Toxicity of nitromusks in early lifestages of South African clawed frog (Xenopus laevis) and zebrafish (Danio rerio).

Musk xylene (MX), musk ketone (MK) and musk moskene (MM) are synthetic nitro-containing fragrances. Due to their inherent lipophilicity and environmental persistence, they are frequently detected in environmental samples and especially in aquatic ecosystems. Despite this, the current environmental toxicity database of nitromusks is limited. Although nitromusks have been shown to accumulate in aquatic organisms, little is known about their potential developmental effects in the respective aquatic species. To investigate the developmental toxicity of these compounds to amphibians and fish, early lifestages of xenopus (Xenopus laevis) and zebrafish (Danio rerio) were exposed to three nitromusks for 96 h to examine the developmental effects of these compounds in the two species. Nitromusk body concentration measurements were carried out in parallel for correlation with potential developmental effects. No increased mortality, malformation or growth inhibition was observed in either species following 96-h exposure to 400 microg/l MX, MK and MM. However, an approximately 20% reduced viability was observed in xenopus larvae when exposed to 400 microg/l MX, MK and MM for 11 days. Xenopus and zebrafish exposed to 10, 153, 871 and 1637 microg/l 14C-MX for 96 h resulted in whole-body concentrations of 0.7 +/- 0.1, 11.1 +/- 1.1, 38.7 +/- 1.9 and 76.3 +/- 18.3 microg/g, and 4.3 +/- 0.6, 73.3 +/- 11.8, 440.0 +/- 72.7 and 664.0 +/- 47.7 microg/g wet body weight, respectively. Exposure of xenopus larvae to 400 microg/l MX, MK and MM for 11 days, resulted in whole body concentrations (extrapolated from gas chromatographic determinations) of 4700 +/- 5000, 1300 + 300 and 4600 + 4800 microg/g wet weight for MX, MK and MM, respectively. The latter toxicity results, in conjunction with the fact that the concentrations used for the above experiments were between 400- and 10000-fold higher than those detected in the environment, suggest that environmental concentrations of nitromusks are not hazardous for early lifestages of fish and amphibians.