Bioaccumulation and health risk assessment of diclofenac and sulfamethoxazole and their biodegradation metabolites in carrot.

Abstract

Pharmaceuticals and personal care products (PPCPs) are increasingly contaminating agricultural systems and entering the food web through green irrigation and fertilization practices. The bioaccumulation of such PPCPs, followed by their degradation in edible crops, is an alarming concern as a potential exposure route to humans. This study selected two commonly prescribed medicines, diclofenac (DLF) and sulfamethoxazole (SMX), to dissect their fate in carrots. Results from carrot cell culture models illustrated their rapid absorption over a 120-h incubation period. Incubation time and initial exposure levels had significant effects on the dissipation of these parent compounds, along with a notable interaction. Metabolites were believed to be transformed through Phase I and II processes, while the hydroxylated and oxidized derivatives were the most abundant products in carrot cells for DLF and SMX, respectively. Whole-plant models further revealed the behavior of the parent compound therein, where DLF and SMX tended to accumulate in the root tissues of carrots rather than leaves, accompanied by limited translocation. Comparable patterns were also observed for their metabolites, with relatively high proportions in roots, attributed to the accumulation and the differences in metabolic activity between the roots and leaves. The consumption of these DLF or SMX-contaminated carrots, together with their metabolites present in the edible part, could pose significant risks to human health, causing concern for adults and toddlers. These findings provided valuable insights for future studies on the bioaccumulation and biodegradation of DLF and SMX in edible crops and the associated health implications.