PCB Exposure and Human Health

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PCB Exposure and Human Health

• David O. Carpenter, MD
• Institute for Health and the Environment
• University at Albany

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What are PCBs?

• PCBs are man made oils that were used for many
  years to fill electrical capacitors, as hydraulic
  fluids, as solvents in paints and window caulking
  and for many other useful purposes. They are
  actually a mixture of 209 different chemicals
  with similar structures.
• Because of their chemical structure, they are
  very persistent, both in the environment and in
  the human body.

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CHARACTERISTICS OF PCBs
? Very stable and persistent in animals and in
the environment. ? Tend to bio-accumulate in the
food chain, especially in fat. ? Lower
chlorinated PCBs are more volatile and water
soluble. ? Even the polar regions of the earth
are highly contaminated with PCBs via atmospheric
transport.
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PCBs in the Environment

• Because PCBs are an oil, they are found primarily
  in fat. This is why they bioaccumulate in the
  food chain from contaminated rivers.
• In rivers, the PCBs tend to be in the sediments,
  then move into the worms that eat the sediments,
  and then into the fish and other wildlife that
  eat the worms and the fish. Finally they end up
  in people who eat the fish, waterfowl or animals.
  

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How can we be exposed to PCBs?

• There are three routes of exposure to PCBs. One
  can eat or drink them, breathe them in from the
  air or absorb them through the skin.
• Eating or drinking PCBs is probably the most
  important route of exposure, but breathing in
  PCBs in very important in certain circumstances.
  You can also absorb them through the skin if you
  go barefoot in contaminated sediment. Since they
  are fat-soluble, they pass right through the skin.

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Air Transport of PCBs

• The polar regions of the earth have high
  concentrations of PCBs even though there are few
  local sources. This is because of air currents
  that transport to cold regions, where the PCBs
  come out of the vapor phase and get into fish and
  animals.
• Recent studies show PCBs in the air near
  contaminated sites, and resultant exposure to
  local residents.
• PCBs in indoor environments are even more serious
  routes of exposure by breathing the air.

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What level of PCBs is safe?

• We all have PCBs in our bodies because they are
  in all of the animal fats in our diet. ATSDR
  says that the average adult has between 0.9 and
  1.5 parts per billion (ppb) in our blood.
• There is no safe level of PCBs. All our
  research indicates that more is worse, but that
  even the level now commonly found in the average
  person increases risk of disease.
• This is why it is so important to reduce our PCB
  exposure to the greatest degree possible without
  excessive disruption of life style.

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How Long do PCBs Stay in Our Bodies?

• The half-life of PCBs in the human body (how long
  it takes to get rid of 50) varies with PCB
  structure.
• Those PCBs with few chlorines stay in the body
  only days to weeks, and are broken down in the
  liver.
• Those PCBs with more chlorines stay in the body
  for decades, since they are much more difficult
  to break down.
• How dangerous the PCBs are is not necessarily
  related to how long they stay in the body, but
  one can get information about exposure by
  measurement of the levels of PCBs in blood.

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Diseases of Concern

• Cancer
• Immune Suppression ? increased infectious
  disease, increased cancer
• Hypothyroidism ? overweight, tired, lacking
  energy
• Diabetes
• Neurobehavioral effects ? reduced IQ, antisocial
  behavior, poor memory, increased mental
  illness
• Cardiovascular disease ? heart attacks,
  hypertension, high serum lipids
• Disruption of sex steroid system ? infertility,
  birth defects of reproductive organs, early
  menarche, endometriosis
• Developmental abnormalities ? low birth weight,
  birth defects

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PCBs Cause a Decrease in IQ.
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We studied over 1,000 individuals for

• Congener specific PCBs (101 congeners).
• Three pesticides (DDE, HCB, mirex).
• Lead and mercury levels in adolescents.
• Serum lipids, fasting glucose, thyroid hormones,
  testosterone, estrogen.
• Medication use and medical diagnoses.

