Information about Endocrine Disruptors - Research Paper Example

?Running head: Air pollution and endocrine disruptors Air Pollution and Endocrine Disruptors Endocrine disruptors mimic hormones in the bodies of humans. These chemicals interfere with the action of hormones and upset normal growth, behavior, and the reproduction of wildlife. However, studies claim that these disruptors also affect humans, not just wildlife. Our endocrine system helps manage our growth, development, and the interaction of our organ systems. Interruptions to this system can cause disruptions and disturbances to our normal processes. Such disruptions manifest among humans with most affectations in the male and female reproduction systems. The US EPA has set forth the screening of thousand of chemicals in order to screen endocrine disruptors before they are introduced to the human body. This screening program has proven to be problematic because of the bulk of chemicals which have to be screened. There are thousands of disruptors which have to be tested and testing them cannot adequately be carried out without incurring high costs which the government agencies and laboratories cannot afford. Nevertheless, these tests help establish clear guidelines and standards for government officials and the general public in the assessment of these products and their use by the general public. There are advantages and disadvantages to these tests; mostly these tests are advantageous because they help determine the health impact of chemicals to the general health of the population. The validation of chemicals and the investigation of the disruptor effects to the endocrine system can be determined through in vitro and in vivo assays. However, carrying out these tests can also be disadvantageous because of the practical considerations for testing. In effect, there is a need for the government to be more prudent and selective in the programs it would implement to evaluate these chemicals. Moreover, people also need to be more cautious about the chemicals they use because they can have negative impacts on both humans and animals. Introduction We are currently in the midst of an era where we are facing various environmental issues. The Global Warming phenomenon has been explained and explored by various experts and politicians as a major cause of concern to our planet because of its growing impact on all living things. One of these issues pertains to air pollution and their effects to our human physiology. Air pollution largely affects our respiratory system because chemical and air-borne toxins enter our body through inhalation. The respiratory system then helps to process the inhaled gases while exchanging carbon dioxide for oxygen which is crucial to our survival. This paper shall consider the role of air pollution in terms of chemical endocrine disruptors which mimic the hormone in our bodies. These chemicals seem to interfere with the actions of hormones – mimicking behavior and upsetting normal growth, behavior, and reproduction of wildlife. This paper shall explain how endocrine disruptors enter the cells. It shall evaluate if these compounds also harm people and how they affect the human body. This paper shall also discuss the pros and cons of the Environmental Protection Agency (EPA) screening thousands of chemicals that are used as endocrine disruptors before they are introduced to the human body. It shall discuss this student’s opinion on whether EPA is right in conducting the screening. This paper is being carried out in order to establish a clear and comprehensive assessment of these endocrine disruptors and their impact on the human body. Body There are various chemical toxins which enter the lungs and the respiratory system and which affect the endocrine and the normal processes of our body. Some of these chemicals are known as endocrine disruptors. These chemicals are often seen in our daily use products, including “plastic bottles, metal food cans, detergents, flame retardants, food, toys, cosmetics, and pesticides” (NIH, 2006, p. 1). There is limited knowledge on the impact of these chemicals to human health; however, concerns have been raised on the negative impact of these products on wildlife species even at low levels. On its simplest conceptualization, endocrine disruptors are man-made or natural chemicals which interfere or disrupt the production and the function of the endocrine system – causing negative health consequences. Some of these chemicals have been known to affect developmental and reproductive processes of wildlife and of laboratory animals (NIH, 2006). Some claims have been made on these chemicals affecting human health, causing lower fertility, and increasing the prevalence of cancers. Our endocrine system is crucial in establishing and protecting our body’s communication networks; it is also responsible for controlling our body functions through hormones (NIH, 2006). They are produced first by the endocrine organs and tissues in the ovaries, testes, pituitary, thyroids, and pancreas; and then released into the blood in order to function as chemical messengers. These hormones help control our energy levels, reproduction, growth and development, internal balance, and our responses to stress and injury (NIH, 2006). The disruptors interfere with the body’s hormone signals, and cause gaps and disruptions in the normal communication process of cells. Endocrine disrupting compounds are exogenous agents which interfere with the synthesis and binding actions of hormones which are present in the body for homeostasis and developmental process (Diamanti-Kandarakis, 2009). These endocrine disruptors affect nuclear receptors, nonnuclear steroid receptors, nonsteroid receptors, orphan receptors and enzymatic pathways involved in steroid synthesis and