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1. What is perchlorate?
Perchlorate is a negatively charged molecule made of one chlorine atom and four oxygen atoms. Perchlorate can occur naturally or be man-made.
2. Where is perchlorate found?
Perchlorate occurs naturally in arid states in the Southwest United States (U.S.), in nitrate fertilizer deposits in Chile, and in potash ore in the U.S. and Canada. Perchlorate also forms naturally in the atmosphere. Manufactured perchlorate is used as an industrial chemical and can be found in rocket propellant, explosives, fireworks, and road flares. Perchlorate has been found in some public drinking water systems and in some foods.
3. What are the effects of perchlorate on the human body?
Human exposure to high dosages of perchlorate can interfere with iodide uptake into the thyroid gland, disrupting the functions of the thyroid and potentially leading to a reduction in the production of thyroid hormone. In fact, perchlorate has been used as a drug to treat hyperthyroidism (excess thyroid hormone production) and to diagnose disorders related to thyroid or iodine metabolism. In adults, the thyroid plays an important role in regulating metabolism. In fetuses and infants, thyroid hormones are critical for normal growth and development of the central nervous system. Pregnant women and their fetuses and newborns have the greatest potential for risk of adverse health effects following exposure to perchlorate.
4. Is perchlorate present in bottled water?
The FDA surveyed bottled water from 2008-2012 and found no perchlorate in 19 of 20 samples tested, with 1 sample with levels at the Environmental Protection Agency’s (EPA) recommended level in the interim health advisory (15 parts per billion). The FDA also surveyed bottled water in 2004/2005 and found no perchlorate in 49 of 51 samples tested, and very low levels, below the recommended level in the interim health advisory, in two water samples (Perchlorate Values in Bottled Water Samples).
5. Is perchlorate allowed in food packaging?
As of May 4, 2017, perchlorate may only be used up to a certain level as a component of antistatic agents used in food packaging for certain dry foods. Any future proposed food additive use of perchlorate in food packaging is subject to pre-market review and approval by the FDA.
6. Should I be worried about preparing my child’s infant formula with tap water?
In December 2008, the EPA issued its interim health advisory to assist state and local officials in addressing local contamination of drinking water supplies from perchlorate. If you live in one of the few areas where perchlorate in the public drinking water is at levels above 15 parts per billion, the FDA recommends using water that is lower in perchlorate levels, such as bottled water or water from a home treatment device certified for perchlorate removal, to reconstitute your infant's formula.
7. Should I supplement my diet with iodine supplements?
In general, if you eat a healthy diet, taking iodine dietary supplements is not necessary to protect you from perchlorate at the levels present in water and foods. However, you should discuss any specific dietary needs or concerns with your health care provider.
8. Should pregnant women and infants supplement their diets with iodine?
Iodine is necessary for a baby's normal brain development, so it is particularly important for pregnant and nursing women to get adequate amounts of iodine. Many over-the-counter and prescribed prenatal supplements contain iodine. For infants, breast milk and infant formulas are good sources of iodine. Women and mothers of young children should consult their health care practitioners before supplementing their diet or the diet of their children with iodine.
9. How is perchlorate regulated?
In 2011, the EPA determined that perchlorate meets the Safe Drinking Water Act criteria for regulation as a contaminant. Since then, the EPA has been reviewing scientific data on issues related to perchlorate in drinking water as part of the process of developing a national primary drinking water regulation for perchlorate. As part of this effort, scientists from the EPA and from FDA’s National Center for Toxicological Research (NCTR) have been collaborating to develop Biologically Based Dose Response (BBDR) models to better understand perchlorate exposures and potential health effects. This modeling work is a result of 2013 recommendations from EPA’s Science Advisory Board.
Note that prior to the 2011 determination, the EPA released (January 8, 2009) an interim drinking water health advisory of 15 parts per billion (ppb) of perchlorate in drinking water. The EPA arrived at this level using the 2005 EPA Integrated Risk Information System reference dose (RfD) for perchlorate which is based on recommendations of the National Research Council (NRC) “Health Implications of Perchlorate Ingestion.” The RfD is an estimate of a daily oral exposure to the human population (including sensitive subgroups) that is not likely to result in adverse health effects during a lifetime. EPA’s 2012 Edition of the Drinking Water Standards and Health Advisories includes the 2009 interim health advisory value for perchlorate.
