are apparent. Four recent pertinent publications, two more general and two more specic, deal with the surfactantsenvironmenthealth relationship issue and can serve to illustrate the importance of reconceptualization in the context of the environmental systems challenge that we are confronting.
It is claimed that since major environmental pollutants are coming under the control of regulatory authorities, this part of ecotoxicology is more or less completed, although there is still work, not expected to call for major scientic innovation and discovery, remaining to be done. It is concluded that the merger between ecotoxicology and ecology would give rise to a new science, stress ecology, at the crossroads of ecology, genomics, and bioinformatrics .
Handbook of detergents [electronic resource] in SearchWorks catalog
Given that the public, many policymakers, and some environmental professionals believe that science and technology can solve most pollution problems,. EPA and recommends that no further testing is needed and that the EPA agreed that there is no need for further studies . Do the apparent dierent approaches to a similar although, obviously, not identical environmental issue in the detergentenvironmentsustainable relationships context represent dierent contradictory? This question and the response to it remain open. Most problems and issues boil down to: Who does what, for what, at what price, at the expense of whom or what , and in what order of priorities?
The widely agreed-upon call for sustainable development requires rational hard choices to be made between either available or to-be-generated options . This poses an even greater challenge to science, technology, and education for sustainability, whatever that means. This is so because dealing eectively and responsively with complex interdisciplinary problems within complex systems in the context of STES interfaces requires evaluative thinking and the application of value judgment by technologically, environmentally, and sociologically i.
This implies an urgent need to strengthen the HOCS-promoting components of STES-oriented education within the corrective-to-preventive paradigm shift process concerning the sustainable management of our environment [1,10,22]. The expected resultant critical thinking and interdisciplinary transfer capabilities mean a rational, logical, reective, and evaluative thinking in terms of what to accept or reject and what to believe in, followed by a decision what to do or not to do about it and taking responsible action accordingly.
Thus, any meaningful response. It follows, then, that what we are dealing with is not just a simple matter of economics that the free market forces which, incidentally, are not Gods creation but, rather, changeable, people-made, and people-controlled will take care of. Rather, we are dealing with an array of very complicated problems within a complex system, the components of which are natural, man-made, and human environments and their related subsystems.
Most of these problems have no right solutions denitely not algorithmic , but rather resolutions that can be worked out via the use of appropriate methodologies, simultaneously guided by a sustainable development oriented value system. Can we meet the systemic challenge of sustainable detergentsenvironment relationships?
The evolutionary pattern of change in the deliberate and steady detergent industry can serve as a test case for a reasonable response, by taking a historical perspective: the switch from DDBS to LABS, the continuing use of the potentially estrogenic? Whether or not each of these is consonant with the new sustainable developmentoriented criteria and in line with the paradigm shift in the STES context remains an open question. It is up to each of us, following our own a evaluative thinking, conceptualization, and assessment process, to respond.
Can we meet the challenge? Are we getting it right? Then we should act accordingly and take responsibility, each in her or his environmentally related milieu. This Part B of the Handbook of Detergents: Environmental Impact deals, from dierent perspectives, with the relevant issues involved. Zoller, U. Glaze, W. Gibbons, M. Higher Educ. Negroponte, N. Huesemann, M. Schnoor, J. Van Straalen, N. Scholz, R. Pikering, A. Bill, A. Keiny, S. Reisch, M. News, Apr 12; They belong to that group of consumer products that are indispensable for the maintenance of cleanliness, health, and hygiene.
It has been said that the amount of soap consumed in a country is a reliable measure of its civilization. The increase in per capita consumption of soap and detergents in various countries was found to correlate well with life span. Cleanliness is essential to our well-being. A clean body, a clean home, and a clean environment are the norm of today and a general concern shared by everyone. Cleanliness is next to godliness was the ultimate historical religious praise of physical cleanliness leading to spiritual purity.
Paraphrasing it, cleanliness was, throughout history, next to environment. For thousands of years soaps, and, in the last century the synthetic detergents, followed by more complex washing and cleaning products, were the blessed way to get it. The use of soaps and detergents always led to a signicant contribution to the modern quality of life, the close environment always being part of this. However, in the past 50 years a new dimension to this obvious positive symbiosis has been imposed, and a long-unnished detergentsenvironment debate opened.
At the outset of the new millenium, the detergent industry is focused on coping with four challenges: economics, safety and environment, technology, and consumer requirements. The products must not just meet consumer needs for quality and ecacy, but must be dangerous neither to manufacture nor to use and must in no way have a detrimental impact on the users health.
The products and their packaging should not accumulate in the environment and shift or harm the ecological balance. Not only the products but also washing habits are changing. In an age of growing environmental concern, a change of attitude toward the washing process has taken place in many countries. Nowadays, the consumption of energy, water, and chemicals 11 Copyright by Marcel Dekker. As a consequence, new raw materials, washing processes, laundry practices, and cleaning technologies have been developed, with the common challenge to use carefully the limited resources of the earth, to exploit the renewable ones, and to prevent environment pollution as much as possible.
The development of surfactants and detergents over the past decades has been aected tremendously by their environmental acceptability. The challenge for the future is to meet the most modern risk assessment approaches. The aim of this chapter is to review this detergentsenvironment interrelated development frame throughout history. First, surfactants and phosphates, as the main components of detergent formulations and cleaning products, have been the subject of longstanding and ongoing detergent regulation and legislation. Second, ecient management has been imposed on sewage treatment, which is being updated continuously.
During the washing process, detergent components are released to the wastewater stream, to become a potentially undesirable troublemaker in sewage treatment plants and in the environment. Wastewaters vary considerably in composition and concentration and hence in their environmental impact. These dierences are geographically dependent and arise partly due to dierences in laundry habits and soil levels and partly to the composition and amount of the detergent used. The environmental impact further depends on the specic ecological requirements and public awareness in each particular geographical area.
Also, household wastewater, generated mainly from laundry and personal care products, diers from that from industrial and institutional outlets. Typical sewage treatment systems in countries with developed environmental protection include intensive biochemical and physical degradation processes that bring about the elimination of the pollutants. The extent of elimination depends on sludge levels, aeration ecacy, and residence time.
In addition to bacterial metabolic reactions, physicochemical processes, such as adsorption on sewage sludge, contribute to the reduction of pollutant levels . Variations in sludge loading and in peak loads of the wastewater are moderated considerably by the predilution of household wastewater in the public sewage system. Wastewater from industrial sources is generally pretreated by pH adjustment and physical separation in on-site sewage plant prior to discharge to municipal sewage treatment plants.
Sometimes a well-designed treatment plant on an industrial site may permit direct discharge. The sewage treatment euents are discharged in the surface waters. Quality requirements for these euents depend upon the intended use of the surface waters. The ultimate use, such as for drinking water, agriculture, or recreation, also governs. Phosphorous and nitrogen elimination normally require additional treatment steps.
