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Last Minute Mischief at EPA

For Immediate Release: 
Tuesday, November 11, 2008

WASHINGTON –- As the clock runs out on the Bush administration, officials at the Environmental Protection Agency (EPA) are trying to hand industry yet another victory by refusing to set safety standards for the toxic rocket fuel ingredient perchlorate. In doing so, EPA leaders have ignored authoritative studies from the Centers for Disease Control and Prevention (CDC) and instead have relied on a chemical industry-funded consulting firm. If the agency leadership’s decision not to regulate perchlorate in drinking water becomes final, defense and aerospace contractors could save hundreds of millions of dollars in cleanup costs.

In 2006 the CDC published the results of a study of 1,100 women that showed clear clinical signs of perchlorate toxicity at real-world exposure levels. When pressed by congressional allies of perchlorate polluters at a hearing of the House Committee on Energy and Commerce, the CDC said that decreases in critical thyroid hormone levels in women exposed to perchlorate were "consistent with causation" -- in other words, that perchlorate probably caused their hormone deficiencies. Based on CDC data, the Environmental Working Group (EWG) estimated that as many as 44 million women who are pregnant, thyroid deficient or have low iodine levels are at heightened risk of exposure to the chemical.

Other CDC studies have found perchlorate in the urine of every person tested and have discovered that children between 6 and 11 had perchlorate levels 1.6 times higher than adults. These CDC reports have aroused great concern because tests show that the chemical disrupts production of thyroid hormones at these levels, and adequate thyroid hormones are crucial to normal brain development and growth in infants and children.

Instead of using this state-of-the-art CDC data, EPA officials contracted the perchlorate assessment out to the Chemical Industry Institute of Toxicology (CIIT), which its website says was created in 1974 by “chemical industry leaders.”

The consulting firm devised a computer model for the assessment that concluded that perchlorate-contaminated water and food presented relatively minor risks to humans. Even though the CIIT computer model has not been validated by a standard peer review by scientists expert in the field, EPA officials cited the CIIT data when they declared Oct. 10 they saw no need to crack down on water pollution caused by perchlorate. They indicated they would finalize the decision before the Bush administration leaves office.

“It’s simply mind-boggling that the EPA would ignore serious warnings from the CDC study about perchlorate risks to women and children and instead base its actions on any advice from the chemical industry, which has millions of dollars at stake in EPA’s position on perchlorate,” said EWG senior scientist Anila Jacob, a medical doctor. “Worse yet, this particular industry consultant is notorious for cooking its results to please the industry. Its computer model is voodoo science, plain and simple.”

“If President Bush moves forward with this giveaway to industry, we will ask the incoming Obama administration to reverse course immediately and implement stringent safety standards to protect future generations from exposure to this toxin,” added Jacob.

CIIT is no stranger to controversy. Its 2004 risk assessment for formaldehyde claimed the chemical was 2,500 to 10,000 times less dangerous than EPA had previously asserted. Since 1981, the U.S. federal government has listed formaldehyde as a “probable human carcinogen.” (Formaldehyde-treated plywood and other components were found to have sickened Hurricane Katrina survivors living in trailers provided by the Federal Emergency Management Agency.)

The U.S. Appeals Court for the District of Columbia overturned EPA’s formaldehyde loophole in 2007. Even so, EPA has continued to use CIIT assessments instead of making its own calculations or turning to risk assessment experts independent of the chemical industry.

In a September 18 report, the U.S. Government Accountability Office (GAO) raised questions about CIIT’s insistence that people are at low risk from formaldehyde emissions. CIIT researchers, GAO said, did not take into account 2003 and 2004 studies by the National Cancer Institute and the National Institute for Occupational Safety and Health that found a “relationship between formaldehyde and certain cancers, including leukemia.”

EPA issued its preliminary decision not to regulate perchlorate on Oct. 10. At that time, the agency set a deadline of 30 days, to Nov. 10 for public comments. EWG, the EPA Science Advisory Board and other interested groups pressed for an extension to allow more time for discussion. On Monday, EPA granted an 18-day extension, to Nov. 28. EWG responded by renewing its request for an extension to Jan. 9.

The letter from EWG to the EPA is attached to this release.

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EWG is a nonprofit research organization based in Washington, DC that uses the power of information to protect human health and the environment.