metabolism. Endocrine disruptors are compounds which change the normal processes of the body. They contain halogen group substitutions through chlorine and bromine and they have qualities which mimic natural steroid hormones which enable interactions with steroid hormone receptors like analogs and antagonists (Diamanti-Kandarakis, 2009). Some of these EDCs have been known to have long half-lives which have served beneficial purposes for industries, but detrimental effects for wildlife and humans. These compounds do not decay easily and may not be metabolized. These disruptors have been known to mimic or partly mimic the naturally occurring hormones in the body, such as estrogen, androgens and thyroid hormones, thereby causing overstimulation in the female and male reproductive systems (NIH, 2006). They also bind to a receptor within the cell and then prevent the endogenous hormone from binding. Consequently, the normal signs do not occur and the system does not respond as it should. These disruptors are known to be anti-estrogens or anti-androgens. They are also known to block the natural path of the hormones or the receptors of these hormones – such as in instances when the metabolism of the liver is blocked (NIH, 2006). In effect, these disruptors significantly affect the overall function of the hormones and alter normal bodily processes. They significantly impact on the normal processes of animals and other wildlife. Various studies have revealed that these effects are also significant among humans. Although more studies are needed in support of these results, the basic groundwork for research has laid out significant ideas which imply relevant theories in understanding the processes. In a study by Warring and Harris (2005), the authors set forth that compounds which can affect any species can also potentially impact on humans. What is unsure are the levels at which these impact on humans. Various factors have to be considered in order to establish a clear answer to the query on levels of impact. For one, the human body has active detoxifying elements and is therefore less vulnerable to environmental toxins. The studies which have been undertaken on animals reveal that animals are not the best models to compare reproductive toxicity in humans. Nevertheless, granting that the pathways are similar to each other, then the impact of these disruptors would be similar to the impact on humans (Warring and Harris, 2005). Damage caused by the disruptors on neuronal development can result in long-term dysfunction in later life (Warring and Harris, 2005). As revealed by studies on seals and polar bears, altered T-cell functions are seen in polluted coastal waters and postnatal exposure to disruptors among Dutch school children was linked to diminished immune functions (Warring and Harris, 2005). Neurodevelopmental impact was manifested as a result of environmental contaminants; and many studies have revealed that a person’s memory and learning seem to be affected by these disruptors. In general, the NIH (2006) sets forth the following as effects of disruptors on animals: reductions in male fertility and lower number of males born; abnormalities in male reproductive organs; reproductive issues among females, including fertility problems, early puberty, and early reproductive senescence; increase in mammary, ovarian, and prostate cancers (NIH, 2006). The impact of disruptors on human beings has mostly been seen on the reproductive system. In a study by Skakkebaek, et.al., (2001) the authors set forth that diminished semen quality and male urogenital tract anomalies may go through the same causal pathways. They hypothesized that disruptors and other environmental chemicals may cause abnormal development of fetal testis, causing testicular dysgenesis that can lead to a higher rate of urogenital abnormalities in newborn males as well as decreased semen quality in young men (Skakkebaek, et.al., 2001). They were able to establish a strong link between male reproductive health issues with the disruptor compounds and similar environmental chemicals. Studies have also revealed that disruptors like phthalates seem to contribute to a decreased semen quality (Diamanti-Kandarakis, 2009). Phthalates are chemicals usually utilized for industrial applications and mostly as plasticizers in the manufacture of flexible vinyl plastic for flooring and wall coverings. Human exposure to these phthalates is mostly through ingestion, inhalation, and skin contact. Epidemiological studies on phthalates and semen quality have revealed that there is a relationship between monobutyl phthalate and subfertile male partners. There was also an apparent dose response relationship between monobenzyl phthalate and sperm concentration (Diamanti-Kandarakis, 2009). In a study which compared male partners of pregnant women, assessing their urinary concentrations of pesticide biomarkers in men with sperm concentration below the normal levels, authors found elevated concentration of endocrine disruptors in their urine. In other studies, sperm motility was also significantly affected (Diamanti-Kandarakis, 2009). Although this study reveals results which imply the significant impact of disruptors on the male reproductive system, the authors nevertheless recommend more studies to be undertaken on the subject matter in order to establish clearly the different patterns which imply more comprehensive results. An important factor to consider in the assessment of the impact of disruptors is the fact that individual differences in a person’s metabolism and body composition may affect the disruptor’s impact on the human body. Therefore, the impact of a disruptor is distinct to each person, depending on individual differences in metabolism; body composition; degradation of body fluids and