Perchlorate: EPA Does Not Systematically Track Incidents of Contamination
Published: 2007-04-25T00:00:00

Fast Facts:

Highlights:
section_title: Why GAO Did This Study
paragraphs: Perchlorate has been used for decades by the Department of Defense, the National Aeronautics and Space Administration, and the defense industry in manufacturing, testing, and firing missiles and rockets. Other uses include fireworks, fertilizers, and explosives. Perchlorate is readily dissolved and transported in water and has been found in groundwater, surface water, and soil across the country. Perchlorate emerged as a contaminant of concern because health studies have shown that it can affect the thyroid gland, which helps regulate the body's metabolism, and may cause developmental impairment in fetuses of pregnant women. In 2005, EPA set a reference dose of 24.5 parts per billion (ppb)--the exposure level not expected to cause adverse effect in humans. Today's testimony updates GAO's May 2005 report, Perchlorate: A System to Track Sampling and Cleanup Results is Needed, GAO-05-462 . It summarizes GAO's (1) compilation of the extent of perchlorate contamination in the U.S. and (2) review of peer-reviewed studies about perchlorate's health risks. GAO's 2005 report recommended that EPA work to track and monitor perchlorate detections and cleanup efforts. In December 2006, EPA reiterated its disagreement with this recommendation. GAO continues to believe such a system would better inform the public and others about perchlorate's presence in their communities.
section_title: What GAO Found
paragraphs: Perchlorate has been found at 395 sites in the U.S.--including 153 public drinking water systems--in concentrations ranging from 4 ppb to more than 3.7 million ppb. More than half the sites are in California and Texas, with the highest concentrations found in Arkansas, California, Texas, Nevada, and Utah. About 28 percent of sites were contaminated by defense and aerospace activities related to propellant manufacturing, rocket motor research and test firing, or explosives disposal. Federal and state agencies are not required to routinely report perchlorate findings to EPA, which does not track or monitor perchlorate detections or cleanup status. EPA recently decided not to regulate perchlorate in drinking water supplies pending further study. GAO reviewed 90 studies of health risks from perchlorate published from 1998 to 2005, and one-quarter indicated that perchlorate had an adverse effect on human health, and thyroid function in particular. In January 2005, the National Academy of Sciences also reviewed several studies and concluded that they did not support a clear link between perchlorate exposure and changes in the thyroid function. The academy did not recommend a drinking water standard but recommended additional research into the effect of perchlorate exposure on children and pregnant women. More recently, a large study by CDC scientists has identified adverse thyroid effects from perchlorate in women with low iodine levels that are found in about 36 percent of U.S. women.

section_title: Letter
paragraphs: I am pleased to be here today to discuss our work on perchlorate, a  chemical most commonly used in rocket fuel. A combination of human  activity and natural sources has led to the widespread presence of  perchlorate in the environment. Perchlorate has been used for decades by  the Department of Defense (DOD), the National Aeronautics and Space  Administration (NASA), and the defense industry in the manufacturing,  testing, and firing of missiles and rockets. According to the Environmental  Protection Agency’s (EPA) estimates, 90 percent of the perchlorate  produced in the United States is manufactured for use by the military and  NASA, with total typical production quantities averaging several million  pounds per year. Private industry also has used perchlorate to  manufacture automobile airbags, fireworks, flares, and commercial  explosives. Natural sources include certain atmospheric processes and  Chilean nitrate salts (saltpeter) that have been mined and refined to  produce commercial fertilizers for use in the U.S. Perchlorate forms salts  that are readily dissolved and transported in water and that have been  found in groundwater, surface water, and soil across the country. People  are exposed to the perchlorate primarily by ingesting it in drinking water  and food, or by working to manufacture products that contain the  chemical. Health studies have shown that exposure to perchlorate can  affect the thyroid gland, which helps regulate the body’s metabolism, and  may cause neurodevelopmental impairment in fetuses of pregnant women.
In 2003, EPA, DOD, NASA, and the Department of Energy asked the  National Academy of Sciences to review the risks of exposure to  perchlorate. In January 2005, the Academy recommended a reference dose  of 0.0007 milligrams of perchlorate per kilogram of body weight per day,  an estimated daily exposure level that is not expected to cause adverse  effects in the children and pregnant women—the most sensitive human  populations. This reference dose equates to a drinking water equivalent  level of 24.5 parts per billion. In February 2005, EPA adopted the  Academy’s reference dose for perchlorate, but it has not established a  national federal standard for perchlorate in drinking water or other  regulatory requirements to clean up perchlorate in groundwater, surface  water, or soil, citing the need for additional study about the health effects  of perchlorate exposure.
