Oct 20 PCBs continued

1

• Oct 20 PCBs continued
• Exposure levels
• EPA provides safety data on desired levels of
  substances in the environment
• For PCBs, level is 0.
• Enforceable standard 0.5 parts per billion
  (ppb) technologically feasible
• known as the MCL maximum contaminant level

2

• Health Effects
• 1. Short-Term exposure gt MCL acnelike
  eruptions dark pigmentation of the skin hearing
  and vision problems muscle spasms. Transient.
• 2. Long Term Effects following repeated exposure
• cancer especially rare forms of liver cancer
  and malignant melanomas
• immune system effects decrease in size of the
  thymus gland reduced antibody responses to
  challenges decreased resistance to certain
  viruses and infections (pneumonia) seen at all
  doses examined
• immune suppression may predispose to cancer
• reduced thyroid hormone levels and some effects
  on androgens
• elevated bllod pressure, triglycerides, and
  cholesterol
• additional effects on skin and eyes

3

• Health Effects
• 3. Reproductive and Developmental Effects
• reduced rates of conception and reduced birth
  rates
• reduced birth weight
• shortened gestational length
• neurological and learning deficits in infants
• immune system deficits in prenatally exposed
  infants and those exposed via breast milk
• no reports of structural birth defects

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• Studies of Neurodevelopmental Effects
• Historical Poisoning Accidents
• Yu-Cheng, Japan 1968 contaminated rice oil
• Dubbed Yusho Disease rice oil disease
• Taiwan, 1979 again contaminated rice oil
• Yu-Cheng Disease
• Effects in adults acnetype lesions, brown
  pigmentation of the skin, swelling of the eyes,
  headache, memory loss, numbness or tingling
  sensations in the limbs

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• Studies of Neurodevelopmental Effects
• Historical Poisoning Accidents
• Effects in the newborns reduced size at birth,
  brown pigmentation of the skin, swollen eyes,
  overgrowth of gums, teeth present at birth,
  abnormal calcification of the skull.
• Childhood - hypotonia, motor clumsiness and
  jerkiness, developmental delays, IQs in mildly
  retarded range, increased bronchitis
• 2. Research Study of Yu-Cheng Children
• 38 of sample followed 12 years later on
  nicely matched cohort based on parental
  variables, age, sex, and neighborhood
• In this more controlled comparison (but only a
  subset of cases), average IQ reduced by 5 points
  in exposed
• Examined PCB levels in maternal and child blood
  at this later time no relationship

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• Studies of Neurodevelopmental Effects
• 2. Research Study of Yu-Cheng Children
• 38 of sample followed 12 years later on
• Also examined neurological, neurophysiological,
  behav. endpoints
• No abnormalities on general neurological exam
• Auditory P300 event related potential latencies
  were longer than controls
• Visual and somatosensory evoked potentials okay
• More behavioral problems identified on a
  standardized questionnaire on emotional and
  behavioral problems
• Higher activity level reported on child activity
  questionnaire
• On measures of spatial ability, exposed boys did
  worse than controls but no difference for girls.
  Male specific spatial learning deficit shown in
  rat models possible androgenic effect due to
  endocrine disruption.

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More Recent Formal Research Studies PCBs in
studies of children prenatally exposed to
contaminated rice oil mixtures were mostly
dioxins and furans. Different mixtures in studies
of kids exposed through maternal diet during
pregnancy or lactation bioaccumulated forms
variable What are the goals of the current
studies? Who is being studied? What is being
measured re exposures? What is being measured re
effects on kids? What effects have been shown?