The sewage treatment euent is diluted in surface waters. The dilution factor varies according to the geographical place. Human waste and some remaining traces of surfactants in the surface waters are further biologically treated by a self-cleaning process . However, the most signicant parameter is the direct measurement of the pollutant levels, mainly surfactant and phosphate concentrations. Highly sensitive analytical test methods have been developed for the accurate determination of surfactant concentration [3,4]. Anionic surfactants are determined as methylene blueactive substances MBAS by a method based on a modied Epton two-phase titration.
Nonionic surfactants are determined as bismuth-active substances BiAS after passage through cation and anion exchange columns. Strict implementation of detergent regulations combined with eective sewage treatment hes led to low surfactant concentrations in large rivers, such as those in the Rhine, which currently are as follows : Anionic surfactants, about 0. It has taken some 40 years to reach the present state from the time when rivers all over began to foam and gave rise to the First Detergent Law.
Foam on rivers was increasing, and tap water, drawn from wells located close to household discharge points, also tended to foam. In , Germany encountered similar diculties when foam formed on German rivers and stable foam layers developed downstream from dams. The sewage treatment of the time, based on physicochemical separations and some biological treatment, was not able to cope with the surfactant load. The impact on sewage treatment was immediate and signicant. The ecacy of the sedimentation. The few biological sewage treatment plants operating with an activated sludge process collapsed, producing foam layers several meters high above the aeration tanks.
Increased surfactant concentrations were found not only in sewage waters and rivers, but also, as a result of soil inltration, in the groundwater. As a result, the drinking water supply was contaminated. The anionic surfactant content of drinking water from the Ruhr River increased to as much as 1. During , increasing surfactant consumption in the United States led to similar ecological problems.
It was soon understood that these serious problems for water management were due to the poor biodegradation prole of DDBS. The abnormal quantities of foam were attributed to the presence of DDBS, which, in turn, was the result of incomplete biodegradation of propylene-based alkylbenzenesulfonates by the natural bacteria present in euents. The branched-chain structure of alkylbenzene seemed to hinder attack by the bacteria.
Supporting evidence for this judgment was provided by the facile degradation of fatty alcohol sulfates and soap. Both are derived from straightchain fatty acids, suggesting that a straight-chain, linear alkylbenzene might also be degradable. However, a directive provided a dynamic test method according to a specied test protocol only for control of anionic surfactants. During the short time between mid and , known as the conversion period, the foaming problems in surface waters and sewage treatment were solved.
The eects of the conversion to biodegradable surfactants were. The conversion from hard to soft surfactants was also legislated during in the United States, as amendments to the Federal Water Pollution Control Act, creating new water pollution control standards . However, none of these measures was implemented. Similar regulations and voluntary agreements were put into place during the late s and early 70s in several countries of Western Europe and in Brazil and Japan.
LABS was made commercially available in The manner in which the DDBS problem was solved is an excellent example of environmental improvements achieved by cooperation of government, industry, and science. However, the detergent industry faced advantages and disadvantages. The change to LABS oered better detergency in heavy-duty formulations and lower cloud points and viscosities in pastes and slurries.
But, on the other hand, while a lower viscosity in slurries oered an advantage for a spray-dry process, the liquid and paste LABS detergent of lower viscosity looked less appealing to the consumer. Also, the LABS powders became sticky and were less free owing . It was found that the actual isomer distribution of the linear alkylate has an eect on the stickiness of the powder, identifying the 2-phenyl isomer as giving the greatest tendency to stickiness.
The dierent phenyl isomers are obtained when, during alkylation, the benzene molecules attach to the dierent carbons along the alkyl chain. For instance, an attachment at the second carbon of the alkyl chain gives a 2phenyl isomer. It was found that the phenyl isomer distribution depends on the catalyst used during alkylation. This catalytic versatility in LAB production, as well as additives further developed, overcame most of the formulation problems.. However, in the case of solid laundry bars the lower viscosity and the less bulky molecular structure of LABS provided a softer bar hardness and a stickier appearance.
Surfactant Biodegradation Biodegradation is the process by which microorganisms in the environment convert complex materials into simpler compounds that are used as food for energy and growth. Biodegradation of the surfactants used in detergents is important because of the large volumes used worldwide and, of course, the detrimental toxic eects on the aqueous and soil environments. Biodegradation is a multistep process that starts with the transformation of the parent compound into a rst degradation product primary degradation and leading, ultimately, to mineralization products carbon dioxide, water and bacterial biomass ultimate or total degradation.
A typical surfactant biodegradation is illustrated by the linear alkylbenzenesulfonate LAS biodegradation path in Figure 1 . A good understating of past and present biodegradation issues requires precise denitions of biodegradability terms [5,10,11]. Primary biodegradability is the change in the chemical structure of an organic substance, resulting from a biological action that causes the loss of the specic chemical and physical properties of the substance.
When this stage of biodegradation is reached, the remaining material is no longer a surfactant; it no longer has any surface-active properties, including the ability to foam. Ultimate biodegradability in the presence of oxygen aerobic conditions represents the total level of degradation by which a test substance is consumed by microorganisms to produce carbon dioxide, water, mineral salts, and constituents of microbe cells biomass.
Ready biodegradability is an arbitrary classication for chemical compounds that satisfy immediate biodegradability tests. The severity of the tests biodegradation and acclimation time ensures that such compounds will degrade quickly and completely in an aquatic environment under aerobic conditions. Anaerobic biodegradability: Most biodegradation processes take place in the presence of oxygen aerobic conditions.
However, biodegradation also proceeds in the absence of oxygen in anaerobic environments, albeit at slower rate. Anaerobic media are known as either anoxic in which the rate of oxygen consumption exceeds the rate of oxygen diusion or strictly anaerobic in which the oxygen is totally absent. Because of concerns about the presence of detergent ingredients in all parts of the environment, anaerobic biodegradability has been proposed as the criterion for several Eco-label requirements.
Experimentally, LAS was found to pose no risk to anaerobic environments . Separation of anionics and nonionics from a detergent com-. The disappearance of the specic analytical species corresponds to the loss of signcant ecological surface activity. Concurrently with the legal biodegradability requirements, specic test methods for measurement of biodegradability of synthetic anionic and nonionic surfactants in laundry detergents and cleaners were elaborated and approved.
They are based mainly on the quantity of consumed oxygen and the disappearance of dissolved organic carbon DOC. In , two biological tests were approved and mandated by the OECD Organization for Economic Cooperation and Development for establishing biodegradability [13,14]: 1. If the level of biodegradability is lower or if the results are in about, a subsequent Conrmatory Test is required. The results of this are decisive and denitive.
The revised edition of this directive was ocially implemented in . The OECD screening test is based on a static shake ask method and corresponds to surface water conditions. The measurements are made at xed intervals up to 19 days. The OECD Conrmatory Test, known also as simulation test, is a continuous procedure run under more realistic environmental conditions, simulating activated sludge plants, as shown in Figure 2 .
The Conrmatory Test can simulate several types of environment, such as lake, sea, and land, and can be run under aerobic or anaerobic conditions conditions . After inoculation of the test system and growth of the activated sludge, an acclimation period is run, following a predetermined procedure. After a minimum 14 days, the degradation rate reaches a plateau for readily biodegradable surfactants, while an irregular curve, with ups and downs of low biodegradation rate, is shown by hard surfactants.