November 11, 2008

U.S. Environmental Protection Agency
Water Docket
EPA Docket Center
1200 Pennsylvania Avenue, NW
Washington, DC 20460

Letter to EPA re: Preliminary Regulatory Determination on Perchlorate (Docket ID No. EPA-HQ-OW-2008-0692)

Dear Administrator Johnson:

Environmental Working Group (EWG) strongly disagrees with EPA’s recent finding that setting a national drinking water standard for perchlorate would not present “a meaningful opportunity for health risk reduction for persons served by public water systems” (EPA 2008). The science provides overwhelming evidence that the tens of millions of people drinking perchlorate in tap water face real health risks that only EPA can protect them from. But the agency has chosen not to act and by failing to act, EPA has sacrificed its scientific integrity.

EPA’s Preliminary Regulatory Determination on Perchlorate is an embarrassment to the agency. It marks the next step in a long journey away from sound science, impartiality, and public health protection towards biased decisions where the agency no longer even attempts to hide its partiality towards industry interests.

Instead of using state of the art science and human bio-monitoring data from the Centers For Disease Control and Prevention (CDC) to assess risks, the agency employs a highly questionable, non-peer reviewed computer model developed by the discredited industry front group, the Chemical Industry Institute of Toxicology (CIIT). The choice to use a model instead of real world data was done for one reason, to make the risks from perchlorate look smaller than they really are. The model did achieve that result, but even this faulty analysis did not completely exonerate this potent thyroid toxin. In the end, this computer model predicts that 30,000 pregnant women would be exposed to perchlorate in drinking water at levels that exceed EPA’s health reference level (HRL) of 15 ppb at any given time (EPA 2008).

Compounding these problems, the CIIT relied heavily on a flawed, industry-funded study (the Greer study) when creating the computer model (Greer et al. 2002) -¬ the problems with the Greer study have been documented in the published scientific literature and by the Massachusetts Department of Environmental Protection (Ginsberg and Rice 2005, MassDEP 2006). Even with the errors and bias that the use of the CIIT computer model injects into EPA’s assessment, EPA still concludes that up to 2 million people may be consuming drinking water that exceeds the HRL, including tens of thousands of infants and young children. The agency then dismisses these impacts as not significant enough to justify setting a drinking water standard for perchlorate. If EPA had used CDC’s real world data in it’s assessment instead of the flawed computer model, a much higher number of infants, children, and women of childbearing age would be found to be at risk.

The combined effect of these multiple layers of corruption has been to make perchlorate look safe when it is not, and to make EPA appear as though it is simply servicing perchlorate polluters, which it is. The agency’s proposed action is nothing less than pandering to perchlorate polluters who would be made to clean up the tap water of 40 million people in 27 states if the agency were to conduct an honest assessment of the human health risks of perchlorate.

This assessment makes a mockery of everything EPA stands for. It must not be adopted.

Introduction:

In this assessment, EPA relies primarily on a physiologically-based pharmacokinetic (PBPK) model to estimate risks to different populations from perchlorate contamination of drinking water. This approach is somewhat suspect to begin with because it is based on a computer model, rather than on the wealth of data from human studies on perchlorate. Recent large, well-conducted human studies on perchlorate have revealed that exposure to this thyroid toxin is widespread among the U.S. population and that women with lower iodine levels are a particularly vulnerable group, in addition to breast-fed infants and young children. Other noteworthy errors and flaws in this assessment include the following:

The scientific evidence clearly points to the need for EPA to set a health protective drinking water standard for perchlorate – that is, a standard lower than the level shown to be associated with altered thyroid hormone levels in American women with low iodine intake. Unfortunately, EPA has relied on questionable science, an even more questionable computer model, and circular logic to justify its proposal to not regulate this harmful contaminant at all in our nation’s drinking water. This is inexcusable.

EWG urges EPA to overhaul its poorly crafted assessment according to the points described in detail below and to live up to its mandate of protecting public health by setting a stringent drinking water standard for perchlorate.

Background

Recent research from the CDC and the Food and Drug Administration (FDA) provide strong evidence that perchlorate exposure among the U.S. population presents potential health threats that justify strong protective measures by public health agencies. The most compelling findings from recent research from government agencies and academic scientists are summarized below:

This body of data from a number of respected sources including CDC, FDA, and academic scientists provides compelling evidence that establishes widespread exposure to perchlorate among the U.S. population and toxicity in a vulnerable population (women with lower iodine levels). The findings of widespread food contamination are especially concerning for young children, who eat more food and drink more water per unit of body weight when compared to adults.

EPA’s decision not to regulate perchlorate in drinking water in the face of such compelling facts is irresponsible and indefensible given the strength of the evidence for stringent regulation. In fact, EPA reached its decision by using flawed models and methodology; following are some of the most glaring reasons that this assessment is inadequate.

