Kathleen Stanton

Environmental Safety of the Use of Major Surfactant Classes in North America

This paper brings together over 250 published and unpublished studies on the environmental properties, fate, and toxicity of the four major, high-volume surfactant classes and relevant feedstocks. The surfactants and feedstocks covered include alcohol sulfate or alcohol sulfate (AS), alcohol ethoxysulfate (AES), linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and long-chain alcohol (LCOH). These chemicals are used in a wide range of personal care and cleaning products. To date, this is the most comprehensive report on these substances chemical structures, use, and volume information, physical/chemical properties, environmental fate properties such as biodegradation and sorption, monitoring studies through sewers, wastewater treatment plants and eventual release to the environment, aquatic and sediment toxicity, and bioaccumulation information. These data are used to illustrate the process for conducting both prospective and retrospective risk assessments for large-volume chemicals and categories of chemicals with wide dispersive use. Prospective risk assessments of AS, AES, AE, LAS, and LCOH demonstrate that these substances, although used in very high volume and widely released to the aquatic environment, have no adverse impact on the aquatic or sediment environments at current levels of use. The retrospective risk assessments of these same substances have clearly demonstrated that the conclusions of the prospective risk assessments are valid and confirm that these substances do not pose a risk to the aquatic or sediment environments. This paper also highlights the many years of research that the surfactant and cleaning products industry has supported, as part of their environmental sustainability commitment, to improve environmental tools, approaches, and develop innovative methods appropriate to address environmental properties of personal care and cleaning product chemicals, many of which have become approved international standard methods.

Human health risk assessment of long chain alcohols.

Representative chemicals from the long chain alcohols category have been extensively tested to define their toxicological hazard properties. These chemicals show low acute and repeat dose toxicity with high-dose effects (if any) related to minimal liver toxicity. These chemicals do not show evidence of activity in genetic toxicity tests or to the reproductive system or the developing organism. These chemicals also are not sensitizers. Irritation is dependant on chain length; generally, alcohols in the range C(6-)C(11) are considered as irritant, intermediate chain lengths (C(12-)C(16)) alcohols are considered to be mild irritants and chain lengths of C(18) and above are considered non-irritants. These chemicals are broadly used across the consumer products industry with highest per person consumer exposures resulting from use in personal care products. Margins of exposure adequate for the protection of human health are documented for the uses of these chemicals.

Relationships between benthic macroinvertebrate community structure and geospatial habitat, in-stream water chemistry, and surfactants in the effluent-dominated Trinity River, Texas, USA.

Over the past 20 years, benthic macroinvertebrate community structure studies have been conducted on the upper Trinity River, Texas, USA, which is dominated by municipal wastewater treatment plant (WWTP) and industrial effluents. The Trinity River is located in the Dallas-Fort Worth metropolitan area, and is the most highly populated and industrialized watershed in Texas. As such, the Trinity River represents a near-worst-case scenario to examine the environmental effects of domestic-municipal and industrial effluents on aquatic life. A 1987 to 1988 study concluded that many stretches of the river supported a diverse benthic community structure; however, a decline in taxa richness occurred immediately downstream of WWTPs. A 2005 study designed to parallel the 1987 to 1988 efforts evaluated how changes in water quality, habitat, and increased urbanization impacted benthic community structure. Physicochemical measurements, habitat quality, geospatial variables, and benthic macroinvertebrates were collected from 10 sites. Surfactants were measured and toxic units (TUs) were calculated for surface water and pore water as indicators of domestic/household use of cleaning products. Total TUs indicated a low potential for biological impacts. Toxic unit distribution was not dependent on WWTP location and did not correlate with any benthic variable. Eight environmental parameters were determined to be useful for predicting changes in benthic macroinvertebrate community structure: surfactant surface water TUs (SWTU), in-stream habitat cover, and surface water total organic carbon were the top three parameters. Abundance, taxa richness, and taxa similarity in 2005 had increased since the earlier study throughout the immediate vicinity of the metropolitan area.

An overview of hazard and risk assessment of the OECD high production volume chemical category - long chain alcohols [C6-C22] (LCOH).

This review summarizes the findings of the assessment report for the category, long chain alcohols (LCOH) with a carbon chain length range of C(6)-C(22) covering 30 substances, and >1.5million tonnes/year consumed globally. The category was evaluated under the Organization for Economic Co-operation and Development (OECD) high production volume chemicals program in 2006. The main findings of the assessment include: (1) no unacceptable human or environmental risks were identified; (2) these materials are rapidly and readily biodegradable; (3) a parabolic relationship was demonstrated between carbon chain length and acute and chronic aquatic toxicity; (4) category-specific (quantitative) structure-activity relationships were developed enabling prediction of properties across the entire category; (5) LCOH occur naturally in the environment in an equilibrium between synthesis and degradation; (6) industry coming together and sharing resources results in minimizing the need for additional animal tests, produces cost savings, and increases scientific quality of the assessment.