This initial period is followed by a day evaluation period in which the high-biodegradation-rate plateau is maintained by the readily biodegradable substance. From Ref. In this test two units are run in parallel. Typical results are presented in Table 1 . Effect of Surfactant Regulation on Sewage and Surface Water Load The implementation of the surfactant regulation solved most of the signicant ecological problems in Europe, the United States, and Japan with respect to residual concentration of surfactants in sewage euents and surface waters.
The order of magnitude of the contribution of laundry detergents and other cleansing agents to the sewage surfactant load in Germany in has been documented comprehensively [1,18,19]. This estimate was based on a liter daily water consumption per capita and took into account the detergent production in Germany as , tons. These gures translate into a Based on production volumes of , tons of anionic, 91, tons of nonionic, and 26, tons of cationic surfactants, the daily per capita consumption of each group has been calculated as 6.
These gures lead to a calculated average concentration of The surfactant concentration in municipal sewage has been checked analytically and found to correspond on average to the theoretical calculated values. Comprehensive and well-documented data based on extensive investigation of measuring points for anionic surfactants and 20 measuring points for nonionic surfactants were summarized in the late s for the main German rivers.
The average concentrations were as follows : Anionic surfactants: V0. The Rhine Water Quality Report of took note of these remarkable improvements and clearly positioned them as an interim results in the Environmental Protection Program of the German Federal Government. The pragmatic decision of the early s on the manner of solving the surfactant issue served as the model for this interdisciplinary Environmental Protection Program, which was announced in and fully achieved its dened waters goals in the late s . Several other reports measured water concentrations of LAS during the two decades, nding them in good agreement with model predictions [6,20].
Extensive references and documented reviews have been published on biodegradation of surfactant in dierent water media. A few selected examples are noted next. Recent monitoring studies of 50 river sites just below wastewater treatment plants determined average LAS concentrations as 35 ppb; while measurements of , U. A representative survey of nonionic surfactants concentration in wastewater inuents and euents in the United States, Europe, and Israel during was compiled by Zoller [21,25] and is presented in Table 2 . The decrease in nonionic levels in U.
In Israel, on.
A study on biodegradation of anionic surfactants in the United States checked the biodegradation with the presence of petroleum pollutants. Under experimental conditions and concentrations, a synergism has been reported in the biodegradability of kerosene and surfactants [6,26]. The synergistic biodegradation behavior of a binary or a multiple-component system has been noted in another publication, recalling also the performance benets and industrial applications of such systems .
Surfactants: Ecotoxicological Profile Water protection demands on surfactants refer mainly to biodegradability and aquatic toxicity. The following objectives and requirements were dened by Malz : 1. The objective of this section is to summarize the toxicity understanding from these available data, and how these data are then used to derive the environmental relevant aquatic PNEC. The reader is recommended to refer those documents for specific details of the toxicity data studies.
Sufficient measured data exist to quantify the acute and chronic aquatic toxicity of essentially pure alcohols and mixtures of these alcohols to fish, invertebrates, and algae OECD, Because alcohols act by nonpolar narcosis Lipnick et al. Furthermore, as discussed in Fisk et al. At higher carbon numbers up to C 22 , the measured acute toxicity shows an absence of acute toxicity as evidenced by reported LC 50 values that are greater than the highest test concentration.
This is explained by the low water solubility of these LCOHs, which limits their bioavailability, such that an acutely toxic concentration is not achieved Fisk et al. Effects have also been observed in tests with C 13 and C 14 alcohols but at concentrations that exceeded the solubility of the alcohols; therefore, the observed toxicity may be due to physical effects rather than true toxicity for these two alcohols OECD, The C 14 and C 16 alcohols were not toxic to algae.
These results suggest that for alcohols in the range of C 12 —C 14 , there are no acute toxicity effects on fish, invertebrates, and algae driven by the low solubility of these alcohols, although there may be physical effects and that the three types of organisms are about equally sensitive acutely to alcohols of the same chain length Table The acute toxicity data for fish, invertebrates, and algae to multicomponent substances of different carbon chain length alcohols as would be found in commercial products OECD, have also been determined.
These multicomponent substances containing alcohols with carbon numbers in the ranges of C 6 —C 12 , where all the components would be completely dissolved, are acutely toxic at concentrations as expected from the contribution of the individual linear alcohols to the mixture. By contrast for multicomponent substances which contain one or more alcohols with chain lengths greater that C 12 —C 14 , where not all components were fully dissolved, toxicity not only appears to be the result of toxic effects from the soluble portion of the alcohols but also includes toxic effects as a result of physical fouling of the test organism by the longer-chained alcohols.
Chronic aquatic toxicity data for fish and algae OECD, are limited to one or two studies Table Invertebrates, represented by D. These QSARs are. There are no data on the acute or chronic toxicity of alcohols to sediment dwelling organisms. As described in OECD , available data suggest that the three taxonomic groups—fish, invertebrates, and algae—are of comparable susceptibility to the individual long-chain aliphatic alcohols, consistent with narcosis structure activity. Therefore, the database for chronic aquatic effects of single carbon number alcohols from D.
Justification for use of the AF of 10 can be found in Belanger et al. However, in the environment, the alcohols will not appear as individual chain lengths but rather as mixtures of chain lengths as evidenced by monitoring studies of WWTP effluents in North America Dyer et al. The most prominent chain length found in those sewage treatment plant effluents across a wide range of treatment types, including lagoons, oxidation ditches, trickling filter, activated sludge and rotating biological contactor, was C 12 —C As described previously, because of the low solubility of LCOH with chain lengths greater than C 15 , no toxic effects will be exerted by these longer chain lengths, and these are thus eliminated from this analysis Belanger et al.
The average chain length based on the range of C 12 —C 15 in the effluent is C The average chain length based on the range of C 12 —C 15 was C 13 after correction was made to the effluent concentrations based on bioavailability corrections for each of the monitored sites based on data in table 4 of Belanger et al. As discussed in Fisk et al. Biotransformation would be expected since alcohols serve as an energy source food through metabolism for a wide range of biota from bacteria to mammals Mudge et al.
Branched structures are predicted to have slightly lower BCF values than the corresponding linear alcohols consistent with their lower log K ow. An extensive review and summary of the AE acute and chronic toxicity data with tabular summaries can be found in Belanger et al. The objective of this section is to summarize the toxicity understanding from the available data, and how these data are used to derive the environmentally relevant PNEC for AE.
The reader is recommended to refer those documents for details of the data and any particular studies. Acute aquatic toxicity studies to AE homologs and commercial mixtures have been conducted for a wide range of species, life forms, feeding strategies, and trophic levels, including green and blue-green algae, diatoms, saltwater shrimp, freshwater isopods, freshwater flatworms, freshwater midge larva, Daphnia , and a wide range of both freshwater and saltwater fish species Madsen et al.
