Hydra as an alternative model organism for toxicity testing: Study using the endocrine disrupting chemical Bisphenol A

In the recent times use of vertebrate animal models in the toxicity testing of chemical entities has come under criticism and surveillance in view of lack of relevance as surrogates to humans and also ethical considerations. Though in vitro and in silico tools can obviate animal models in toxicity testing, use of some simple organisms, the sentience level of which is not a big issue, as animal model is also considered pertinent. Hydra, a simple freshwater cnidarian is already a model organism for studies in developmental biology, and is also thought to be suitable for environmental toxicity assessments. Our group has conducted studies along this direction and found it appropriate for testing a few bulk as well as nano-materials. In the present study, we have tested Bisphenol A (BPA), an environmental chemical which is also an endocrine disruptor, in Hydra towards furtherance of biotechnological application of this simple organism. We worked out the LC50 of BPA adopting the morphological assay. Effective sub-lethal doses were fixed and tested for toxicity adopting regeneration and feeding assays. Since the anatomy of Hydra is such that all the cells in its two body layers can potentially be continuously exposed to the toxicant present in the water, the present study justifies another of its application viz., environmental risk assessment.