Synthetic musk toxicity to early life stages of zebrafish (Danio rerio)

Synthetic musk substances have been found in a number of environmental samples. Some of these chemicals have been detected in concentrations above I mug/L in water, which raises concern about possible effects on aquatic life. The toxicity of four synthetic musks, 4-tert-butyl-2,6-dimethyl-3,5-dinitrophenylethanone (musk ketone), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene), 1-(5,6,7,8-tetrahydro-3,5,5,6,8,8-hexamethyl-2-naphthalenyl)ethanone (AHTN, tonalide) and 1, 3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta-[g]-2-benzopyrane (HHCB, galaxolide), were studied in zebrafish by the use of two different early life-stage methods. In the first method, specific developmental characteristics during the first 48 hours were studied. In the second method, hatching and survival times were studied on eggs and larvae. The results on heart rate in the first test gave the following LOECs: musk ketone 10 mug/L, musk xylene and AHTN 33 mug/L, and HHCB showed no effect up to 1000 mug/L. In the study of survival time, LOEC for musk ketone was 100 mug/L, for musk xylene 33 mug/L, and AHTN gave no effect on survival time up to 100 mug/L. The LOECs for musk ketone, musk xylene, and AHTN in this study are in the range of what has been measured in sewage effluents and recipients, and consequently these substances may have adverse impact on wild fish.