These data Table 16 illustrate that algae appear somewhat more sensitive to AE than either invertebrates or fish. The acute fish, invertebrate, and algal acute eco-toxicity test results also indicate that the branched and essentially linear AE are not more toxic than the linear AE of the same hydrocarbon chain length and EO number. The acute toxicity data also show that toxicity decreases with increasing EO chain length and increases with increasing hydrocarbon chain length, so long as the AE remains soluble in water.
Sources: Madsen et al. Chronic aquatic toxicity Table 17 has also been determined for 17 different aquatic species, ranging from algae, Daphnia , mollusks, rotifers, and to several fish species, for AEs representing a range in hydrocarbon chainlength distribution and the EO chainlength distribution HERA, b. These studies demonstrate that the rainbow trout, a mollusk clam , and rotifers are amongst the most sensitive taxa, although differences in sensitivity across trophic levels were not significantly different Belanger et al.
As was seen with acute toxicity, chronic toxicity increases with increasing hydrocarbon chain length and decreases with increasing EO chainlength. Source: HERA b. The relationship between hydrophobicity and toxicity demonstrated by both the complete acute and chronic toxicity data sets were used as the basis for developing AE chronic QSARs for algae, Daphnia , and fish based on selected studies of specific AE homologues and their K ow.
The resulting QSAR is. The chronic D. The AE homologues provided a good representation of the hydrocarbon range from C 9 to C 15 and good coverage of the EO range from 0 to Due to the limited number of data points, Boeije et al. Thus, Wind and Belanger concluded that no one trophic group appears to be uniquely sensitive or insensitive to AEs, based upon the chronic data.
Belanger et al. AEs have an unparalleled set of mesocosm studies Table These are summarized in Belanger et al. These studies came from a strategy to test the range of commercial mixtures from a relatively low alkyl carbon range C 9 —C 11 to relatively high C 14—15 and short 6 to moderate 9 ethoxylation. Studies were detailed ecological investigations including microbial and invertebrate communities and caged fish of 1—2 months duration of exposure to the test materials. Boeije et al. Source: Table 5 in Belanger et al. Both the acute and chronic aquatic toxicity data sets for sediment dwelling taxa, such as Chironomus tentans and Corbicula fluminea , and others which live near or in the top sediment surface such as Hyallela azteca , Dugesia gonocephala, Chlorella vulgaris , and Navicula pelliculosa.
Aquatic macrophytes have also been assessed Lemna minor. These aquatic test data Table 19 are reported as the concentration in the water above the sediment. Source: Table 1 in Belanger et al. The use of this linear AE data is considered appropriate because the acute toxicity data show that the toxicity is essentially the same for the essentially linear and branched AEs.
Using the first approach, namely the chronic D. The reader is referred to Belanger et al. No additional AF is required to be applied to the resulting chronic toxicity SSD because of the high quality of the data approximately 60 chronic studies and the range of species 17 different taxa represented by the QSARs. Source: Table 4 in Belanger et al.
The final approach is to use the data from the mesocosm studies Table 19 on various AEs which were conducted in the mids to derive a PNEC. The AE mixtures represented in these mesocosm studies cover the full range of commercially relevant uses in detergents. Toxicity predictions based on both the previous approaches and this mesocosm approach provided very similar results.
The fact that mesocosm and the chronic toxicity QSAR outcomes are so similar supports the use of no additional application factor to the results in Table Ultimately, the SSD approach, approach two, is considerably more flexible and spans a greater range of AE mixtures and is, therefore, used to develop the PNEC for the environmentally relevant form of AE. Based on this average distribution of AE structure in effluent and the HC 5 values in Belanger et al. The limited toxicity data for sediment dwelling or associated organisms suggest that this same PNEC could be used to represent sediment toxicity when expressed as the interstitial water concentration because the EC 10 value for the most sensitive chronic end point for a sediment dwelling taxa of 0.
Bioaccumulation of AE in aquatic organisms had been determined only for fish Madsen et al.
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Furthermore, the majority of the limited data were based on studies with 14 C-labeled compounds that do not allow the distinction between the parent compound and metabolites, or material incorporated into the cells during growth. Because AEs are metabolized in aquatic organisms Madsen et al. Tolls and Tolls et al. This showed that the parent AE e. The time to steady state and the BCF for AE increase with decreasing length of the ethoxylate chain e.
They concluded that the AE metabolism rates prevent any significant accumulation. The objective of this section is to summarize the toxicity understanding from the available data and how these data are used to derive the environmentally relevant PNEC for AE. The reader is recommended to go to those documents for specific details of the toxicity studies. Extensive acute and chronic toxicity data to fish, both freshwater and marine species, invertebrates, and algae for AS ranging from chainlengths of C 8 —C 18 both as single chainlengths and in mixtures of chain lengths, are presented in HERA and OECD While data exist for chain lengths ranging from C 8 to C 18 , the homologue C 12 has the largest ecotoxicological database of the group.
The acute toxicity database Table 21 for fish is quite extensive with reliable studies available for 13 different species covering a variety of both freshwater and marine species OECD, For those AS chain lengths up to C 16 , toxicity values appear to be independent of the fish species tested, the counterions present or the test conditions. In fact, the range in toxicity is rather homogenous for a given chain length in this range despite toxicity tests done with highly varied exposure methods i.
There also appears to be no influence of the counterion e. The toxicity reported for AS of chain lengths of C 16 and higher are inconsistent, probably due to variability in bioavailability as a result of reduced water solubility. Toxicity increased with increasing alkyl chain length for the freshwater species of D.
The Dyer et al. Furthermore, the Dyer et al. In summary, for invertebrates, AS acute toxicity increases with increasing length of the hydrocarbon chain up to C 16 and decreases at C The results do not allow for the prediction of a chain length dependency of algal toxicity due to the fact that most of the available studies were conducted with mixtures containing a range of chain lengths.
However, the overall impression is that algae are more variable in their sensitivity to AS exposure compared to fish and invertebrates. The tests were conducted on embryo-larval or juvenile stages of several different fish species under flow-through or semistatic conditions, ensuring the stability of the test solutions. The lowest measured toxicity was obtained from a day chronic early life stage test to P. Using analytical measurements of the test substance, the NOEC was calculated to be 0. Long-term tests with invertebrates in either semistatic or flow-through systems are summarized in OECD and in Table In addition to acute toxicity, Dyer et al.
Unlike the linear response observed in the acute tests, a parabolic structure—activity relationship was observed from the chronic tests where C 14 AS was the most toxic single chain length. However, toxicity decreased with chain lengths beyond C 14 AS most likely due to solubility constraints. These data were used to develop a QSAR:. The lowest effect value obtained from the various algal chronic tests is a h NOEC of 0. C 12 AS and C 14—15 AS have been investigated by various authors in a number of multispecies tests at ecosystem level Table Extensive experiments were conducted for C 12 AS in an experimental stream facility ESF , which was run with natural river water under outdoor conditions Belanger et al.
A second study was performed on C 14—15 AS in the same system and is summarized in Belanger et al. The experimental design was the same in both studies. These mesocosms were assessed for algal, bacterial, protozoan, and invertebrate population and community structure and function. Measured end points included, but were not limited to, total and population abundance, total and population biomass, relative abundance, taxa richness, Shannon diversity, trophic functional feeding group abundance and biomass, drift rate and density, drift richness, and drift Shannon diversity.