EPA relies on PBPK model that was designed by industry-funded group: EPA relies heavily on the PBPK model in their assessment; this model was designed in part by scientists who work for the CIIT, which is an industry-funded organization that is sponsored by corporations such as 3M, BASF, Dow, and ExxonMobil and trade groups such as the American Chemistry Council and the American Petroleum Institute.

The CIIT has a history of conducting assessments that result in outcomes that favor industry. In a 2008 report, the Government Accountability Office (GAO) notes that the CIIT developed a risk assessment for formaldehyde that was 2,400 times less stringent than a previous Integrated Risk Information System (IRIS) estimate (GAO 2008). The GAO report goes on to note “The decision to use the CIIT assessment in the plywood national emissions standard was controversial, and officials in EPA’s National Center for Environmental Assessment said the center identified numerous problems with the CIIT estimate” (GAO 2008).

In 2004 the CIIT also published a model for the contaminant trichloroethylene (TCE) that proposed cancer risk values for TCE inhalation that were 300 times less protective than EPA's 2001 proposed values (Clewell et al. 2004). Leading EPA researchers subsequently published a critique of the CIIT's work, stating that their literature review did not present a "sufficiently current, complete, accurate, and transparent review of the pertinent literature," and concluding that the resulting model had not been adequately described or validated (Caldwell et al. 2006). EPA scientists also noted that the CIIT had failed to disclose their funding for the TCE model, and inappropriately implied that it had been funded by EPA.

In addition, EPA itself has noted errors in the CIIT PBPK model used in the perchlorate assessment, explaining in their report, “EPA evaluated the PBPK model code provided by the model authors and found minor errors in mathematical equations and computer code, as well as some inconsistencies between model code files” (EPA 2008). It is unclear why EPA relies so heavily on the CIIT generated PBPK model when the CIIT has a history of conducting industry friendly assessments, as with the formaldehyde example, and there are clear errors in the perchlorate model, as acknowledged by EPA.

The PBPK model relies heavily on industry-funded Greer study: The CIIT generated PBPK model uses data from the Greer study, which showed a dose-dependent decrease in iodine uptake (RAIU) by the thyroid gland with increasing perchlorate ingestion (Greer et al. 2002). This study included only 37 participants who were divided into several study groups and administered different doses of perchlorate for 14 days; the researchers determined that 0.007 mg/kg/day was the no observed effect level (NOEL) for perchlorate. The results from this study were used by the National Academy of Sciences (NAS) in setting the reference dose for perchlorate of 0.7 ug/kg/day.

However, the Greer study results and assumptions drawn from these results have been questioned in a peer-reviewed article that was published in Environmental Health Perspectives in 2005 (Ginsberg and Rice 2005). Two toxicologists, one from the Connecticut Department of Public Health and the other from the Maine Bureau of Health, conducted an analysis of the raw data from the Greer study and concluded that the “Individual results of Greer et al. point to an effect in four of the seven individuals tested at the lowest dose (0.007 mg/kg/day), indicating that this dose is an effect level.” In other words, while Greer et al. and the NAS both concluded that 0.007 mg/kg/day is a NOEL, closer analysis of the data reveals that several of the 7 study subjects in this group experienced effects at this dose, thereby invalidating 0.007 mg/kg/day as a NOEL.

The Massachusetts Department of Environmental Protection (Mass DEP), which has set the most stringent drinking water standard for perchlorate nationally, had the following observations about the Greer study:

“MassDEP has concerns about the lowest dose in the Greer study being a no-effect level based on the facts that: due to the small number of subjects in the lowest dose group, there is low power to detect a statistically significant effect; averaging of group responses obscures positive individual inhibition; a non-statistically significant IUI (iodine uptake inhibition) effect was observed at the lowest dose tested; and, good low dose corroborating data is lacking” (MassDEP 2006).

In light of these valid criticisms of the Greer study, it is unclear why EPA chose to rely so heavily on the PBPK model that incorporates data from this study while essentially ignoring much more relevant data from the CDC.

EPA relies on flawed computer model while downplaying significance of human data: As noted above, EPA relies heavily on a deeply flawed computer model that predicts RAIU inhibition at various levels of perchlorate contamination of drinking water. The dependence on such a computer model would be more understandable were there not comprehensive human data on perchlorate exposure and toxicity. However, in the last two years, government agencies like CDC and FDA, as well as prominent academic scientists, have published studies establishing widespread perchlorate exposure among the U.S. population, with especially high exposures among breast-fed infants and young children, and evidence of toxicity among women with lower iodine levels.

