Ecological risk assessment of beryllium and beryllium compounds in aquatic species

Beryllium (Be) and Be compounds may be released into aquatic environment. Under the United Nations Globally Harmonized System (GHS), soluble Be compounds are classified as Category 2 (moderate hazard) for aquatic chronic toxicity (H411), with no aquatic hazard classifications for insoluble Be forms. The scientific basis for these classifications, or lack thereof, is unclear, and a limited number of studies assessed risks of Be and Be compounds in aquatic species. Therefore, this study aimed to conduct a screening-level assessment of potential risks to aquatic species and determine Classification, Labelling, and Packaging (CLP) intrinsic hazard classifications. Toxicity thresholds for aquatic species were reviewed and compared with the U.S. Environmental Protection Agency hazard categories and Be concentrations in water. Toxicity data were then used to derive CLP classifications. We found that Be and its compounds ranged from "practically nontoxic" to "moderately toxic", with toxicity thresholds orders of magnitude higher than Be concentrations in water bodies in the United States Chronic toxicity classifications were derived, with insoluble Be metal and Be(OH)2 matching Category 2 and 4 (low hazard), respectively, and soluble Be compounds matching Category 1 (high hazard; BeSO4×4H2O), Category 2 (BeCl2 and BeNO3), and Category 3 (low to moderate hazard; Be(NO3)2). For acute toxicity, Be metal, BeCl2, BeNO3, and BeSO4×4H2O matched Category 1, whereas Be(OH)2 and Be(NO3)2 were "Not Classifiable." Screening-level risk characterization, based on measured concentrations and toxicity thresholds, suggests that adverse effects on aquatic organisms are unlikely under the exposure conditions represented in available datasets. However, this conclusion is constrained by limited chronic data, low taxonomic diversity, reliance on legacy studies, and absence of robust species sensitivity distributions and 5th percentile hazardous concentration derivations. Our results support Be form-specific CLP classification and highlight data limitation impacts on the development and interpretation of benchmarks and criteria for the protection of aquatic life.