A NOEC of 0. The chain length used has very low solubility and would most likely be sorbed to sewage solids. Due to AS's rapid biodegradability, observed toxicity in sediment tests Table 24 has shown AS to be similar to or less toxic compared to aqueous studies Madsen et al. The authors suggested that this decrease in toxicity with increasing alkyl chain length was attributable to reduced solubility in water of the longer alkyl chain length AS. The range of sediment toxicity expressed as LC 50 or EC 50 based on the water concentration is 0. In the aquatic environment, the AS will not be present in just one chain length but rather as a range of chain lengths.
The weighted average chain length was Using the PNEC values in Table 22 and the relative proportion of these chain lengths in this effluent 0. This approach, based on toxic units, can be used to determine the PNEC for any mixture of AS chain lengths found in the aquatic environment. The sediment PNEC can be estimated from the limited set of sediment toxicity data described previously and would be close to 0. This is very similar to the aquatic PNEC of 0. These BCF values are possibly overestimated due to the use of radiolabeled compounds, since AS is subject to metabolism.
Due to this metabolism, AS is generally considered to have a low potential for bioconcentration in aquatic organisms Madsen et al. Fish fathead minnow, channel catfish and invertebrates C. The burden of C 15 AS was 6. From these results, it can be concluded that some chain length dependency and interspecies differences exist with respect to bioaccumulation of AS, but that generally bioaccumulation is low. The objective of this section is to summarize the toxicity understanding from the available data and the approach used to generate the PNEC value from these data.
Acute aquatic toxicity studies to AES homologs and commercial mixtures have been conducted for green algae, Daphnia species, and a wide range of freshwater fish species. NVZ reports that the geometric average EC 50 for 12 different fish species is 4. Several invertebrate species have been tested for toxicity e.
NVZ, Due to the large variation in toxicity values across the various trophic levels to AES, no taxa appears to be especially sensitive, although it may be argued that fish and invertebrates appear to be the most sensitive. Because there is a substantial chronic database available for AES, including freshwater fish, rotifer, daphnids, freshwater clam, gastropod, caddisfly, and green algae which is described in details in HERA , these data were used to derive the PNEC. Because the toxicity studies were conducted for a range of AES carbon alkyl chain lengths and number of ethoxylate groups, it is difficult to compare the toxicity results.
HANDBOOK OF DETERGENTS
The process involves first identifying the structure of the AES that is typically present in the environment i. The normalization procedure is based on the use of a chronic toxicity-based QSAR. Dyer et al. Using this QSAR, the alkyl chain length and number of ethoxylate groups for the specific AES in Table 26 , the ratio between the predicted EC 50 for the structure found in the environment, and the predicted EC 50 for the tested structure are calculated. The normalized toxicity values using C As can be seen in Table 26 by comparing the normalized NOEC values and the geometric means for a species when there are several toxicity measurements, there is very little difference in sensitivity among the species tested.
The NOEC was determined to be 0. The second study tested C 12—15 EO 3 S linear AES in a d outdoor stream mesocosm which contained invertebrates, fish, periphyton, and an aquatic macrophyte. These mesocosm studies incorporate both direct and indirect effects. Thus, these provide the greatest ecological realism.
There are no data on the acute or chronic toxicity of AESs to sediment dwelling organisms. The normalized HC 5 was 0. The data used to develop this distribution are given in Table Because there are no data on the acute or chronic toxicity of AES to sediment dwelling organisms, no PNEC for sediments could be estimated. Even so, given the relative lack of sorptivity of AES, it is reasonable to conclude that PNECs based on aqueous exposure would be protective of sediment dwelling organisms.
Due to AES's polarity, it is not expected to bioconcentrate in aquatic organisms. Experimental data confirm that AES is not bioconcentrated in fish. Kikuchi et al. Whole body BCFs measured as 35 S residue were 18 and 4. Predicted BCFs were The toxicity of LAS has been widely investigated, and studies are available on acute, chronic, microcosm, mesocosm, and in situ exposures in the aquatic, and sediment environment. The objective of this section is to summarize the toxicity of LAS and the relationship between the physical and chemical properties of LAS associated with toxicity and to describe how the PNEC which will be used in the prospective risk assessment was determined.
A thorough summary of the toxicity of LAS is beyond the scope of this chapter, therefore the reader is recommended to go to the specific references for details on the toxicity studies cited. Intra and interspecies variability is large, particularly in the case of algae due to the fact that these toxicity values refer to different individual compounds and mixtures of isomers of LAS.
Differences in test design as well as can account for some of this large range of species sensitivity. Data for algae refer to various species. The values in Table 27 are the geometric means of several studies, demonstrating the abundance of acute toxicity test data. These data are only for information because the abundance of higher tier data for LAS i.
The chronic freshwater aquatic toxicity of LAS, based on effects on growth, survival, and reproduction, and evaluated in 19 different species with a broad taxonomic distribution, is summarized in OECD This data set included algae, aquatic macrophytes, invertebrates, and fish. Photosynthetic organisms include blue-green and green algae as well as two floating aquatic macrophytes. Mollusks, water fleas, rotifers, and insects are representative invertebrates. Fish species include members of the salmonids, centrarchid, and cyprinid families and cover warm and cold water species. Across this large data set, the chronic aquatic toxicity to C A variety of model aquatic ecosystem and mesocosm studies have been conducted on LAS.
Many of these studies have been evaluated and summarized in two papers Van de Plassche et al. There is a substantial level of variability in the data among the 13 studies Maki, ; Lewis, ; Lewis and Hamm, ; Huber et al. The extremes in the NOEC values are reported for lentic studies that were primarily conducted as single dose exposures. There was less variability in the NOECs when the test system was composed of lentic species and test solutions were renewed during the exposure Maki, ; Huber et al.
The structure and study design of the systems significantly impacts the study outcome because the lentic studies focused primarily on the autotrophic portion of the aquatic ecosystem. As reported by Fendinger et al. Therefore, effects on autotrophs, which are the principal taxonomic group assessed in the lentic studies, would be observed at a higher concentration than for lotic studies that focused more on benthic fauna. Dodecyl LAS was dosed for 56 days, and microbial and invertebrate populations and communities were assessed.
In addition, several species of invertebrates and fish were evaluated in cage enclosures in the flowing freshwater channels Versteeg and Rawlings, An integrated mesocosm NOEC of 0. The long-term comprehensive nature of the mesocosm study and its close reflection of natural systems have resulted in the direct use of the mesocosm NOEC in PNEC derivation Versteeg et al.
Similar to the other surfactants, these aquatic toxicity data demonstrate that an increase in the chain length of LAS is associated with increases in toxicity. Increasing chain length causes an increase in the overall hydrophobicity of LAS, in conformity with the general observation that toxicity increases with increased hydrophobicity Auer et al. Fendinger et al. Branching and the location of the phenyl position have also been associated with changes in toxicity due to changes in hydrophobicity Roberts, For example, homologues with the same molecular weight i.
