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

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 overtime (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.