My testimony today is based largely on our 2005 report for this Committee  and summarizes (1) our analysis of the estimated extent of perchlorate  found in the United States and (2) the results of our review of published  studies on the health effects of perchlorate. In the 2005 report, we  recommended that EPA develop a tracking system for perchlorate releases  and cleanup efforts across the federal government and state agencies. This  statement also includes information from my February 2007 testimony  about EPA’s recent response to our recommendation.
To provide an estimate of the extent of perchlorate found in the United  States, we compiled and analyzed data on perchlorate detections from  EPA, DOD, the U.S. Geological Survey, and state agencies. To identify  studies of the potential health risks from perchlorate, who conducted  them, and what methodologies were used, we conducted a literature  search for studies of perchlorate health risks published since 1998,  interviewed DOD and EPA officials on what studies they considered  important in assessing perchlorate health risks, and examined the  references of each study for other studies we had not obtained. We  identified 125 studies on perchlorate and the thyroid, of which we  reviewed 90 that were relevant to our review. A more detailed description  of our scope and methodology is presented in appendix I of our 2005  report.
In summary, we found the following:    As of our May 2005 review, perchlorate had been found by federal and  state agencies in groundwater, surface water, soil, or public drinking water  systems at almost 400 sites across the country in concentrations that  ranged from 4 parts per billion (ppb) to more than 3.7 million ppb.  However, there is not a standardized approach to reporting perchlorate  data nationwide, therefore there may be more contaminated sites than we  identified. These sites are located across 37 states and U.S. territories, but  more than half were found in California and Texas. The sources of  perchlorate at the sites vary, but the greatest known source is defense and  aerospace activities such as propellant manufacturing, rocket motor  research and test firing, or explosives disposal. More than one-third of the  sites were public drinking water systems, where perchlorate  concentrations ranged from 4 to 420 ppb. Fourteen of these 153 public  water systems had concentration levels above 24.5 parts per billion, the  drinking water equivalent of EPA’s perchlorate reference dose. EPA and  state officials told us they had not cleaned up contaminated public  drinking water systems, principally because there was no federal drinking  water standard or specific federal requirement to clean up perchlorate.  Further, it is difficult to determine the extent of perchlorate in the United  States or the status of any cleanup actions because EPA does not centrally  track or monitor perchlorate detections, environmental releases, or  cleanup activities.
Recent research indicates that low-level perchlorate exposure may  adversely affect the thyroid and increase the risk of neurodevelopmental  impairment in fetuses of pregnant women. In our May 2005 review, we  identified and summarized 90 peer-reviewed studies published from 1998  to 2005 on the health effects of perchlorate. The findings of 26 of these  studies indicated that perchlorate had an adverse effect on thyroid  function and human health. Most studies on adult populations were unable  to determine whether the thyroid was adversely affected, because adverse  effects of perchlorate on the adult thyroid, such as cancer, may happen  over longer time periods than are generally observed in a research study.  In contrast, the adverse effects of perchlorate on human development can  be more easily studied and measured within study time frames, and 18  studies found adverse effects on development resulting from maternal  exposure to perchlorate. We also found that some studies considered the  same perchlorate dose but found different effects. The precise cause of the  different results may be attributed to the studies’ designs or to the physical  conditions—such as sex, age, and blood iodine levels—of studies’  subjects. Such unresolved questions were one of the bases for the differing  conclusions among EPA, DOD, and other researchers on perchlorate  doses and human health effects. In its January 2005 report, the National  Academy of Sciences called for additional research on perchlorate  exposure to help resolve questions about its effect on children and  pregnant women. More recently, an October 2006 CDC study found that,  for women with lower iodine levels, perchlorate reduced the thyroid  hormone that helps regulate metabolism and that plays a part in central  nervous system development in the fetus.
