Teratogens1 1

The Importance of Timing,Example 3: Teratogens

Teratogens are outside agents, such as disease or chemicals, whose presence increases the risk of deviation or abnormality in prenatal development.

Each organ system is most vulnerable to disruption at the time when it is developing most rapidly.

Germinal Embryo Fetal . . .

Thalidomide

Europe, 1956-1962 Taken to alleviate

morning sickness (The United States

never had thalidomide babies – why not?)

Effect Depends on Timing

Weeks 3-4 exposure: maximal detrimental effect

Beginning of 3rd week: Deformed ears

End of 3rd, beginning of 4th: Deformed arms Under-developed

intestinal tracts Heart defects

End of 4th week: Deformed legs

Thalidomide is interesting for the specificity of its effect…

While brain damage occured in some cases, many affected babies had only physical deficits.

Complex issue: It is now believed that 40% of affected babies die at birth; more may be miscarried.

Sylvia Plath wrote about Thalidomide (1962)

Thalidomide interferes with the growth of new blood vessels (Anti-angiogenic effect)

Why were underdeveloped limbs the most common result?

Morning sickness coincides with the time of fetal limb growth

In the last 10 years, Thalidomide has been re-examined. Its now a treatment for leprosy, inflammation, AIDS and cancer. Cancer tumors require new blood

vessels.Thalidomide halts HIV progression.

Could Thalidomide affect victims’ DNA?

Of 380 children born to thalidomide victims, 11 have congenital limb defects

This rate is 5 times higher than in the general population.

Thalidomide can alter the DNA of eggs/sperm in rats.

Main Categories of Teratogens

Environmental toxins Nuclear radiation, waste; solvents, PCBs, dioxin Chemicals that mimic estrogens (feminization of the

environment, affects sex differentiation) Drugs and Pharmaceuticals

Many legal, over-the-counter drugs are teratogenic (alcohol severely, nicotine somewhat)

Prescription Drugs (Pregnancy categories D,X) Recreational drugs

All are known or suspected teratogens. Legality of the drug irrelevant. Alcohol is worse than cocaine.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

Environmental Hazards

Radiation: High doses of radiation lead to: Chromosomal abnormalities Prenatal death Mental retardation

Environmental pollutants and toxic wastes, such as mercury and lead. Prenatal exposure to lead affects mental

development Mercury poisoning (minimata disease) leads to

disorders of the central nervous system, small heads

Exposure often occurs at the work place.

Pesticides

Men: Don't paint your house 6 months before trying to conceive; don't work on a farm picking fruit or vegetables

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

In the U.S., a chemical is innocent until proven guilty (their defense lawyers have reams

of cash)

Lead and mercury disrupt brain development in the fetus.

Glycol ethers and epichlorohydrin damage male reproductive function.

Workers exposed to pesticides, industrial solvents, platicizers, are at increased risk of spontaneous abortion and birth defects in offspring.

Do tampons and toilet paper have to be white? "Dioxin begins in the Board room"

Animal testing: single dose of a tiny amount of dioxin administered during a critical "window of vulnerability” in pregnancy can lead to life-long health effects in offspring.

Dioxin and PCBs derail human development by interfering with hormones.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

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.

QuickTime™ and aTIFF (Uncompressed) decompressorare needed to see this picture.

Cosmetics Cosmetics: from make-up and deodorant to lotions and

mouthwashes, according to the U.S. FDA U.S. doesn’t require health studies on personal care

products. “89 percent of 10,500 ingredients used in personal

care products have not been evaluated for safety”-Environmental Working Group

Found to contain carcinogens and mutagens

Phthalates: group of industrialchemicals linked to birth defects that are used in many cosmetic products, from nail polish to deodorant.

Cosmetics

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.

"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."

QuickTime™ and aTIFF (Uncompressed) decompressor

are needed to see this picture.