New Term Paper Due Dates

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New Term Paper Due Dates
November 18 final version of paper for peer
editing. December 2 return edited papers to
classmates. December 9 Final edited paper due.
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Persistent Organics in the Environment

• Some common persistent organics
• DDT
• PCBs
• Dioxins
• PBDE
• MTBE

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Persistent Organics in the Environment

• Why are we concerned?
• Bioaccumulation
• Stability
• Toxicity

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Persistent Organics in the Environment
1. Bioaccumulation Due to their low solubility,
persistent organics tend to partition to soils
and animal fats. This partitioning can be
modeled to within about a factor of 10 using
octanol (C8H17OH).
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Persistent Organics in the Environment
1. Bioaccumulation
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Persistent Organics in the Environment
1. Bioaccumulation This is usually reported as
the logKow because the values for molecules of
interest can be quite large. Online
database http//logkow.cisti.nrc.ca/logkow/index.
jsp
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Persistent Organics in the Environment
1. Bioaccumulation
Do to the stability and partitioning of organics
in fatty tissue, the concentration of organics
may magnify many orders of magnitude through
several trophic levels.
From www.absc.usgs.gov
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Persistent Organics in the Environment
2. Stability Low volatility no gas phase
sink. Low solubility not very mobile. Usually
consist of chlorine or bromine bonded to an
aromatic ring not very reactive. Long lifetime
can be transported long distances over time.
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Persistent Organics in the Environment
2. Stability
From Thomann, Environmental Health Perspectives
Volume 103, Supplement 5, June 1995
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Persistent Organics in the Environment

• 3. Toxicity
• exposure
• acute versus chronic toxicity
• mode of toxicity
• mutagen
• carcinogen
• teratogen
• dose-response relationship

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Persistent Organics in the Environment

• 3. Toxicity
• Exposure depends on Kow.

From Thomann, Environmental Health Perspectives
Volume 103, Supplement 5, June 1995
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Persistent Organics in the Environment
3. Toxicity
Dose is usually expressed as a mass of chemical
per mass of organism. Response is usually
expressed as the of the population that has a
specific response (or dies) after exposure to the
corresponding dose.
From www.rstp.uwaterloo.ca
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Persistent Organics in the Environment

• 3. Toxicity
• Major health concerns
• Chronic
• hormone disruption
• cancer development
• birth defects
• Acute
• all of the above
• allergic reaction
• respiratory issues

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para-dichlorodiphenyltrichloroethane (DDT)

• Used to control typhus and malaria during WWII.
• Used as an agricultural pesticide since WWII.
• 1.8 million metric tonnes released to the
  environment worldwide.
• Banned in the US in 1972 and subsequently
  worldwide.
• Still used today in the tropics to control
  mosquitoes that carry malaria.

DDT log Kow 6.2
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para-dichlorodiphenyltrichloroethane (DDT)
DDT
DDE

• DDE (dichlorodiphenyldichloroethane) is a major
  derivative of DDT and is responsible for much of
  both the effectiveness of DDT and its
  harmfulness.

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para-dichlorodiphenyltrichloroethane (DDT)

• Kills bugs by interfering with their neurological
  activity.
• Causes thinning of shells in predatory birds.
• Low acute toxicity for humans (LD 50 113mg/kg)

DDT
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para-dichlorodiphenyltrichloroethane (DDT)
log Kow 6.91
From www.geo.arizona.edu
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para-dichlorodiphenyltrichloroethane (DDT)
From National Resources Defense Council
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Polychlorinated biphenyl (PCBs)
209 individual compounds, about 130 were commonly
used.
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Polychlorinated biphenyl (PCB)

• Industrial production began in 1929
• Approximately 1.5 million metric tonnes have been
  produced globally.
• Production peaked in the 1960s.
• Mostly banned in the 1970s for open uses.
• No new production today, however, some PCBs are
  still in use.
• insulating fluid for transformers and capacitors
• plasticizer
• fire retardant

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Polychlorinated biphenyl (PCB)

