Unravelling the developmental toxicity of heavy metals using zebrafish as a model: a narrative review.

Developmental toxicity is the disruption of an organism's normal development which may occur in either the parent before conception or in the growing creature itself. Zebrafish (Danio rerio) are being employed as effective vertebrate models to evaluate the safety and toxicity of chemicals because they can breed multiple times in a year so we can observe the toxic effects in the next generation and their development mental stages can be observed and define clearly because their 1 cell stage to prime stage is transparent so we can observe the development of every organ also they have nearly about 80% genetic similarity with humans and shares the similar neuromodulatory structure along with multiple neurotransmitter. The recent research endeavours to examine the harmful outcome of various heavy metals such as cadmium, chromium, nickel, arsenic, lead, mercury, bismuth, iron, manganese, and thallium along with microplastics on zebrafish embryos when subjected to environmentally acceptable levels of every single metal in addition to co-exposure at various points in time. These heavy metals can alter the mRNA expression levels, increase the reactive oxygen species (ROS) generation, decrease antioxidant expression, damage neuronal function, alter neurotransmitter release, alter the expression of several apoptotic proteins, interfere with the different signalling pathways, decrease heat rates, increase malformations like - pericardial oedema, heart oedema, reduce in length tail bending abnormal formation in fins. Thereafter we concluded that due to its involvement in the food chain, it also causes severe effects on human beings.