Impact of plasticiser exposure on oyster Crassostrea (Magallana) saidii: assessing oxidative stress and biomarker responses

Plasticisers are prevalent chemical contaminants that leach from plastics into aquatic ecosystems, posing potential risks to marine life. This study investigated the effects of alternative plasticisers [epoxidised methyl oleate (EMO), di-(2-ethylhexyl) adipate (DEHA), and diisononyl phthalate (DINP)] at 100 µg/L in oysters Crassostrea (Magallana) saidii over 21 days under controlled laboratory conditions. This study focused on changes in body weight, antioxidant enzyme activities such as superoxide dismutase (SOD) and catalase (CAT), non-enzymatic antioxidant reduced glutathione (GSH), lipid peroxidation (malondialdehyde (MDA) levels) after plasticisers exposure for 7, 14 and 21 days. The results indicated a decline in body weight in DINP-exposed oysters, indicating metabolic alterations. DEHA and DINP showed a pronounced increase in SOD activity at the end of the experiment, indicating elevated oxidative stress. CAT activity increased with EMO exposure, but decreased in oysters treated with DEHA and DINP. GSH levels were inversely proportional to CAT activity. Oysters exposed to DEHA and DINP exhibited higher MDA levels, indicating oxidative lipid damage associated with these plasticisers. Multi-biomarker data were integrated using the Integrated Biomarker Response (IBR) index, which ranked the plasticisers' oxidative stress potential as DEHA > DINP > EMO. The IBR analysis also suggested distinct modes of action among the plasticisers and provided insights into their toxicity mechanisms. Notably, EMO exhibited lower toxicity compared to DEHA and DINP, supporting its potential as a more friendly alternative to conventional plasticisers, albeit not exempt from toxic effects. These insights underscore the importance of environmental risk assessments in the future development of safer chemical alternatives.