Download Perchloratepresentation - Harvard University Department of

Tengbo Li, Annie Slivka, Jennifer Xia
Overview of Present Situation
• Perchlorate is a chemical that has been detected in many
drinking water sources as well as in food.
• It has been linked to various health problems, especially
those related to the thyroid.
• There is currently no national regulation regarding
perchlorate.
Question: Should we clean-up perchlorate? If so, who is
responsible, how should we go about it, and to what extent?
How do the costs and benefits compare?
• Naturally occurring and manufactured
• “easily dissolved and transported in water”
• Has been found in groundwater, surface water, and soil
across the country
• Potassium/ Ammonium perchlorate - salts - commonly
found in rocket fuels
• The least reactive oxidizer of the generalized chlorates > useful because it won't explode easily
T3
V.
Perchlorate
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•
•
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Rocket Fuel/Missiles
Explosives
Flares
Fireworks
Matches
Dyes/Paints
• Department of Defense +
NASA
o 90% in US
manufactured solely for
NASA and DoD
o so 65% plus 90% of
the 21% really due to
DoD -> 84%
Why Perchlorate?
" Since the 1940s, DoD has used potassium and ammonium
perchlorate as an oxidizer in explosives, pyrotechnics, rocket
fuel, and missiles. If it by far the safest, most efficient and stable
propellant oxidizer available. Perchlorate has a high
ignition temperature, controllable burn rate,
and stable chemical characteristics that reduce
handling and storage risks and the likelihood of unexpected
detonations."
Mr. Alex Beehler - Assistant Deputy under the Secretary of Defense (Environment, Safety, &
Occupational Health)in address to subcommittee on environment and hazardous materials of the
House Energy and Commerce Committee April 25, 2007
• “400 sites in groundwater”
o More might exist because of unclear regulation, but most are
not expected to be of extremely high levels
• 3700 ‘public drinking water systems’ across states
o 153 contaminated
o Only 14 of these have higher than EPA reference dose of
24.5 ppb
• 70% of contaminated sites have 24.5ppb
or less of perchlorate detected
Perchlorate contamination by State
Jan. 2005
• Solubility in water
o Easily infiltrates drinking water
o Gets in food such as milk and produce
•
• Not only is in drinking water, as it is in ground water - gets into
agricultural products as well...far reaching effects!
o Lettuce
 California (2003): "perchlorate above 30 parts per billion
in 4 of 22 samples."
o Milk
 Texas (2003): "sampled 8 bottles of milk and 1 can of
evaporated milk and found perchlorate concentrations
up to 6 parts per billion in seven of the milk samples and
more than 1 part per billion in the evaporated milk
sample." (Source 1 p8)
FDA Studies of Perchlorate
Consumption
•
•
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Spinach - 115 ppb
Collard Greens - 92 ppb
Melon - 29 ppb
Tomatoes 13 ppb
Lettuce - 10ppb
Milk - 6ppb
Botted Water - <0.5ppb
These are means collected by the
FDA in 2004-05, however do not
represent too many samples. The
produce data might also be biased
high, because the FDA
intentionally took high-water
samples in areas, such as
southern California and Arizona,
which had reportedly been
identified as areas of high-level
perchlorate contamination.
Upon analysis of this data in 2007, the EPA determined the
average consumption levels in people aged 2 and up to be
0.053 micrograms/kg of bodyweight/day, mostly due to milk
and then tomato consumption.
The Players
Let's Start at the Very Beginning... A Very Good Place to Start
1)Thyroid Gland:
Produces two hormones: T3
(triiodothyronine)and
T4(thyroxine)
•
•
•
T4 "largely a precursor hormone with little
or no intrinsic biologic activity" that is
converted into...
T3 required for normal development of
central nervous system and skeletal growth
in fetuses and infants
They are "critical determinants of metabolic
activity and affect virtually every organ in
system".
