| H U M A N H E A L T H E F F E C T S |
| Immune Suppression |
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Presently, little is known about the potential impact that endocrine-disrupting chemicals could have on the immune system during development. There is evidence that exposure to the synthetic estrogen drug DES during development in the womb leads to permanent changes in the immune system of both laboratory rodents and humans. For example, women who were exposed to DES in the womb, had changes in some immune system cells, and had an increased susceptibility to auto-immune and other diseases
Animal studies do show that exposure to some estrogenic chemicals during development, including DDT and chlordane, cause suppression of the immune system.
Since TCDD (dioxin) alters the normal differentiation of immune system cells, the human embryo may be very susceptible to long-term impairment of immune function from in utero effects of TCDD on developing immune tissue. US EPA Draft Chapter on Dioxin Risk Characterisation, Dated May 2, 1994 Several studies have shown that some women of the general population have body levels PCBs and/or dioxins, which are within the range at which changes in the immune systems of their babies may occur. Increased Infections Inuit women inhabiting Arctic Quebec have relatively high body levels of persistent organochlorines because of their seafood-rich diet. Research has shown that higher levels of PCBs and dioxins in their breastmilk were linked with an increased incidence of ear infections in their babies. Other studies on women who ate fish from the Great Lakes before becoming pregnant, reported that higher body levels of PCBs in the women were associated with an increased incidence of bacterial infections in their children. Changes in Immune System Cells In the 1970s, residents of Times Beach in Missouri, USA, were accidentally exposed to high levels of dioxins because waste oil which was sprayed on roads for dust control was contaminated. Children born to women who were pregnant during the incident, were found to have changes in the number of some immune system cells at the ages of 9-14. This indicated that effects on their immune systems were long-term. A recent study in The Netherlands focused on healthy women and their babies from the general population. Some of the women had higher levels of PCBs and dioxins in their bodies and breastmilk than others. It was found that infants who were exposed to higher levels of these chemicals in the womb, and via breastfeeding, had changes in the number of certain immune system cells. Ultraviolet radiation suppresses the immune system Chlorine chemicals responsible for the ozone hole also act on the immune system of humans and animals. Increased ultraviolet radiation has the ability to suppress the human immune system leaving the body vulnerable to many diseases caused by bacteria and viruses entering through or affecting the skin. While darker skinned individuals are less likely to contract a skin cancer from sun exposure, dark skin is not a protection against immune suppression by UV-B. Dark skin requires a greater dosage of UV-B than white skin to initiate immune suppression. However, the required dosage for suppression in darker skins is easily obtained by occupational and recreational exposure to the sun. Viruses responsible for diseases such as herpes, chicken pox, the human immunodeficiency virus HIV-1 are directly activated or reactivated by exposure to UV-B radiation.
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