Transcript Endocrine Disrupters: Effects on Wildlife

Endocrine Disrupters: Effects on
Wildlife
What Are Endocrine Disrupters?
The Endocrine System Regulates Numerous
Biological Functions
 The hormones secreted act like messengers
within various cells or organs
 These messages are extremely vital before
birth for development of sexual
differentiation and proper brain
development

What are Endocrine Disrupters?

Cells have specifice receptor sites for
specific hormones
Endocrine Disrupters
Endocrine disrupters are chemicals that can
fit into these receptor sites
 They can then interfere with hormone
function
 They can alter hormone synthesis, storage,
release, secretion, transport, elimination, or
binding action.

Environmental Estrogens (EEs)
Some substances in the environment can act
like the hormone estrogen
 Naturally occurring EEs are known as
phytoestrogens

 clover
 soybeans,
legumes
 whole grains
 fruits and vegetables

Other EEs are man made:
 pesticides:
DDT, chlordane, methoxychlor, etc..
 plastics containing bisphenol A
 pharmaceuticals:DES, birth control pills
 detergents and surfactants
 industrial chemicals:PCBs
Estrogen: What does it do?
Steroid hormone found in male and female
sex organs
 Females: regulates and sustains female
sexual development and behavior, regulates
reproductive cycles
 Males: regulates fluid reabsorption in the
tubules that carry sperm from the testis to
the epididymis

Effects on Wildlife

Various wildlife studies have shown a direct
relationship between exposure to endocrine
disrupters and:
 abnormal
thyroid function
 sex alteration
 poor hatching success
 decreased fertility and growth
 altered behavior
Fish

England: fish found near a municipal
sewage outlet known to dump several
different chemicals including alkylphenols
 had
both male and female sex organs
 male livers had produced a female egg-yolk
protein normally found in females only
 fish closest to the outlet showed more severe
abnormalities
Fish

Mollusks have been found to exhibit a
condition known as imposex:
 male
characteristics are imposed on genetic
females
 found in areas where tributyl tin is used as an
“anti-fouling paint on ships”
Fish

Great Lakes trout extinction now thought to
be due to high levels of dioxin in the fish
which caused the developing trout within
the egg to die:
 concentrations
could be as low as 5 parts per
trillion (University of Wisconsin)
Fish

Female fish downstream from pulp and
paper mills:
 developed
male sex organs
 tried to mate with normal females or each other
 males were “hypermasculinized”, exhibiting
very aggressive mating behavior

Salmon in Great Lakes region have been
found whit enlarged irregular thyroid glands
Alligators
Lake Apopka in Florida had DDT spill in
1980, alligator population declined severely
over next 10 years
 Mortality among eggs and newborns higher
than normal
 females had estrogen levels 2X normal level
 males had lower testosterone levels and
abnormal sex organs

Alligators

Other Florida lakes were found to have
alligators with abnormal reproductive and
thyroid hormones
Birds
DDT and softened eggshells
 Gulls and terns in Great Lakes exhibit
abnormal thyroid levels

 supernormal
egg clutches
 female to female pairing
 excessive chick mortality
 birth defects
 skewed sex ratios (excess of females)
Birds

Also exhibit suppression of immune system:
 T-cell
mediated immunity, probably caused by
PCBs

Nesting Albatross in North Pacific, and
Gulls in the Puget Sound also show
contamination of DDTs and PCBs
Mammals

In the 1980s and 90s, several outbreaks of
marine mammal epidemics were
documented:
 Russia
1987- 10,000 seals died from a virus
 United States 1987- 700 bottlenose dolphins
died
 North Sea 1988- 20,000 harbor seals died
Mammals
 Mediterranean
Sea 1990-93-1,000 striped
dolphins washed up dead on shore
 Diminished reproductive success in seals in the
Netherlands has also been observed
 Minke whales study shows increasing levels of
PCBs in body
Mammals
Autopsies revealed PCBs present in animal
bodies
 PCBs are known to suppress immune
system

Mammals

Studies were prompted to investigate:
 US
and Dutch conducted experiments that
revealed suppressed immune systems in seals
fed contaminated fish
 T-cell responses were significantly below
normal
Mammals

Reproductive hormones also affected:
 populations
of harbor, ringed and gray seals
declining
 high levels of PCB’s in body
 beluga whales in St.. Lawrence River showing
lower rate of pregnancy and fewer offspring
produced
Amphibians
Frogs especially vulnerable to
environmental contaminants because of
permeable skin
 Pesticides and PCBs are stored in frog’s fat
and enter the bloodstream again during
metamorphosis
 Many scientists now believe that the
commonly used chemical methoprene
degrades in sunlight into an endocrine
disrupter

Laboratory Experiments

University of Missouri:
 female
mice exposed to low doses of bisphenol
A altered the reproductive organs of their male
offspring

EPA in Research Triangle Park:
 Direct
link made between thyroid dysfunction
and PCBs in rats
Effects on Humans

Wayne State University:
 children
whose mothers had eaten contaminated
fish from Lake Michigan in the six years prior
to pregnancy had significant deficits in
intelligence and learning
 mothers themselves however were not
contaminated
Effects on Humans

Similar study in NY State:
 measurable
neurobehavioral deficits in the
newborn children who’s mothers had eaten the
equivalent of 40 pounds of Lake Ontario
salmon in a lifetime.
 children tended to have abnormal reflexes,
shorter attention span and an intolerance to
stress
Effects on Humans
Early exposure of males to endocrine
disrupters (DES) causes major problems
such as undescended testes, and increased
incidence of testicular and prostate cancer
 Sperm densities in the US are decreasing
1.5% every year

Conclusions
Thousands of chemicals need to be tested
for endocrine disruption
 October 1998: EPA unveils its strategy to
start testing chemicals
 No current plan to start testing common
household products
 On the cellular level, we are not very
different from animals, if they are being
affected by endocrine disrupters, so are we.