tissues; genetic polymorphisms; chronic exposure to low amounts of disruptors; latency between exposure to the disruptor; and the occurrence of clinical disorders (Diamanti-Kandarakis, 2009). Environmental Protection Agency There are various pros and cons in the EPA setting forth screening for endocrine disruptors before they even enter the body. Animal tests proposed are classified into in vivo tests (to identify endocrine disrupting chemicals) and existing test guidelines (reproductive and developmental toxicity tests) supply data using standard or slightly enhanced protocols (Baker, 2001). The issue of endocrine disruption is one which is important to the public and to regulators. The causal link between the environmental exposure to specific chemicals and negative health effects on humans has not been fully established. More research is needed in order to fully evaluate the adverse effects from exposure to endocrine disrupting chemicals (Baker, 2001). More focus is also needed in order to consider additional endpoints in relation to the central nervous system and to conceptualize test methods for potential targets. There is also a need to specify the impact of mixtures in resolving low-dose effects of these disruptors. More effort has been given in the past few years on the detection of endocrine disrupting chemicals, when used in combination and in characterizing mechanisms of action and potency (Baker, 2001). In vitro assays do not always reliably indicate outcomes in vivo due to issues in metabolic capabilities of the test systems and because of the diverse mechanisms by which disruptors may act. There is also no single in vitro test which can detect all the elements of a hormonally active substance (Baker, 2001). There are complicating factors in the EPA’s screening tests and these factors prevent the test from actually protecting public health. One factor is related to the practical considerations of the disruptor tests. There are about 87,000 endocrine disruptors, testing all of these chemicals would require a considerable amount of time and resources; even when these chemicals are prioritized, they would still require more time and money than can be afforded by the EPA (Vogel, 2004). Another complication is on hazard complexity. Establishing the relationship between the disruptors and health hazards is a more difficult undertaking. Endocrine disruptors do not exactly follow similar patterns as other toxic chemicals and chemical regulation (Vogel, 2004). Without establishing simple assumptions, science cannot adequately determine cause and effect efficiently or with certainty. Another complication is related to exposure complexity. Establishing the degree of exposure is important but difficult because the low-dose impact of some disruptors implies that low-dose and temporary exposure can also be as dangerous as high-dose and prolonged exposure (Vogel, 2004). Different evaluations disregard these inadequately defined exposures, however such exposures cannot be considered insignificant. Another complication involves regulatory deficiencies. Even as the EPA created new offices and units in order to evaluate endocrine disruption, they did not provide for new authorities in the management and regulation of these disruptors. Consequently, numerous government agencies have been prompted to manage future test-positive disruptors under their purview through incomplete statutes and standards (Vogel, 2004). In effect, there is a significant amount of confusion in the institutional and decision-making aspects of the disruptor screening management framework. The EPA should conduct the screening for selected disruptors only because the process for carrying out a lengthy screening for each disruptor is long and tedious. Moreover, it cannot afford to carry out such tests for all these chemicals. It is already apparent that no chemical regulatory program has ever been able to successfully test all these chemicals. There are too many impracticalities in the process of screening which need to be resolved before the process can be successfully carried out for all chemicals. In the meantime, the EPA is hemorrhaging resources on a process which can only yield inadequate results. There are 20,000 pesticides and endocrine disruptors in the market which are being reviewed and only about 31 of these are being reviewed for registration. If these disruptors would all be reviewed, it would reach the year 15, 520 AD before such a review would be completed (Vogel, 2004). Moreover, even if there are resources to carry out the screening process, there are not enough facilities and laboratories in the country to carry out the tests. There is much doubt in our capability to carry out the goals of the disruptor screening. Moreover, the country’s best efforts to regulate chemical use have not been effective in containing disruptor use. Some pesticides are still being registered by passing through alternative processes which bypass important screenings (Vogel, 2004). Politics also often has a greater role in affecting chemical regulations and such political maneuverings can sometimes affect actual policy processes towards manipulation. On the other hand, carrying out disruptor screenings can help in the validation of chemicals and in the investigation of the disruptor effects to the endocrine system through in vitro and in vivo assays. Through in vitro systems, early screening for a large number of chemicals can help characterize the mechanism of action and potency of these chemicals (Baker, 2001). The EPA screening program is an important process which helps establish the impact of endocrine disruptors to humans as well as animals; this program helps establish an authority in the testing process and to determine the cumulative effect of pesticide chemicals (US EPA, 