Shorter lifetime of a soil invertebrate species when exposed to copper oxide nanoparticles in a full lifespan exposure test

Abstract

Toxicity tests that last the all life duration of the organisms are not common, instead, long-term tests usually include one reproductive cycle. In the present study we optimized and propose a lifespan (all life) term test using Enchytraeus crypticus (Oligochaeta). The effect of copper oxide nanoparticles (CuO-NPs) was assessed in this lifespan test and compared to copper salt (CuCl2), using the same effect concentrations on reproduction (EC50). Monitored endpoints included survival and reproduction over-time (202 days). Results from survival showed that CuO-NPs caused shorter life of the adults compared to CuCl2 (control LT50: 218 days > CuCl2 LT50: 175 days > CuO-NPs LT50: 145 days). The effect was even more amplified in terms of reproduction (control ET50: 158 days > CuCl2 ET50: 138 days > CuO-NPs ET50: 92 days). Results suggest that CuO-NPs may cause a higher Cu effect via a trojan horse mechanism. The use of lifespan tests brings a novel concept in soil ecotoxicity, the longevity. This is a particularly important aspect when the subject is nanomaterials toxicity, where longer term exposure time is expected to reveal unpredicted effects via the current short/long-term tests. The present study confirms this higher effect for CuO-NPs.