Polycyclic aromatic compounds are ubiquitously distributed pollutants in the aquatic and terrestrial environment containing harmful properties on creatures such as carcinogenicity, teratogenicity and toxicity, but are not so well analyzed yet.
In the present study, the embryotoxic and teratogenic effects of selected hydroxylated and methylated PACs on the embryonal development of Danio rerio as an aquatic model organism were analyzed with the Fish Embryo Toxicity Test (FET) and the Tail Length Test (TLT) to obtain information on the toxic and teratogenic impact of the tested PACs on the environment.
Two of the five tested PACs, 9-MA and DMBA, showed embryotoxic respectively teratogenic effects on the embryonal development of the zebrafish. The embryotoxicity of 9-MA was indicated in the high mortality rate of the exposed zebrafish embryos, whereas the teratogenic effect of DMBA was revealed in the emergence of sub-lethal malformations during the embryonal development such as a shortened tail length, tail curvatures, tail tip deformity or the formation of edema on the yolk sac and pericard as well as abnormal heartbeat and blood circulation.
The high mortality rate of the zebrafish embryos exposed to 9-MA did not increase over the exposure time of 96h, which suggests that the chorion of the zebrafish egg could not protect the embryo at all against the strong embryotoxic effect of 9-MA.
The sub-lethal malformations of the zebrafish embryos exposed to DMBA could be induced to the metabolic activation of AhR-agonist DMBA through the AhR-pathway or the accumulation of the neurotransmitter Acetylcholine due to the inhibitory function of DMBA on the ACh-Esterase, which caused a neuromuscular system defect or uncontrolled contractions of the axis musculature.
Further research, may focus on the mode of action of PACs such as 9-MA and DMBA and their impact on organisms in order to take reasonable precautions to avoid or to diminish the uptake of PACs from the environment.