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Teratogens1 1


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Teratogens1 1

  1. 1. The Importance of Timing, Example 3: Teratogens <ul><li>Teratogens are outside agents, such as disease or chemicals, whose presence increases the risk of deviation or abnormality in prenatal development. </li></ul><ul><li>Each organ system is most vulnerable to disruption at the time when it is developing most rapidly. </li></ul>
  2. 2. Germinal  Embryo  Fetal . . .
  3. 3. Thalidomide <ul><li>Europe, 1956-1962 </li></ul><ul><li>Taken to alleviate morning sickness </li></ul><ul><li>(The United States never had thalidomide babies – why not?) </li></ul>
  4. 4. Effect Depends on Timing <ul><li>Weeks 3-4 exposure: maximal detrimental effect </li></ul><ul><li>Beginning of 3rd week: </li></ul><ul><ul><li>Deformed ears </li></ul></ul><ul><li>End of 3rd, beginning of 4th: </li></ul><ul><ul><li>Deformed arms </li></ul></ul><ul><ul><li>Under-developed intestinal tracts </li></ul></ul><ul><ul><li>Heart defects </li></ul></ul><ul><li>End of 4th week: </li></ul><ul><ul><li>Deformed legs </li></ul></ul>
  5. 5. Thalidomide is interesting for the specificity of its effect… <ul><li>While brain damage occured in some cases, many affected babies had only physical deficits. </li></ul><ul><li>Complex issue: It is now believed that 40% of affected babies die at birth; more may be miscarried. </li></ul>
  6. 6. Sylvia Plath wrote about Thalidomide (1962)
  7. 7. Thalidomide interferes with the growth of new blood vessels (Anti-angiogenic effect) <ul><li>Why were underdeveloped limbs the most common result? </li></ul><ul><li>Morning sickness coincides with the time of fetal limb growth </li></ul>
  8. 8. In the last 10 years, Thalidomide has been re-examined. Its now a treatment for leprosy, inflammation, AIDS and cancer. <ul><li>Cancer tumors require new blood vessels. </li></ul><ul><li>Thalidomide halts HIV progression. </li></ul>
  9. 9. Could Thalidomide affect victims’ DNA? <ul><li>Of 380 children born to thalidomide victims, 11 have congenital limb defects </li></ul><ul><li>This rate is 5 times higher than in the general population. </li></ul><ul><li>Thalidomide can alter the DNA of eggs/sperm in rats. </li></ul>
  10. 11. Main Categories of Teratogens <ul><li>Environmental toxins </li></ul><ul><ul><li>Nuclear radiation, waste; solvents, PCBs, dioxin </li></ul></ul><ul><ul><li>Chemicals that mimic estrogens (feminization of the environment, affects sex differentiation) </li></ul></ul><ul><li>Drugs and Pharmaceuticals </li></ul><ul><ul><li>Many legal, over-the-counter drugs are teratogenic (alcohol severely, nicotine somewhat) </li></ul></ul><ul><ul><li>Prescription Drugs (Pregnancy categories D,X) </li></ul></ul><ul><li>Recreational drugs </li></ul><ul><ul><li>All are known or suspected teratogens. </li></ul></ul><ul><ul><li>Legality of the drug irrelevant. </li></ul></ul><ul><ul><li>Alcohol is worse than cocaine. </li></ul></ul>
  11. 12. Environmental Hazards <ul><li>Radiation : High doses of radiation lead to: </li></ul><ul><ul><li>Chromosomal abnormalities </li></ul></ul><ul><ul><li>Prenatal death </li></ul></ul><ul><ul><li>Mental retardation </li></ul></ul><ul><li>Environmental pollutants and toxic wastes, such as mercury and lead. </li></ul><ul><ul><li>Prenatal exposure to lead affects mental development </li></ul></ul><ul><ul><li>Mercury poisoning ( minimata disease) leads to disorders of the central nervous system, small heads </li></ul></ul><ul><li>Exposure often occurs at the work place. </li></ul>
  12. 13. Pesticides
  13. 15. Men: Don't paint your house 6 months before trying to conceive; don't work on a farm picking fruit or vegetables
  14. 17. In the U.S., a chemical is innocent until proven guilty (their defense lawyers have reams of cash) <ul><li>Lead and mercury disrupt brain development in the fetus. </li></ul><ul><li>Glycol ethers and epichlorohydrin damage male reproductive function. </li></ul><ul><li>Workers exposed to pesticides, industrial solvents, platicizers, are at increased risk of spontaneous abortion and birth defects in offspring. </li></ul>
  15. 18. Do tampons and toilet paper have to be white? &quot;Dioxin begins in the Board room&quot; <ul><li>Animal testing: single dose of a tiny amount of dioxin administered during a critical &quot;window of vulnerability” in pregnancy can lead to life-long health effects in offspring . </li></ul><ul><li>Dioxin and PCBs derail human development by interfering with hormones. </li></ul>
  16. 19. Pregnant women who are exposed in their jobs to organic solvents , such as those used in the computer chip industry, have 13-times greater risk of major malformations in their babies, and an increased risk for miscarriages, than women who are not exposed to solvents.
  17. 23. Cosmetics <ul><li>Cosmetics: from make-up and deodorant to lotions and mouthwashes, according to the U.S. FDA </li></ul><ul><li>U.S. doesn’t require health studies on personal care products. </li></ul><ul><li>“ 89 percent of 10,500 ingredients used in personal care products have not been evaluated for safety” </li></ul><ul><ul><li>-Environmental Working Group </li></ul></ul><ul><li>Found to contain carcinogens and </li></ul><ul><ul><li>mutagens </li></ul></ul><ul><li>Phthalates : group of industrial </li></ul><ul><ul><li>chemicals linked to birth defects that </li></ul></ul><ul><ul><li>are used in many cosmetic products, </li></ul></ul><ul><ul><li>from nail polish to deodorant. </li></ul></ul>
  18. 24. Cosmetics &quot;We think that women of childbearing are should avoid all exposures to dibutyl phthalate when they're considering becoming pregnant, when they're pregnant or when they're nursing.&quot;