2010). It also provides a program by which our drinking water can be tested at their source and can be determined as fit for human consumption Through the screening process, the impact of pesticides, chemicals, and environmental contaminants on the estrogen, androgen, and thyroid hormones can be determined (US EPA, 2010). In effect, these tests help the government determine the direction of regulatory programs and policies for the protection of people’s general safety and health. The regulation of endocrine disruptors is an important consideration because of their significant impact on our hormones and our reproductive processes. The screening process established by the EPA is also very encouraging because it has involved the public, the stakeholders, and other international organizations (US EPA, 2010). The EPA has secured representation of different sectors, including federal agencies, agrichemical companies, commodity chemical companies, and environmental public health organizations for the coordination and validation of tests. The screening process is an appropriate process to carry out because it helps ensure the safety and health of humans and animals. Through the different assays used in the screening process, there is a better identification and characterization of contaminants and pesticides, helping validate and harmonize the screening tests for international application. I strongly support the screening process being carried out by the US EPA because its processes would eventually help the government regulate the use of chemicals in our daily activities. I believe that the screening process of the US EPA can also help improve the characterization of disruptors and the specification of their impact on the hormones, the endocrine system, and on the human reproductive system. Without this screening program, the general public would be using these chemicals without implementing the proper precautions to avoid the toxic effects of these chemicals. Conclusion This study revealed background information about endocrine disruptors. These disruptors have been known to significantly affect the endocrine and the reproductive system. These disruptors are seen in many of our daily household items which contribute to possible health issues among the general population. Endocrine disruptors affect the male and female reproductive processes, mostly impacting on the fertility and reproductive development of men and women. Chemicals mimic hormones in the bodies of humans and some of these chemicals interfere with the action of hormones, thereby upsetting normal growth, behavior, and reproduction of wildlife. Such effects, based on studies are also seen among humans. More studies are however needed in order to establish clearly the relationship between endocrine disruptors and health issues in normal growth, development, and behavior. EPA screening tests are disadvantageous because of various practical considerations which relate to inadequate resources and testing centers for such chemical disruptors. Nevertheless, these screening tests help ensure that the daily products which people use are safe for their health and for the health of animals and wildlife. All in all, general lessons learned from endocrine disruptors set forth that there are various chemicals which are commonly used by humans which by nature are harmful to people and to animals. In effect, humans need to be more cautious in their use of such chemicals and to allow for government processes to regulate the use of products with potential for endocrine disruption. Works Cited Baker, V. (2001) Endocrine disruptors —testing strategies to assess human hazard. Toxicology in Vitro, volume 15, pp. 413–419 This is a peer-reviewed article which discusses the different testing strategies carried out by the US EPA and the OECD in order to evaluate chemicals for their endocrine disrupting activities. Diamanti-Kandarakis, E., Bourguignon, J., Giudice, L., Hauser, R., Prins, G., Soto, A., Zoeller, R., & Gore, A. (2009) Endocrine-Disrupting Chemicals: An Endocrine Society Scientific Statement. Endocrine Reviews, volume 30 (4): pp. 293-342. This is also a peer-reviewed article which discusses the specific qualities of endocrine-disrupting chemicals. Endocrine Disruptors (2006) National Institute of Environmental Health Sciences. Retrieved 01 March 2011 from http://www.niehs.nih.gov/health/topics/agents/endocrine/docs/endocrine.pdf This is an internet article authored by the NIEHS agency discussing specific details about endocrine disrupters and their impact on human health. Endocrine Disruptor Screening Program (EDSP). (2010) US Environmental Protection Agency. Retrieved 01 March 2011 from http://www.epa.gov/endo/pubs/edspoverview/development.htm This is an internet article from the EPA which discusses the details in relation to the screening program for endocrine disrupters. Skakkebaek NE, Rajpert-De Meyts E, Main KM (2001). Testicular dysgenesis syndrome: an increasingly common developmental disorder with environmental aspects. Hum Reprod, volume 16: pp. 972–978 This is a peer-reviewed study which discusses the health impact of endocrine disrupters on the human reproductive system. Vogel, J. (2005) Perils of paradigm: Complexity, policy design, and the Endocrine Disruptor Screening Program. Environmental Health Journal. Retrieved 01 March 2011 from http://www.ehjournal.net/content/4/1/2 This is a journal article which discusses more details about the endocrine disrupter screening program, including its design and implementation. Waring, R. & Harris, R. (2005) Endocrine disruptors: A human risk? Molecular and Cellular Endocrinology, volume 244, pp. 2–9 This is a peer-reviewed article which discusses the cellular risks posed by endocrine disruptors and their overall impact on human life. Read More