High production volume chemical amine oxides [C8-C20] category environmental risk assessment.

An environmental assessment of amine oxides has been conducted under the OECD SIDS High Production Volume (HPV) Program via the Global International Council of Chemical Associations (ICCA) Amine Oxides Consortium. Amine oxides are primarily used in conjunction with surfactants in cleaning and personal care products. Given the lack of persistence or bioaccumulation, and the low likelihood of these chemicals partitioning to soil, the focus of the environmental assessment is on the aquatic environment. In the United States, the E-FAST model is used to estimate effluent concentrations in the United States from manufacturing facilities and from municipal facilities resulting from consumer product uses. Reasonable worst-case ratios of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) range from 0.04 to 0.003, demonstrating that these chemicals are a low risk to the environment.

Comparison of species sensitivity distributions derived from interspecies correlation models to distributions used to derive water quality criteria.

Species sensitivity distributions (SSD) require a large number of measured toxicity values to define a hazard level protective of multiple species. This investigation comprehensively evaluated the accuracy of SSDs generated from toxicity values predicted from interspecies correlation estimation (ICE) models. ICE models are log-log correlations of multiple chemical toxicity values for a pair of species that allow the toxicity of multiple species to be predicted from a single measured acute toxicity value for a surrogate species. ICE SSDs were generated using four surrogate species (fathead minnow, Pimephales promelas; rainbow trout, Oncorhynchus mykiss; sheepshead minnow, Cyprinodon varigatus; and water flea, Daphnia magna). ICE-based hazard concentrations (HC5s) from the 5th percentile of the log-logistic distribution of toxicity values were compared to HC5s determined from the acute toxicity of 55 chemicals from the United States Environmental Protection Agency Ambient Water Quality Criteria (AWQC). Measured fish and invertebrate acute toxicity data and HC5s from the AWQC data sets were compared to ICE-based HC5s. Surrogate species choice was found to be an important consideration in developing predictive HC5s. These results illustrated that fish predict fish betterthan invertebrates and D. magna predicted invertebrates better than most fish. For example, a mixed model of predicted fish and invertebrates from fathead minnow and D. magna as surrogate species provided predictive relationships with an average factor of 3.0 (+/- 6.7) over 7 orders of toxic magnitude and several chemical classes (HC5(predicted)/HC5(measured)). The application of ICE models is recommended as a valid approach for generating SSDs and hazard concentrations for chemicals with limited toxicity data.

European risk assessment of LAS in agricultural soil revisited: species sensitivity distribution and risk estimates.

Linear alkylbenzene sulphonate (LAS) is used at a rate of approximately 430,000 tons/y in Western Europe, mainly in laundry detergents. It is present in sewage sludge (70-5,600 mg/kg; 5-95th percentile) because of its high usage per capita, its sorption and precipitation in primary settlers, and its lack of degradation in anaerobic digesters. Immediately after amendment, calculated and measured concentrations are <1 to 60 mg LAS/kg soil. LAS biodegrades rapidly in soil with primary and ultimate half-lives of up to 7 and 30 days, respectively. Calculated residual concentrations after the averaging time (30 days) are 0.24-18 mg LAS/kg soil. The long-term ecotoxicity to soil microbiota is relatively low (EC10 >or=26 mg sludge-associated LAS/kg soil). An extensive review of the invertebrate and plant ecotoxicological data, combined with a probabilistic assessment approach, led to a PNEC value of 35 mg LAS/kg soil, i.e. the 5th percentile (HC5) of the species sensitivity distribution (lognormal distribution of the EC10 and NOEC values). Risk ratios were identified to fall within a range of 0.01 (median LAS concentration in sludge) to 0.1 (95th percentile) and always below 0.5 (maximum LAS concentration measured in sludge) according to various scenarios covering different factors such as local sewage influent concentration, water hardness, and sewage sludge stabilisation process. Based on the present information, it can be concluded that LAS does not represent an ecological risk in Western Europe when applied via normal sludge amendment to agricultural soil.

Interspecies correlation estimates predict protective environmental concentrations.

Environmental risk assessments often use multiple single species toxicity test results and species sensitivity distributions (SSDs) to derive a predicted no-effect concentration in the environment, typically the 5th percentile of the SSD, termed the HC5. The shape and location of the distribution are best known when populated with numerous toxicity values. To help overcome the cost of multiple toxicity tests, we explored the potential of the U.S. EPA's Interspecies Correlation Estimation (ICE) program to predict single species toxicity values from a single known toxicity value. ICE uses the initial toxicity estimate for one species to produce correlation toxicity values for multiple species, which can be used to develop SSD and HC5. To test this approach to deriving HC5, we generated toxicity values based on measured toxicity values for three surrogate species Pimephales promelas (Fathead minnow), Onchorynchus mykiss (Rainbow trout), and Daphnia magna (water flea). Algal taxa were not used due to the paucity of high quality algal-aquatic invertebrate and algal-fish correlations. The compounds used (dodecyl linear alkylbenzenesulfonate (LAS), nonylphenol, fenvalerate, atrazine, and copper) have multiple measured toxicity values and diverse modes of action and toxicities. Distribution parameters and HC5 values from the measured toxicity values were compared with ICE predicted distributions and HC5 values. While distributional parameters (scale and intercept) differed between measured and predicted distributions, in general, the ICE-based SSDs had HC5 values that were within an order of magnitude of the measured HC5 values. Examination of species placements within the SSDs indicated that the most sensitive species were coldwater species (e.g., salmonids and Gammarus pseudolimnaeus). These results raise the potential of using quantitative structure activity models to estimate HC5s.