10. Has a safe level of exposure for perchlorate been established?
In 2003, the EPA, the Department of Defense (DOD), the Department of Energy (DOE), and the National Aeronautics and Space Administration (NASA) asked the National Academy of Sciences (NAS) to review the EPA’s draft health assessment for perchlorate. In January 2005, the NRC committee of the NAS that assessed the health implications of perchlorate ingestion released its study report “Health Implications of Perchlorate Ingestion,” which recommended a perchlorate reference dose (RfD) of 0.7 microgram per kilogram body weight per day (µg/kg bw/d).
The RfD is an estimate of a daily oral exposure to the human population (including sensitive subgroups) that is not likely to result in adverse health effects during a lifetime. In addition, the NRC committee used a non-adverse end point, inhibition of iodine uptake, to derive the RfD. Inhibition of iodine uptake is a precursor that can lead to hypothyroidism, the adverse effect considered by the NRC committee. As a result, the RfD was considered conservative and protective of health by the NRC committee. The NRC committee also considered pregnant women and their fetuses to be the most sensitive populations to the health effects of perchlorate and emphasized the importance of ensuring that all pregnant women have adequate iodine intake.
In February 2005, the EPA adopted the NAS recommended RfD of 0.7 µg/kg bw/day for perchlorate, which focuses on protecting the most sensitive population, the fetuses of pregnant women who might have hypothyroidism or iodine deficiency.
11. When did the FDA start testing for perchlorate?
During FY04, the FDA conducted an initial exploratory survey that involved the collection and analysis of samples of domestic origin including bottled water, milk, lettuce, tomatoes, carrots, spinach, and cantaloupe.
For FY05, the FDA expanded the exploratory survey, collecting additional samples of tomatoes, carrots, spinach, and cantaloupe, as well as samples of other high water content foods. These included fruits and fruit juices such as apples, oranges, and grapes; vegetables such as cucumbers, green beans, and greens; and seafood such as aquaculture fish and shrimp. In FY05, the FDA also collected and analyzed a limited number of imported products commonly entering the U.S. market (e.g., produce from Mexico, grapes from Chile, aquaculture salmon from Canada, and shrimp from Southeast Asia).
Prior to testing, the FDA developed a rapid, sensitive, and specific ion chromatography-tandem mass spectrometry (IC-MS/MS) method for determining perchlorate in selected foods. The limit of quantitation (LOQ) is 1.0 ppb in fruits and vegetables, 0.50 µg/L in bottled water, 3.0 µg/L in milk, and 3.0 ppb in low moisture foods such as oats, wheat flour, corn meal, and cattle feed. The method is posted on the FDA’s website and is also published in the journal Analytical Chemistry (Analytical Chemistry. 2004, 76, 5518-5522).
12. Has the FDA made results from the FY04/FY05 exploratory surveys available?
Yes, the complete set of perchlorate data obtained from the FY04 and FY05 exploratory surveys is available on FDA's website.
13. What was the exposure estimate based on the exploratory surveys and how did it compare to the EPA's Reference Dose (RfD)?
The FDA's preliminary perchlorate exposure assessment ("Preliminary Estimation of Perchlorate Dietary Exposure Based on FDA 2004/2005 Exploratory Data") showed that the perchlorate levels found in the 27 foods and beverages tested are not likely to present a public health risk. The estimated total average population perchlorate exposure for all persons aged 2 and above was 0.053 µg/kg bw/day, which is below the EPA’s RfD of 0.7 µg/kg bw/day.
FDA's preliminary exposure estimate was similar to an estimate previously reported in the scientific literature (Perchlorate Exposure of the U.S. Population, 2001-2002, Blount et al., Journal of Exposure Science and Environmental Epidemiology (2006), 1-8).