CDC published a ground breaking study in 2006 showing that current perchlorate exposures are associated with significant effects on thyroid hormone levels in women with low urinary iodine levels. EPA deliberately downplays the significance of these findings, noting that CDC findings are contradicted by another study: “Results from studies of the effects of perchlorate exposure on hormone levels have been mixed. One recent study did not identify any effects of perchlorate on blood serum hormones (Amitai et al. 2007), while another study (Blount et al. 2006b) did identify such effects” (EPA 2008).

However, when the Amitai et al. study is reviewed, it is clear that the results of this study do not contradict the results from Blount et al.; in fact, the study authors themselves note, “Based on differences in iodine intake and life stages for the two studies, our findings do not contradict those of Blount et al.” (Amitai et al. 2007). Yet, EPA maintains that the results from Amitai et al. provide evidence to doubt CDC results although the two studies are completely different and the CDC study is the only one to have established unique vulnerability to perchlorate among women with lower urinary iodine levels. By raising doubts about the validity of CDC findings, despite no scientific justification, EPA is able to downplay the significance of these findings to justify excluding them in their assessment.

EPA focuses on risks to pregnant women while ignoring evidence of risks to breast-fed infants and young children: There have been at least four published studies that highlight widespread perchlorate contamination of human breast milk. The most recent of these also postulated that perchlorate is preferentially excreted into breast milk when compared with iodine. Just as troubling, the average levels of perchlorate in breast milk in these studies would expose a significant number of breast fed infants to perchlorate levels above EPA RfD of 0.7 ug/kg/day. Breast fed infants do not get thyroid hormones through breast milk and must produce these hormones themselves; they are completely dependent on maternal iodine for thyroid hormone production and perchlorate exposure through breast milk could significantly inhibit this process. Adequate levels of thyroid hormones during infancy are integral to normal growth and brain development.

Yet, despite growing evidence that breast fed infants are one of the most highly exposed populations and are uniquely vulnerable to perchlorate, EPA chooses to ignore this data. EPA does not even acknowledge this population as being at risk. In fact, EPA notes that “The subpopulation that is the most sensitive to perchlorate exposure is the fetus of the iodine-deficient pregnant women” while ignoring the evidence of risks to infants (EPA 2008).

Similarly, young children are also highly exposed to perchlorate; FDA found that perchlorate contaminates 74% of 300 commonly consumed foods and beverages (Murray et al. 2008). It is well established that children eat and drink more, pound for pound, than adults. For this reason, perchlorate contamination of food is especially concerning for young children. FDA finds that among 2 year olds, perchlorate exposures from contaminated food and beverages alone fall between 50 and 56% of EPA RfD of 0.7 ug/kg/day (Murray et al. 2008). EWG analysis of FDA data finds that additional exposures to perchlorate from contaminated drinking water could easily result in combined exposures that exceed the EPA RfD. The average two year old will exceed EPA’s RfD for perchlorate by drinking water that is contaminated with as little as 4 ppb of perchlorate (EWG 2008).

EPA does not explore risks to young children in any detail in their assessment, despite clear evidence from FDA research that perchlorate exposures from food are higher for young children than any other demographic group. As mentioned earlier, EPA focuses on the developing fetus of iodine-deficient pregnant women as the subpopulation that is at highest risk from perchlorate exposure while explicitly ignoring evidence that breast-fed infants and young children are also at risk.

EPA presents new information from unpublished study that does not include young children: In its assessment, EPA presents an unpublished study in which EPA and CDC researchers merged urine perchlorate levels from the NHANES study and water contamination data from the Unregulated Contaminants Monitoring Regulation with the goal being to “derive the dose of perchlorate coming from food alone by eliminating possible sources of water contribution” (EPA 2008). Individuals from the NHANES study were categorized into three groups depending on whether the counties in which they resided were found to have drinking water contaminated with perchlorate or not. Using this approach, EPA was able to estimate daily perchlorate intakes for those with likely perchlorate exposure through drinking water and those without; EPA concluded that “The mean total exposure for people that are more likely to be exposed to perchlorate in food and water was calculated to be 0.101 ug/kg/day. The average exposure for people more likely to be exposed to perchlorate from food alone was 0.090 ug/kg/day” (EPA 2008).

