Toxic Bioaccumulative Chemicals

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Toxic Bioaccumulative Chemicals
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Mercury
Most mercury enters aquatic environments from the
atmosphere
The dominant inorganic forms are Hgo and Hg2.
Positively charged Hg2 can become attached to
negatively charged organic and inorganic
particles in soils and sediments which tends to
immobilize them.
Under anaerobic conditions, Hg2 can be converted
to organic Methylmercury which is more toxic and
persistent in organisms.
Mercury methylation is related to the metabolism
of Sulfur-reducing bacterial under anaerobic
conditions
The exact biochemical mechanism is poorly
understood.
High sulfur concentrations increase mercury
methylation
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The following are required for mercury methylation
Inorganic Mercury Anaerobic Conditions Carbon
Source (sediments) Sulfate/Sulfate-Reducing
Bacteria
Methylmercury is more directly toxic and remains
in The tissues of organisms longer than inorganic
Hg2.
This allows methymercury to bioaccumulate in
organisms
Bioaccumulation occurs when an organism absorbs
a toxic substance at a rate greater than that at
which the substance is lost from the body.
Bioaccumulation allows for biomagnification
which is the increase in concentration of a
chemical in organisms higher up in the food chain.
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Biomagnification concentration of a chemical in
organisms as it moves up the food chain.
Organisms near the top of the food chain may have
concentrations of mercury millions of times
greater than in the aquatic environment
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Other Bioaccumulative Toxins
Synthetic Organic Chemicals
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Synthetic Organic Chemicals
Organic carbon-rich compounds
Dioxin
Dioxins Pesticides
PBDE
PCBs
Flame Retardants
PCB
DDT
Organochlorines
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Potential Toxicity
July November
2004
Viktor Yushchenko Ukrainian President
6,000 times the usual concentration in his body
the second highest dioxin level ever measured in
a human
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Chemicals like dioxin are acutely toxic In high
doses, but they also can bioaccumulate creating
chronic toxicity at lower doses
The cause of their ability to bioaccumulate is
related to their water solubility.
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Water Solubility
NaCl Na Cl-
Sodium Chloride 350 g/L Potassium Chloride 280
g/L
Why?
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Water Molecules are Polar


Unequal distribution of electrons
Oxygen is electron-greedy
-
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NaCl Na Cl-
Na
Cl-
Sodium Chloride water solubility 350 g/L
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Contrast with Organic Chemicals
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Organic Chemicals
Carbon-rich compounds
Greases, Oils, Paints, Pesticides, Industrial
Chemicals
Grease and Oil
Oil Paint

Carbon 83 to 87
Hydrogen 10 to 14

C16H14OS
Composed mostly of carbon and hydrogen, and
possessing no electrical charge.
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Dioxin
C11H18O2Cl4
DDT
C14H22Cl5
C12H21Cl2
PCB
Principally carbon, hydrogen
Do not possess an electrical charge
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Dioxin
Dioxin water solubility 0.2 µg/L
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Dioxin
0.2 µg/L
DDT
lt 0.1 µg/L
PCB
10 µg/L
Uncharged and principally carbon, hydrogen
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Toxaphene 3 mg/L
Dieldrin 186 ug/L
Chlordane 9 ug/L
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Greases, Oils, Paints, Pesticides, Industrial
Chemicals
These types of chemicals are poorly soluble in
water
In what substances do they dissolve?
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Common Organic Solvents
Carbon-based
D-limonene oil
petroleum
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Organic Solvents
carbon
Hexane
carbon
Acetone
Dioxin
Lipids
carbon
carbon
Carbon-based compounds dissolve more easily in
carbon- based solvents.
water
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Soap
hydrophobic
hydrophilic
High Carbon Concentration
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Bioaccumulation in Organisms
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Bioaccumulation in Organisms
Lipid Tissue in Organisms
carbon
Fundamental similarity between the chemical and
the solvent.
The chemical essentially dissolves into the lipid
tissues
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Synthetic organic chemicals are poorly soluble in
water
They are soluble in organic solvents and lipids
Lipids are found in all organisms
Despite low levels of organic chemicals in water
due to their low water solubility, high amounts
can accumulate in the tissues of living organisms
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Water Concentration 0.2µg/L
Zooplankton concentration 160 µg/L
Magnification of 800 x
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Bio-Magnification
Water and phytoplankton to zooplankton 800 x
Overall 120,000 times original concentration in
water
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PCBs and Pesticides
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PCBs
Used as insulating fluids and coolants in
electrical equipment and machinery from 1929-1977.
Electrical equipment plasticizers in paints,
plastics and rubber products pigments, dyes and
carbonless copy paper
EPA estimates that 150 million pounds of PCBs
are dispersed throughout the environment, includi
ng air and water supplies an additional 290
million pounds are located in landfills in this
country
some PCBs act like hormones, and other PCBs are
nerve poisons
PCBs were banned in 1979
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Killer Whales (1000 ppm)
PCBs in Marine Mammals
High on food chain Lipid tissues
Hazardous Waste level (Canada)
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Toxaphene
(670 chemicals)
lipid
carbon
400,000 tons 1946 to 1974
Seawater
0.0003 ppb
Arctic cod muscle
14 - 46 ppb
50,000 X
Narwhal blubber
2440 - 9160 ppb
8 M X
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Toxaphene and Mirex 1959 - 1976
highest levels ever recorded in a living
organism.
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Summary