14. Did the results from the FY04/FY05 exploratory surveys provide an accurate measure of perchlorate exposure?
The 27 foods and beverages sampled during the exploratory study were intended to provide an initial estimate of perchlorate exposure. The samples collected in FY04/FY05 represented only about 32 percent of the total diet for the U.S. population, ages 2 years and older, and 42 percent of the total diet for children, age 2 to 5 years.
The FDA conducted a more comprehensive and nationally representative exposure assessment based on perchlorate data obtained from FY05 and FY06 Total Diet Study surveys. Results from this assessment indicated that average perchlorate intake ranged from 0.08 to 0.39 µg/kg bw/day for the various age-gender subgroups examined, and was below the EPA’s RfD of 0.7 µg/kg bw/day, consistent with the exploratory survey results.
15. What is the FDA's Total Diet Study?
The FDA’s Total Diet Study (TDS) is the Agency's ongoing market basket survey in which about 280 core foods (TDS foods) in the U.S. food supply are collected, prepared as for consumption, and analyzed to determine levels of various contaminants and nutrients in those foods. The foods collected in the TDS (referred to as the TDS food list) represent the major components of the diet of the U.S. population. The food list is based on results of national food consumption surveys and is updated from time to time to reflect changes in food consumption patterns.
Four market baskets are generally collected each year, one in each of four geographic regions of the U.S. (West, North Central, South, and Northeast). For each market basket, samples of the TDS foods are collected from grocery stores and fast food restaurants in three cities within the region, prepared as for consumption, and composited for analysis. Therefore, each data point for a contaminant or a nutrient represents the analytical result for a composite of three samples of the TDS food. For more information on the TDS, see Total Diet Study.
16. Has the FDA tested Total Diet Study (TDS) foods for perchlorate and iodine?
Yes, the FDA has tested TDS foods for both perchlorate and iodine. For perchlorate, 54 out of 57 TDS baby foods were analyzed in four market baskets collected in FY05; the remaining three baby foods were analyzed in three market baskets because they were not available for analysis in the fourth market basket for FY05. The other 228 TDS foods were collected and analyzed in FY06; of those, 128 were analyzed for four market baskets and 100 were analyzed for two market baskets. The complete set of perchlorate data obtained from FY05 and FY06 TDS surveys is available on the FDA's website. Iodine data has been collected yearly since FY03, and results are also available on the Total Diet Study website.
In January 2008, the FDA published a study entitled "U.S. Food and Drug Administration's Total Diet Study: Dietary Intake of Perchlorate and Iodine" in the Journal of Exposure Science and Environmental Epidemiology. This study reports on the estimated average dietary intakes of perchlorate and iodine in 14 age-gender subgroups based on analytical results for perchlorate from the FDA's TDS samples collected in FY 05-FY06 and for iodine from TDS samples collected in five market baskets from late FY03 through FY04.
In addition, from FY08-FY12, perchlorate and iodine were analyzed in four market baskets per year in about 280 foods. These data were used to determine dietary intakes to perchlorate and iodine and results were published in 2016 in a study entitled “Update on dietary intake of perchlorate and iodine from U.S. food and drug administration’s total diet study: 2008-2012,” in the Journal of Exposure Science and Environmental Epidemiology. The average perchlorate intake levels for 14 age-gender subgroups examined in both the 2008 and 2016 studies (listed in items 19 and 21 below) were below the EPA’s perchlorate RfD. The complete set of perchlorate data obtained from FY08-FY12 TDS surveys is available on FDA’s website. Iodine data are available on the Total Diet Study website.
17. What were the estimates of dietary intake of perchlorate from the "U.S. Food and Drug Administration's Total Diet Study: Dietary Intake of Perchlorate and Iodine" 2008 publication?
The estimated average perchlorate intakes for all subgroups are all below the EPA’s recommended RfD of 0.7 µg/kg bw/day and range from 0.08 to 0.39 µg/kg bw/day. The FDA looked at 14 different age-gender subgroups.
