Inorganic Arsenic Concentration in Fish Governed by Trophic Level and Size, not Water Concentration: Implications for Human Health Water Quality Criteria.

In 2019, the Idaho Department of Environmental Quality implemented a paired surface water and fish tissue data collection program to derive a state-specific bioaccumulation factor (BAF) for inorganic arsenic (iAs) as part of the development of new human health water quality criteria (HHWQC). No statistically significant relationship was found between total arsenic (tAs) or iAs in surface water and fish tissue. Fish body weight was the only parameter with a statistically significant effect on iAs concentration in fish tissue. The ratio of iAs to tAs in fish tissue declined significantly with both increasing trophic level and increasing body weight. The decrease in iAs concentration in fish tissue with increasing size and trophic level as well as the decrease in the proportion of tAs that is iAs with increasing trophic level are likely the result of metabolic transformation of iAs to organic As by organisms in each level of the aquatic food web. Although the linear regression-based BAF using the Idaho paired fish and water data best predicted observed iAs fish tissue concentrations compared to several alternative BAFs, it was not statistically significant (p < 0.05) and was a poor predictor (R2 = 0.01) of iAs concentrations in fish tissue. These results illustrate that iAs, and possibly other metals, in the natural environment do not conform with commonly used bioaccumulation models and the paradigm used by the US Environmental Protection Agency for determining HHWQC. These results indicate that modifications to the paradigm are necessary, such as a fish tissue criterion as Idaho has proposed, to assure that public health is protected. Environ Toxicol Chem 2023;42:1542-1552. © 2023 SETAC.

Effects of in situ selenium exposure and maternal transfer on survival and deformities of brown trout (Salmo trutta) fry.

Offspring of wild adult brown trout exposed to a range of Se concentrations were reared in a laboratory setting to primarily assess effects on survival and deformities. Maternal whole-body Se concentrations ranged from 4.7 to 22.6 mg/kg dry weight for wild fish. Corresponding Se concentrations in embryos ranged from 6.2 to 40.3 mg/kg dry weight. Significant relationships were found between embryo and whole-body tissue concentrations. Increasing egg Se concentrations were correlated with decreasing survival; however, hatch success was not significantly correlated with increasing embryo Se. The best fit effect concentration, 10% (EC10) for survival in the hatch to swim-up period was 20.6 mg/kg dry weight, and the EC10 for hatch to test termination at 88 d was 20.5 mg/kg dry weight egg Se. The best fit model for deformities was based on a baseline-adjusted severity index and resulted in an EC10 of 21.8 mg/kg dry weight egg Se. Both the best fit model EC10s represent more sensitive values than the published range of trout species EC10s. An egg to whole-body tissue conversion factor derived from the paired data resulted in a conversion factor for brown trout of 1.46, which resulted in a whole-body tissue EC10 of 14.04 mg/kg dry weight at an egg tissue EC10 of 20.5 mg/kg dry weight. Environ Toxicol Chem 2018;37:1396-1408. © 2018 SETAC.