2)TSH (Thyrotropin a.k.a. thyroid
stimulating hormone)
•
•
Produced by the pituitary gland
Acutely regulates the levels of thyroid
horomones
Cellular movements of T3 and T4
The Players
Let's Start at the Very Beginning... A Very Good Place to Start
3) Iodide:
•
•
•
Plays essential role in synthesis of T3 and T4
Only gained through consumption - WHO recommends 150 (micrograms/day) for
adults, 200 for pregnant women, 90-120 for children 2-11, and 50 for infants under 2
WHO considers 50-99 mild iodide deficiency, 20-49 moderate, and under 20 severe
4) NIS Protein (Sodium/iodide symporter):
•
•
Mediates transport of iodide into thyroid
High affinity to iodide, but will also bind with other ions - could create an iodide
deficiency in thyroid
5) Perchlorate (ClO4-)
•
An ion that competitively binds to NIS - higher affinity to perchlorate than iodide
Production of T3 and T4
Effects of Perchlorate on Humans
• Should we be worried about perchlorate contamination in drinking
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•
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water and foods?
Studies from 1998-2005 conclude:
o 26 / 90 studies say perchlorate is harmful in amounts likely to
appear in drinking water
o 18 / 90 say perchlorate has "adverse effects on development
resulting from maternal exposure to perchlorate"
Majority "unable to determine whether the thyroid was adversely
affected"
(Source 1 p4)
Other potential harmful effects not expected at perchlorate levels
lower than that at which thyroid is affected, (e.g. immunotoxicity,
other organs) (4 p.165-169)
Mode-of-Action Model of
Perchlorate
Hypothyroidism - Low levels of T3 and T4
Ameliorating the Effects of Perchlorate
• TSH
Decreased Iodide triggers more production of TSH
2. Increased TSH triggers more synthesis and secretion of
T3 and T4
3. T3 and T4 levels stabilize, TSH levels return to normal
4. Few/no symptoms of temporarily low T3 and T4, may
have enlarged thyroid gland
1.
• Increased Conversion in Other Tissues
o
o
80% of T3 converted from T4 outside of Thyroid
Especially brain
• The CDC conducted a study of 2299 Americans that showed that
perchlorate may induce hypothyroidism in 36% of American
women -- 44 million people
• These women have urine iodine concentrations of < 100
micrograms/L. Among adults, they are most susceptible to
perchlorate
• Along with pregnant and low-iodine intaking women,
infants and fetuses are the most susceptible populations
o Can receive perchlorate through placenta and
lactation
• Perchlorate contamination leads to about 1% inhibition
of key hormones in infants
• Lower iodide intake by infants and their pregnant
mothers
o Can lead to slower development and learning
handicaps
• University of Arizona study shows their may be link
between high levels of perchlorate in Colorado River and
lower thyroid function in infants who live near it
Different Effects on Infants
"The consequences of severe combined maternal and fetal hypothyroidism during
fetal life and in newborn infants include microcephaly (small brain), mental retardation,
deaf-mutism, paraplegia or quadriplegia, and movement disorders. Those abnormalities
are not reversible by treatment with T4."
"Newborn infants who have hypothyroidism may have other abnormalities, including
lethargy, poor muscle tone, poor feeding, constipation, and persistent jaundice, if not at
birth then thereafter. The changes are similar to those which occur in older children and
adults who have hypothyroidism, and, in contrast with the neurologic abnormalities, they
are reversible with adequate T4 treatment."
Why?