The 14 age-gender subgroups consisted of infants (6-11 months), children (2 years), children (6 years), children (10 years), teenage girls (14-16 years), teenage boys (14-16 years), women (25-30 years), men (25-30 years), women (40-45 years), men (40-45 years), women (60-65 years), men (60-65 years), women (70 + years), and men (70 + years). Although children 2 years of age, with estimated average intakes ranging from 0.35 to 0.39 µg/kg bw/day, had the highest total perchlorate intake per kilogram body weight per day, they were still below the EPA’s recommended RfD of 0.7 µg/kg bw/day. Total average intake ranges for infants 6-11 months, children 6, and children 10 years of age were estimated to be 0.26 to 0.29 µg/kg bw/day, 0.25 to 0.28 µg/kg bw/day, and 0.17 to 0.20 µg/kg bw/day, respectively. The estimated total average intakes by the other age-gender subgroups ranged from 0.08 to 0.14 µg/kg bw/day.
18. What were the estimates of the dietary intake of iodine from the "U.S. Food and Drug Administration's Total Diet Study: Dietary Intake of Perchlorate and Iodine" 2008 publication?
The estimated average iodine intakes by the 14 age-gender subgroups range from 138 to 353 µg/person/day. The estimated average iodine intakes for infants (6-11 months) exceeded their adequate intake (AI) of 130 µg/person/day. The estimated average iodine intakes by all 13 other age-gender subgroups exceeded their relevant estimated average requirements (EARs) of 65 µg/person/day for children (2 and 6 years), 73 µg/person/day for children (10 years), and 95 µg/person/day for the remaining 10 age-gender subgroups.
The EARs are defined by the NAS as the nutrient intake levels estimated to meet the requirements of half the healthy individuals within a particular age group. An AI is set by the NAS when there is insufficient evidence to determine an EAR and is defined as the recommended average daily intake level of a nutrient that is assumed to be adequate for a group of apparently healthy individuals.
19. What were the estimates of the dietary intake of perchlorate from the 2016 publication?
This 2016 publication reports ranges of average perchlorate and iodine intake for the total U.S. population and for the same 14 age-gender subgroups in the U.S. population presented in the 2008 publication. Estimated average perchlorate intake for the total U.S. population ranged between 0.13 to 0.15 µg/kg bw/day, with estimated average intakes for all of the 14 age-gender subgroups ranging between 0.09 and 0.48 µg/kg bw/day. The estimated average intakes of perchlorate for all age-gender subgroups were below EPA’s perchlorate RfD of 0.7 µg/kg bw/day, consistent with results from the 2008 publication.
Although children 2 years of age had the highest estimated average intakes ranging from 0.44 to 0.48 µg/kg bw/day, this is still below the EPA’s perchlorate RfD of 0.7 µg/kg bw/day. Average intake for infants 6-11 months, children 6 years, and children 10 years of age were estimated to be 0.36 to 0.39 µg/kg bw/day, 0.28 to 0.31 µg/kg bw/day, and 0.16 to 0.18 µg/kg bw/day, respectively.
20. What were the estimates of the dietary intake of iodine from the 2016 publication?
The estimated average iodine intake for the total U.S. population ranged from 214.6 to 268.5 µg/person/day, with average intakes for all of the 14 age-gender subgroups ranging between 134.8 to 334.3 µg/person/day. The estimated average iodine intake for infants (6-11 months) exceeded their adequate intake (AI) of 130 µg/person/day. The estimated average iodine intakes by all 13 other age-gender subgroups exceeded their relevant estimated average requirements (EARs) of 65 µg/person/day for children (2 and 6 years), 73 µg/person/day for children (10 years), and 95 µg/person/day for the remaining 10 age-gender subgroups. These results reflect those found for iodine in the 2008 published publication.
21. Is the FDA continuing to study perchlorate?
Yes, FDA-NCTR scientists have been collaborating with the EPA to develop Biologically Based Dose Response (BBDR) models to better understand perchlorate exposures and potential health effects as part of 2013 recommendations from EPA’s Science Advisory Board.