Rapid fate of benzophenone in artificial soil and comprehensive toxicity assessment in Eisenia fetida

Benzophenone (BP) is a widely used organic UV filter in personal care products. Despite its frequent detection in soil ecosystems, its toxicity to soil biota has not been extensively explored. This study investigates the effects of BP on earthworms (Eisenia fetida) exposed in artificial soil. Soil degradation kinetics followed a single first-order model at low (1.69 mg/kg) and medium (3.39 mg/kg) concentrations, and a biphasic double first-order in parallel model at high (16.9 mg/kg) concentration. The calculated DT₅₀ (time to 50 % degradation) and DT₉₀ (time to 90 % degradation) ranged from 0.499 days to 2.09 days, and 3.99 days to 7.85 days, indicating rapid elimination in artificial soil. Sublethal BP exposure for 56 days did not affect growth rate or cocoon weight but reduced cocoon production at 3.39 mg/kg and hatchling formation at 3.39 mg/kg and 16.9 mg/kg, indicating reproductive toxicity in E. fetida. Histology studies revealed a concentration-dependent tissue damage in the body wall, intestine, and reproductive organs at 3.39 mg/kg and 16.9 mg/kg. Biochemical analyses showed elevated reactive oxygen species and suppressed glutathione S-transferase and carboxylesterase activities, indicating oxidative stress and impaired BP metabolism. The integrated biomarker response increased on day 7 and day 28 but decreased on day 14, reflecting a time-dependent stress. These changes correlated with altered expression of genes involved in stress response, detoxification, reproduction, and endocrine regulation. The findings indicate that although BP degrades rapidly, prolonged exposure still poses ecological risks to terrestrial biota.