Galaxolide and tonalide modulate neuroendocrine activity in marine species from two taxonomic groups.

Galaxolide (HHCB) and tonalide (AHTN) are polycyclic musk compounds (PMCs) used in household and personal care products that have been included on the list as emerging contaminants of environmental concern due to their ubiquity in aquatic and terrestrial environments. There still exists a dearth of information on the neurotoxicity and endocrine disrupting effects of these contaminants, especially for marine and estuarine species. Here, we assessed the neuroendocrine effects of HHCB and AHTN using adult clams, Ruditapes philippinarum, and yolk-sac larvae of sheepshead minnow, Cyprinodon variegatus. The clams were treated with concentrations (0.005-50 µg/L) of each compound for 21 days. Meanwhile, sheepshead minnow larvae were exposed to 0.5, 5 and 50 µg/L of HHCB and AHTN for 3 days. Enzyme activities related to neurotoxicity (acetylcholinesterase - AChE), neuroendocrine function (cyclooxygenase - COX), and energy reserves (total lipids - TL) were assessed in R. philippinarum. Gene expression levels of cyp19 and vtg1 were measured in C. variegatus using qPCR. Our results indicated induction of AChE and COX in the clams exposed to HHCB while AHTN exposure significantly inhibited AChE and COX. Gene expression of cyp19 and vtg1 in yolk-sac C. variegatus larvae exposed to 50 µg/L AHTN was significantly downregulated versus the control. The results of this study demonstrate that HHCB and AHTN might pose neurotoxic and endocrine disrupting effects in coastal ecosystems.

Avoidance behaviour of the shrimp Palaemon varians regarding a contaminant gradient of galaxolide and tonalide in seawater.

The musk fragrances galaxolide (HHCB) and tonalide (AHTN) are compounds of emerging concern that have been found in various environmental compartments. The present study addressed the ability of HHCB and AHTN to elicit the avoidance response in the estuarine shrimp Palaemon varians and to predict the population immediate decline (PID) of P. varians when exposed to HHCB and AHTN by integrating both avoidance (non-forced exposure) and lethality (forced exposure) responses. The avoidance response was tested in a non-forced multi-compartmented static system, in which the shrimps could move freely among the compartments with different concentrations. The shrimps (n = 3 shrimps per compartment/concentration; 18 shrimps per system) were exposed to a gradient (0, 0.005, 0.05, 0.5, 5 and 50 µg/L) of both substances and their positions were checked at every 20 min for a 3 h period. The results from 24-h forced exposure showed no dose-response relationship and the highest percentage mortality was 17% for HHCB at 0.005 and 0.5 µg/L. In the 3-h non-forced exposure to a gradient of HHCB and AHTN, significant concentration-dependent spatial avoidance was observed for both substances. The shrimps avoided the lowest concentration of HHCB and AHTN (0.005 µg/L) by 15% and 16%. The avoidance increased significantly (p < 0.005) to a 61% and 57%, respectively, for the highest concentration (50 µg/L). The population immediate decline was driven by the avoidance behaviour of the shrimps rather than mortality. These results indicated that the aversiveness of HHCB and AHTN might have serious consequences for habitat selection processes by organisms.