Letters to the Editor
Environmental safety aspects of personal care products—A European perspective†
Published on the Web 8/14/2009.
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Personal care products are applied to the external body surface for cleaning, protecting, and keeping it in good condition. After their use, a significant amount of these products goes down the drain and enters the “wastewater-sewage plant—receiving water” route. As a result, they may ultimately end up in the aquatic environment. This is not only true for typical rinse-off products such as shampoos, shower gels, and toothpastes but also for leave-on products such as hair-care products and make-up. A large percentage of these products can be removed from the body by subsequent body cleaning processes such as bathing; thus, cosmetic ingredients may ultimately be measurable in surface waters. Whether or not their presence gives rise to concern regarding actual effects in ecosystems is subject to risk assessments, which compare actual or predicted environmental concentrations to effect thresholds.
This letter gives an industry perspective of the environmental risks of personal care product ingredients and focuses on the situation in the European Union (EU), outlining the relevant cosmetic product groups, their composition, and aspects of the present regulations regarding the safety of personal care products, also referred to as cosmetic products or cosmetics in the EU. The discussion of the ecological properties and possible environmental risks of the main cosmetic product ingredient groups is illustrated with a collection of examples of typical personal care product formulas and an overview of biodegradability and ecotoxicity data (Supporting Information, Table S1; http://dx.doi.org/10.1897/09-104.S1).
Considerable amounts of personal care products are utilized each day, resulting in large quantities of chemical substances that could potentially reach environmental compartments, particularly water, but also soil and air. The environmental relevance is evident with an annual production of 790,000 tons of personal care products in Germany . The totals for the different product groups are detailed in Table S1 (Supporting Information, Table S1). In this context we must particularly consider the high-volume rinse-off products with high content in water; however, the production volume of individual chemical constituents of the various personal care products ranges from <1 to >1,000 tons per annum.
Generally, personal care products include a number of ingredients with individual, substance-specific properties that will influence the product performance. Considering the tonnages, ingredient composition, and consequently, the potential environmental impact, some cosmetic products exhibit similarities to detergents, another large household product group. Personal care products and detergents are sometimes classified as pharmaceuticals and personal care products, a group that also includes disinfecting agents, antiseptic products, and pharmaceuticals. After use, all of the products may have a similar environmental entry route; however, the chemical composition of the pharmaceutical products shows significant differences from cosmetic and household products. Consequently, it can be expected that the environmental behavior and impact of pharmaceuticals is generally not comparable with those of personal care products.
In all regions of the world personal care products are regulated nationally, particularly in terms of their impact on human health. In Europe, such products are defined in Article 1 of the EC Cosmetics Directive 76/768/EC  as follows:
A “cosmetic product” shall mean any substance or preparation intended to be placed in contact with the various external parts of the human body (epidermis, hair system, nails, lips and external genital organs) or with the teeth and the mucous membranes of the oral cavity with a view exclusively or mainly to cleaning them, perfuming them, changing their appearance and/or correcting body odors and/or protecting them or keeping them in good condition.
Annex I of the EC Cosmetics Directive contains an illustrative list of products considered to be cosmetics: body care products, soaps, perfumes, sun tanning and sunscreen products, nail care products, lip care products, bath and shower products, depilatories, shaving products, deodorants and antiperspirants, makeup removers, anti-wrinkle products, external intimate hygiene products, and hair-care products.
The EC Cosmetics Directive demands that cosmetic products be safe for human health under normal and reasonably foreseeable use conditions. Strict labeling requirements include the name of the manufacturer or importer, information about shelf life, conditions of use or warnings, certain provisions concerning marketing claims, etc. A description of the function of the cosmetic product and the ingredients is also required.
Certain cosmetic ingredients are regulated under the annexes of the EC Cosmetics Directive. The annexes include substances banned for use in cosmetic products, ingredients subject to restrictions, and permitted colorants, preservatives, and UV filters. Each list is based on a safety evaluation performed by the EU Scientific Committee on Consumer Products. Only a fraction of the cosmetic ingredients is explicitly listed in the national cosmetic regulations of the EU member states. Many ingredients are covered by the general safety requirements for personal care products, which means each cosmetic product has to undergo a safety assessment that must be documented and made accessible to official control bodies.
