Feed-driven transfer and bioaccumulation of phthalate esters in aquaculture pond ecosystems

This study investigates the trophic transfer and bioaccumulation of phthalate esters (PAEs) in aquaculture ponds within China's Pearl River Delta. Two representative food chains (omnivorous and carnivorous) were analyzed using stable nitrogen isotope analysis and lipid-normalized contaminant concentrations. Human health risks associated with dietary PAE exposure were evaluated following USEPA risk assessment guidelines. Concentrations of ∑₁₃PAEs varied considerably among fish species. The highest level was detected in bighead carp (2.84 mg/kg ww), while the lowest was found in largemouth bass (0.19 mg/kg ww). The six priority PAEs constituted 77.23 to 90.59% of the total ∑₁₃PAEs, with di-2-ethylhexyl phthalate (DEHP) alone accounting for over 50% in fish tissues. Long-chain PAEs exhibited significant biomagnification in the omnivorous food chain, with a trophic magnification factor (TMF) of 2.45 for DEHP. In contrast, metabolic degradation was the dominant process in the carnivorous chain. The human health risk assessment indicated low overall carcinogenic and non-carcinogenic risks, with hazard quotients well below 1 and carcinogenic risks ranging from 10⁻⁶ to 10⁻⁴ for the majority of fish species. Nonetheless, certain species such as bighead carp showed a marginally higher cancer risk (6.60 × 10⁻⁵ ± 3.61 × 10⁻⁵). The findings provide new insights into the behavior of PAEs in aquaculture ecosystems and support the development of monitoring and management strategies for environmental pollutants.