Third Hour Exam Review

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Third Hour Exam Review
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• The figure on the left shows the different
  degradation pathways for a compound released into
  the water column. (a) Explain what
  characteristics (site and compound) would favor
  attachment to sediment, and (b) what
  characteristics (site and compound) would favor
  volatilization.
• You must keep in mind what parameters cause
  binding.
• For (a) the site should have high carbon content
  and the compound should have high Kow. These
  characteristics will result in sediment
  attachment. For (b) insolubility, low molecular
  weight of the compound in water and a rapid
  moving, bubbling water column will increase the
  probability of volatilization.

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• The use of DDT was banned in 1973, and yet there
  continues to be a concern in this country
  regarding its presence. List three reasons why
  there is still a concern.
• long residual time (long half-life)
• uptake by plants
• legal migration

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For the chlorinated phenol below, draw and name
the dioxin(s) formed.
Cl
Cl
2,7-dichlordibenzo-p-dioxin
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• 5. (15 pts) The figure on the left is
  illustrative of a dose-response curve. On the
  figure, label the points that are designated as
  LOAEL, NOAEL, LC50, and LC100. Explain why the
  x-axis is in units of mg/Kg/day for the dose.
• The x-axis is in mg/Kg/day to normalize the data
  so that when comparing large organisms with small
  organisms the size of the organism should not be
  a factor.

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• List three significant findings from the
  Jacobsons study involving children born to
  mothers who ate fish 2-3 times/week from Lake
  Michigan.
• (1) effects were due to pre-natal exposure
• (2) The Jacobsons discovered that at birth the
  children born to mothers who had transmitted the
  highest amounts of PCBs to the children had
• slightly lower birth weight
• slightly smaller head circumference
• slightly more premature
• (3) After ELEVEN years, those children most
  exposed to PCBs were three times as likely to
  have low average IQ scores and twice as likely to
  be at least two years behind in reading
  comprehension.

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• (10 pts) A large amount of money has been spent
  on research related to the toxicity of dioxins
  and furans, and recent studies have shown that
  farm-grown salmon have dioxins at a concerning
  level. What are the major concerns of people
  eating salmon, and is there a specific group of
  people that should be more cautious than others?
• The major concern with dioxins is the potential
  for cancer to develop later as well as to
  reproductive problems, abnormalities in fetal
  development, immune alterations, and disruption
  of hormones.
• The group of people that should be more cautious
  are women in child-bearing age, young children
  and older people because immune systems not fully
  developed or not as viable, in the case of older
  people, as young adults.

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• 8. (10 pts) The figure on the left is a general
  dose-response curve for essential and
  non-essential chemicals. (a) Identify the
  regions A, B, C, and D, and (b) show the optimal
  region of concentrations for essential chemicals,
  and the area where acute toxicity studies are
  performed.
• A death
• B irreversible effects
• C reversible effects
• D no harmful effects

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