Presentation on theme: "Tengbo Li, Annie Slivka, Jennifer Xia. Overview of Present Situation Perchlorate is a chemical that has been detected in many drinking water sources as."— Presentation transcript:
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 Perchlorate V.
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
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 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
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
Effects of Perchlorate on Humans Should we be worried about perchlorate contamination in drinking 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 1. 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 Increased Conversion in Other Tissues o 80% of T3 converted from T4 outside of Thyroid o 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 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 Uncertainty factors were considered, and only the intraspecies factor was ultimately implemented o 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 “regulate the discharge of pollutants into waters” o Pollutant = “virtually all waste material” o Need permit to discharge (determines quantity of what you can do) Federal Facility Compliance Act o 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 Safe Drinking Water Act o 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 Amendment Requires EPA to look at the unregulated To see whether chemicals occur often enough to warrant further study
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 n 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 o 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
Methods of Removal Three ways: o Biological and biochemical reactor treatment systems o Conventional chemical reactor treatment systems o 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 Perchlorate → chloride and oxygen o Anoxic Conditions needed alcohol "electron donor to sustain the microbes." Advantages o No waste o Less expensive Disadvantages o Not accepted on drinking water
Ion Exchange System Replaces perchlorate ions with chloride ions Advantages o Viable over more conditions o More manufacturers o 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 o 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" Lockheed Martin o 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
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.