Mammals disruptors

Depending upon the circumstance and desired effects, endocrine-disrupting chemicals can be either good or bad. The endocrine system is a finely balanced system responsible for fertility and many of the feminine and masculine traits we are all familiar with. Endocrine disruptors are used by millions of women in the form of the pill to control fertility. Chemicals in birth control pills subtly manipulate the endocrine system to reduce fertility. Unfortunately, we now know that many chemicals are capable of influencing the endocrine systems. When these chemicals, such as DDT and TCDD, are released into the environment, they reduce the fertility of wildlife. Exposure to endocrine disruptors is linked to decreased fertility in shellfish, fish, birds, and mammals. Endocrine disruptors such as nonylphenol have been shown to feminize male fish, interfering with reproduction. Some studies have also linked exposure to endocrine disruptors to decreases in human male sperm count. Ironically, urinary metabolites of the birth control pill as well as the female hormone estrogen pass through waste treatment plants and are released into the aquatic environment, where even small concentrations cause feminization of male fish. 

The government has been measuring PCB, HCB, DDT, chlordane, heptachlor epoxide and dieldrin since 1998 to identify their effects on wildlife as part of the Environmental Survey on Endocrine Disruptors. The specimens taken include land animals such as raccoons, bears, monkeys and frog, and marine mammals such as seals and whales, in addition to domestic birds and birds of prey. A relatively high concentration of POPs was seen in birds of prey and Phalacrocorax carbo. Eggs of mountain hawk eagles were also found to have a higher concentration of PCB, DDT, heptachlor epoxide, chlordane and dieldrin than other wildlife specimens... 

Fossi, M. C. and Marsili, L., Effects of endocrine disruptors in aquatic mammals. Pure Appl. Chem., 75( 11-12) 2235-2247, 2003. 

Exposure to xenobiotics raises the risk of male infertility, breast cancer in females, feminization of male animals and the evolution of antibiotic resistant strains of bacteria. Of particular concern are endocrine disruptors such as polychlorinated biphenyls (PCBs), which are chemicals that at certain doses can interfere with the endocrine (or hormone) system in mammals. These disruptions can cause cancerous tumours, birth defects and other developmental disorders. 

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