We concluded in our report that EPA needed more reliable information on  the extent of sites contaminated with perchlorate and the status of  cleanup efforts, and recommended that EPA work with the Department of  Defense and the states to establish a formal structure for tracking  perchlorate information. In December 2006, EPA reiterated its  disagreement with the recommendation stating that perchlorate  information already exists from a variety of other sources. However, we  continue to believe that the inconsistency and omissions in available data  that we found during the course of our study underscore the need for a  more structured and formal tracking system.
subsections: section_title: Background
paragraphs: According to EPA, perchlorate can interfere with the normal functioning  of the thyroid gland by competitively inhibiting the transport of iodide into  the thyroid, which can then affect production of thyroid hormones. The  fetus depends on an adequate supply of maternal thyroid hormone for its  central nervous system development during the first trimester of  pregnancy. The National Academy of Sciences reported that inhibition of  iodide uptake from low-level perchlorate exposure may increase the risk  of neurodevelopmental impairment in fetuses of high-risk mothers— pregnant women who might have iodine deficiency or hypothyroidism  (reduced thyroid functioning). The Academy recognized the differences in  sensitivity to perchlorate exposure between the healthy adults used in  some studies and the most sensitive population and the fetuses of these  high-risk mothers. Consequently, the Academy included a 10-fold  uncertainty factor in its recommended reference dose to protect these  sensitive populations. The Academy also called for additional research to  help determine what effects low-level perchlorate exposure may have on  children and pregnant women.
EPA has issued drinking water regulations for more than 90 contaminants.  The Safe Drinking Water Act, as amended in 1996, requires EPA to make  regulatory determinations on at least five unregulated contaminants and  decide whether to regulate these contaminants with a national primary  drinking water regulation. The act requires that these determinations be  made every five years. The unregulated contaminants are typically chosen  from a list known as the Contaminant Candidate List (CCL), which the act  also requires EPA to publish every five years. EPA published the second  CCL on February 24, 2005. On April 11, 2007, EPA announced its  preliminary determination not to regulate 11 of the contaminants on this  list. The agency also announced that it was not making a regulatory  determination for perchlorate because EPA believed that additional  information may be needed to more fully characterize perchlorate  exposure and determine whether regulating perchlorate in drinking water  presents a meaningful opportunity for health risk reduction.
Several federal environmental laws provide EPA and states authorized by  EPA with broad authorities to respond to actual or threatened releases of  substances that may endanger public health or the environment. For  example, the Comprehensive Environmental Response, Compensation,  and Liability Act of 1980 (CERCLA), as amended, authorizes EPA to  investigate the release of any hazardous substance, pollutant, or  contaminant. The Resource Conservation and Recovery Act of 1976  (RCRA) gives EPA authority to order a cleanup of hazardous waste when  there is an imminent and substantial endangerment to public health or the  environment, and one federal court has ruled that perchlorate is a  hazardous waste under RCRA. The Clean Water Act’s National Pollutant  Discharge Elimination System (NPDES) provisions authorize EPA, which  may, in turn, authorize states, to regulate the discharge of pollutants into  waters of the United States. These pollutants may include contaminants  such as perchlorate. The Safe Drinking Water Act authorizes EPA to  respond to actual or threatened releases of contaminants into public water  systems or underground sources of drinking water, regardless of whether  the contaminant is regulated or unregulated, where there is an imminent  and substantial endangerment to health and the appropriate state and  local governments have not taken appropriate actions. Under certain  environmental laws such as RCRA, EPA can authorize states to implement  the requirements as long as the state programs are at least equivalent to  the federal program and provide for adequate enforcement.
In addition, some states have their own environmental and water quality  laws that provide state and local agencies with the authority to monitor,  sample, and require cleanup of various regulated and unregulated  hazardous substances that pose an imminent and substantial danger to  public health. For example, the California Water Code authorizes Regional  Water Control Boards to require sampling of waste discharges and to  direct cleanup and abatement, if necessary, of any threat to water,  including the release of an unregulated contaminant such as perchlorate.  Finally, according to EPA and state officials, at least 9 states have  established nonregulatory action levels or perchlorate advisories, ranging  from under 1 part per billion to 18 parts per billion, under which  responsible parties have been required to sample and clean up  perchlorate. For example, according to California officials, the state of  California has a public health goal for perchlorate of 6 parts per billion and  has used the goal to require cleanup at one site.
section_title: Perchlorate Has Been Found At 395 Sites Including 153 Public Drinking Water Systems
paragraphs: Because information on the extent of perchlorate contamination was not  readily available, we thoroughly reviewed available perchlorate sampling  reports and discussed them with federal and state environmental officials.  We identified 395 sites in 35 states, the District of Columbia, and 2  commonwealths of the United States where perchlorate has been found in  drinking water, groundwater, surface water, sediment, or soil. The  perchlorate concentrations ranged from the minimum reporting level of 4  parts per billion to in more than 3.7 million parts per billion—a level found  in groundwater at one of the sites. Roughly one-half of the contaminated  sites were found in Texas (118) and California (106), where both states  conducted broad investigations to determine the extent of perchlorate  contamination. As shown in figure 1, the highest perchlorate  concentrations were found in five states—Arkansas, California, Nevada,  Texas, and Utah—where, collectively, 11 sites had concentrations  exceeding 500,000 parts per billion. However, most of the 395 sites did not  have such high levels of contamination. We found 271 sites where the  concentration was less than 24.5 parts per billion, the drinking water  concentration equivalent calculated on the basis of EPA’s reference dose.
