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Lecture 4

EESA10H3 Lecture Notes - Lecture 4: Biomonitoring, Diethylstilbestrol, Miscarriage

Environmental Science
Course Code
Jovan Stefanovic

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Chemical Hazards and Human Health
Endocrine Disrupters
-Data mostly from animal studies, not much from human exposure
-They are chemicals (obviously)
-Have a similar structure and properties as some of the hormones. Our body can mistakenly
absorb some of these chemicals (They are not hormones). Disrupt the function of the hormones
1. Direct effects: Bind to hormone receptors Alter the appearance of some genes Changes in
the level of produced proteins
2. Indirect effects: Altering hormone production Altering hormone transport Altering hormone
-Fetus more sensitive than adults
DES (diethylstilbestrol)
• Synthetic estrogen used by physicians to prevent spontaneous abortion (1948-1971)
• Administered for early pregnancy until 35 weeks
• > 1million women took it between 1960-1970
Daughters whose mothers took DES have increased incidents of :
Reproductive organ dysfunction
Abnormal pregnancies
Reduction in fertility
Immune system disorders
Health Implications
• Feminization of males
• Abnormal sexual behavior
• Birth defects
• Altered time to puberty
• Cancer of mammary glands or testes
• Thyroid dysfunction
-Thyroid produces hormones (TSH...T1….T2) that are regulated by hormones from the
pituitary gland.
-Hypo=very low
-Hyper=Higher concentration
Neurobehavioral Effects
• Prenatal and early postnatal exposures
PCBs: polychlorinated...
Impaired learning in nonhuman primates
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Delayed psychomotor development
Poor IQ tests
• Organophosphates
Brain development
Chemical Body Burdens
• Quantity of chemicals accumulated in the body
Not stable over time
Not distributed homogeneously in a body
Not possible to detect if present in very low concentrations
“normal level”
Blood and fat analysis
-Compared burdens with other people to tell if burdens are high or low. But everyone has body they would be compared to a average person who would have an average amount
of body burden.
Organochlorine substances
• Dioxins
• Phthalate Plasticizers and Bisphenol A
-Belong to the dirty dozen group
-Do not break down very easily
• Dioxins have no commercial usefulness by themselves
• Formed during
combustion process such as waste incineration, forest fires and backyard trash
manufacturing processes such as herbicide manufacture and paper manufacture
-Also called “Agent Orange” as a spray to destroy leaves off of trees
-To kill crops
-Caused diabetes and or cancer to those who used it during the war
• Group of chemical compounds with similar chemical structure
One of the most toxic and most studied is 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD)
• In food
• Very slowly removed from the body (POP-persistent organic pollutants)
-Stays in the body for a very long time
-Doesn't dissolve in water
Accumulate in fat tissue
• Affects cells in similar ways as hormones such as estrogen
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