• Many synthetic organic chemicals are uncharged.
• 2. Because they are uncharged, they do not permit
• orientation of water molecules and are poorly
  soluble
• in water.
• 3. Ionic compounds (e.g. NaCl) are about 1
  billion times
• more water-soluble than uncharged organics.
• 4. Uncharged organic chemicals, however, tend to
  be
• soluble in organic solvents and organic
  materials
• because of similar carbon-based chemistry.
• 5. These materials can include lipid tissues in
  organisms
• which can lead to biomagnification

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Solubility
carbon
Hexane
carbon
Acetone
Dioxin
Lipids
carbon
carbon
Carbon-based compounds dissolve more easily in
carbon- based solvents.
water
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Many synthetic organic chemicals,
particularly those like PCBs and DDT are very
persistent in the environment. They last for
decades.
They become stored in organic materials that
naturally occur in aquatic and terrestrial systems
Where in these environments do we find high
levels of carbon?
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Organic Matter
Carbon Hydrogen Oxygen
Coiled and convoluted chains of carbon, hydrogen,
and oxygen
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Organic Matter
Carbon Hydrogen Oxygen
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Partitioning/Distribution
Organic matter
Soil Solution
Absorption
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Partitioning of neutral organic chemicals into
soil organic matter limits their mobility in the
environment
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Aquatic Systems
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Environmental Persistence
Water
DDT
Organic Sediments
Organic chemicals become stored in organic
sediments
This protects them from degradation and increases
their lifetime in the environment
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Lake Michigan
PCBs
banned in 1979
EPA 2004
PCBs
µg PCB/Kg sediment (parts per billion)
Open water PCB concentration lt 1 part per
trillion
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Lake Erie PCB levels
PCBs
EPA, 2004
After 30 years, PCBs continue to persist in the
Environment
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Persistence in the Environment
Old sediments
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Florida and Organic Chemicals
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DDT
dichloro-diphenyl-trichloroethane
First Modern Pesticide
Insecticide developed to combat insect-borne
disease
Use was later expanded to include agriculture
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Rita Island, Okeechobee
Organic soils
DDT levels ranging from 2,200 to 110,000 µg/kg
(ppb) in organic soils and sediments.
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Lake Apopka
30,800 acres
mean depth is 5.4 feet
15 miles northwest of Orlando
Historically characterized by clear water and a
highly prized sports fishery, it served as a
popular destination for boaters, swimmers, and
fishermen for decades.
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In the 1970s, scientists considered Lake Apopka
a prime place to harvest eggs and hatchlings to
study them in captivity. In 1980 and 1981,
scientists counted populations of 1,200 to 2,000
alligators in a single night on the lake
By the late 1980s, they counted only 150 per night
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Pesticide Use in Agricultural Area
Agriculture
Pesticide use included high amounts of DDT
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"Lake Apopka is a big chemical soup,"
Michael Fry, a researcher from the University of
California
Tower Chemical Company
TOC content ranges from 33 to 37
Produced dicofol, a mixture of the pesticide DDT
and DDE, a by-product of DDT. Periodic spills
occurred there, but a particularly large
accident in 1980 caused dicofol to spread into
the lake
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Alligator Population crash was linked to poor egg
viability
DDE, a breakdown product of DDT, is a major
contaminant in Lake Apopka DDE is known to
block the action of testosterone
Apopka's juvenile alligators have abnormal
testes and ovaries and abnormal hormone balances
Estradiol Testosterone
Apopka males had high levels of estradiol
relative to testosterone
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' Teeny Weenies ' Alligators in Florida's Lake
Apopka have Smaller Penises  Kyla Dunne for PBS
June, 1998
