Environmental Fate, Aquatic Toxicology and Risk Assessment of Polymeric Quaternary Ammonium ...

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Environmental Fate, Aquatic Toxicology and Risk Assessment
of Polymeric Quaternary Ammonium Salts from Cosmetic
Uses
Author
Cumming, Janet L
Published
2008
Thesis Type
Thesis (PhD Doctorate)
School
School of Environment
DOI
https://doi.org/10.25904/1912/2683
Copyright Statement
The author owns the copyright in this thesis, unless stated otherwise.
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Environmental Fate, Aquatic Toxicology and Risk Assessment of
Polymeric Quaternary Ammonium Salts from Cosmetic Uses.

Janet L. Cumming
B.Sc. (Hons)

Submitted in fulfilment of the requirements of the degree of Doctor of Philosophy

Griffith School of Environment
Science, Environment, Engineering and Technology Group
Griffith University

February 2008
Removal Notice

Figure 2.5 (p. 34) has been removed from the digital version of this thesis for
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Figure 3.3 (p. 61) has been removed from the digital version of this thesis for
copyright reasons.

Figures 3.4 & 3.5 (p. 62) have been removed from the digital version of this thesis for
copyright reasons.
Synopsis
The consumption of household and personal care products in Australia is similar to
that of more highly regulated agricultural and veterinary chemicals. One class of
chemical used in cosmetic applications, polymeric quaternary ammonium salts
(polyquaterniums), is thought to have adverse effects on aquatic organisms. These
polymers belong to a larger class of polymers, cationic polyelectrolytes, that are
widely used in industry, largely for water treatment, and that have been extensively
studied and regulated. The cosmetic polyquaterniums, however, have not been subject
to the same scrutiny, even though differences in, or expectations of, their behaviour
are known to exist.
The aim of this study was to examine the fate and toxicity of some cosmetic
polyquaterniums, and particularly to examine the impact of the presence of the
anionic surfactant, sodium dodecyl sulphate, that is often complexed with the
polyquaterniums in cosmetic formulations on fate and toxicity. The polyquaterniums
studied consisted of six samples of Polyquaternium-10 of provided by Amerchol (The
Dow Chemical Company, Midland, MI U.S.A.), five samples of three
polyquaterniums (Polyquaternium-11, Polyquaternium-28, Polyquaternium-55)
provided by International Specialty Products (ISP, Wayne, New Jersey, USA), and
polydimethyldiallyl ammonium chloride (poly(DADMAC), Polyquaternium-6),
widely used in water treatment but less commonly in cosmetic applications purchased
from Sigma-Aldrich (Castle Hill, NSW, Australia). The four-step risk assessment
paradigm (hazard identification, exposure assessment, hazard assessment, risk
characterisation) provided the framework for this study.
Metachromatic polyelectrolyte titration was used to analyse polyquaterniums in
aqueous solution. Although the method is generally not viable in the presence of other
ions due to interference, it was found to be viable in the presence of the anionic
surfactant sodium dodecyl sulphate. Further, the method was found to work with the
supernatant following a sorption experiment involving humic acid. It was not possible
to titrate solutions following exposure to bentonite, or in solutions prepared for
toxicity tests. Metachromatic Colloid Titration was found to be useful in determining
the charge density of the polyquaterniums, and in measuring the concentration of
polyquaterniums of known charge density.
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To establish the extent of exposure of vulnerable aquatic organisms to
polyquaterniums released from cosmetic usage, it is necessary to estimate the
concentration of polyquaterniums in the aquatic environment. The volume usage of
polyquaterniums was estimated from available published data and standard emission
scenarios used in the risk assessment of new and existing chemicals. The partitioning
of the polyquaternium from the aqueous to the biosolid phase from wastewater
treatment plants was estimated from the determination of the partition coefficient
between water and humic acid. The latter was assumed to be a suitable surrogate for
the biosolids. The fate of polyquaterniums in wastewater treatment plants was
modelled using a fugacity approach based on a typical wastewater treatment plant.
The import/manufacture volume of polyquaterniums for cosmetic uses was estimated
to be between 20 and 60 tonnes per annum. The partition coefficient for
polyquaterniums between the aqueous phase and humic acid was lower than expected,
generally between 100 and 1000 for the polyquaterniums in this study. Fugacity
modelling results suggested that the partitioning of polyquaterniums to the solid phase
in wastewater treatment may be less than the default values normally assumed in
regulatory risk assessment. Therefore, the estimate of the predicted environmental
concentration (PEC) of polyquaterniums in Australian waters is between 0.7 µg/L and
40 µg/L depending on the assumptions and methodology used.
Effects assessment, or hazard assessment, is concerned with determining the capacity
of the cosmetic polyquaterniums to cause harm to aquatic organisms in the
environment. In this study, the aim was to determine if the hazard of the
polyquaternium from cosmetic usage is the same as that of the better studied water
treatment polymers; and if the complexing of the polyquaternium with the anionic
surfactant makes any difference to the toxicity. One species from each of three trophic
levels, viz fish, crustacean and algae were selected. Using assessment factors
developed for the risk assessment of new chemicals, the environmental concentration
likely to be hazardous to the most sensitive species was estimated. The
polyquaterniums studied were found to be just as hazardous to the most sensitive
species for a typical cosmetic polyquaternium when complexed with the anionic
surfactant. The lowest concentration at which a toxic effect occurred was for 50%
growth inhibition for algae, 0.3 mg/L for the most toxic polyquaternium. With
assessment factors, and using the concentration at which cosmetic polyquaterniums
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were likely to be hazardous to aquatic organisms, the predicted no effect
concentration (PNEC) was estimated to be between 0.3 µg/L and 1.2 µg/L.
The risk characterisation process combines the information obtained from the effects
and exposure assessments to evaluate the nature of the potential risk. Commonly, the
level of risk is estimated based on the PEC/PNEC ratio. In this study, using point
estimates and probabilistic methods (Monte Carlo Simulation), the risk of
polyquaterniums from cosmetic uses was estimated. Based on the behaviour and
toxicity determined in this study, there may be some risk to aquatic organisms from
individual polyquaterniums at even low import volumes. As a class of compounds,
polyquaterniums from cosmetic uses may present a significant risk to environmental
waters in Australia. Sensitivity analysis showed that the prediction of risk was most
sensitive to those parameters for which the least amount of data was available, such as
the import volume and dilution to receiving waters.
A recently developed method of estimating potential risk based on the concept of an
Environmental Threshold of No Concern (ETNC), was applied to the use of cosmetic
polyquaterniums in Australia. Using the fugacity model approach, the usage volume
at which the environmental concentration would exceed the critical threshold was
estimated. The volume was found to be significantly lower than the estimated usage
determined by either of the methods employed in estimating the current usage
volume.
While some problems remain in identifying the risk from polyquaterniums to the
Australian environment, particularly those associated with the difficulties of
quantifying polymers in environmental samples, this thesis has made substantial
progress in the risk assessment. Particularly, it has been shown that the use of default
assumptions that are largely unsubstantiated, and the sensitivity of the methodology to
information that is often unavailable, may result in an estimation of risk that may not
be able to protect vulnerable environments.
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Acknowledgements