According to EPA and state agency officials, the greatest known source of  contamination was defense and aerospace activities. As shown in figure 2,  our analysis found that, at 110 of the 395 sites, the perchlorate source was  related to propellant manufacturing, rocket motor testing firing, and  explosives testing and disposal at DOD, NASA, and defense-related  industries. Officials said the source of the contamination at another 58  sites was agriculture, a variety of other commercial activities such as  fireworks and flare manufacturing, and perchlorate manufacturing and  handling. At the remaining sites, state agency officials said the source of  the perchlorate was either undetermined (122 sites) or naturally occurring  (105 sites). Further, all 105 sites with naturally occurring perchlorate are  located in the Texas high plains region where perchlorate concentrations  range from 4 to 59 parts per billion.
Of the sites we identified, 153 were public drinking water systems. The  Safe Drinking Water Act’s Unregulated Contaminant Monitoring  Regulation required sampling of public drinking water systems for a 12- month period between 2001 and 2003. . As of January 2005, 153 (about 4  percent) of 3,722 systems that were sampled and reported reported finding  perchlorate to EPA. Located across 26 states and 2 commonwealths, these  153 sites accounted for more than one-third of the sites we identified  where perchlorate concentrations reported ranged from 4 parts per billion  to 420 parts per billion but averaged less than 10 parts per billion. Only 14  of the 153 public drinking water systems had concentration levels above  24.5 parts per billion, the drinking water equivalent calculated on the basis  of EPA’s revised perchlorate reference dose. California had the most  public water systems with perchlorate, where 58 systems reported finding  perchlorate in drinking water. The highest drinking water perchlorate  concentration of 420 parts per billion was found in Puerto Rico in 2002.  Subsequent sampling in Puerto Rico did not find any perchlorate, and  officials said the source of the initial finding was undetermined.
These 153 public drinking water systems that found perchlorate serve  populated areas, and an EPA official estimated that as many as 10 million  people may have been exposed to the chemical. EPA officials told us they  do not know the source of most of the contamination found in public  drinking water systems, but that 32 systems in Arizona, California, and  Nevada were likely due to previous perchlorate manufacturing at a Kerr  McGee Chemical Company site in Henderson, Nevada. Regional EPA and  state officials told us they did not plan to clean up perchlorate found at  public drinking water sites until EPA establishes a drinking water standard  for perchlorate. In some cases, officials did not plan to clean up because  subsequent sampling was unable to confirm that perchlorate was present.
EPA officials said the agency does not centrally track or monitor  perchlorate detections or the status of cleanup activities. As a result, it is  difficult to determine the extent of perchlorate contamination in the U.S.  EPA maintains a list of sites where cleanup or other response actions are  underway but the list does not include sites not reported to EPA. As a  result, EPA officials said they did not always know whether other federal  and state agencies found perchlorate because, as is generally the case with  unregulated contaminants, there is no requirement for states or other  federal agencies to routinely report perchlorate findings to EPA.
For example, DOD is not required to report to EPA when perchlorate is  found on active installations and facilities. Consequently, EPA region  officials in California said they did not know the Navy found perchlorate at  the Naval Air Weapons Station at China Lake because the Navy did not  report the finding to EPA. Further, states are not required to routinely  notify EPA about perchlorate contamination they discover. For example,  EPA region officials in California said the Nevada state agency did not tell  them perchlorate was found at Rocketdyne, an aerospace facility in Reno,  or that it was being cleaned up. EPA only learned about the perchlorate  contamination when the facility’s RCRA permit was renewed.
section_title: Recent Research Indicates that Perchlorate Exposure May be a Concern for Pregnant Women
paragraphs: In our May 2005 review, we conducted a literature search for studies of  perchlorate health risks published from 1998 to 2005 and identified 125  studies on perchlorate and the thyroid. After interviewing DOD and EPA  officials about which studies they considered important in assessing  perchlorate health risks, we reviewed 90 that were relevant to our work.  The findings of 26 of these studies indicated that perchlorate had an  adverse effect on thyroid function and human health. In January 2005, the  National Academy of Sciences considered many of these same studies and  concluded that the studies did not support a clear link between  perchlorate exposure and changes in the thyroid function or thyroid  cancer in adults. Consequently, the Academy recommended additional  research into the effect of perchlorate exposure on children and pregnant  women but did not recommend a drinking water standard.
