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www.cfsan fda.gov/~ dms/clo4meth.html and it has been published.[i]   The method was updated during fiscal year 2005 for determining perchlorate in grain products, fruits and fruit juices, fish, and shrimp.   The smallest amounts of perchlorate this method can quantify are 1 part per billion (ppb) for produce, including fruits and fruit juices; 3 ppb for milk, grain products, fish, and shrimp; and 0.5 ppb for bottled water.

Fiscal Year 2004 Perchlorate Survey and Preliminary Exposure Assessment

In December 2003, FDA began an initial exploratory survey to investigate perchlorate levels in various foods, particularly in produce and bottled water.   The initial survey called for a total of 500 samples of domestic origin to be collected and analyzed by the FDA.   The first collection of data, which spanned from December 2003 until August 2004, involved two phases.   For the first phase of the survey, 150 samples of lettuce and 50 samples of bottled water were collected and analyzed for perchlorate.   The second phase of the survey, conducted beginning in August 2004, called for collection and analysis of 120 milk, 55 tomato, 45 carrot, 45 cantaloupe, and 35 spinach samples.

In November 2004, FDA posted on its Web site the initial set of perchlorate data collected from December 2003 to August 2004 to inform the public of FDA’s progress and share its initial exploratory data.   The data included perchlorate levels found in lettuce, bottled water, and milk samples collected as part of the exploratory survey issued in December 2003 (http://www.cfsan.fda.gov/~dms/c1o4data.html).   FDA also posted Perchlorate Questions and Answers to explain and provide context to the survey data (http://www.cfsan.fda.gov/~dms/clo4qa.html).   Some additional samples, also collected in 2004 but not analyzed until 2005, were later posted at this site.

The values for perchlorate found in the foods sampled in 2004 were similar to those reported by other researchers external to FDA.   These data confirmed that we should continue to investigate the occurrence of perchlorate in a greater variety of foods and in other regions of the country, which we proceeded to do in 2005, as discussed below.   It is important to note that the results we obtained are preliminary and do not reflect the distribution of perchlorate in the U.S. food supply.   The sampling methodology used was not intended to be representative; rather, it was specifically targeted at foods that we anticipated to contain higher levels of perchlorate due to where the food was grown and its high water content. 

We want to stress that the 2004 preliminary perchlorate exposure assessment was based on perchlorate data collected in 2004 for a small number of food types and a small number of samples within a food type.   Additionally, these samples came from areas where there was known perchlorate occurrence, thus they are not representative of samples throughout the U.S.   Because of these limitations, it would not be appropriate to consider the 2004 preliminary exposure assessment to be a reflection of the actual perchlorate exposure of the U.S. population.

Fiscal Year 2005 Perchlorate Survey and Updated Preliminary Exposure Assessment

In February 2005, FDA issued a second perchlorate survey assignment to obtain information on the distribution of perchlorate in a wider variety of foods.   This survey called for a total of 450 samples, domestic and imported, to be collected in two phases during fiscal year 2005.   The first phase consisted of collection of additional samples of tomatoes, carrots, spinach, and cantaloupe, and collection of a wider variety of foods that included fruits and fruit juices such as apples, oranges, and grapes; vegetables such as broccoli; and grain products such as cornmeal and oatmeal.   The second phase consisted of the collection of additional types of fruits, vegetables and grain products, as well as aquaculture fish. 

As part of a separate survey assignment issued in December 2004, FDA collected and analyzed for perchlorate content in 105 farm milk samples, 105 associated feed samples, and 105 water samples from dairy farms in top milk producing states to determine potential sources of contamination at the farm level.   In addition, FDA collected and analyzed a total of 228 baby food samples, including a few infant formula samples,obtained from four market baskets (57 samples per market basket) under the FDA’s Total Diet Study (TDS) survey program (described in more detail below).   Separately, we also collected and analyzed a total of 21 samples of different types of infant formula and have plans to collect and analyze an additional 40 infant formula samples in 2007.  

FDA has compiled the preliminary results of the mean perchlorate exposure assessment for the general population (all persons aged 2 and above), based on FY 2004/2005 exploratory survey data for 27 types of food and beverages (milk, fruit and fruit juices, vegetables, grain products, and seafood (aquaculture fish and shrimp).   The analysis of these preliminary results has been reviewed by three external government experts and has been shared with the Interagency Working Group.   When finalized, we plan to release the updated exploratory exposure assessment.   It is important to reiterate that this preliminary exposure assessment is based on non-representative food data and is not necessarily a reflection of perchlorate exposure to the U.S. population.   We expect to have representative exposure estimates following the analysis of the total diet study which is described below.

Total Diet Study

FDA’s Total Diet Study (TDS), sometimes called the market basket study, is an ongoing program to determine the levels of various contaminants and nutrients in foods.   Using data obtained through the TDS program, dietary intakes of the analyzed substances by the U.S. population can be estimated.   Since its inception in 1961 as a program to monitor for radioactive contamination of foods, the TDS has grown to encompass additional substances, including pesticide residues, industrial chemicals, and toxic and nutrient elements. 

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.   Currently, there are about 280 foods collected and analyzed in the TDS.   A unique aspect of the TDS is that foods are prepared as they would be consumed (table-ready) prior to analysis, so the analytical results provide the basis for realistic estimates of the dietary intake of these analyzed substances. 

In FY 2005 and 2006, FDA analyzed samples from the TDS survey for perchlorate to obtain information on the distribution of the contaminant in a wide variety of foods.   FDA plans to publish, in late 2007, an assessment of the exposure to perchlorate from food, based on the levels in TDS foods collected and analyzed during FY 2005/2006.   Because of the size of the dataset and the design of this study, these data will provide a robust estimate of the exposure of U.S. consumers to perchlorate through food consumption than the updated preliminary exposure assessment, based on the 2004/2005 targeted sampling.

Additional Steps

In FY 2007, FDA is continuing to test samples of specific food types collected through additional targeted surveys (e.g., infant formulas, sweet potatoes, celery, green peppers, grapes, apples, oranges, apple juice, whole wheat bread, aquaculture catfish, aquaculture salmon, and shrimp).   Information on the distribution of perchlorate in a wider variety of foods obtained from these surveys will further enhance FDA’s assessment of the dietary exposure of U.S. consumers to perchlorate.   FDA will continue to inform the public of its findings as more knowledge is gained. 

FDA continues to work with the U.S. Department of Agriculture (USDA) and the EPA to determine the occurrence of perchlorate in foods for continuing assessment of the dietary exposure to perchlorate.   FDA is aware that other data on perchlorate levels in foods are under development and welcomes external research that can assist us in describing the distribution of perchlorate in foods and in developing exposure estimates.

Recommendations for Consumers

Consumers should not view the low levels of perchlorate in the foods tested as an indicator of  the "risk" of eating certain foods, particularly when many of the foods are important components of a nutritious and balanced diet.   Some of these food items are also important sources of iodine.   Until more is known concerning perchlorates occurrence in foods, FDA continues to recommend that consumers eat a balanced diet, choosing a variety of foods that are low in trans fat and saturated fat, and rich in high-fiber grains, fruits, and vegetables. 

Thank you for the opportunity to provide this information and discuss these important public health issues with you.

 

Endnotes

[i]  Krynitsky, A.J., R.A. Niemam, and D.A. Nortrup. 2004. Determination of Perchlorate Anion in Foods by Ion Chromatography-Tandem Mass Spectrometry. Anal. Chem. 76:5518-5522.

 

Last revised: August 29,2008