Freshwater Environmental Risk Assessment of Down-the-Drain Octinoxate Emissions in the United States.

Organic ultraviolet (UV) filters are used in a variety of cosmetic and personal care products (CPCPs), including sunscreens, due to their ability to absorb solar radiation. These UV filters can be washed down the drain through bathing, cleansing, or the laundering of clothing, therefore UV filters can enter the freshwater environment via wastewater treatment plant effluent, and so a freshwater risk assessment is necessary to establish the environmentally safe use of these important CPCP ingredients. In the present study, an environmental safety assessment for a UV filter of regulatory concern, octinoxate, was conducted. An established risk assessment framework designed specifically for CPCPs released to the freshwater environment in the United States was used for the assessment. A distribution of predicted environmental concentrations (PECs) representative of conditions across the region was calculated using the spatially resolved probabilistic exposure model iSTREEM. A review of available hazard data was conducted to derive a predicted no-effect concentration (PNEC). The safety assessment was conducted by comparing the PEC distribution to the PNEC. A substantial margin of safety was found between the 90th percentile PEC, which is representative of the reasonable worst-case environmental exposure, and the PNEC. Owing to this finding of negligible risk, further refinement of the risk assessment through the generation of experimental data or refinement of conservative assumptions is not prioritized. These results are critical for demonstrating the environmental safety of UV filters in the US freshwater environment and will help guide future work. Environ Toxicol Chem 2022;41:3116-3124. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Understanding Ecotoxicological Responses of Fish Embryos and Gill Cells to Cationic Polymers.

Cationic polymers are considered by the scientific and regulatory communities as a group of greater interest amongst the polymers in commerce. As a category, relatively little hazard information is available in the public literature. Very few examples exist of published, high-quality polymer characterization and quantification of exposure. In the present study we describe a series of fish embryo toxicity (FET) and fish gill cytotoxicity assays used to establish a baseline understanding of several representative polyquaternium categories (PQ-6, PQ-10, PQ-16) in animal alternative models, accompanied by high-quality analytical characterization. Materials were chosen to encompass a range of molecular weights and charge densities to determine the influence of test material characteristics on toxicity. Both chorionated and dechorionated FET assays were generally similar to published acute fish toxicity data. Toxicity was correlated with cationic polymer charge density, and not with molecular weight, and was a combination of physical effects and likely toxicity at the site of action. Toxicity could be ameliorated by humic acid in a dose-dependent manner. Fish gill cytotoxicity results were orders of magnitude less sensitive than FET test responses. Environ Toxicol Chem 2022;41:2259-2272. © 2022 SETAC.

National scale down-the-drain environmental risk assessment of oxybenzone in the United States.

Organic ultraviolet (UV) filters are used in cosmetic and personal care products (CPCPs) and over-the-counter (OTC) sunscreens, due to their ability to absorb solar radiation. When OTC and CPCP ingredients are washed down the drain, they can then enter freshwaters that receive wastewater treatment plant effluents. This paper presents a freshwater environmental safety assessment of a key UV filter, oxybenzone, used in OTC sunscreens and CPCPs in the United States. Exposure was characterized using iSTREEM® , a spatially resolved aquatic exposure model developed for chemicals disposed of down the drain. iSTREEM® provides a comprehensive exposure assessment of oxybenzone concentrations in United States receiving waters through predicted environmental concentration (PEC) distributions representative of conditions across the region. A review of available hazard data was used to derive a predicted no-effect concentration (PNEC) using aquatic toxicity data and assessment factors. A safety assessment was conducted by comparing the PEC distribution with the PNEC. The results indicate that oxybenzone is of low concern and there is a significant margin of safety as the 90th percentile PEC is two orders of magnitude below the PNEC. These results are instrumental in demonstrating the environmental safety of key organic UV filters in the U.S. freshwater environment and will help prioritize future work. Integr Environ Assess Manag 2021;17:951-960. © 2021 Personal Care Products Council. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Gonadosomatic index as a confounding variable in fish-based screening assays for the detection of anti-estrogens and nonaromatizable androgens.

The presence of reproductive endocrine-disrupting compounds (REDCs) in the environment poses a potential threat to fish and wildlife, because exposures are capable of altering sexual development, reproductive success, and behavior. Fish-based screening assays are often utilized to screen for the presence of REDCs in surface waters and to assess single chemicals for potential endocrine-disrupting activity. In an effort to improve such screening assays, the goal of the present study was to determine whether the gonadosomatic index (GSI) of female fathead minnows (Pimephales promelas), as assessed via external characteristics, influences their response to REDC exposure. Specifically, we sought to determine whether low-GSI females differed from high-GSI females in their responses to the model anti-estrogen fadrozole and the model androgen 17ß-trenbolone, and whether there was a preferable classification in the context of REDC screening. Low-GSI females were more sensitive to fadrozole at the lower concentration of fadrozole (5 µg/L) and to the higher concentration of trenbolone (50 ng/L), whereas high-GSI females were more sensitive at the lower concentration of trenbolone (5 ng/L). The differential response of low- and high-GSI females to REDCs indicates that GSI influences exposure outcome, and should subsequently be taken into consideration in the implementation of screening assays, as failure to utilize fish of the appropriate reproductive status may skew the test results. Environ Toxicol Chem 2019;38:603-615. © 2019 SETAC.

Enhancing the fathead minnow fish embryo toxicity test: Optimizing embryo production and assessing the utility of additional test endpoints.

The fathead minnow fish embryo toxicity (FET) test has been identified as a potential alternative to toxicity test methods that utilize older fish. However, several challenges have been identified with the fathead minnow FET test, including: 1) difficulties in obtaining appropriately-staged embryos for FET test initiation, 2) a paucity of data comparing fathead minnow FET test performance to the fathead minnow larval growth and survival (LGS) test and 3) a lack of sublethal endpoints that could be used to estimate chronic toxicity and/or predict adverse effects. These challenges were addressed through three study objectives. The first objective was to optimize embryo production by assessing the effect of breeding group composition (number of males and females) on egg production. Results showed that groups containing one male and four females produced the largest clutches, enhancing the likelihood of procuring sufficient numbers of embryos for FET test initiation. The second study objective was to compare the performance of the FET test to that of the fathead minnow LGS test using three reference toxicants. The FET and LGS tests were similar in their ability to predict the acute toxicity of sodium chloride and ethanol, but the FET test was found to be more sensitive than the LGS test for sodium dodecyl sulfate. The last objective of the study was to evaluate the utility and practicality of several sublethal metrics (i.e., growth, developmental abnormalities and growth- and stress-related gene expression) as FET test endpoints. Developmental abnormalities, including pericardial edema and hatch success, were found to offer the most promise as additional FET test endpoints, given their responsiveness, potential for predicting adverse effects, ease of assessment and low cost of measurement.