Dottorato in MALATTIE INFETTIVE, MICROBIOLOGIA E SANITA' PUBBLICA

Titolo della tesi: LETHAL AND SUBLETHAL EFFECTS ON ZEBRAFISH EMBRYOS SUPPORTING HUMAN HEALTH PROTECTION

The aim of my thesis is to evaluate the efficacy and sensitivity of sublethal endpoints than lethality in fish embryos, in order to detect the effects of mixtures of contaminants in environmental samples and emerging contaminants. For this purpose, in the first year, we have performed with my colleagues of ISS a specific literature review in order to critically evaluate previous studies that adopted early life stages of zebrafish (i.e. embryos and early larvae) as innovative experimental models for identifying and investigating the ecotoxicological profiles of chemicals that are listed as priority or emerging substances under the WFD. The work has been published in Microchemical Journal in 2019. In the other two years, experimental studies have been performed on zebrafish embryo, in particular we applied the acute Fish Embryo Toxicity (FET) test on environmental samples (river Tiber), focusing on the sub-lethal endpoints detected. Therefore in the first part of the experiments we wanted to compare the acute lethality test with the sublethal responses, in the second part, however, we developed a protocol for the detection of neurotoxic substances in the environment proposing a valid and at the same time and a rapid endpoint to detect, the early movement of the embryo's tail called Coiling Activity Test (CAT). The protocol was accepted by the reviewers and is in publication (Lacchetti et al., 2021 in press). Finally, it was applied and tested on a river sample and an emerging compound (liquid of e-cigarette). The sublethal effects are demonstrated a valid tool expecially in early warning systems, they are also strategic for the detection of indirect effects caused by climate changes on human health. Furthermore, the CAT could be improved through the knowledge on the different patterns of chemical substances combining this method with other EBMs mentioned in this article, e.g. AChE, Locomotion and FET test. Finally, the CAT could make a valuable contribution to implementing EU regulatory guidelines and strategies for identifying neurotoxic risks in the ecosystem and for this reason its forthcoming harmonization and standardization of method would be required.