DOD, EPA, and industry sponsored the majority of the 90 health studies  we reviewed; the remaining studies were conducted by academic  researchers and other federal agencies. Of these 90 studies, 49 were  experiments that sought to determine the effects of perchlorate on  humans, mammals, fish, and/or amphibians by exposing these groups to  different doses of perchlorate over varied time periods and comparing the  results with other groups that were not exposed. Twelve were field studies  that compared humans, mammals, fish, and/or amphibians in areas known  to be contaminated with the same groups in areas known to be  uncontaminated. Both types of studies have limitations: the experimental  studies were generally short in duration, and the field studies were  generally limited by the researchers’ inability to control whether, how  much, or how long the population in the contaminated areas was exposed.  For another 29 studies, researchers reviewed several publicly available  human and animal studies and used data derived from these studies to  determine the process by which perchlorate affects the human thyroid and  the highest exposure levels that did not adversely affect humans. The 3  remaining studies used another methodology. Many of the studies we  reviewed contained only research findings, rather than conclusions or  observations on the health effects of perchlorate. Appendix III from our  2005 report provides data on these studies, including who sponsored them;  what methodologies were used; and, where presented, the author’s  conclusions or findings on the effects of perchlorate.
Only 44 of the studies we reviewed had conclusions on whether  perchlorate had an adverse effect. However, adverse effects of perchlorate  on the adult thyroid are difficult to evaluate because they may happen  over longer time periods than can be observed in a typical research study.  Moreover, different studies used the same perchlorate dose amount but  observed different effects, which were attributed to variables such as the  study design type or age of the subjects. Such unresolved questions were  one of the bases for the differing conclusions in EPA, DOD, and academic  studies on perchlorate dose amounts and effects.
The adverse effects of perchlorate on development can be more easily  studied and measured within typical study time frames. Of the studies we  reviewed, 29 evaluated the effect of perchlorate on development, and 18 of  these found adverse effects resulting from maternal exposure to  perchlorate. According to EPA officials, the most sensitive population for  perchlorate exposure is the fetus of a pregnant woman who is also nearly  iodine-deficient. However, none of the 90 studies that we reviewed  considered this population. Some studies reviewed the effect on the  thyroid of pregnant rats, but we did not find any studies that considered  perchlorate’s effect on the thyroid of nearly iodine-deficient pregnant rats.
In January 2005, the National Academy of Sciences issued its report on  EPA’s draft health assessment and the potential health effects of  perchlorate. The Academy reported that although perchlorate affects  thyroid functioning, there was not enough evidence to show that  perchlorate causes adverse effects at the levels found in most  environmental samples. Most of the studies that the Academy reviewed  were field studies, the report said, which are limited because they cannot  control whether, how much, or how long a population in a contaminated  area is exposed. The Academy concluded that the studies did not support  a clear link between perchlorate exposure and changes in the thyroid  function in newborns and hypothyroidism or thyroid cancer in adults. In  its report, the Academy noted that only 1 study examined the relationship  between perchlorate exposure and adverse effects on children, and that no  studies investigated the relationship between perchlorate exposure and  adverse effects on vulnerable groups, such as low-birth-weight infants. The  Academy concluded that an exposure level higher than initially  recommended by EPA may not adversely affect a healthy adult. The  Academy recommended that additional research be conducted on  perchlorate exposure and its effect on children and pregnant women but  did not recommend that EPA establish a drinking water standard. To  address these issues, in October 2006, CDC researchers published the  results of the first large study to examine the relationship between low- level perchlorate exposure and thyroid function in women with lower  iodine levels. About 36 percent of U.S. women have these lower iodine  levels. The study found decreases in a thyroid hormone that helps regulate  the body’s metabolism and is needed for proper fetal neural development  in pregnant women.
Mr. Chairman, this concludes my testimony. I would be pleased to answer  any questions that you or other Members of the Subcommittee may have at  this time.
section_title: GAO Contacts and Staff Acknowledgments
paragraphs: For further information about this presentation, please contact me, John  Stephenson, at (202) 512-3841 or stephensonj@gao.gov. Contact points for  our Offices of Congressional Relations and Public Affairs may be found on  the last page of this statement. Contributors to this testimony include  Steven Elstein, Assistant Director, and Terrance Horner, Senior Analyst;  Richard Johnson, Alison O’Neill, Kathleen Robertson, and Joe Thompson  also made key contributions.
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