This approach allows EPA to estimate that the population they consider to be most at risk, pregnant women and the developing fetus, can be exposed to perchlorate levels in drinking water as high as 15 ug/L and still not exceed the RfD. The most glaring flaw with EPA’s study is that it does not include young children. The FDA research establishes that young children have the highest perchlorate exposures from food and therefore, are most likely to exceed EPA’s RfD from additional exposures to contaminated drinking water. The NHANES data does not include information on children under the age of 6 so EPA’s study using NHANES data has an enormous data gap which basically invalidates the findings from this study.

EPA’s flawed assessment still finds that millions of people are exposed to potentially harmful levels of perchlorate: EPA’s assessment is fundamentally flawed for the reasons described above. In this assessment, EPA determines that 15 ug/L (15 ppb) is an appropriate health reference level (HRL); this number was arrived at, in part, by using data from the unpublished study that was just described in the preceding section of this document. It should be noted that in the Blount study, women with lower iodine levels who had exposure to perchlorate in drinking water as low as 2 ppb had an associated 11% decrease in thyroid hormone levels (Blount et al. 2006b). It is clear that the EPA HRL is not protective of public health since levels of perchlorate exposure far below 15 ug/L result in significant changes in thyroid hormone levels.

However, even with the many errors, flaws, and omissions in EPA’s assessment, EPA still estimates that up to 2 million people throughout the U.S. could potentially be consuming water with levels of perchlorate that exceed this HRL. Here is EPA’s exact statement:

“EPA’s best estimate is that 0.9 million people (with an upper bound estimate of 2 million people) may be consuming water containing perchlorate at levels that could exceed the HRL for perchlorate and the Agency estimates that fewer than 30,000 of them are pregnant women at any given time” (EPA 2008).

It is astounding that EPA does not think it is necessary to set a stringent drinking water standard for perchlorate in order to protect 30,000 pregnancies annually. In addition, the 2 million people at risk include infants and children, so the subpopulations within this number that would benefit from a stringent drinking water standard would far exceed 30,000.

Conclusion

As outlined above, EPA’s preliminary regulatory determination on perchlorate is rife with errors, omissions, and wrong assumptions. EPA relies on a computer model that was generated using the now discredited Greer study. In addition, EPA chooses to ignore the valuable data from human studies like the Blount study that show potential health risks to millions of U.S. residents from perchlorate exposures much lower that the proposed HRL of 15 ppb. EPA also disregards the vulnerability of breast fed infants and young children, in whom current perchlorate exposures could potentially result in decreases in thyroid hormone levels that have long-term adverse effects on brain development and growth. Perhaps most egregious is EPA’s finding that protecting 30,000 pregnancies annually is not a sufficient reason to regulate this dangerous contaminant in drinking water.

In light of the extremely short initial public comment period of 30 days and the complexity of the EPA assessment, EWG and other environmental groups requested a 60- day extension of the comment period. On November 10th, EPA granted an 18-day extension to the initial comment period. EWG respectfully requests that the 60-day extension that we had initially requested be granted to allow for a more thorough review of EPA’s assessment.

In the meantime, EWG calls on EPA to fix the numerous glaring errors in its assessment and to quickly move to set a health protective drinking water standard for perchlorate.

Sincerely,

Dr. Anila Jacob, MD, MPH
Senior Scientist
Environmental Working Group

References:

Amitai Y, Winston G, Sack J, Wasser J, Lewis M, Blount BC, Valentin-Blasini L, Fisher N, Israeli A, Leventhal A. 2007. Gestational Exposure to High Perchlorate Concentrations in Drinking Water and Neonatal Thyroxine Levels. Thyriod 17(9): 843-50.

Blount BC, Valentin-Blasini L, Osterloh JD, Mauldin JP, Pirkle JL. 2006a. Perchlorate Exposure of the US population, 2001-2002. Journal of Exposure Science and Environmental Epidemiology 17(4): 400-07.

Blount BC, Pirkle JL, Osterloh JD, Valentin-Blasini L, Caldwell LK. 2006b. Urinary Perchlorate and Thyroid Hormone Levels in Adolescent and Adult Men and Women living in the United States. Environmental Health Perspectives 114(12): 1865-71.

Dasgupta PK, Kirk AB, Dyke JB, Ochira S. 2008. Intake of Iodine and Perchlorate and Excretion in Human Milk. Environmental Science and Technology. 9/17/2008: epub ahead of print.