Environmental properties of long chain alcohols. Part 1: Physicochemical, environmental fate and acute aquatic toxicity properties

This paper summarises the physicochemical, biodegradation and acute aquatic ecotoxicity properties of long chain aliphatic alcohols. Properties of pure compounds are shown to follow somewhat predictable trends, which are amenable to estimation by quantitative structure-activity relationships ((Q)SARs). This allows predictions of data relating to human and environmental safety profiles and patterns. These alcohols have been shown to be rapidly degradable under standard conditions up to C(18). Furthermore, evidence suggests that longer chain lengths are also rapidly biodegradable. While logK(ow) values suggest possible bioaccumulation potential, available data suggest that these substances are not as bioaccumulative as estimations would predict. For acute aquatic toxicity, solubility limits the possibility of effects being appropriately observed and become increasingly challenging above C(12). Further, a model has been developed for multi-component mixtures which give an excellent account of aquatic ecotoxicity allowing for the prediction of acute effects of un-tested mixtures.

Occurrence and risk screening of alcohol ethoxylate surfactants in three U.S. river sediments associated with wastewater treatment plants.

Alcohol ethoxylates (AE) are high production volume (HPV) chemicals globally used in detergent and personal care products and are truly a work-horse for the household and personal care industries. Commercial AE generally consist of a mixture of several homologues of varying carbon chain length and degree of ethoxylation. Homologues that are not ethoxylated are also known as aliphatic alcohols or simply fatty alcohols (FA). This group of homologues represents a special interest in the context of environmental risk, as these are also abundant and ubiquitous naturally occurring compounds (e.g. animal fats and in human feces). Hence, in a risk assessment one needs to distinguish between the natural (background) concentrations and the added contribution from anthropogenic activities. We conducted a weight-of-evidence risk assessment in three streams, documenting the exposure and predicted risk, and compared these to the habitat and in situ biota. We found that the parameters (e.g., habitat quality and total perturbations hereunder total suspended solids (TSS) and other abiotic and biotic stressors) contributed to the abundance of biota rather than the predicted risk from AE and FA. Moreover, the documented natural de novo synthesis and rapid degradation of FA highlight the need to carefully consider the procedures for environmental risk assessment of naturally occurring compounds such as FA, e.g. in line with the added risk concept known from metal risk assessment.

Environmental risk assessment of hydrotropes in the United States, Europe, and Australia

An environmental assessment of hydrotropes was conducted under the Organisation for Economic Co-operation and Development (OECD) Screening Information Data Sets (SIDS) for High Production Volume (HPV) Program via the Global International Council of Chemical Associations (ICCA) Hydrotropes Consortium. The assessment and its conclusions were presented at a meeting of the OECD member countries in Washington, DC in 2005. The SIDS Initial Assessment Report (SIAR) was accepted by the membership. Their conclusion was “The chemicals in this [hydrotropes] category are of low priority for further work because of their low hazard profile.” Hydrotropes are used to solubilize the water-insoluble ingredients of cleaning and personal care products including, for example, powder and liquid laundry detergents, hard-surface cleaners, machine dishwashing rinse aids, hand dishwashing liquids, body washes, shampoos, hair conditioners, and liquid hand and face soaps. Global production equals approximately 46 500 metric tons, a little more than half of which is used in the United States. The 8 chemicals accounted for in the “hydrotropes category” include ammonium, Ca, K, and Na salts that are described by 10 Chemical Abstract Service (CAS) registration numbers. The 8 chemical entities are generally comparable and predictable in their chemical behavior and that measured and/or modeled data for members from one subgroup can be applied to other subgroups and to the hydrotropes category as a whole. The assessment is based on a search for and evaluation of available data on physical–chemical properties, biodegradability, removal by wastewater treatment, and aquatic toxicity. Reliable ecotoxicity and environmental fate data were found for selected members of the category. Partitioning, once released into the environment, and exposure in surface waters were modeled for consumer use and manufacturing scenarios relevant to the United States, Europe, and Australia. The models indicate 99+% of the hydrotropes will partition to water. Furthermore, given the low potential for hydrotropes reaching the terrestrial environment and their lack of persistence or bioaccumulation, the focus of the assessment is on the aquatic environment, specifically the water compartment. Aquatic risks were assessed in each scenario using what is referred to as the PEC/PNEC ratio. The modeled predicted environmental concentration (PEC), accounting for volume released and wastewater treatment, is divided by the predicted no effect concentration (PNEC) derived from the aquatic toxicity tests. The closest a predicted environmental concentration came to the toxicity threshold is 0.125 (or 12.5% of the no effect concentration) and that is for a hypothetical manufacturing facility that produces the entire annual volume of hydrotropes and discharges to a small (10%ile) stream under low flow (7Q10) conditions. PEC/PNEC ratios were considerably smaller for consumer use scenarios. The ratios were 0.0002 for a low flow (7Q10) stream scenario in the United States, 0.026 to 0.089 for regional and local water bodies, respectively, in Europe, and 0.004 to 0.036 for oceans and rivers, respectively, in Australia. In conclusion, aquatic hazard levels are not expected to be reached under exaggerated conditions of manufacture or normal consumer use of hydrotropes. Hydrotropes are neither persistent nor bioaccumulative in the environment.