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We Gave Adolescents Four IQ Tests

• We found that the higher the PCB level in the
  blood, the less well the adolescents did on each
  of these four tests.

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Correlations between PCBs and Cognitive
Variables in Mohawk adolescents.(Controlling
for confounding variables)Coefficients with
are statistically significant (plt.05) all others
listed are significant at (plt.1).
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What About Adults?

• We tested about 350 adults with memory and IQ
  tests.
• Individuals with higher blood PCB levels did not
  do as well on these tests as those people with
  lower levels.

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• PCBs look very similar to thyroid hormone, the
  natural hormone that drives our metabolism and
  makes energy.
• Because of this, PCBs interfere with thyroid
  function.

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Risk of Hypothyroidism in Mohawk Adults in
Relation to PCB and Pesticide Exposures

• Toxicant OR (95 CI)
• Most PCBs 4.46 (1.47-13.54)
• Estro NP 0.29 (0.11-0.74)
• DDE1 0.83 (0.35-1.98)
• DDE2 3.79 (1.39-10.31)
• Mirex 0.84 (0.42-1.69)
• HCB 0.17 (0.07-0.42)

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PCBs and Sex Hormones

• PCBs can act like the female sex hormone,
  estrogen. This may change the age at which a
  young girl reaches puberty.
• PCBs also can alter levels of the male sex
  hormone, testosterone.

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Testosterone levels in men in
relation to PCBs

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PCBs and Heart Disease

• PCBs can increase the risk of a heart attack in
  several different ways they can cause an
  increase in the levels of fat in the blood, they
  can damage the walls of blood vessels and they
  can cause high blood pressure.

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PCBs and Diabetes

• New evidence shows that people with high PCBs are
  more likely to have diabetes.

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NHANES, Lee et al.

• Data from 2 dioxins, one PCB and three
  pesticides. (Diabetes Care 29 1638 2006)
• When risk of diabetes was classified according to
  the sum of all six POPs, adjusted ORs were 1.0,
  14.0, 14.7, and 38.3.
• Later (Diabetes Care 30 1596 2007) they
  conclude that the relation is strongest for
  dioxin-like PCBs and chlorinated pesticides, but
  weak for dioxins and non-dioxin-like PCBs.

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Organochlorine Compounds Increase Risks of
Diabetes
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Obesity and Diabetes

• Lee et al. (2006) looked at obese persons (BMI gt
  30 kg/m3) in relation to sum of 6 POPs
• lt25th 1 of 129 people
• 25th to 50th 14 of 153 people
• 50th to 75th 29 of 176 people
• 75th to 90th 32 of 87 people
• gt90th 31 of 80 people
• Conclusion Obesity does not cause diabetes!

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We have also studied an Alaskan Native population

• We obtained blood samples from over 100 adult
  Siberian Yupik people.
• There is a waste site on the island, and we have
  tested to see whether the people who have hunting
  camps near the waste site have higher PCB levels.
  
• We now are analyzing some of their traditional
  foods for PCBs and pesticides.

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PCB Levels (ppt) in Human Serum
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• These results show that those persons who have
  hunting camps near to the PCB waste site have
  higher levels of PCBs in their bodies.
• However all of the Yupiks have high levels of
  PCBs.
• The PCBs come from the animal fats they eat. The
  PCBs in reindeer were low, but those in the polar
  bears were very high. All of the marine mammal
  fat contain PCBs. Even the health of the animals
  is affected.

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POLAR BEARS
Survival of cubs reduced to ½ in Norwegian
Arctic. In past 42 of bears live to age 15 now
down to 11. We frequently find hermophroditic
bears never used to.
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Conclusions

• PCBs are dangerous chemicals that cause several
  different diseases.
• We are exposed to PCBs primarily from the food we
  eat, especially animal fats.
• Waste sites containing PCBs pose a serious threat
  to human health.