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. Graphical abstract