Exploratory Data on Perchlorate in Food

Perchlorate is both a naturally occurring and manmade chemical. Naturally occurring perchlorate, for example, is found in nitrate fertilizer deposits in Chile. Most of the perchlorate manufactured in the United States is used as the primary ingredient of solid rocket propellant. Perchlorate is also used in pyrotechnics, such as fireworks, gun powder, explosives, and highway flares. In addition, perchlorate is used in a wide variety of industrial processes, including, but not limited to, tanning and leather finishing, rubber manufacture, paint and enamel production and additives in lubricating oils. In recent years there has been increasing interest in perchlorate levels in soil, ground water, drinking water, and irrigation water around the country and what health effects it may have.

FDA recognizes the potential for perchlorate contamination in food through the use of contaminated irrigation water, processing water, and source waters for bottling. In order to better understand the answers to these questions, FDA has begun to determine the occurrence of perchlorate in a variety of foods to evaluate exposure to perchlorate from food and to support any action that might be needed to protect the public health.

The data

FDA is now posting an initial set of perchlorate data that were collected through August 19, 2004, to inform the public of FDA's progress. The results reflect perchlorate levels detected in samples of individual food products.

Tables 1 and 2 show perchlorate levels in lettuce and bottled water samples, respectively, collected as part of the initial phase of FDA's field assignment, "Collection and Analysis of Food for Perchlorate," that was issued on December 23, 2003, and posted on FDA's website. Lettuce samples were collected at the grower or packing shed while bottled water samples were collected at retail locations. For sample analysis, outermost leaves of each lettuce head were removed, similar to the actions typically taken by a consumer prior to consumption.

Table 3 shows perchlorate levels found in milk samples that were collected and analyzed as part of FDA's research and method development, as well as part of the second phase of FDA's field assignment. All milk samples, except for raw milk samples that were obtained from a research facility in Maryland, were collected at retail.

Limits of the data

These data are exploratory and should not be understood to be a reflection of the distribution of perchlorate in the U.S. food supply. The data cover a limited number of food categories, a limited number of products in those categories, and a limited number of brands. Also, the data do not fully address the variation from one unit of a food product to another unit of the same product, or from one production lot or production area of a food product to another lot. Also, the choice of food products for testing in this exploratory survey should not be taken as an indicator of food product choices by consumers.

What consumers should understand

Consumers should not view the perchlorate levels as an indicator of perchlorate exposure, or as the "risk" of eating certain foods. First, perchlorate levels alone do not equate to perchlorate exposure; calculating exposure requires consideration of both perchlorate levels, and the amounts of food that consumers eat. Second, estimates of perchlorate exposure take into account not single food items, but the wide variety of foods found in a range of diets. Third, the scope of the data is too limited to properly consider potential sources of variation in measured perchlorate levels, such as variability between different units or lots of food.

Until more is known about the health effects of perchlorate and its 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. FDA does not recommend at this time that consumers should alter their infants' and children's diets and eating habits to avoid exposure to perchlorate.

Table 1: Perchlorate Values in Lettuce Samples

Notes:
(1) NQ = non-quantifiable
(2) The estimated limit of quantitation (LOQ) is 1.00 ppb for lettuce.
(3) For calculating the means, NQ = 0.5 ppb (1/2 LOQ)

Table 2: Perchlorate Values in Bottled Water Samples

Notes:
(1) NQ = non-quantifiable
(2) The estimated limit of quantitation (LOQ) is 0.50 ppb for water.

Table 3: Perchlorate Values in Milk Samples

Notes:
(1) NQ = non-quantifiable
(2) The estimated limit of quantitation (LOQ) is 3.00 ppb for milk.
(3) For calculating the mean, NQ = 1.5 ppb (1/2 LOQ)

Pesticides, Metals, Chemical Contaminants, & Natural Toxins