This appears to be due to the intrachain carbon—carbon interactions which require fewer water molecules to solvate the alkyl chain leading to reduced hydrophobicity Roberts, Similarly, branching on the alkyl chain causes reduced toxicity via a similar mechanism. Three studies have been conducted that determine the toxicity of LAS to sediment organisms. The first study Comber et al. Exposure lasted 28 days, at which time the survival and change in biomass were determined. Significant degradation was measured over the day duration of the study, equating to a half-life of 20 days in sediment.
The second study Comber et al. Exposure lasted 3 days, at which time the survival and reproduction were determined. In the third toxicity study, Pittinger et al. In day survival and growth studies of L. In both sediments, larval wet weight was a more sensitive indicator of toxicity than head capsule length.
In the aquatic environment, different homologues and isomers are present. This value can be used as an environmental fingerprint in receiving water. However, because toxicity is not linearly related with chain length, the actual ecotoxicity of the environmental fingerprint is not the same as the ecotoxicity associated with this average structure. This resulted in a toxicity-weighted average corresponding to a structure of C The ecotoxicity associated with a C To determine a single species-based PNEC, freshwater chronic toxicity values were normalized to C When corrected to a chain length of Given the duration of the mesocosm study, the rigor of the methods, diversity of species, and the need to assess effects at the community level, the mesocosm value of 0.
SSD for the full C The predicted HC 5 of 0. In the seventh column, the toxicity values are reported as normalized to a single average environmentally relevant LAS structure i. The PNEC for sediment can be derived from the chronic sediment toxicity data for the three species that represent different living and feeding conditions. The test system used single homologue and isomer representatives of the commercial LAS to determine their uptake and elimination rates in fish.
In addition, BCF was determined for P. In general, bioconcentration was affected by isomer position, exposure concentration, and species. BCF values tended to decrease as isomer position moved from external e. BCFs also decreased as exposure concentration increased. BCFs for L. To estimate the potential impact on the aquatic environment from each of the four surfactants and LCOHs, a prospective risk assessment is conducted. This prospective risk assessment calculates the ratio of the predicted surface water exposure concentrations PEC at the 90th percentile low flow and 90th percentile mean flow with the predicted no-effect concentration PNEC for each of the surfactants.
Values less than 1 indicate that there is a low potential for adverse effects in the aquatic environment because the predicted exposure concentration is less than the concentration that would not cause any adverse effects. Table 29 summarizes the environmentally relevant structure for each of the chemicals and the calculated PNEC from Section V, as well as the exposure predictions from Section IV for this environmentally relevant structure.
The risk quotient for each of the chemicals is below 1 for the aquatic environment. In fact, for most of the scenarios evaluated, the risk quotient is almost 2 orders of magnitude less than 1, indicating that the potential for any adverse effect on the environment from the use of these surfactants and LCOH as a result of dispersive release to the aquatic environment after wastewater treatment is very low.
For most of these surfactants i. The exposure concentration in the sediment can be calculated using the approach discussed in Section III. Using the 90th percentile low flow concentration of LAS predicted for the surface water Table 13 of 7. E , the sediment exposure concentration would be 7. Using the same 90th percentile low flow concentration for LAS, an organic carbon content of the sediment of 0. Thus, the risk quotient for sediments using these two exposure calculations would be 0. Both indicate that no adverse effect on the sediment dwelling organisms is expected.
Thus, in addition to no adverse effects upon direct contact with the surfactant in surface waters or sediments, there is no concern for any secondary effect of these surfactants on organisms that could be exposed to the surfactant through food. For chemicals that have been in commerce for an extended time, like the surfactants that are the subject of this paper, retrospective risk assessments can be done through comparison of chemical and biological environmental monitoring. Retrospective approaches require building an integrated assessment that provides a measure of the importance of the chemical discharges relative to other factors that can cause adverse biological responses.
These other factors include in-stream habitat, and altered hydrology which impact the biological quality e. These factors, among others, occur in the ecosystem independently of the potential effects of the chemical. Because retrospective approaches evaluate the contribution of all of these potential causes of adverse impacts on the ecosystem, these approaches provide an ecological reality check by identifying which of the factors is a priority concern pertinent for appropriate management.
Furthermore, a retrospective risk assessment can be used to verify and give confidence in the predictive risk assessment methods and to confirm the conclusions of prospective risk assessment. In order to conduct a retrospective risk assessment, there are several important factors to consider in choosing the site, designing the monitoring program, and conducting the analysis of the results.
When choosing sites for conducting the retrospective risk assessment for these surfactants, the ideal site would include a river that receives well-treated WWTP effluent, has little or no industrial discharges either to the water body or the WWTP, other stressors, natural habitat, low to minimal dilution, and is easily accessed for collecting samples.
To choose sites that would meet as many of these criteria as possible, several pieces of information are required. These include:. Information on the location of the discharge point s and quality and quantity of the effluent from the WWTP s ;. Characteristics of the associated receiving water body. The presence of industrial discharges either directly to the water body or to the WWTP;. This information can be obtained from a variety of sources such as satellite images, WWTP databases e.
Typically, these data are managed spatially via geographic information systems GIS. For example, in Sanderson et al. The presence of industrial contributions to domestic wastewater can both provide potential confounding chemical influences to wastewater treatment efficiencies as well as dilute the domestic sources of surfactants. Type II errors i. Hence the conclusions from the Sanderson, Atkinson, and Slye studies can be considered conservative.
Another key attribute in site selection is an assessment of the physical habitat for aquatic fauna. For Sanderson et al. EPA, was used. For the Trinity River studies by Atkinson et al. Adequate habitat quality for fish and macroinvertebrates is essential for assessing the potential effects of chemicals. That is, there is an expectation that less human-altered habitats will yield the greatest potential for a diverse and highly functional ecological community. Sites that have reference-like qualities have the greatest potential to provide statistically significant relationships between chemical stressors and biological impacts e.
The second component of designing a retrospective assessment is to have a well-designed and executed monitoring program that provides information not only on the chemical s of interest but also on other potential stressors and the biological community status of the receiving water body. The subsequent paragraphs represent a synthesis of several surfactant monitoring studies, including Sanderson et al. Typically composite samples of influent are used to average out fluctuations during the day. Due to the hydrologic retention period of most WWTPs, a grab sample of effluents is typically sufficient.
The number of upstream and downstream samples depends on the goals of the study and especially on whether the sites are on a single water course. At least one sample of water and sediment should be taken upstream of the first WWTP discharge to allow for characterization of background conditions.
Other sample locations are located downstream of effluent mixing zones to ensure complete mixing of the effluent and the receiving water. Sediment sampling should be biased towards areas of fine, recently deposited sediments, since these are most likely to contain surfactants and other chemicals of interest.
Sediment samples should be taken from the upper 5—10 cm depth and from several locations in the deposition zone and composited. The composited samples would be centrifuged to remove the porewater which should also be analyzed for water chemistry and the surfactant of interest. In addition to the surfactants, the monitoring studies should include other chemicals to allow for determining if other stressors may be present. Therefore, all samples that are collected i.