Until recently, regulations specifically addressing environmental aspects of personal care products were limited. Today, the new European regulation on chemicals, REACH (; http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1976L0768:20070919:EN:pdf), have a strong impact on the environmental safety assessment of cosmetic ingredients and thus will considerably increase the attention to the environmental aspects of personal care products.
COMPOSITION OF PERSONAL CARE PRODUCTS
Most cosmetic product categories display a typical composition, examples of which are published in monographs, such as that by Umbach . A closer look into typical formulations of the high-volume products reveals surfactants as an ingredient group present in all rinse-off products at relatively high concentrations (Supporting Information, Table S2; http://dx.doi.org/10.1897/09-104.S1). The overview of the quantitatively relevant cosmetic rinse-off product groups such as shower gels, shampoos, and face wash lotions as well as of leave-on products such as hair conditioners and skin creams reveals that lipophilic and emulsifying substances are another important group of ingredients. Those include fatty alcohols, glycerol esters, paraffins, and waxes. Polymeric ingredients such as silicon oils and components containing polymer structures such as fatty acid-protein condensates, fatty acid esters with polyols, and quaternary cellulose derivatives also play an important role in some product types. Depending on the product group, specific agents as well as perfumes may also be present.
ENVIRONMENTAL SAFETY ASSESSMENT OF FORMULATED PRODUCTS
The environmental safety of household products is assessed based on the ecological properties of their many components. Two basic issues determine their environmental safety: the environmental fate and potential effects on the environment. The environmental fate of chemical substances depends mainly on the physicochemical properties, such as water solubility, adsorption behavior, and volatility, and on their degradability, which is overwhelmingly affected by microorganisms (biological degradation) present in sewage treatment plants, surface waters, and soils. These fate-relevant properties control the distribution of a chemical in the environmental compartments (water, soil, air) and its final removal by degradation processes. This and information about the quantities emitted to the environment are used in exposure assessments to arrive at so-called predicted environmental concentrations (PECs).
The second assessment aspect, the potential impact of a chemical on the organisms living in the environmental compartments, also depends on substance-specific properties, i.e. the ecotoxicity. Data from standardized tests on representative organisms are required by European chemicals legislation . Again, depending on the type and quantity of the available effects data that trigger application of more or less conservative assessment factors, a tiered environmental effects assessment can be made delivering the predicted no-effect concentration (PNEC), that is, the maximum concentration at which toxicological effects are not to be expected in the real environment.
Comparison of the PEC and the PNEC constitutes the core of the environmental risk assessment as it is applied in the EU. Only if the PEC can be shown not to exceed the PNEC, can one expect that a substance or the products based on it are ecologically safe . The safety assessment of any chemical is a tiered process: The requirements on the type and extent of fate and effects data depend at first on the production volume of a chemical and subsequently on the result obtained in the effective stage of risk assessment process. Hence, the availability of data from relatively simple low-cost tests may be sufficient in some cases to conclude low environmental concern (PEC < PNEC) while such an evaluation may need expensive chronic toxicity tests, simulation tests, or even environmental monitoring studies in other cases.
ENVIRONMENTAL PROPERTIES AND RISKS OF COSMETIC PRODUCT INGREDIENTS
Surfactants generally are the key components in cleaning products, such as detergents as well as in cosmetic rinse-off products. Their function is to detach soils from solid surfaces like textiles and from human hair and skin, respectively. It is important to note that most of the surfactant types used in cosmetic products do not differ significantly from the ones used in detergents except they are milder to the skin. A comprehensive compilation of relevant environmental data and the safety assessments based upon it has been conducted and published in the context of the Human and Environmental Risk Assessment (HERA) project (www.heraproject.com) by the manufacturers of household cleaning products and the ingredient suppliers. In addition, several monographs and publications [5,6] have discussed the environmental aspects of surfactants used in detergents.
Most surfactants used in personal care products are readily biodegradable, exhibiting a rapid biodegradation under stringent test conditions according to test protocols used internationally. It is generally accepted that substances shown to be readily biodegradable will undergo a rapid and ultimately complete biodegradation in the environment. In-depth laboratory simulation studies and monitoring studies in the real environment have shown that many of the cosmetically relevant surfactants (alcohol ethoxylates, alcohol sulfates, and alcohol ether sulfates) are eliminated in municipal sewage treatment plants by more than 98%. This elimination is mostly due to ultimate biodegradation, the conversion of chemical structure into mineralization products (carbon dioxide, water, inorganic salts) leading to a complete re-integration of the compound's constituents into the natural cycle of materials.