EPA. 2008. Drinking water: Preliminary Regulatory Determination on Perchlorate. http://www.epa.gov/safewater/ccl/reg_determine2.html#perchlorate

EWG. 2006. Thyroid Threat. http://www.ewg.org/reports/thyroidthreat

EWG. 2008. FDA Food Testing Shows Widespread Rocket Fuel Contamination of Commonly Consumed Foods and Beverages. www.ewg.org/node/25875

GAO. Testimony before the Subcommittee on Investigations and Oversight, Committee on Science and Technology, House of Representatives: Chemical assessments. www.gao.gov/new.items/d08810t.pdf

Greer MA, Goodman G, Pleuss RC, Greer SE. 2002. Health Effect Assessment for Environmental Perchlorate Contamination: the Dose Response for Inhibition of Thyroidal Radioiodide Uptake in Humans. Environmental Health Perspectives (110): 927-37.

Kirk AB, Martinelango PK, Tian K, Dutta A, Smith EE, Dasgupta PK. 2005. Perchlorate and iodide in dairy and breast milk. Environmental Science and Technology 39(7) 2011-17.

Kirk AB, Dyke JV, Martin CF, Dasgupta PK. 2007. Temporal patterns in Perchlorate, thiocyanate, and Iodide Excretion in Human Milk. Environmental Health Perspectives 115(2) 182-86.

MassDEP. 2006. Update to “Perchlorate Toxicological Profile and Health Assessment”. http://www.mass.gov/portal/gog_cache.jsp?q=cache:DvvnPHJtRYwJ:www.mass.g...

Murray WM, Egan SR, Kim H, Beru N, Bolger PM. 2008. US Food and Drug Administration's Total Diet Study: Dietary Intake of Perchlorate and Iodine. Journal of Exposure Science and Environmental Epidemiology 2008 (1-10)Epub ahead of print.

Pearce EN, Leung AM, Blount BC, Bazrafshan HR, He X, Valentin-Blasini L, Braverman LE. 2007. Breast Milk Iodine and Perchlorate concentrations in Lactating Boston Area Women. Journal of Clinical Endocrinology and Metabolism 92(5):1673-7

  • The physiologically-based PBPK model that EPA uses in their assessment was designed by researchers who work for the CIIT, an industry funded research organization with a history of providing assessments to EPA that favor industry interests;
  • The PBPK model that EPA uses in their assessment relies heavily on the flawed, industry-funded Greer study;
  • EPA essentially ignores data from large, well-conducted human studies in favor of a PBPK computer model;
  • EPA continues to consider pregnant women to be the population most at risk and ignores recent evidence that breast-fed infants and young children are the most highly exposed populations;
  • EPA presents results from an unpublished study and relies on this study to justify a HRL of 15 ug/L (ppb) for perchlorate in drinking water, although this study does not look at risks to young children or breast-fed infants;
  • Even EPA’s own flawed assessment finds that up to 2 million people may be exposed to perchlorate at levels that are of concern and yet, EPA chooses not to take any meaningful action.
    • CDC tested 2,820 U.S. residents (ages 6 an older) in a nationally representative sample and found detectable levels of perchlorate in the urine of every person tested (Blount et al. 2006a);
    • Urinary perchlorate levels in children ages 6 to 11 were 1.6 times higher than levels in adults (Blount et al. 2006a);
    • CDC scientists analyzed both perchlorate and thyroid hormone levels in more that 1,000 U.S. women and found that in the one third of women with lower iodine levels, perchlorate exposure far below EPA RfD of 0.7 ug/kg/day was associated with significant changes in thyroid hormone levels (Blount et al. 2006b);
    • Using CDC data, an EWG analysis found that 2 million women of childbearing age may be at risk for abnormal thyroid hormone levels during pregnancy (EWG 2006);
    • CDC and academic scientists have tested a combined 118 samples of U.S. breast milk in 4 different studies and have found perchlorate in every sample tested (Dasgupta et al. 2008, Kirk et al. 2005, Kirk et al. 2007, Pearce et al. 2007);
    • Breast milk studies suggest that a significant number of breast fed infants may be exposed to perchlorate at levels that exceed the EPA RfD of 0.7 ug/kg/day (Dasgupta et al. 2008, Kirk et al. 2005, Kirk et al. 2007, Pearce et al. 2007);
    • FDA scientists found perchlorate in three quarters of nearly 300 commonly consumed foods and beverages; young children are exposed to perchlorate doses that fall between 50 to 56% of EPA’s RfD from food alone and could easily exceed EPA’s RfD with additional drinking water exposures (Murray et al. 2008);
    • A recent study from scientists at the University of Texas found that breast tissue concentrates perchlorate at 3 times the rate of iodine (Dasgupta et al. 2008).