Ecotoxicological assessment of galaxolide and tonalide as contaminants of emerging concern in marine ecosystems

Abstract

The polycyclic musk compounds Galaxolide (HHCB) and Tonalide (AHTN) are the most frequently consumed fragrance materials applied in many household and personal care products. These substances have been detected in all environmental compartments and, due to their inherent lipophilicity, they easily bioaccumulate in aquatic organism. The aim of this PhD thesis was to assess the risk of environmental concentrations of HHCB and AHTN in the marine environments. In order to provide a more complete assessment on marine biota, empirical approach based on data of ecotoxicological assays was explored based on environmental risk assessment (ERA) scheme. In this case, it was intended to employ organisms from different trophic levels like microalgae, echinoderms, bivalves, shrimps, and fish. This diversification in the species allows assessing how organisms with different biological complexity can be affected. In addition, different endpoints were used for each species, taking as basis the sensitivity and relevance of the endpoints. Another important aspect considered to select the endpoints was their level of biological organization, so that the responses measured were based on acute and chronic exposure, focusing on growth, survival, development, behaviour, and biomarkers at the biochemical and molecular levels. The results obtained in this thesis show that environmental concentrations of both compounds are detrimental to microalgae growth posing significant risk to Phaeodactylum tricornutum and Isochrysis galbana. It was also observed that environmental concentrations of HHCB and AHTN significantly altered the early life stages endpoints such as fertilization, larval development, and survival in tested species. Furthermore, this thesis has proven that in a scenario of heterogenous pollution where lethality is not expected to occur, HHCB and AHTN may trigger spatial avoidance, which might reduce the local biodiversity of ecosystems due to emigration to safer environments. Sublethal effects assessed in bivalves after chronic exposure to HHCB and AHTN showed that these substances are bioavailable to marine organisms and they have the potential to induce oxidative stress, genotoxicity, neurotoxicity and alter the health status of marine organisms. It was also observed that both compounds modulated endocrine disruption biomarkers in small fish. Despite the significant alterations in endocrine disruption biomarkers induced by both compounds, AHTN appeared to be a more potent inhibitor of endocrine activity in the marine environments. This PhD Thesis has demonstrated the adverse effects of environmental concentrations of HHCB and AHTN in marine ecosystems. Therefore, the data presented in this study should be integrated with other available data required for policy actions that will aid the conservation and management of the sea.