Environmental Toxicology deals with the deleterious effects of anthropogenic pollutants and ionising radiation on plants, animals, and humans. Specific industrial and agricultural chemicals might cause mutagenic, teratogenic and, carcinogenic expressions of genes. Obviously these outcomes indicate that genetic defense mechanisms failed to overcome or to repair gene damage. Gene expression is regulated by structural and chemical modifications of DNA. Anthropogenic pollutants might interfere with the gene regulatory network. The existence of homologue genes shared by some animals and humans enables us to investigate the pathological effects of pollutants on animal models and to relate these relevant mechanisms to humans. This presentation will demonstrate various deleterious mechanisms of harmful chemicals that cause obesogenic, endocrine disruptive, and carcinogenic effects.