Nervous system
•
•
stimulates development and growth of: neurons, glial cells, synapses, myelin
sheaths, neurotransmitters
stimulates transcription of "several genes whose products are important for neural
development"
Skeletal system
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needed for normal growth of long bones
stimulates production of pituitary growth hormone and insulin-like growth factor
Thus..."severely affected infants are unlikely to have normal stature"
• National Academy of Sciences: conducted a study to determine
"safe level" of perchlorate intake per day
o Safe level defined as NOEL -- No-observed-effect-level
 At this level, the population being exposed to experimental
levels of perchlorate shows no statistically
significant deviations from control population
• Used Greer study value of of .007 mg/kg per day
o
o
Uncertainty factors were considered, and only the intraspecies
factor was ultimately implemented
A factor of 10 was used to account for pregnant women and
infants, thus bringing the NOEL to .0007 mg/kg per day
 NAS determined that this was the safe level of perchlorate
exposure in humans
 The value of this safe level takes into account long term
exposure
• Resource Conservation and Recovery Act (RCRA)
 Hazardous Waste
 “ignitable, corrosive, reactive, or toxic”
 Must get permits from EPA to handle the waste
 EPA “orders cleanups” or states
 California Courts: Perchlorate is
• Comprehensive Environmental Response, Compensation, and Liability Act
(the “Superfund”)
 “cleanup of releases or threatened releases of hazardous substances”
o Gives authority to EPA to act / fund
 • DoD “has responded to perchlorate found on military installations and facilities”
o Short term
• Clean Water Act
o
o
o
“regulate the discharge of pollutants into waters”
Pollutant = “virtually all waste material”
Need permit to discharge (determines quantity of what you can do)
• Federal Facility Compliance Act
EPA and DoD “rule identifying when military munitions become hazardous waste under RCRA”
 Used muitions = waste if waste is taken off site
 “known sources of perchlorate
o DoD must monitor
o
• Safe Drinking Water Act
EPA set “maximum containment-level goals” “that must be met by public water systems”
 Max = 90 contaminants
o BUT
 “more than 200 chemical contaminants associated with munitions use, including perchlorate, are
currently unregulated”
o
History of EPA Perchlorate
Regulations
1985:
First seen as hazardous
1995:
EPA "provisional" 0.0001-.0005 milligrams per kilogram of body weight per day
= 4-18 parts per billion
1997:
New technology allows for actual testing
First found in groundwater near a California manufacturer
1998:
EPA issues first risk report
1999:
States are testing drinking water and finding perchlorate: are alarmed
2002:
Revised to "concentration of 1 part per billion in drinking water" (0.00003 mg/kg of body weight per day)
2003: Government agencies disagree on health affects and EPA's risk study
2005: NAS: no "link between perchlorate exposure and developmental effects"; reference dose should be 0.0007
mg/kg of body weight per day
this "is conservative and includes safeguards to protect the most sensitive population, the fetus of the nearly
iodine-deficient pregnant woman" (20.825 parts per billion)
EPA new reference does: 24.5 part per billion:
"adult weight ...154 pounds consumes 2 liters of drinking water per day"
NOW: EPA still has not issued the formal report it was commissioned to write ten years ago...
The EPA Strikes Back
• On December 30, 2008, the Inspector General of the EPA released
a study that criticized previous methods of regulating perchlorate
concentration levels
o In particular the study criticizes the NAS study, which set intake
level at 0.0007 mg/kg/day, and the EPA level of 24 ppb
• Neither NAS study nor the first EPA study took into account
three other factors that can lead to thyroidal inhibition: the
chemicals
thiocyanate and nitrate, and lack of iodide intake
• These three additional factors have a significant impact on thyroid
function; according to the EPA, these factors are even more
hazardous to human health than perchlorate
o Adequate risk assessment must take into account all four factors
EPA Study: Problems with Previous
Studies
• Of the four factors, perchlorate has the least impact on thyroid
function
o Even making extremely conservative estimates for safe levels of
perchlorate intake will "not prevent mental damage in children"
o Exposure to all four factors must be limited in order to circumvent
the problems originally attributed just to perchlorate
• Hypothyroxinemia, deprivation of T4 in pregnant women and their
infants, actually occurs before hypothyroidism, used as the first step
in toxicity in the NAS study
o 6.9% of American infants (~276,000) born each year are at risk for
the effects of T4 deprivation
o Effects include lower IQ, ADHD, and lower motor performance
Interpretation of New EPA Study
• Critical information
Decreasing the level of perchlorate in drinking water from
24 ppb to 6 ppb would only increase maternal thyroid
iodide intake by 1%
o The REAL culprit is lack of iodide in the diet, which can
affect thyroid function much more significantly (by a factor
of 50) than perchlorate
o Even nitrate can decrease T4 function more than
perchlorate -- by a factor of 12
• A long term solution to the problems associated with
perchlorate, thiocyanate, nitrate, and lack of iodide intake
should be focused primarily on the lack of iodide intake
factor, as cleaning up perchlorate would have little effect on
improving public health
o
Methods of Removal
• Three ways:
o
o
o
Biological and biochemical reactor treatment systems
Conventional chemical reactor treatment systems
Separation and concentration technology
• Problems
o
With Perchlorate

Not very reactive to chemical treatments
 Cannot remove low levels of perchlorate contamination.