Surface-active substances can also interact with biological surfaces, such as cell membranes, and are therefore relatively toxic to aquatic organisms. Acute effects impacting the survival rate of these organisms are generally found in a concentration range of 1 to 10 mg/L (lethal/effect concentration EC/LC50). Sublethal long-term effects such as influences on growth and reproduction have been found at concentrations that are generally a factor 10 lower than those leading to acute effects (www.heraproject.com; ).
Considering their ecotoxicity and the large amounts used in consumer products, surfactants are certainly the ingredient category most relevant for the potential environmental impact of formulated products. Environmental risk assessment of the quantitatively most important surfactant groups (linear alkylbenzene sulfonates, ether sulfates, alcohol ethoxylates, and soaps) have confirmed  that the resulting PEC is below the PNEC. Consequently, the use of these surfactants is not associated with a risk to aquatic organisms. From these findings a general conclusion can be drawn: If the surfactants used in cosmetic products have a comparable ecological profile, that is, they are readily biodegradable and do not differ significantly in terms of their aquatic toxicity from the ones investigated in detail, no environmental risk is to be expected.
Lipophilic care components and emulsifiers
Substances belonging to these ingredient types are also used in large amounts in personal care products. They are preferably based on fatty alcohols or acids often bound to another residue by an ester or ether bond. The poor water solubility of many of these ingredients may often lead to considerable difficulties in experimental testing for biodegradability and ecotoxicity testing . However, it is well established that the chemical structure of many of these compounds resemble naturally occurring molecules, particularly with regard to the ester/ether bonds ubiquitously present in molecules of natural origin, and are easily accessible to biodegradation. Thus it is not surprising that fatty alcohols and their esters, glycerol esters, etc., are readily biodegradable and will reach the aquatic environment in very minute amounts. Paraffins are also biodegradable, but their high removal in wastewater plants may largely be due to adsorption onto sludge. In terms of ecotoxicological effects, care components and emulsifiers do not exhibit an acute toxicity below their water-solubility limit. Although chronic toxicity data are scarce due to the mentioned difficulties, a recently developed concept for the environmental risk assessment of poorly water-soluble compounds used in consumer products  supports the notion that cosmetic emulsifiers do not pose a significant risk to aquatic organisms.
Fruit acids and solvent alcohols
Cosmetic ingredients of this type are employed as chelating or buffering agents (citric acid, malic acid, and others) and as solvents such as ethanol, the most common solvent, and higher alcohols. They are readily biodegradable and have a moderate acute aquatic toxicity (EC/LC50 10–100 mg/L). Based on this ecological profile it is easy to conclude that materials of this type are not harmful for the environment.
Polymeric ingredients such as silicon oils or derivatives from polymeric structures such as protein condensates and cellulose- and poly(ethylene glycol)-based compounds are used as care components in many cosmetic products. While protein condensates and poly(ethylene glycol) derivatives undergo rapid or moderately rapid biodegradation, the water-insoluble silicon oils and the soluble polymeric quaternary ammonium compounds are poorly biodegradable. However, the latter polymers are eliminated to a large extent in wastewater treatment plants by adsorption onto sewage sludge. Most of the polymers exhibit a very low aquatic toxicity (EC/LC50 > 100 mg/L) so that a favorable result can be obtained in preliminary aquatic risk assessments. In contrast, the soluble polymers with cationic functional groups exhibit a pronounced acute aquatic toxicity (EC/LC50 >0.1 mg/L) which is presumably due to physical effects . In view of their high elimination potential the resulting low concentrations of cationic polymers in receiving waters do not represent a significant threat to aquatic organisms.
Cyclic volatile methylsiloxanes, such as D4 and D5, are commonly used in personal care products and have a strong tendency to partition from water to air. Though poorly biodegradable, these substances are not persistent as they are photo-mineralized in the atmosphere and undergo claycatalyzed hydrolysis in soils . Because of the ongoing discussion in Europe and Canada regarding the potential persistent and bioaccumulative and toxic classification of cyclic volatile methylsiloxanes, pertinent monitoring and research programs are being run by the silicon industry and the results are underway.
