Evaluation of critical body residue data for acute narcosis in aquatic organisms
The Environmental Residue Effects Database (ERED) was evaluated to identify critical body residues (CBRs) of organic chemicals causing acute baseline neutral narcosis in aquatic organisms. Over 15,000 records for >400 chemicals were evaluated. Mean molar CBRs in the final dataset of 161 records for 29 chemicals were within published ranges, but varied within and among chemicals and species (∼3 orders of magnitude) and lipid normalization did not consistently decrease variability. All 29 chemicals can act as baseline neutral narcotics, but chemicals and/or their metabolites may also act by non‐narcotic modes of action. Specifically, non‐narcotic toxicity of PAHs and/or their biotransformation derivatives may be a significant source of variability. Complete testing of the narcosis‐CBR hypothesis was confounded by data gaps for key toxicity modifying factors such as metabolite formation/toxicity, lipid content/composition, other modes of toxic action, and lack of steady‐state status. Such problems impede determination of the precise, accurate toxicity estimates necessary for sound toxicological comparisons. Thus, neither the data nor the chemicals in the final dataset should be considered definitive. Changes to testing designs/methods are necessary to improve data collection and CBR interpretation for hazard and risk assessment. The toxicity metrics discussed – wet weight and lipid weight CBRs, volume fraction in organism lipid, and chemical activity – each have advantages, but all are subject to the same toxicity modifying factors.
Environ Toxicol Chem 2013;9999:XX–XX. © 2013 SETAC