Di-(2-ethylhexyl) phthalate (DEHP) is extensively used as an additive to produce plastics, but it may damage non-target organisms in soil. In this study, the effects of DEHP on Folsomia candida in terms of survival, reproduction, enzyme activities, and DNA damage were investigated in spiked artificial soil using a multi-biomarker strategy. The 7-day LC50 (median lethal concentration) and 28-day EC50 (median effect concentration) values of DEHP were 1256.25 and 19.72 mg a.i. (active ingredient) kg-1 dry soil, respectively. Biomarkers involved in antioxidant defense including catalase (CAT-catalase), glutathione S-transferases (GST), detoxifying enzymes including acetylcholinesterase (AChE), Cytochrome P450 (CYP450), and peroxidative damage (LPO-lipid peroxide) were also measured (EC10, EC20, and EC50) after exposure for 2, 4, 7, and 14 days. The Comet assay was also applied to assess the level of genetic damage. The activity of CAT and LPO was drastically enhanced by the highest dose (EC50) of DEHP on day two. The activities of GST and AChE in DEHP treatment groups were found to be blocked. In contrast, the activity of CYP450 was significantly enhanced compared to the respective control groups during the first four days of incubation. The Comet assay in F.candida demonstrated that DEHP (EC50) could induce DNA damage. The obtained multi-biomarker data were analyzed using an integrated biomarker response (IBR) index, indicating that limited-time exposure triggered higher stress than long-term exposure at low concentrations of DEHP. These results demonstrate that DEHP may cause biochemical and genetic toxicity to F. candida, which illustrated the potential risks of DEHP in the soil environment and might affect soil ecosystem processes. Further studies are necessary to elucidate the toxic mechanisms of DEHP on other non-target organisms in soil.
Keywords: DNA damage; Di-(2-ethylhexyl) phthalate; Folsomia candida; Integrated biomarker response; Multi-biomarker.
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