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Lecture 5

EESA10H3 Lecture Notes - Lecture 5: Viktor Yushchenko, Biomonitoring, Chloracne

Environmental Science
Course Code
Jovan Stefanovic

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Chemical Hazards and Human Health
Chemical Hazards
l Endocrine disrupters (we produce hormones in our bodies that perform very important
functionsreproductive or sexual functions)
l Chemical body burdenschemical pollutants mimics hormones, as a result these chemicals
disrupt the normal function of the hormone
Data mostly from animal studies, not much from human exposure
Endocrine disrupters
1. Direct effects:
Bind to hormone receptors = carry hormones in the body
Alter the appearance of some genes (genes may change)
Changes in the level of produced proteins
2. Indirect effects:
Altering hormone production (amount/level of hormones changes)
Altering hormone transport
Altering hormone metabolism
Fetus more sensitive than adultshealth problems in adults can result in recovery or not permanent,
however in fetuses they may be permanent and affect their whole life
DES (diethylstilbesteol) = something thats been prescribed as synthetic hormone
l Synthetic estrogen used by physicians to prevent spontaneous abortion (1948-1971)
l Administered for early pregnancy until 35 weeks
l > 1million women took it between 1960-1970
l Daughters whose mothers took DES have increased incidents of:
ol Reproductive organ dysfunction
ol Abnormal pregnancies
ol Reduction in fertility
ol Immune system disorders
ol Carcinoma
Endocrine disrupters - Health Implications
l Feminization of males
l Abnormal sexual behavior
l Birth defects
l Altered time to puberty
l Cancer of mammary glands or testis
l Thyroid dysfunction
Endocrine disruptersNeurobehavioral effects (destruction in mental development, low IQ, learning
disabilities later and later in life)
l Prenatal and early postnatal exposures
l PCBs (poly chlorinated bi contaminants):
ol Impaired learning in nonhuman primates
ol Delayed psychomotor development
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ol Distractibility
ol Poor IQ tests
ol Organophosphates - Brain development
Chemical body burdens
l Quantity of chemicals accumulated in the body (started before you were born, through breast
milk, air, water, food you consumeetc.)
Its everywhere and everybody has a high quantity of chemicals accumulated in the body
There are thousands of chemicals already, and every year there are thousands of new chemicals
ol Not stable over time (level of chemicals change over time in the body)
ol Not distributed homogeneously/evenly in a body
ol Not possible to detect if present in very low concentrations (our knowledge is limited)
We are not aware of the new chemicals in our bodies, have no idea they exist
ol Biomonitoring – normal level = chemical body burden level is higher than normal
Organochlorine Substances (the most famous ones:)
l Dioxins
Dioxins (a group of chemicals)
l Dioxins have no commercial usefulness by themselves
l Formed during
ol combustion process such as waste incineration, forest fires and backyard trash burning
ol manufacturing processes such as herbicide manufacture and paper manufacture
l Group of chemical compounds with similar chemical structure
l One of the most toxic and most studied is 2,3,7,8- tetrachlorodibenzo-p-dioxin (TCDD)
The more chlorines there are, the more toxic it is
l In food
l Very slowly removed from the body (POP-persistent organic pollutants)
l Accumulate in fat tissue (soluble in fats)
A chart illustrating how much dioxin the average American (USA) consumes per day. (Note: pg =
picogram, or one trillionth of a gram)
The fatty foods contain more dioxins than the less fat
Dioxinsdestruct hormone function in your body
l Affect cells in similar way as hormones such as estrogen
ol Binds to a protein (Ah receptor) present in cells
ol Then receptor can bind to DNA and alter the appearance of some genes
ol This can lead to changes in the level of specific proteins and enzymes in the cell
l At low levels- Effect of constant exposure to low levels is not known
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