Eco-toxicological effect of polycyclic musks for C. elegans

Laundry detergents, soaps and cosmetics often include fragrance compounds such as 7-acetyl1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydro naphthalene (AHTN) and 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8hexamethylcyclopenta-γ-2-benzopyran (HHCB), that are polycyclic musks (PCMs). We assessed the potential toxicological effects associated with AHTN and HHCB using Caenorhabditis elegans (C. elegans) as a model soil organism. We examined changes in the test endpoints of growth and maturation such as body length, ratio (%) of gravid worms and fecundity. The 50% lethal concentrations (LC50) in C. elegans were >255.2 mg/l (AHTN) and >194.6 mg/l (HHCB), respectively. Growth tests showed that the lowest observed effective concentrations (LOEC) of AHTN and HHCB in C. elegans were 12.8 and 9.8 mg/l, respectively. The estimated LOEC values in maturation tests were 6.4 mg/l for AHTN and 9.8 mg/l for HHCB. The estimated LOEC for HHCB in reproduction tests was 19.5 mg/l, but this could not be determined for AHTN. We also investigated the suitability of the DNA microarray as an eco-toxicogenomic approach to determine the physiological function of PCMs in C. elegans. Both AHTN (25.5 mg/l) and HHCB (19.5 mg/l) were examined mainly as cytochrome P450 (CYP) gene expression using a customized chip for C. elegans. Among 79 CYP genes, 26 and 17 were up-regulated upon exposure to AHTN and HHCB, respectively.