Oral Presentation SETAC Asia-Pacific Virtual Conference 2022

Applicability of equilibrium sampling in informing tissue residues and dietary risks of legacy and current-use organic chemicals in aquaculture (#41)

Qian Wang 1 , Juan-ying Li 1
  1. Shanghai Ocean University, Shanghai, CHINA, China

Equilibrium sampling techniques based on silicone polydimethylsiloxane (PDMS) have been extensively used to determine the concentrations of freely dissolved hydrophobic organic compounds (HOCs) and assess the thermodynamic potentials for bioaccumulation of these compounds in the aquatic environment. This allows the use of PDMS-based equilibrium sampling techniques in assisting conventional sampling and extraction methods for the determination of the concentrations of HOCs in aquaculture products. This study presented an ex-situ demonstration of how well PDMS-based equilibrium sampling can inform the tissue residues and dietary risks of legacy or current-use organic chemicals in aquaculture species with reference to 21 farm ponds in Eastern China. For legacy contaminants such as polybrominated diphenyl ethers (PBDEs, n=10), a good agreement between the predicted concentrations based on equilibrium PDMS and the measured lipid-normalized concentrations was observed for 60% of the studied biota, including pelagic fish and benthic species. For pesticides widely used in aquaculture or agriculture, such as pyrethroid (PE, n=4) and organophosphate pesticides (OPPs, n=8), the measured tissue residues were consistently higher than that predicted by equilibrium sampling, possibly caused by the continuous input from surroundings into the pond. For the organochlorine pesticides (OCPs, n=5), only β-HCH could be detected in both aquaculture species and PDMS. β-HCH was underestimated as well. Adjusted by ingestion rates of aquaculture products and toxicology data of the chemicals, the target hazard quotients (THQs) of these chemicals predicted from equilibrium sampling were generally comparable to those derived from measured concentrations in tissue due to the predominance of PBDEs. Overall, PDMS-based equilibrium sampling offered an alternative approach for the prediction of the tissue residues and dietary risks of PBDEs. Moreover, it should be applied with caution for current-use chemicals, such as PEs, OPPs and OCPs. Finally, improving the application of PDMS for these chemicals in the farm ponds warrants future study.