http//www.mindfully.org/Pesticide/Alligators-Apop
ka-PBS2jun98.htm
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Solubility
carbon
Hexane
carbon
Acetone
Dioxin
Lipids
carbon
carbon
Carbon-based compounds dissolve more easily in
carbon- based solvents.
water
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What is the most common way we daily dissolve
organic substances/chemicals?
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Soap
hydrophobic
hydrophilic
High Carbon Concentration
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Soap
Soap micelle
Oil drop in water
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Assessing the Danger Octanol
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An Important Organic Solvent Octanol
C8H18O
c
c
c
c
c
c
c
c
Neutral organic chemicals are soluble in organic
solvents
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Octanol-Water Partitioning
C8H18O
Octanol and water are immiscible
Octanol Density 0.824 g/cm3
C8H18O
octanol
water
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Partitioning Between Octanol and Water
Carbon/hydrogen
Octanol (Carbon/Hydrogen)
water
C10H20
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Octanol-Water Partitioning Coefficient
Concentration of chemical in octanol Concentration
of chemical in water
Kow
At equilibrium
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Add 10 mg chemical
1 L Octanol 1L Water
octanol
water
Analyze the water phase for the
chemical. Difference between initial amount and
amount in water amount in octanol The ratio
between the two yields the Kow
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Add 10 mg chemical
1 L Octanol 1L Waterl
9.99 mg L
0.01 mg L
9.99 mg L
Kow
999
0.01 mg L
Water phase
octanol phase
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Kow of some Organochlorine Compounds DDT
4,000,000 PCBs 2,000,000 Dioxin 6,0
00,000
chemical in octanol chemical in water
A high Kow indicates strong interaction with
organic solvents and lipid tissues
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PCBs
Kow 2,000,000
Used as insulating fluids and coolants in
electrical equipment and machinery from 1929-1977.
Electrical equipment plasticizers in paints,
plastics and rubber products pigments, dyes and
carbonless copy paper
EPA estimates that 150 million pounds of PCBs
are dispersed throughout the environment, includi
ng air and water supplies an additional 290
million pounds are located in landfills in this
country
some PCBs act like hormones, and other PCBs are
nerve poisons
PCBs were banned in 1979
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DDT
Kow 4,000,000
first modern pesticide (Nobel Prize, 1948)
used with to combat mosquitoes spreading malaria
(mosquitoes), and typhus (lice)
Insoluble in water. Soluble in most organic
solvents, fat, and oils.
Banned in 1972 (U.S.)
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Launch of the Environmental Movement
Thinning egg shells Lower hatching
rates Declining Eagle population Carcinogenic
decline in the eagle population occurred before
the DDT years (bounties between 1917 and 1942)
primates were fed 33,000 times more DDT than the
estimated exposure
human volunteers ingested 35 mg of DDT
1962
http//faculty.unionky.edu/rbotkin/RECM_480_ISSUE_
16A_YES_BLUE.PPT291,22,Issue201620Yes
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Water Filters
Simple Filtration
Ion Removal
Carbon (most common component)
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Activated Carbon
Activation by heating
Extremely porous with high surface area 500 m2/g
Large surface area high contact with
contaminants
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Activated Carbon
Absorption spontaneous movement of primarily
organic contaminants from water
to carbon matrix.
Pesticides and other organics essentially
dissolve in the carbon
Chlorine sticks to the extensive surfaces
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Ethylbenzene Monochlorobenzene MTBE O-Dichlorobenz
ene P-Dichlorobenzene Styrene Tetrachloroethene To
luene Trichloroethene VOCs Antidepressants Steroid
s/Hormones Prednisone, Prednisolone, Progesterone,
Testosterone, Cortisol/Hydrocortisone Antibiotics
Ciprooxacin, Trimethroprin, Sulfamethoxazole Anxi
olytics Meprobamate
Carbon Filter Removal
2,4-D 2.4.5-TP (Silvex) Alachlor Atrazine Carbofur
an Chlordane Endrin Heptachlor Epoxide Lindane Met
hoxychlor Simazine Toxaphene Benzene Carbon
Tetrachloride Chlorobenzene
Does not remove bacteria or most metals
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