This work was supported by the Society of Environmental Toxicology and Chemistry
(SETAC)/Procter & Gamble Company Global Fellowship for Doctoral Research in
Environmental Science, sponsored by the Procter & Gamble Company.

I would like to thank my supervisors, Dr Darryl Hawker, Dr Heather Chapman and Dr
Kerry Nugent for their guidance, support and encouragement through all aspects of
my candidature.

Thank you to the technical and support staff at the Griffith School of Environment,
particularly Scott Byrnes and Jane Gifkin for their assistance and support in the
laboratory.

Thank you to my research assistant, Melanie Crook, for many dedicated hours in the
field and the laboratory; Alan and Joyce Hodder for access to their property for
collecting Gambusia; and the undergrad students who helped sort the blighters.

I would like to acknowledge the CRC for Water Quality and Treatment and the Centre
for Environmental Systems Research for financial support and encouragement. Also
important were Jenny Stauber and her team at CSIRO for their endeavours in teaching
me algal toxicity testing.

I am especially grateful to SETAC and Procter & Gamble, whose support made a
significant contribution to this research, which might have been barely possible
otherwise.

Thank you to Fiona de Mestre for the final editing.

I would like to thank my fellow candidates at Griffith School of Environment; the
friendship and encouragement of peers is invaluable.

Finally, a special thank you to my family – my sister Alison, my daughters Jeanne and
Heather, their father Fred, and my niece Darcy; with their love and support, anything
is possible.
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Dedicated to
Alyssa Lenore Hannaford
(8/7/1989 to 16/9/2003)
and
Michael Thomas Wakeham
(8/10/1989 to 9/4/2007)

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Declaration of Originality

The experimentation, analysis, presentation and interpretation of results presented in
this thesis represent my original work and have not previously been submitted for a
degree or diploma in any university. To the best of my knowledge and belief, the
thesis contains no material previously published or written by another person except
where due reference is made in the thesis itself.

