Endocrine disruptors function

Recently, attention has focused on the potential hazardous effects of certain chemicals on the endocrine system because of the abihty of these chemicals to mimic or block endogenous hormones, or otherwise interfere with the normal function of the endocrine system. Chemicals with this type of activity are most commonly referred to as endocrine disruptors. Some scientists believe that chemicals with the ability to disrupt the endocrine system are a potential threat to the health of humans, aquatic animals, and wildlife. Others believe that endocrine disrupting chemicals do not pose a significant health risk, particularly in light of the fact that hormone mimics exist in the natural environment. Examples of natural hormone mimics are the isoflavinoid phytoestrogens (Adlercreutz 1995 Livingston 1978 Mayr et al. 1992). 

Endocrine disruptors apparently affect all nuclear receptors. Thus, a notable increment in impotence, alterations of the libido and of oligospermia in workers exposed to pesticides has been described. These alterations are due to the action of some compounds with estrogen-mimetic action and to their interaction with the androgen receptor. Additionally, alterations of thyroid function have been detected in rats exposed to dioxin and other toxic agents,... 

Xenobiotics can adversely affect the normal functions of the cells/organs of the reproductive system. These agents may induce a variety of outcomes, including prevention of ovulation and impairment of ovum transport, fertilization, or implantation. Endocrine disruptors may mimic endogenous hormones as well as directly destroy cellular components, leading to cell death. More indirect effects may include inhibition of key enzymes involved in steroid synthesis. 

Most POPs are readily absorbed (via the digestive system and inhalation) and accumulate in fatty tissue, including brain and adipose tissue and human milk. These substances can induce neurological effects and cause altered functioning of the nervous system as well as acting as endocrine disruptors. 

Endocrine disruptor. An exogenous substance or mixture that alters function(s) of the endocrine system and consequently causes adverse health effects in an intact organism or its progeny or (sub)popu-lations. 

In addition [103,104], a new type of composite that combines DNA with silica components via a sol-gel method was described. The DNA-silica hybrid material is advantageous with respect to its mechanical and chemical stability in both aqueous and organic solvents. Similar to the previously described hybrids, the specific functions of the DNA molecules were retained and maintained the DNA-silica hybrid materials adsorb DNA-interactive chemicals from diluted aqueous solution. In another series of reports [105-109], DNA-loaded PSf microspheres were fabricated by means of a liquid-liquid phase separation technique. The release rate of DNA from the microspheres can be controlled by manipulating the microsphere structure. Increasing the polymer concentration causes lower porosity and smaller pores on the outer surface of the microspheres, and leads to a low release rate of DNA from the microspheres. The DNA-loaded PSf microspheres could effectively accumulate harmful DNA-intercalating pollutants and endocrine disruptors, as described in previous reports. 

Endocrine disruptors are chemicals that cause adverse health effects in an animal or its offspring due to changes in hormone function. In recent years some scientists have concluded from a number of coincidental observations that certain chemicals in the environment may be interfering with the hormonal systems of animals and possibly of humans. These endocrine disruptors coidd be responsible for a range of dysfunctions that have been observed in the reproductive systems of humans and other animals. The effects in wildhfe have been well documented and can be reproduced experimentally. The human effects are more difficult to... 

Thomas, P., Khan, LA. (2005). Disruption of nongenomic steroid actions on gametes and serotonergic pathways controlling reproductive neuroendocrine function by environmental chemicals. In Endocrine Disruptors Effects on Male and Female Reproductive Systems, 2nd edition (R.K. Naz, ed.), pp. 3-45. CRC Press/Taylor Francis Group, LLC, Boca Raton. 

Concerns over their potential to function as endocrine disruptors led to a Japanese study on the levels of alkylphenols in 60 rubber products. Such compounds are used as starting materials in the manufacture of a number of mbber additives, particularly oligomeric phenolic antioxidants. The work concentrated on four compounds p-/er/.butyl phenol (PTBP), p-/er/.octylphenol... 

Endocrine disruptors are chemical substances that interfere with, or have adverse effects on, the production, distribution, or function of these same hormones . These substances do not affect growth or cause increased mortality. They affect the development of organisms which is manifested in alterations of reproductive capacity or metabolic disorders of many steroid hormones. Some aquatic invertebrate species (cladocerans, mollusks) with a short reproduction time have been intensively studied as the... 

Endocrine disruptors often are structural analogs of endogenous hormones (hormones produced naturally in the host). Hormone analogs may act like the endogenous hormone if the analog-receptor complex in the target cell mimics the function of the hormone-receptor complex. Hydroxy metabolites of both o,p -DDT and methoxychlor bind to estrogen... 

Chia SE (2000) Endocrine disruptors and male reproductive function - A short review. International Journal of Andrology 23(Suppl. 2) 45-46. 

Bigsby R, Chapin RE, Daston GP, et al. Evaluating the effects of endocrine disruptors on endocrine function during development. Environ Health Perspect 1999 107 (Suppl 4) 613 18. 

Fig. 1. Estrogen and estrogen mimics. Many natural plant compounds (e.g. coumestrol) and synthetic chemicals (e.g. ethynylestradiol, diethylstilbestrol, 4-nonylphenol, o,p DDT, and kepone) act as endocrine disruptors by mimicking or blocking normal estrogen function via estrogen receptor dependent or independent mechanisms.

Leatherland, J.F. Contaminant altered thyroid function in wildlife. In Environmental Endocrine Disruptors An Evolutionary Perspective, edited by L.J. Guillette and D.A. Crain, New York, Taylor Francis, pp. 155-181, 2000. 

According to Susan Brien et al. (2000, the single hit obtained by combining DDT and impotence), 33 million American men have erection problems, which may be caused by environmental contaminants. This problem inspired her and her co-workers to see if p,p-DDE disturbed erection in rats. They found that high doses (500 mg/kg) of DDE indeed had such an effect and concluded "The endocrine disruptor p,p-DDE can markedly interfere with erectile function and demonstrates persistence after a single dose. This supports our novel concept that environmental hormones may cause erectile dysfunction."... 

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