When sunscreens reach the soil: Impacts of a UV filter on the life cycle of earthworms

Abstract

4-hydroxybenzophenone (4-OHBP) is a UV filter used in sunscreens, perfumery and containers for food products that may end up in soil. The impacts of 4-OHBP in earthworms (Eisenia fetida and Dendrobaena veneta) were investigated. To prove the consequence of its direct application on earthworms' epidermis, a contact test (48 h) was performed. Significant mortality was already observed at 4-OHBP concentrations of 2 mg ml−1 at 24 h, and juveniles showed higher mortality than matures at 0.2 and 0.02 mg ml−1. In order to investigate the effects in their natural habitat, a soil test was performed with mature earthworms. Results showed that reproduction success of E. fetida was impacted by the toxicant. The number of hatched juveniles (EC50 = 152.68 mg kg−1) and the number (EC50 = 94.05 mg kg−1) and weight of unhatched cocoons decreased with an increasing concentration of 4-OHBP. The LC50 for E. fetida at 28 days was 1800.12 mg kg−1, but LC50 and EC50 values could not be calculated for D. veneta adults because of lack of effect. For the latter, the soil test was continued with juveniles in a transgenerational study showing that their mortality increased with 4-OHBP concentrations above 10 mg kg−1 (LC50 = 72.02 mg kg−1 at 7 days and 19.49 mg kg−1 at 14 days). Results showed that 4-OHBP is harmful for both species, by causing reproduction decrease for E. fetida adults (F0) and mortality increase for D. veneta juveniles (F1). However, concentrations at which 4-OHBP affects earthworm populations are much higher than those reported in the environment, and therefore, there seems to be no risk for them, except in case of accidental spill.