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 nitr o-containing fragrances. Due to their inherent lipophilicity and environmen tal persistence, they are frequently detected in environmental samples and especially in aquatic ecosystems. Despite this, the current environmental t oxicity database of nitromusks is limited. Although nitromusks have been sh own to accumulate in aquatic organisms, little is known about their potenti al 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 ex posed to three nitromusks for 96 h to examine the developmental effects of these compounds in the two species. Nitromusk body concentration measuremen ts were carried out in parallel for correlation with potential developmenta l effects. No increased mortality, malformation or growth inhibition was ob served in either species following 96-h exposure to 400 mu g/l MX, MK and M M. However, an approximately 20% reduced viability was observed in xenopus larvae when exposed to 400 mu g/l MX, MK and MM for 11 days. Xenopus and ze brafish exposed to 10, 153, 871 and 1637 mu g/l C-14-MX for 96 h resulted i n whole-body concentrations of 0.7 +/- 0.1, 11.1 +/- 1.1, 38.7 +/- 1.9 and 76.3 +/- 18.3 mu g/g, and 4.3 +/- 0.6, 73.3 +/- 11.8, 440.0 +/- 72.7 and 66 4.0 +/- 47.7 mu g/g wet body weight, respectively. Exposure of xenopus larv ae to 400 mu g/l MX, MK and MM for 11 days, resulted in whole body concentr ations (extrapolated from gas chromatographic determinations) of 4700 +/- 5 000, 1300 +/- 300 and 4600 +/- 4800 mu g/g wet weight for MX, MK and MM, re spectively. The latter toxicity results, in conjunction with the fact that the concentrations used for the above experiments were between 400- and 100 00-fold higher than those detected in the environment, suggest that environ mental concentrations of nitromusks are not hazardous for early lifestages of fish and amphibians. (C) 1999 Elsevier Science Ireland Ltd. All rights r eserved.