Many personal care products need preservatives to improve their stability and to prevent bacterial or fungal growth. Preservative concentrations in formulated products are generally low (<0.5%); thus, their concentrations in wastewater are below the threshold of biocidal action. Aldehydes, alcohols, and acids (benzoic acid, salicylic acid) as well as parabens used as preservatives are readily biodegradable and exhibit a moderate toxicity to aquatic organisms with LC/EC50 values in the range of 10 to 100 mg/L. Quaternary ammonium compounds (e.g., alkyldimethylbenzyl ammonium chloride) are readily biodegradable or largely eliminated by adsorption onto sludge. Although they have a high aquatic toxicity (LC/EC50 >0.1 mg/L), the amounts used in cosmetic products are low, and the removal in sewage treatment plants is high. As a result, the assessment of these substances does not indicate an environmental risk. Some personal care products such as triclosan may contain preservatives that are not readily biodegradable and are very toxic to aquatic organisms. A recent risk assessment  did not indicate an environmental risk. Nevertheless, aspects such as environmental metabolites, bioaccumulation, and biochemical responses including endocrine-related effects deserve further attention.
These functional components of hair coloring products represent a large group of chemicals with similar physicochemical properties but varying chemical structures. Consequently, the ecological profiles of these ingredients may differ considerably. Readily as well as poorly biodegradable dye components can be present in such products. Their aquatic toxicity (EC/LC50) ranges between 0.1 and 10 mg/L. Although a systematic environmental safety assessment of this group is not yet available, the requirements by the new European chemicals regulation, REACH, will provide a solid basis for the ecological evaluation of all important hair dye representatives in the near future.
The concentrations of the compounds required for coloring household products are low (<0.1%). They represent a large variety of chemical structures; hence, they are likely to exhibit different ecological properties. Based on the available ecological information they are generally poorly biodegradable and show low acute aquatic toxicity. Although it seems unlikely that their use could pose an environmental problem, a sound safety assessment cannot be made for most of these materials due to insufficient ecological data.
This group of chemicals is structurally heterogenous; they are primarily used in sun protection products and to a lesser extent in skincare products and other niche applications. Basic ecological data on biodegradability and acute aquatic toxicity are available for relevant representatives of this ingredient class. Generally, these substances are not readily biodegradable but are eliminated from the aquatic phase to a large extent due to adsorption and photodegradation. The ecotoxicity of most of these compounds is significant with acute EC/LC50 values at approximately 1 mg/L. Proving their environmental safety on the basis of a conservative preliminary risk assessment is difficult. However, considering environmental concentration data obtained in recent monitoring studies  leads to a favorable environmental risk assessment of the respective substances. Nevertheless, additional ecotoxicity information is required for a more conclusive safety assessment. Discussions about the potential endocrine activity of some UV filters have recently triggered more detailed investigations that have put the environmental relevance of pertinent laboratory results in perspective .
Most personal care products contain perfume oils in relatively low concentrations (0.1–1%). Usually they represent a complex mixture of a large number of structurally different fragrance chemicals and an alcoholic solvent. Many perfume oil components, including solvents, are readily biodegradable; the ecological information for many individual perfume ingredients is still incomplete.
In the past, certain fragrance components such as nitro musk compounds have been detected in surface waters and in fish because they are poorly biodegradable and represent a significant bioaccumulation potential. As a result, ingredients with such unfavorable ecological property profiles have been replaced in perfume formulations used in detergents and in cosmetic products, despite the fact that a PEC to PNEC ratio of <1 was obtained in previous environmental risk assessments . Perfume oil manufacturers are putting considerable effort into safety assessment programs to generate more ecological information about perfume ingredients.
While this letter focuses on the aquatic environment, cosmetic ingredients used as propellants particularly in aerosol sprays such as hair and deodorant sprays should not be neglected. The most common propellants in personal care products—propane, butane, or dimethyl ether—are released only to the air. When solvents such as ethanol are used in aerosol sprays, they also enter the air compartment. The substances released to the air are considered to be volatile organic compounds that might contribute to the formation of ground level ozone. However, the emissions from cosmetic aerosols in general and from personal care products in particular seem negligible in terms of their contribution to the greenhouse effect .
Human safety of personal care products and their ingredients has long been regulated in depth by the national laws of EU member states based on the EC Cosmetics Directive (; http://eur-lex.europa.eu/LexUriServ/LexUriServ.do?uri=CONSLEG:1976L0768:20080424:EN:PDF).