Understanding of conventional pollutants, such as BOD and ammonia, provides an indication of how well the WWTP are performing at the time of the study.
Poor performance of a WWTP could confound relationships to biological impacts. The parameters measured for the Trinity River studies are given in Table 31 Atkinson et al. Each parameter is scored according to a predefined algorithm, and the scores are summed for an overall index of quality for each transect. These habitat parameters are useful in determining Habitat Quality Index Score that indicates if there have been beneficial or detrimental effects to vertebrate and invertebrate fauna. For example, the Habitat Quality Index Score established by the Texas Commission of Environmental Quality are based on nine parameters: available instream cover, bottom substrate stability, number of riffles, dimensions of largest pool, channel flow status, bank stability, channel sinuosity, riparian buffer vegetation, and esthetics of reach.
Each parameter is rated according to predefined scoring categories potential scores range from 0 to 4 , and then the nine scores are summed for an overall index of quality for each sampling site. Theoretically, the HQIS can range from 4 to 31 with the higher scores indicating a higher quality habitat. Analytical analyses typically conducted on water and sediment samples with methods indicated. Biological monitoring for the invertebrate and vertebrate fauna should be included to determine the ecological status at the sites.
Status can be expressed in a myriad of ways, including species richness, evenness, ecological functional groups, and pollution tolerance. Macroinvertebrate community monitoring can be conducted via direct sampling such as D-frame dip net, or by artificial substrates. Artificial substrate samplers should be placed in depositional areas and to the extent possible arranged in similar substrate types along the course of the river, downstream from the WWTPs. The number of jabs for each habitat type would be proportional to habitat types present in each location.
Samples should be collected from similar habitats at each location at each stream. Each sample should be placed in plastic jars, preserved with ethanol, and stored for identification and enumeration in the laboratory. If no differences in biological status are found at sites downstream of WWTPs, as compared to reference sites, then it can be concluded that these surfactants as well as other chemicals that co-emanate from the selected wastewater discharge site do not adversely affect ecological status and, therefore, do not cause concern. The relative confidence of such conclusions and their application to non-monitored sites will be based upon the quality of the site selection.
However, once it is determined that the state of the water body is less than that expected by the reference condition and the degree to which it is impacted, the next step is to determine the cause or causes for this reduction in state before any attempt is to be made to develop or implement remediation or environmental management action.
A framework for relating measured biological impacts to the presence of potential chemical mixtures has been described by ECETOC and is shown in Figure 6. Suggested approach to assessment of ecologic risk of mixtures of chemicals in the aquatic environment. The summations of exposures of surfactants described in this review have the potential to exceed an additive PNEC. Consequently, it is important that prospective approaches, as described in Section VI, be verified via field studies.
Figure 6 illustrates the potential analysis options when conducting a retrospective field study on surfactants. On the contrary, because surfactants are discharged from thousands of WWTPs in North America, a retrospective study of surfactants should be considered on a multisite, even a river basin-based scale. As illustrated in Figure 6 , the primary analysis option is to consider potential effects to be dispersive in nature not localized.
If in the analysis surfactants are found to be associated with localized impacts, further verification could be pursued via traditional whole effluent toxicity or directed toxicity assessment approaches followed by appropriate risk management schemes. However, given that whole effluent studies typically indicate that surfactants are not a primary cause of toxicity, other analysis methods are needed to more fully assess the potential effects. These methods need to include potentially cooccurring stressors associated with effluent discharge, such as conventional pollutants, local in-stream habitat alterations, and hydrological and chemical perturbations caused by changes in land-use and land-cover e.
In essence, these field studies require methods that will allow the relative effect of the surfactants relative to other stressors to be evaluated. Relative causality can be established via statistical as well as WoE approaches. If the exposure to surfactants provides a relatively low weight compared to that of other stressors with regard to measured in-stream biological impacts, or lack of impact, then it can be reasonably concluded there is no need for surfactant mitigation efforts. However, if there is an impact, management of other chemicals or nonchemical stressors may be required.
The team developed a WoE assessment methodology as described previously. Biota and habitat information was collected to ground-truth the predicted risk levels within field assessments and to correlate the collected variables. Each variable constituted a line-of-evidence LoE which was summarized in a WoE analysis. This information was used to test different hypotheses—e. Evaluation of surfactant risks in surface water and sediments required the assessment of surfactant exposure, presence of other environmental stressors and statistically relate these to biological community condition—hence, a complex analysis Dyer and Wang, A framework for considering all data associated with the potentially perturbed locations warranted a WoE approach.
Chapman and Anderson provided a comprehensive and pragmatic framework for assessment of sediment contamination on a WoE basis. Since the Sanderson et al. That is, upstream of the WWTP served as the reference condition in this approach. Ecological status was determined by examining species richness and percent EPT i. The toxicity statement was substituted with a risk expression based on the measured environmental concentrations divided by the PNEC, plus the biomagnification potential of the compound as suggested by Chapman and Anderson Chapman and Anderson's three ordinal ranking levels were adapted to achieve a semiquantitative analysis 0, 1, and 2 , which could then be summed across various LoE.
Atkinson et al. The Trinity River system has been extensively studied. For the past 20 years, benthic macro-invertebrate community structure studies have been conducted on the upper Texas Trinity River, USA, which is dominated by municipal WWTP and industrial effluents. As such, the Trinity River represents a near-worst-case scenario and presents an opportunity to examine the environmental effects of domestic-municipal and industrial effluents on aquatic life. The Trinity River studies indicate that many stretches of the river support a diverse benthic community structure Slye et al.
This conclusion was verified via regression modeling, where benthic macroinvertebrate metrics were not correlated with surfactant levels. However, surface water surfactant levels may act as surrogates to other potential stressors emanating from WWTPs, as multiple linear regression modeling indicates that surfactant toxic units were often found within the top three factors associated with various aspects of ecological status.
Another retrospective study De Zwart et al. This study combined several existing databases using GIS software. The baseline river mapping data for Ohio came from the U. EPA, Local, site-specific, fish habitat data by location was also provided by the Ohio EPA. Habitat data included sampling location latitude, longitude , drainage area above each sample site, and the individual metrics used to derive Ohio EPA's qualitative habitat evaluation index QHEI; Rankin, Ambient water-chemistry data for Ohio streams from U.
Parameters were total metal concentrations Cd, Cu, Pb, Ni, Zn , dissolved oxygen, hardness, total ammonia, pH, and total suspended solids for the years —, the same time period over which data on fish assemblages were compiled. The median and 90th-percentile concentrations for each water-chemistry parameter were determined per site from these data.
Using mean flow data for all receiving waters from U. EPA, and flow data obtained from municipal WWTPs, the cumulative percentage WWTP effluent as a surrogate measure of persistent wastewater constituents within stream reaches was estimated. Using SSDs for the metals, ammonia and the chemicals in household products, the potentially affected fraction PAF of species at a given concentration was estimated for each particular site, these values were then added to derive msPAF multi substance values for the sites.
