Effects of bisphenol S on the life cycle of earthworms and its assessment in the context of climate change

Abstract

Two of the main challenges facing soil organisms nowadays are emerging contaminants and climate change. The biosolids used in agriculture can contain xenobiotics, such as bisphenols, not regulated in soil. The proven harmful effect of bisphenol A (BPA) has urged the search for replacements such as bisphenol S (BPS) but no studies have tested the effects of this substitute on soil organisms. Our aim was to study the impacts of BPS on the biological cycle of two earthworm species, Dendrobaena veneta and Eisenia fetida, and compare to earlier results with BPA to confirm its suitability as replacement. Moreover, interactions with temperature were investigated, the increase of which is expected due to climate change. Sublethal concentrations (10, 100, 1000 mg kg−1 ) were evaluated by an artificial soil test at 21 °C. Additional tests with D. veneta were performed at 26 °C, to observe whether a 5 °C increase affected the toxicity of BPS in earthworms. In E. fetida, reproduction (number of juveniles and cocoons) was negatively affected by BPS but growth was not negatively impacted. InD. veneta reproduction was not affected and greater growth was detected in the lowest concentration tested only at 26 °C. Increase in temperature showed no interaction on BPS toxicity but had a greater negative impact than the toxicant and adults showed significantly lower growth and reproductive rate at 26 °C. A direct contact test with BPS was performed to evaluate mortality and enzymatic activity of glutathione-S-transferase (GST). The measured enzymatic activity was higher with increasing concentration of BPS at 48 h and 21 °C inD. veneta but not in E. fetida or at 26 °C. Our results suggest that BPS is slightly less toxic than BPA supporting its use as alternative and also highlight the harmful effects that an increase in temperature can have in earthworm populations, exceeding those of certain toxicants.