The environmental safety of personal care product ingredients has been considered an important element of the general product safety requirements imposed by producers' liability and pertinent EU legislation on existing and new chemicals. As the number of potential cosmetic product ingredients is very high, it is not surprising that ecological data have been available for only a fraction of these chemicals. This situation is expected to change because of the recent European chemicals legislation, REACH , requiring a minimum data set for each chemical with a production tonnage over one ton per year.
Analysis of typical formulations of relevant product categories and the ecological profile of their ingredients shows that most personal care products consist of components with established favorable environmental properties. Most of the surfactants can be considered safe for the aquatic environment based on comprehensive risk assessments. Basic biodegradability data are available for most cosmetic ingredients; conservative default values assuming poor degradation are used in the residual cases. The ecotoxicity data is based on experimental results or on quantitative structure-activity relationships. These estimations are deemed sufficiently accurate for nonpolar or polar narcotics such as most cosmetic ingredients.
The overall picture of the ecological profile of typical product formulations of the various cosmetic product categories (Supporting Information, Table S3; http://dx.doi.org/10.1897/09-104.S1) shows that in most cases (15 of 19) more than 80% of the mass of organic product ingredients is readily biodegradable. This is particularly true for typical rinse-off products such as shower gels and shampoos, which represent the highest consumption figures of all cosmetic product categories. Of the remaining four product types (sun protection lotion, eye cream, conditioner for normal hair, and coloring cream for permanent hair color) more than 60% of the organic product ingredients are readily biodegradable. These products typically are leave-on products containing a significant portion of polymeric and/or poorly soluble ingredients that biodegrade slowly or not at all. Nevertheless, they are eliminated in wastewater treatment plants to a significant extent due to adsorption onto sewage sludge. Thus, the bulk of ingredients in the cosmetic product categories is not likely to enter receiving surface waters in significant amounts as the ingredients are predominantly biodegraded or retained in wastewater treatment plants. The agricultural use of sewage sludge in European countries has decreased over the last two decades. As a result, soils are less impacted with poorly degradable chemicals originating from household products.
A similarly favorable view in terms of potential environmental hazards can be obtained from the formal calculation of the aquatic toxicity of personal care products (Supporting Information, Table S3) considering the available data on the individual ingredients. The high-tonnage rinse-off products exhibit a moderate aquatic toxicity (LC50 for fish is > 10 to 100 mg/L) mainly due to the contained surfactants. However, as discussed previously, this toxicity is compensated for by their excellent biodegradability. This also holds true for syndet soap, the only product in Supporting Information, Table S3 for which the LC50 for fish ranges between 1 to 10 mg/L. In the residual cases of the exercise, the calculated ecotoxicity was low (LC50 for fish > 100 mg/L) despite the fact that conservative default values were used when data were missing for some minor components.
From the ecological characteristics of the important cosmetic ingredient groups and the biodegradability and ecotoxicity profile of the formulated cosmetic products, it can be concluded that subsuming pharmaceuticals and personal care products under one term (i.e., pharmaceuticals and personal care products) is not justified and is rather erroneous. While pharmaceuticals contain highly biologically active materials with drug-specific physiological effects that may require a detailed evaluation of the ecological profile, the quantitatively predominant part of cosmetic ingredients is well assessed in terms of environmental behavior and shows overall acceptable ecological properties. We acknowledge that data gaps still exist for a number of cosmetic ingredients. The environmental safety of a small number of personal care products ingredients is presently subject to discussion. Examples are decamethylcyclopentasiloxane and octamethyl-cyclotetrasiloxane, triclosan, triclocarban, and certain UV filters as well. At this time additional ecological information is necessary to allow for a sound environmental risk assessment. Pertinent processes to improve the present situation are underway in the context of new regulation demands (e.g., REACH) and cooperation between national authorities and industry as well as of industry internal projects.
Table S1. Production figures (metric tons) of cosmetic products in Germany in 2002.
Table S2. Examples of formulas of typical cosmetic products. The product ingredients are mainly referred to with their INCI-names and are assigned to the respective ingredient types. The typical ingredient concentrations are taken from the Umbach monograph.
Table S3. Biodegradability and ecotoxicity data of cosmetic products.
All found at DOI: 10.1897/09-104.S1 (25 KB PDF).