Toxic effects of dioctyl adipate and dioctyl phthalate used as plasticiser in industry on zebrafish larvae

It is a well-known fact that interference of the majority of industrial wastes and wastewater discharges into rivers, lakes and coastal waters. Therefore, contamination of the aquatic environment by the plastic industrial products and also by-products is inevitable. Also, due to their physical, chemical and biological degradation resistant, plasticisers can accumulate in the body and enter the food chain of living organisms and generate toxic effects. The present study compare potential toxic effects of dioctyl adipate (DOA) and dioctyl phthalate (DOP) plasticisers to larval (72 h post fertilization) zebrafish (Danio rerio) by analysing changes in expression levels of stress-related genes (p53, rad51, and xrcc5) by real-time quantitative PCR (RT-qPCR). Another objective was to assess genotoxicity of DOA and DOP plasticisers. The lethal concentrations for 50% mortality (LC50) in larval zebrafish exposed (96 h) to 0-200 mg/L DOA and 0-150 mg/L DOP plasticisers were 89.99 ± 8.03 mg/L and 54.02 ± 11.49 mg/L, respectively. A concentration-dependent increase in DNA strand breaks was detected in blood cells from larvae exposed (96 h) to DOA and DOP plasticisers. DNA damage was higher in DOP (31.1%) than DOA (20.8%) plasticisers exposed larvae. While there were no significant differences in induction of stress-related genes in larvae exposed to plasticisers, there was only statistically significant increase (5 fold) in expression of xrcc5 gene in larvae exposed to 10 mg/L DOP substance relative to control. The results of the study were shown that consisted low level toxic effects were generally similar in larvae exposed to plasticisers. However, DOP was 1.5 times more toxic than DOA in larvae.