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Dietary bioaccumulation and biotransformation of hydrophobic organic sunscreen agents in rainbow trout
Citation:
Saunders, L., A. Hoffman, J. Nichols, AND F. Gobas. Dietary bioaccumulation and biotransformation of hydrophobic organic sunscreen agents in rainbow trout. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY. Society of Environmental Toxicology and Chemistry, Pensacola, FL, 39(3):574-586, (2020). https://doi.org/10.1002/etc.4638
Impact/Purpose:
Organic ultraviolet filters (UVFs; also known as sunscreen agents) used in personal care and consumer products can enter the aquatic environment via wastewater treatment plant effluents or by loss from skin during swimming and other recreational activities. Some UVFs are hydrophobic (log Kow > 4) which has led to concern that they may bioaccumulate in aquatic organisms. The purpose of this study was to investigate the bioaccumulation and biotransformation of two widely-used UVFs, 2-ethylhexyl-4-methoxycinnamate (EHMC) and octocrylene (OCT) in rainbow trout exposed via the diet. EHMC and OCT were significantly metabolized by trout and this metabolism substantially reduced bioaccumulation relative to levels observed for a set of poorly transformed chemicals having similar log Kow values. Derived bioconcentration factors (BCFs) and biomagnification factors (BMFs) for both UVFs were well below established bioaccumulation criteria, suggesting that EHMC and OCT are unlikely to pose a bioaccumulation hazard in trout. This research substantially increases existing knowledge concerning the fate and effects of UVFs in the environment.
Description:
This study investigated the dietary bioaccumulation and biotransformation of hydrophobic organic sunscreen agents, 2-ethylhexyl-4-methoxycinnamate (EHMC) and octocrylene (OCT), in rainbow trout using a modified OECD 305 dietary bioaccumulation test that incorporated non-biotransformed reference chemicals. Trout were exposed to three dietary concentrations of each chemical to investigate the relationship between dietary exposure concentration and observed accumulation and depuration. EHMC and OCT were significantly biotransformed, resulting in mean in vivo biotransformation rate constants (kMET) of 0.54 ± 0.06 and 0.09 ± 0.01 d-1, respectively. The kMET values generated for both chemicals did not differ between dietary exposure concentrations, indicating that chemical concentrations in the fish were not high enough to saturate biotransformation enzymes. Both somatic and luminal biotransformation substantially reduce EHMC and OCT bioaccumulation potential in trout. Biomagnification factors (BMF) and bioconcentration factors (BCF) of EHMC averaged 0.0035 kg lipid kg lipid-1 and 396 L kg-1, respectively, while those of OCT averaged 0.0084 kg lipid kg lipid-1 and 1267 L kg-1. These values are one to two orders of magnitude lower than the BMFs and BCFs generated for reference chemicals of similar log KOW. Additionally, for both chemicals, derived BMFs and BCFs fell below established bioaccumulation criteria (1.0 kg lipid kg lipid-1 and 2000 L kg-1, respectively), suggesting that EHMC and OCT are unlikely to pose a bioaccumulation hazard in rainbow trout.
URLs/Downloads:
DOI: Dietary bioaccumulation and biotransformation of hydrophobic organic sunscreen agents in rainbow trout