o
Environment differs site to site
o
With the treatments



High costs
Technical Problems
Cannot remove low-concentrations of perchlorate from drinking water
• More research
Biological Treatment
• Above ground tank filled with Microbes
o
o
Perchlorate → chloride and oxygen
Anoxic Conditions needed
 alcohol
 "electron donor to sustain the microbes."
• Advantages
o
o
No waste
Less expensive
• Disadvantages
o
Not accepted on drinking water
Ion Exchange System
• Replaces perchlorate ions with chloride ions
• Advantages
o
o
o
Viable over more conditions
More manufacturers
Accepted on drinking water
• Disadvantages
o
Removal not Destruction
 Waste product
 Expensive
• More research is being done
Cost of Removal
Cleanup of JUST highly-contaminated Colorado River
= $ 40 Billion
to meet standard of 1 ppb
Private Manufacturers: Liable?
• Kerr-McGee Chemical Plant
Nevada
• 20 millions pounds in Colorado river
 20 million drinkers
 next 50 years
• American Pacific
sole current producer of the chemical
in US
 20 million pounds in 2004
o Nearby:
 750,000 ppb
 up to 300 feet below
 "through fiver groundwater
layers"
o Poor disposal = Contaminated "Lake
Louise"
o
•
Lockheed Martin
7 mile plume
 47 drinking water wells
 5 shut down
 800 individuals have filed suit
for health reasons including
cancer
o 1998: $80 million on clean up
 Another $180 million in next 20
years
o
HOWEVER
Example of High
Concentrations due to Military:
High Costs for Defense Department
$16-165 Billion
•
Large range
o Varies from agency


•
1 acre clean up: $800 to $7,600
total of 24 million acres of possible cleanup
 More possible
Need Identification / record system
What they are doing
• DoD will work on a clean up only for sites that are clearly
theirs and are clearly health hazards
o If anything is above the appropriate level, DoD will act!
• Taking new samples
• Research
o
$114 million
 Substitutes, recycling, detection
Cost-Benefit Analysis
If Clean-up...
• Cost of Clean up
o $40 Billion Colorado River
o $16-165 Billion Defense of Department Areas
 .84/$100=1.00/x -> x= $120 Billion
• Cost of Treatment of those exposed
o Once removed from perchlorate, hypothyroidism is temporary
If Medical Treatment...
• Prenatal Care:
o 276,000 U.S. infants born each year at risk (mothers with low T4 levels)
• Costs of screening Adults: Simple Blood Test - Radioimmunoassay(RIA) $5
• Costs of treating Adults:
o CDC estimate 44 million women at risk (low iodine levels) - must be in
environment of consistently high exposure of perchlorate
o If hypothyroidism: Levothyroxine (pure synthetic T4) : $120 / year (for lifetime)
• Overall Cost:??? (But less than Clean-up)
Conclusion
Therefore,
We recommend:
 Cleaning up the areas of high concentration (very few)
 14 drinking water systems detected with above 24. 5
 Other DoD and Private sites with high, high
concentrations
 Not cleaning up all sites
 Implement better cross-agency monitoring system
 EPA + DoD together
 Require safe storage and disposal of future
 Both DoD and Private
 Legislate to enforce
 Screening
 Women at risk
 Low-Cost screening for low iodine individuals
Acknowledgments
Thank you, Professor Wilson, for providing us with relevant
Perchlorate Studies.
For full works cited please see the accompanying report.