The acute and chronic toxicity of hexadecyl and heptadecyl sulfate to aquatic organisms.

HSAS (high-solubility alkyl sulfate) is a new anionic surfactant composed predominantly of methyl and ethyl branched hexadecyl and heptadecyl sulfate. Effects of HSAS on a wide range of fish, algae, and invertebrates were investigated in conventional laboratory toxicity tests as well as in exposures conducted as part of an experimental stream model ecosystem study. For invertebrates and fish, C(16.7)HSAS (average alkyl chain length 16.7) acute LC(50) values ranged from 0.23 (channel catfish) to 2.9 (Asiatic clam, Corbicula) mg/L in well and river waters. LC(50) values for those species tested in both waters were typically within a factor of 1.5 and all were within a factor of 2 of each other, suggesting bioavailability is similar in these waters. Chronic toxicity values ranged from 0.070 (fathead minnow) to 0.42 (amphipod, Hyalella) mg/L across fish and invertebrates with algal chronic toxicity values ranging from 0.5 (blue-green algae, Anabaena flos-aquae) to 7.8 (green algae, Scenedesmus) mg/L. The order of sensitivity to HSAS acute and chronic toxicity was fish = invertebrate > algae. Based on the chronic single species sensitivity distribution, the concentrations protective of 90 and 95% of species were estimated to be 0.058 and 0.036 mg/L, respectively. These compare well with the model ecosystem NOEC of 0.064 mg/L.

Assessing the toxicity of dodecylbenzene sulfonate to the midge Chironomus riparius using body residues as the dose metric.

Dodecylbenzene sulfonate (DBS) is a component of linear alkylbenzene sulfonate (LAS), an anionic surfactant, mainly used in household detergents. Due to the large quantity of DBS in use, there is concern over adverse environmental effects. This work examined the toxicokinetics and toxicity of the 2-phenyl isomer of dodecylbenzene sulfonate in 4-d, 10-d, and partial life-cycle tests on the midge, Chironomus riparius, exposed to aqueous solutions. Toxicokinetics were determined in 10-d uptake and 5-d elimination tests. The toxicokinetics were based on parent compound concentration in water and yielded an uptake coefficient (ku) of 17.5 (14.87-20.20) ml/g/h, an elimination rate constant (ke) of 0.073 (0.062-0.085) per h, a bioconcentration factor (BCF) of 56 to 240, and a half-life (t 1/2) of 9.5 (8.0-11.0) h. Biotransformation measurements did not reveal evidence for DBS metabolism. Thus, body residues, determined in the toxicity study, represent parent compound. In toxicity tests, 4- and 10-d LR50s (the body residue required to cause 50% mortality) in live midges were 0.72 (0.65-0.79) and 0.18 (0.08-0.42) mmol/kg, respectively. Thirty-day LR50s were 0.18 (0.09-1.64) and 0.21 (0.15-0.39) mmol/kg in duplicate studies. Of the sublethal endpoints, only developmental time increase was significant, with the lowest-observed-effect residues of 0.085 (0.067-0.105) and 0.100 (0.087-0.114) mmol/kg for male and female midges, respectively. Deformities in surviving larvae were also observed as chronic responses for body residues exceeding the 30-d LR50. The body residues required for mortality suggest that DBS acts like a polar narcotic in the midge.

Aquatic toxicity of triclosan.

The aquatic toxicity of triclosan (TCS), a chlorinated biphenyl ether used as an antimicrobial in consumer products, was studied with activated-sludge microorganisms, algae, invertebrates, and fish. Triclosan, a compound used for inhibiting microbial growth, was not toxic to wastewater microorganisms at concentrations less than aqueous solubility. The 48-h Daphnia magna median effective concentration (EC50) was 390 microg/L and the 96-h median lethal concentration values for Pimephales promelas and Lepomis macrochirus were 260 and 370 microg/L, respectively. A no-observed-effect concentration (NOEC) and lowest-observed-effect concentration of 34.1 microg/L and 71.3 microg/L, respectively, were determined with an early life-stage toxicity test with Oncorhynchus mykiss. During a 96-h Scenedesmus study, the 96-h biomass EC50 was 1.4 microg/L and the 96-h NOEC was 0.69 microg/L. Other algae and Lemna also were investigated. Bioconcentration was assessed with Danio rerio. The average TCS accumulation factor over the five-week test period was 4,157 at 3 microg/L and 2,532 at 30 microg/L. Algae were determined to be the most susceptible organisms. Toxicity of a TCS-containing wastewater secondary effluent to P. promelas and Ceriodaphnia was evaluated and no observed differences in toxicity between control and TCS-treated laboratory units were detected. The neutral form of TCS was determined to be associated with toxic effects. Ionization and sorption will mitigate those effects in the aquatic compartment.