EESA10H3 Lecture Notes - Lecture 4: Persistent Organic Pollutant, Distillation, Mirex

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13 May 2011

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Lecture #4: Chemical Hazards and Human Health
Wednesday, February 9th/2011
Chemical Hazards
Our bodies produce hormones from endocrine glands
Some chemicals are able to mimic hormones because they are similar in
chemistry and structure etc.
When these chemicals enter our body, our body isnt able to differentiate whether
it is a hormone or a foreign chemical; thus the chemical ends up disrupting the
endocrine functions of the hormone it is mimicking
**Note: The data collected with regards to this matter is mostly from animal
studies, not much from human exposure
Endocrine disrupters
1.Direct Effects:
Bind to hormone receptors
Alter the appearance of some genes
Changes in the level of produced proteins (unwanted proteins are
2. Indirect Effects:
Altering hormone production
Altering hormne transport
Altering hormone metabolism
Fetus is more sensitive than adults
If we, as adults are exposed to chemicals/endocrine disrupters, well be able to
recover; we can cope quite well
On the other hand, babies would be born with many defects if exposed to
chemicals in the womb, because fetuses are very sensitive to these substances
DES (diethlstilbesteol
Synthetic estrogen used by physicians to prevent spontaneous abortion (1948-
Administered for early pregnancy until 35 weeks
More than 1 million women took it between 1960-1970
Daughters whose mothers took DES have increased incidents of:
oReproductive organ dysfunction
oAbnormal pregnancies
oReduction in fertility
oImmune system disorders
Effects were seen some 30-40 years later in kids of the mothers who had taken
the drug
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No immediate effects were observed, both mother and babies were perfectly
healthy; however when it came time for these kids to grow and have children
themselves, the daughters had all sorts of problems as outlined above
Health Implications of Endocrine Disrupters
Endocrine disrupters mostly effect the reproductive system
oFeminization of males
oAbnormal sexual behaviour
oBirth defects
oAltered time to puberty
oCancer of mammary glands or testis
oThyroid dysfunction
Thyroid gland produces two major hormones (T4 & T3); another
hormone produced by pituitary gland TSH (needed for
production of T4 and T3)
Lower levels of these hormones will have severe effect on the
development of the fetus
Neurobehavioural Effects of Endocrine Disrupters
Prenatal and early postnantal (shortly after birth) exposures
PCBs (polychlorinated biphenyls):
oImpaired learning in nonhuman primates
may also be seen in children; mental development is slowed e.g. a
7-yr-old will draw a picture as though he were a 3-yr-old
oDelayed psychomotor development
oPoor IQ tests
oOrganophosphates brain development
directly affect brain; not learning, but actual structure of the brain
Chemical body burdens
Every single person has chemicals inside of them, therefore chemical burdens
affect everyone
From air, clothing, etc, everywhere
Our bodies fight back, maybe absorb, excrete, metabolize and break these
chemicals down to lower the quantity that stays within our body
The amount of chemicals ingested/inhaled is diff. (far greater) than found when
our body is analyzed
Chemical body burdens = quantity of chemicals accumulated in the body
Not stable over time
Not distributed homogenously in a body
oaccumulate in certain tissues in certain parts of the body
oe.g. arsenic likes to accumulate in males in hair, nails???
oe.g. DDT etc? accumulates in fats –animals with more fats accumulate
more chemicals in their body
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