Janet L. Cumming

Publications arising from this work
Cumming, J.L. 2007 ‘Polyelectrolytes’. in Chemicals of Concern in Wastewater
Treatment Plant Effluent. CRC for Water Quality and Treatment Occasional Paper
No 8. Cooperative Research Centre for Water Quality and Treatment, Adelaide.
Cumming, J.L, Hawker D.W., Nugent K.W. and Chapman, H.F. 2008 Ecotoxicities of
,
Polyquaterniums and their associated polyelectrolyte surfactant aggregates (PSA) to
Gambusia holbrooki. Journal of Environmental Science and Health, Part A
Toxic/Hazardous Substances and Environmental Engineering, Volume 43 Issue 2, 113
Cumming, J.L, Hawker D.W., Nugent K.W. and Chapman, H.F. 2006 Toxicity of
,
cosmetic polyquaterniums to Gambusia holbrooki. Oral Presentation, SETAC Asia
Pacific, Beijing.
Janet Cumming, 2006 Environmental Fate and Aquatic Toxicology of Polymeric
Quaternary Ammonium Salts. Oral Presentation, CRCWQT Postgraduate Students
Conference, Melbourne, July 2006.
Janet Cumming, Darryl Hawker, Heather Chapman. 2005 Mitigation of Toxicity of
Quaternary Polyelectrolytes – Fact or Fiction? Oral Presentation, Australian Society
for Ecotoxicology Conference, Melbourne.
Cumming, J.L. Hawker D.W and Chapman, H.F 2005 Polyquaternium Ammonium
Salts: Using data obtained in the study of water treatment polyelectrolytes in the risk
assessment of cosmetic polymers. Presentation and Paper (peer reviewed) Australian
Water Association Contaminants of Concern Conference, Canberra.

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Table of Contents
Synopsis.....................................................................................................................ii
Acknowledgements....................................................................................................v
Declaration of Originality........................................................................................vii
Publications arising from this work.........................................................................vii
Table of Contents......................................................................................................xi
List of Tables..........................................................................................................xiv
List of Figures......................................................................................................xviii
Abbreviations..........................................................................................................xix
Definitions..............................................................................................................xxii
1. Introduction............................................................................................................1
1.1. Non-cosmetic Uses of Polyquaterniums........................................................3
1.2. Regulation of Chemicals in Australia............................................................7
1.3. The Risk Assessment Framework................................................................11
1.3.1. Hazard Identification...........................................................................12
1.3.2. Effects Assessment..............................................................................13
1.3.3. Exposure Assessment...........................................................................13
1.3.4. Risk Characterisation...........................................................................13
1.3.5. Assessment Reports.............................................................................14
1.3.6. Data Requirements...............................................................................14
1.3.7. Globally Harmonised Labelling...........................................................15
1.3.8. GHS and the Aquatic Environment.....................................................16
1.4. Conclusion...................................................................................................17
1.4.1. Aims.....................................................................................................18
1.4.2. Structure...............................................................................................18
2. Literature Review.................................................................................................19
2.1. Structure of Polyquaterniums......................................................................19
2.1.1. Quaternary Ammonium Salts..............................................................19
2.1.2. Polymers..............................................................................................19
2.1.3. Polyelectrolytes....................................................................................20
2.1.4. Common Features of Polyquaterniums................................................20
2.1.5. Variation Between Polyquaterniums...................................................21
2.1.6. Variation Within Polyelectrolytes........................................................23
2.2. Nomenclature...............................................................................................24
2.3. Relevant Polyquaternium Physical-Chemical Properties............................24
2.3.1. Molecular Weight Distribution............................................................25
2.3.2. Charge Density.....................................................................................27
2.3.3. Aqueous Solubility...............................................................................29
2.3.4. Biodegradation.....................................................................................31
2.3.5. Chemical/physical Degradation...........................................................32
2.4. Exposure Assessment (Environmental Fate)...............................................33
2.4.1. Sorption-desorption..............................................................................33
2.4.2. Sorption of Polymers...........................................................................33
2.4.3. Sorption of Polyelectrolytes.................................................................35
2.5. Effects Assessment (Aquatic Toxicology)...................................................40
2.5.1. Toxicity of Surfactants.........................................................................40
2.5.2. Toxicity of Polymers............................................................................41
2.5.3. Toxicity of Polyelectrolytes – General Considerations.......................41
2.5.4. Meta-analysis.......................................................................................46
2.5.5. Mechanism...........................................................................................51
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