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Endocrine Disrupters: Effects on Wildlife

Endocrine Disrupters: Effects on Wildlife

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Endocrine Disrupters: Effects on Wildlife

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  1. Endocrine Disrupters: Effects on Wildlife

  2. What Are Endocrine Disrupters? • The Endocrine System Regulates Numerous Biological Functions • The hormones secreted act like messengers within various cells or organs • These messages are extremely vital before birth for development of sexual differentiation and proper brain development

  3. What are Endocrine Disrupters? • Cells have specifice receptor sites for specific hormones

  4. Endocrine Disrupters • Endocrine disrupters are chemicals that can fit into these receptor sites • They can then interfere with hormone function • They can alter hormone synthesis, storage, release, secretion, transport, elimination, or binding action.

  5. Environmental Estrogens (EEs) • Some substances in the environment can act like the hormone estrogen • Naturally occurring EEs are known as phytoestrogens • clover • soybeans, legumes • whole grains • fruits and vegetables

  6. Other EEs are man made: • pesticides: DDT, chlordane, methoxychlor, etc.. • plastics containing bisphenol A • pharmaceuticals:DES, birth control pills • detergents and surfactants • industrial chemicals:PCBs

  7. Estrogen: What does it do? • Steroid hormone found in male and female sex organs • Females: regulates and sustains female sexual development and behavior, regulates reproductive cycles • Males: regulates fluid reabsorption in the tubules that carry sperm from the testis to the epididymis

  8. Effects on Wildlife • Various wildlife studies have shown a direct relationship between exposure to endocrine disrupters and: • abnormal thyroid function • sex alteration • poor hatching success • decreased fertility and growth • altered behavior

  9. Fish • England: fish found near a municipal sewage outlet known to dump several different chemicals including alkylphenols • had both male and female sex organs • male livers had produced a female egg-yolk protein normally found in females only • fish closest to the outlet showed more severe abnormalities

  10. Fish • Mollusks have been found to exhibit a condition known as imposex: • male characteristics are imposed on genetic females • found in areas where tributyl tin is used as an “anti-fouling paint on ships”

  11. Fish • Great Lakes trout extinction now thought to be due to high levels of dioxin in the fish which caused the developing trout within the egg to die: • concentrations could be as low as 5 parts per trillion (University of Wisconsin)

  12. Fish • Female fish downstream from pulp and paper mills: • developed male sex organs • tried to mate with normal females or each other • males were “hypermasculinized”, exhibiting very aggressive mating behavior • Salmon in Great Lakes region have been found whit enlarged irregular thyroid glands

  13. Alligators • Lake Apopka in Florida had DDT spill in 1980, alligator population declined severely over next 10 years • Mortality among eggs and newborns higher than normal • females had estrogen levels 2X normal level • males had lower testosterone levels and abnormal sex organs

  14. Alligators • Other Florida lakes were found to have alligators with abnormal reproductive and thyroid hormones

  15. Birds • DDT and softened eggshells • Gulls and terns in Great Lakes exhibit abnormal thyroid levels • supernormal egg clutches • female to female pairing • excessive chick mortality • birth defects • skewed sex ratios (excess of females)

  16. Birds • Also exhibit suppression of immune system: • T-cell mediated immunity, probably caused by PCBs • Nesting Albatross in North Pacific, and Gulls in the Puget Sound also show contamination of DDTs and PCBs

  17. Mammals • In the 1980s and 90s, several outbreaks of marine mammal epidemics were documented: • Russia 1987- 10,000 seals died from a virus • United States 1987- 700 bottlenose dolphins died • North Sea 1988- 20,000 harbor seals died

  18. Mammals • Mediterranean Sea 1990-93-1,000 striped dolphins washed up dead on shore • Diminished reproductive success in seals in the Netherlands has also been observed • Minke whales study shows increasing levels of PCBs in body

  19. Mammals • Autopsies revealed PCBs present in animal bodies • PCBs are known to suppress immune system

  20. Mammals • Studies were prompted to investigate: • US and Dutch conducted experiments that revealed suppressed immune systems in seals fed contaminated fish • T-cell responses were significantly below normal

  21. Mammals • Reproductive hormones also affected: • populations of harbor, ringed and gray seals declining • high levels of PCB’s in body • beluga whales in St.. Lawrence River showing lower rate of pregnancy and fewer offspring produced

  22. Amphibians • Frogs especially vulnerable to environmental contaminants because of permeable skin • Pesticides and PCBs are stored in frog’s fat and enter the bloodstream again during metamorphosis • Many scientists now believe that the commonly used chemical methoprene degrades in sunlight into an endocrine disrupter

  23. Laboratory Experiments • University of Missouri: • female mice exposed to low doses of bisphenol A altered the reproductive organs of their male offspring • EPA in Research Triangle Park: • Direct link made between thyroid dysfunction and PCBs in rats

  24. Effects on Humans • Wayne State University: • children whose mothers had eaten contaminated fish from Lake Michigan in the six years prior to pregnancy had significant deficits in intelligence and learning • mothers themselves however were not contaminated

  25. Effects on Humans • Similar study in NY State: • measurable neurobehavioral deficits in the newborn children who’s mothers had eaten the equivalent of 40 pounds of Lake Ontario salmon in a lifetime. • children tended to have abnormal reflexes, shorter attention span and an intolerance to stress

  26. Effects on Humans • Early exposure of males to endocrine disrupters (DES) causes major problems such as undescended testes, and increased incidence of testicular and prostate cancer • Sperm densities in the US are decreasing 1.5% every year

  27. Conclusions • Thousands of chemicals need to be tested for endocrine disruption • October 1998: EPA unveils its strategy to start testing chemicals • No current plan to start testing common household products • On the cellular level, we are not very different from animals, if they are being affected by endocrine disrupters, so are we.