ABSTRACT
More than 60% of the 100,000 man-made chemicals are in routine use worldwide since 1990s. Every year 200 to 1,000 new synthetic chemicals enter the market (Shane, 1994). Over 900 of these chemicals are identifi ed as established or potential endocrine disrupters (Soffker and Tyler, 2012). The chemicals that either mimic or antagonize the actions of endogenous hormones are known as endocrine disrupters or Endocrine Disrupting Chemicals (EDCs) (Hiramatsu et al., 2006). After use in domestic (into sewage), agricultural (e.g., pesticides, fungicides, herbicides) and industrial (e.g., 4-Nonylphenol) sectors, hundreds of estrogens and their mimics are discharged into aquatic habitats. These EDCs are broadly grouped as: 1. Natural and synthetic estrogens, 2. Phytoestrogens, 3. Mycoestrogens, 4. Phthalates, 5. Pesticides, 6. Herbicides and Fungicides, 7. Plasticizers, 8. Food antoxidants, 9. Organohalines and 10. Estrogen receptor modulators. Scholz and Kluver (2009), Iwanowicz and Blazer (2011) and Brander (2013) have listed some of them. For a list of robust estrogen-sensitive genes, Gunnarsson et al. (2007) may be consulted. As brain aromatase activity is up to 1,000 times higher in fi shes than that of mammals, fi shes are more susceptible to negative effects of estrogenic EDCs (Mills et al., 2014). Similarly, as many as 15 synthetic androgens (Soffker and Tyler, 2012) and antiestrogenics (e.g., industrial biproducts like β-sitosterol) are also released into waters; they are listed by Babin (1992), Pait and Nelson (2002) and Brander (2013). Briefl y, the EDCs may be grouped under: (i) chemicals that mimic endogenous hormones (e.g., endosulfan, Balasubramani and Pandian, 2008a), (ii) chemicals that
antagonize endogenous hormones (e.g., tributyltin [TBT], Balasubramani and Pandian, 2008b), (iii) chemicals that alter synthesis and metabolism of endogenous hormones (e.g., Barse et al., 2006) and (iv) chemicals that modify endogenous hormones (Sonnenschein and Soto 1998).