• Properties
• Low water solubility
• High organic solubility
• Generally low vapor pressures
• Chemically stable
• log Kow 5.2 (4,4-dichlorobiphenol)
• Acute toxicity for humans
• grams/kg
• For fish
• µg/kg

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Polychlorinated biphenyl (PCB)

• Removal from the environment involves
• dispersion slow due to bioaccumulation
• chemical breakdown slow due to stability
• removal of contaminated soils or sediments must
  then store the contaminated material
• incineration potential to create other
  hazardous materials furans and dioxins
• microbial conversion to Cl2 and biphenyl

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Polychlorinated biphenyl (PCB)

• Hudson River PCBs
• General Electric dumped up to 1.3 million lbs of
  PCB into the Hudson river between 1947 and 1977.
• Dredging to remove contaminated sediments began
  earlier this year (2009).

From www.riverkeeper.org
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Polychlorinated biphenyl (PCB)
From New York State Dept of Environmental
Conservation
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Polychlorinated biphenyl (PCB)
USEPA suggests a maximum safe level for
consumption is 3 ppm in dairy, meat, and seafood.
From National Resources Defense Council
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Dioxin

• Sources
• Natural is created anytime organic material is
  burned in the presence of chlorine.
• Industrial is created anytime organic material
  is burned in the presence of chlorine.
• incineration
• pulp and paper bleaching
• Mostly a by-product of other processes, however
  has been used directly.
• defoliant Agent Orange
• poison

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Dioxin
chloracne
Viktor Yushchenko, president of Ukraine, was
allegedly poisoned with dioxin and had dioxin
levels thousands of times greater than found in
average blood.
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Dioxin
Toxicity LD50 100s of µg/kg for the most
toxic form.
2,3,7,8-Tetrachlorodibenzodioxin (TCDD)
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Dioxin
From Natural Resources Defense Council
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Dioxin
log Kow 6.8 (TCDD)
From Natural Resources Defense Council
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Polybrominated diphenyl ethers(PBDE)

• Flame retardant
• Integrated into many consumer products including
  plastics and fabrics.
• Still produced in the US, recently banned in
  California, Washington, and Maine. Banned in the
  European Union.
• LD50 is grams/kg
• log Kow 5.8

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Polybrominated diphenyl ethers(PBDE)
From Natural Resources Defense Council
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Polybrominated diphenyl ethers(PBDE)
From Natural Resources Defense Council
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Methyl tert-butyl ether (MTBE)

• Fuel additive
• Increases octane number.
• Reduces engine knocking replaced lead
• Reduces VOC emissions from gasoline.
• LD50 4g/kg (comparable to pure ethanol)
• log Kow 0.94

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Methyl tert-butyl ether (MTBE)
Seeps into groundwater from underground fuel
storage tanks. -gives water an unpleasant taste
at 5µg/L Has been measured in well water around
Santa Monica and Lake Tahoe -California now has
regulations for MTBE (5µg/L)
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Next Weeks Exam

• The exam is on Wednesday, November 4 during the
  first 50 minutes of regular class time.
• You are allowed to use a calculator (no PDAs or
  cell phone calculators).
• You may not use your calculator to look at
  pre-recorded notes this is considered cheating.
• Dont forget your calculator, there will be no
  extras to hand out.

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Next Weeks Exam

• No aids in addition to a calculator are allowed.
• Do everything possible to avoid even the
  suggestion of cheating
• no hats, sunglasses, wandering eyes, etc.
• Partial credit can be given only if your work is
  well organized and easily readable.
• All calculations need to be worked out on the
  exam to receive credit, even if you have the
  correct answer.

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Next Weeks Exam

• The form of the exam
• Multiple choice
• 20-30
• Short answer
• 30-40
• Worked out calculations
• 30-40
• This exam is worth 22 of your grade.

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Next Weeks Exam

• Priority of material on the exam
• Topics covered in lecture
• Topics covered by the assigned reading
• You are responsible for material in the readings,
  even if it was not explicitly covered in lecture.
• Preparing for the exam
• Do the suggested problems
• Study the lecture notes
• Study text