Endocrine systems exposure levels

Pregnant women, infants and children face unique and possibly significant developmental and endocrine-system mediated risks from low-level pesticide exposure during critical windows of development, some with serious life-long consequences. 

Effects have also been observed on the environment. Rachel Carson s Silent Spring in the 1960s drew attention to effects on wildlife. Our Stolen Future (Colbom et al. 1996) created an interest in disruption of the endocrine system by chemicals, even in animals. Many cases of effects on natural animal populations can now be inferred from laboratory experiments, although confirmation in the environment is extremely difficult. For instance, organochlorinc concentrations in adult male bottlenose dolphins are approaching the levels associated with adverse effects found in marine mammals (Carballo et al. 2008), and exposures of tadpoles to a mixture of nine pesticides at environmentally occurring levels lead to developmental effects in most frogs, while none were observed when the pesticides were applied one at a time (Hayes et al. 2006). 

Studies are beginning to assess the effects of some drugs in fish to explore the basic biology of a particular physiological or endocrine system. However, it is not yet known if chronic low-level exposure to environmental levels of GEM, CBZ or any of... 

Some evidence for adverse effects on the endocrine system has also been found following intermediate and chronic oral exposure to elevated levels of dietary selenium in humans and animals. Human studies have demonstrated a decrease in triiodothyronine levels in response to increased dietary selenium, although the hormone levels remained within the normal range. Intermediate-duration studies of rats have shown reductions in type-I-deiodinase activity in response to selenium. However, the levels of thyroid hormones in these animals did not show a consistent pattern. 

If released uncontrolled to the environment, dioxins and furans find their way in very low concentrations into many food sources. They are known to be toxic species, depending however, on the level of exposure. Above the Tolerable Daily Intake (TDI) [1] exposure to dioxins or furans may result in skin lesions and altered liver function. Long-term exposure is linked to impairment of the immune system, the developing nervous system, the endocrine system and reproductive functions. Chronic exposure of animals to dioxins has resulted in several types of cancer. 

Ozone causes a multiplex effect on the endocrine system [254]. The authors report an inhibiting effect on I (ozone 4 ppm, 5 h), which was observed even 12 days after exposure. Plasma thyrotropin was reduced by 50%. The thyroid gland increased its size. The authors suggest that decreased thyroid hormone levels appear to be prophylactic against ozone damage. 

In some animals, consumption of a phytoestrogen-rich diet can cause temporary infertility and reproductive system disorders (Irvine, 1999). In humans, lower testosterone levels and a decline in human semen quality over the past century have been luiked to increased exposure to environmental endocrine disrupters (EDCs) (Sharpe and Skakkebaek, 1993). Furthermore, cases of sexual impotence have been reported in males exposed to synthetic estrogens in the pharmaceutical industry (Mattison et al., 1990). If this might be the case, the fetal-prepubertal period and Sertoli cell development would be of critical importance (Sharpe and Skakkebaek, 1993). However, an adverse effect of phytoestrogens on male fertility has yet to be proven. Recent work (Mitchell et al., 2001) addressing this point led to the conclusion that up to 40 mg/day of isoflavones over a two-month period had no effects on gonadotrophin and... 

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