Endocrine disrupting compounds and human fertility Essay

In the past 100 years, humans have introduced several hundreds of new compounds into the environment, which actually have affected the physiology of both plants and animals including humans (Propper, 2005). In most cases these deleterious effects are unintended and it was not predicted before that these compounds could have such effects on organisms. Therefore the actual mechanisms by which these compounds affect physiological functions of other organisms are not yet properly researched. When such compounds affect the endocrine systems they are called endocrine disrupting compounds. These compounds would affect different hormonal pathways and physiological functions such as reproduction, development, metabolism and even the behavior of humans and other animals. The present essay is intended to identify some of the endocrine disrupting compounds that affect human fertility, the mechanism of affecting, to analyze the weight of different evidences available and to analyze the current investigation techniques. Endocrine disrupting compounds have been defined as â€Å"an exogenous agent that interferes with the synthesis, secretion, transport, binding, action, or elimination of natural hormones in the body which are responsible for the maintenance of homeostasis, reproduction, development and/or behavior† (Kavloc et al. , 1996). The United States Environmental Protection Agency (USEPA) has accepted this definition as the most appropriate one in the year 2004. These compounds are capable of interfering with normal signaling mechanisms of the endocrine system. Either they could block or make changes in the synthesis of hormones, or they could mimic some of the endocrine compounds, thereby affecting the target organs. They could also affect the release of these hormones from the concerned glands and its transportation. They could also bind with the specific molecules to which hormone binds. These compounds are usually seen in pesticides, industrial effluents, pharmaceutical compounds, etc. Heavy metals also could induce endocrine disruption. Wastewater effluents from cities as well as from agricultural fields are sources of such compounds. The neuro- endocrine system might also get affected by these compounds causing changes in the reproductive organs and associated behaviors in humans. Most of the researches in this filed are concentrated towards the effect of these compounds on estrogen and other steroids responsible for reproduction (Propper, 2005). According to Caserto et al. (2008) these compounds could affect human heath seriously even when present in very small amounts. This is especially because many such chemicals would be these affecting a single target. There are many studies which reveal that waste water discharge in to natural waters have resulted in the changes in reproductive organs of aquatic fauna. This is because of the presence of 17 beta estradiol, estrogens, androgens, etc, in wastewater. These compounds are highly stable and therefore could not be removed completely from wastewater by various treatment procedures to reclaim the water. Traces of these compounds would be present in the drinking water, which is prepared from these natural waters into which the wastewater has been disposed. Bioaccumulation of these compounds in humans is expected to affect fertility (Falconer, 2006). Wagner and Oehlmann (2009) have conducted a study to determine the level of endocrine disrupting compounds in usual food stuffs of humans and they selected bottled mineral water as one of the sources of this compounds. The effort was taken based on the fact that endocrine disrupting hormones reaches the body of human mainly through foodstuffs. They used estrogen receptor alpha for the identification. They found that the mineral waters in plastic bottles are seriously contaminated with phthalates that are getting leached into the water from plastic bottle. Thus it was proved beyond doubt that endocrine disrupting compounds are present in plastic wares and extensive use of plastic wares to store food would result in increased level of these compounds in the foodstuffs with a deleterious effect on fertility. According to Rhind (2005) there is an urgent need to study the effects of endocrine disrupting compounds on animals. Very little is known regarding the concentration of these compounds in the different tissues of animals, the concentration required to produce a deleterious effect on the animals, effect of prolonged exposure to an single compound, the effects of different classes of compounds, effect of the exposure to more than one compounds at a time etc. With the available information it is possible to establish that the endocrine disrupting compounds in the environment is affecting human health adversely with a high impact on fertility. The effect of these endocrine disrupting compounds on human reproduction is different for different compounds. Compounds such as diethylstilbestrol affect female reproductive system and cause abnormal follicular growth, ovulation, abnormal formation of corpus luteum and the overall maintenance of ovary would be affected. It would also affect the normal sexual differentiation in females. Pregnancy would be affected because of the negative effects on fertilization and implantation of the embryo in the uterus. Another pollutant called dioxin has been reported to cause endometriosis in women, which is a very painful disease that leads to infertility (Crisp et al. , 1998). There are some compounds, which are naturally occuring such as phytoestrogens produced by plant that could mimic the properties of estrogens produced by humans (Caserta et al. , 2008). Natural sex hormones are used extensively for different purposes in farms as well as in urban areas and there is every chance that these would become harmful to non-targeted organisms including humans because of the concentrating effect. There are many evidences, which prove that environmental contaminants are causing problems in female fecundity as well as fertility (Louis et al. , 2006). There are evidences to prove that puberty, menstruation, endometriosis, pregnancy, senescence period for reproduction etc are affected by exposure to these compounds. Diethyl stilbestrol was given to pregnant women during 1950’s to prevent miscarriage. But later on due to the adverse effects of these compounds most of the kids developed abnormalities. Finally the compound was withdrawn from the market. The female child produced in such cases developed menstrual abnormalities, vaginal hypoplasia, sudden abortion, premature delivery, uterine malformation and overall low fertility. If the child is a male, it was found to develop testicular dysgenesis syndrome (Milhan 1992). Maternal exposure during pregnancy and exposure to these compounds present in the mother’s milk during the prenatal period are believed to be the reasons for such defects. This occurs due to the lipophilic nature of these compounds, which in turn gets stored in the adipose tissues of the mother. This is one of the strongest evidences of the deleterious effect of these compounds on human reproductive system. There are reports that state that human sperm production has decreased in the past 50 years. Although accurate evidence is not there, the reasons for this decrease is attributed to the presence of endocrine disrupting compounds in the environment (Crisp, 1998). Leydig cells tumors are increasingly believed to be caused by this factor. Same is the case of prostrate cancer. Studies conducted in Coke-oven workers have revealed that there has been an increase of mortality among them due to prostrate cancer due to occupational exposure to these compounds. However more research is required to find out the actual cause of this cancer, whether it is due to endocrine disruption by any chemicals in the environment.