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Lecture 4

EESA10H3 Lecture Notes - Lecture 4: Endocrine Disruptor, Thyroid, Pituitary Gland


Department
Environmental Science
Course Code
EESA10H3
Professor
Jovan Stefanovic
Lecture
4

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EESA10 LEC 4
Chem Haz
Endocrine disrupters
Endocrine glands produce hormones
hormones have important func in body: regulate everything; they are
usually very speci"c in function
some chem are able to mimic; b/c they're similar in chem struc to
hormones; can mimic hormones--> our metabolism won't know if its a
hormone or chem
- they disrupt normal func of metabolism
- b/c they just look like hormones
as a result of disruption; numerous health probs
thus call these endocrine disruptors; disrupt normal hormone func
very little is known about these chem from human research
- most results are from animal studies
Endocrine Disrup
every hormone recep binds to protein; proteins are recep and carry
hormones to place where they will work
since recep recog hormones; they also recog chem which mimics
- thus there are probs in genes, proteins, dna
- if there is prob w/ genes, there is prob w/ protein synth
adults are less sensitive to hormonal dysfunc
but mother and fetus hormones are important for develop
DES
some synthetic estrogen given to women (period of 30 years)
things were ok for long time until, the daughters (and less signif, the
sons) of these women reached their reproductive stage
- so about 20-30 yrs after
when it was observed that daughters of these women have trouble
having kids
- reproductive func was disruptive
moms weren't impacted but their daughters were
they linked this hormone w/ that prob
that supports idea that adults are less sensitive than fetus
Health Impacts
when using DDT for 1st time: domestic roosters start changing and
getting femme characs over time
now, many other animals such as frogs, crocs, "sh change from M to F
Birth defects: teratogenic defects
Thyroid dysfunction: 2nd ex on how adults are less sensitive than fetus
- Thyroid gland produces hormones: T1 and T2
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- Pituitary gland produces some other Thyroid Stimulatory
hormone
- if a woman wanting to get prego has low level of T1/2--> called
Hypothyroidism
- but this doesn't have huge impact on health
- but if she gets prego: she needs hormonal supplement (TSH, T3
tablets) during preg--> to avoid impact on fetus
these hormones are important during prego--> if there are chem that
can mimic t1/2, it can harm fetus
Neurobeh E8ects
babies: before and after they're born--> most sensitive at that time
PCB: poly carbonated biphanials???
Organophosphates: poor brain develop
Chemical Body Burdens
all chem that accumulate in human body over time
there is no region anywhere in world: even the most pristine regions-->
if ppl live their, they have some chem in their body
di8 b/w Contaminant and Pollutant??
- COntaminant: are not causing human health impacts all the
time, are in increased conc- may or may not (ex. NItrogen in air and
Carbon Dioxide, you inhale both everyday but still healthy)
- POllutants are always toxic even in small conc
we can break down, metabolise and excrete chem--> thats why
quantity of chem in body not stable over time
some chem like certain tissues and accumulate in them--> not distrib
homogen in body
- ex. Arsenic accumulates in nails and hair
- ex. Liver: known as lab of organisms- all chemicals go there
not possible to detect if present in low conc: why can't we detect
them?
- we can detect it only if conc is above detection limit of
instruments
its better to "nd indicator or trace that chem is present
that tells you that # of chem in Body Burden is bigger than what we
think
Who is the background: avg person?
- won't be person who lives near polluted area or exposed to it
regularly
- background/control will be avg person
Organochlorine Substances
Dioxins: group of chemicals
DDT: 1 type of chem
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