The identification of sites with impairment involved comparing the biological condition from the fish survey data with predictions from RIVPACS-type models Moss et al. Statistically significant associations between impacts on species abundances and stressor variables, represented by the PAF values, were used to identify likely causes of biological impairment.
Of the sites assessed, De Zwart et al. The relatively minor contributions of down-the-drain chemicals determined in the Trinity River and Ohio studies are further verified by Dyer and Wang , where they used simple t -tests to determine upstream to downstream differences in macroinvertebrate and fish communities. No significant differences in macroinvertebrate and fish community status were observed in rural environments.
Therefore, considering all the retrospective studies mentioned above, there is little evidence to suggest that surfactants as a whole e. The environmental risk assessment of surfactants described in this paper would not have progressed as far as it has without the development of key technologies. In the absence of measured data, advances in our predictive capabilities for exposure and effects have significantly reduced the uncertainty associated with evaluating chemical risk in the aquatic environment.
Development of the environmental exposure is premised upon the ability to measure surfactant and surfactant components in environmental media. The detection limits for total surfactants using these methods were approximately 0. As the need for lower detection limits arose, new methods emerged that increased sensitivity. These methods still lacked specificity, for example, the hydrogen bromide derivitization method for measuring alcohol-based surfactants by Fendinger et al.
For example, low ppt concentrations of AE could now be detected in the environment, and individual homologues could be identified and quantified. The number of homologues for AE is quite large. For this example, the number of homologues could be greater than Significant improvements were also achieved in our ability to measure fate parameters in wastewater, activated sludge, and aquatic environments. Advanced methods for biodegradation testing including the shake flask test and semiCAS procedure SDA, became approved international methods i.
The most important advances were facilitated by advances in radiolabel 14 C synthesis and analysis of parent compounds. For example, the use of LC-and TLC-RAD techniques to measure parent compounds at extremely low concentrations allowed for more accurate determinations of biodegradation rate constants Steber and Wierich, ; Steber et al. In addition to improved laboratory testing methodologies, better predictive mathematical models were developed for assessing the fate and transport of surfactants in activated sludge treatment and receiving waters.
For example, the ASTreat model Lee et al. Accurate fate data are needed for predicting exposure concentrations in aquatic environments, thus improvements in the fate laboratory testing methods has also improved our predictive capabilities. The improvements in analytical chemistry for quantification of surfactant concentration and homologues have also facilitated the development of higher-order toxicity testing.
Laboratory toxicity testing methods were improved because acute tests in 24—96 hr exposures were found inadequate for estimating environmental toxicity of surfactants at low ppb concentrations. Chronic laboratory methods were modified to enable testing of readily biodegradable surfactants with half-lives DT 50 from a few days to less than 1 day. Morrall et al. Dosing techniques were developed for highly insoluble materials and those that were readily biodegradable.
The analytical development mirrored the toxicity testing development to provide chronic exposures for many species using measured concentrations. However, closer to field exposures were desired to further quantify environmental effects of surfactants. Flowing water experiments in artificially derived indoor and outdoor streams mesocosms were developed so as to expose in situ biological communities natural to an area to a quantified dose and concentration of surfactant.
The mesocosms allowed algae, macrophysics, stream invertebrates, fish and amphibians of different life stages to be exposed under controlled surfactant exposures allowing for replication and exposure series of carefully dosed chemicals that were fingerprinted to describe exposures Belanger, ; Belanger et al. Other structure—activity-related developments included advancements relative to biodegradation Federle and Itrich, and sorption van Compernolle et al. This approach, initially explored in van de Plaasche et al.
Environmental Safety of the Use of Major Surfactant Classes in North America
Homologue-specific monitoring and experience has refined how this approach can be used for environmental risk assessment, which is exemplified by AE Belanger et al. The QSAR developments allowed the use of homologue fingerprint to predict the toxicity in an environment from environmental samples taken from either a discharge effluent or in a water body. This ability to use a fingerprint to predict toxicity from QSAR s of species or species distributions modified for sorption to particles enabled refinement of the AF that had been used in past assessments.
The use of AF was believed to account for toxicological uncertainty between acute and chronic, chronic and mesocosm as well as interspecies differences. Using fingerprint specific, HC 5 distributions and site factors e. In addition, these studies supported the refinement of the AF based on the level of data available i. The chemicals described in this paper are all HPV chemicals with tonnages well above 1, tons per year, and are included in the voluntary HPV programs of the U.
Policy makers recognize that the assessment and regulation of chemicals globally is best accomplished by assessing categories of chemicals, rather than individual chemicals, whenever possible. The surfactant industry has conducted and submitted some of the largest HPV category assessments, both in terms of CAS s and tonnage in the world. These assessments serve as examples of how category assessments can be successfully conducted under emerging chemical regulations, e.
Moreover, in developing this category assessment, the LCOHs challenged the science and current toxicity and biodegradation test methods in a number of ways, e. These challenges and their solutions were described in a special issue of Ecotoxicology and Environmental Safety ; vol. Once these challenges were met, the next challenge from a risk perspective was the environmental forensic sorting of the surfactant contribution of LCOH from LCOH coming from natural sources as well as understanding the contribution of in-stream loss of LCOH versus LCOH formed from degradation and in situ de novo synthesis.
How these challenges were addressed and overcome is described in Mudge et al. Ground-truthing of environmental risk assessment results in the environment is a difficult endeavor, especially for chemicals with wide-dispersive use such as the detergent surfactants discussed in this paper. For this reason, the science of eco-epidemiology was pioneered. The goal of eco-epidemiology is to develop a WoE ecological approach that can be used to determine the relative contributions of down-the-drain chemicals and all other stressors to environmental impacts observed in receiving environments.
The relative contributions can be used to identify the degree to which down-the-drain consumer product ingredients contribute to the ecological status and quality downstream of wastewater treatment facilities in the context of all other potential stressors and whether any risk management actions are required. The Association of American Soap and Glycerine Producers first started to study and make publicly available the environmental fate and hazards of synthetic surfactants in the s to understand the potential for environmental effects associated with their usage.
Successor organizations, including The SDA and the ACI, have continued the commitment to ensure that high-quality data and risk assessments are available in order to illustrate the environmental safety of surfactants, and continuously improve the sustainability of the industry and the transparency of data.
Moreover, this compilation includes a review of the most relevant surfactant monitoring studies through sewers, WWTPs and eventual release to the environment. Further, this paper includes a comprehensive summary of aquatic and sediment toxicity information, drawing from fish, algae and microorganism acute and chronic toxicity studies and numerous stream mesocosm assessments for the surfactant categories.
These data are then used in the paper to illustrate the process for conducting both prospective and retrospective risk assessments for large-volume chemicals and categories of chemicals with wide dispersive use. The prospective assessment approach builds on a thorough understanding of the processes that lead to release of these types of chemicals into the aqueous environment, and the fate of the chemical along this fate train. The surfactant and cleaning products industry has devoted many years and countless resources in understanding, for example, how wastewater treatment processes effect the fate and eventual release to surface waters of a chemical in WWTP effluents.