We generally collect TDS “market baskets” (abbreviated “MB”) – the specific foods to be analyzed – four times each year, once in each of four regions of the country (North Central, West, South, and Northeast). To the extent possible, the market baskets are identical from region to region. Each region consists of three cities that differ every year, in which the foods are collected from supermarkets, grocery stores, and fast-food restaurants. 

The foods collected for the TDS market baskets represent the major components of the average diet of the U.S. population, from infants to adults, based on results of national food- consumption surveys. For the first TDS update shown on this website, in which we had analyzed market baskets collected between 1991 - 2002, we had based the list of foods to be collected on the USDA 1987-88 Nationwide Food Consumption Survey (USDA, 1990).

In the 2003 food-list update, which we began applying to market-basket collections in 2003, we based the food list on the USDA's 1994-96, 1998 Continuing Survey of Food Intakes by Individuals (CSFII) (USDA, 2000). The survey included detailed information on the types and amounts of food consumed by the survey participants, who collectively reported on more than 5,000 different foods (USDA, 2000).

We made this large number of foods more manageable by aggregating the foods into groups according to similarity (for example, a given group might include the various kinds of fish included in the survey). For each group, we then assigned the most-consumed food within that group as the representative of all the foods in the group, and designated it as the TDS food; in other words, each of the 280 foods on the TDS Food List may actually represent several foods. 

After we collect the foods, we ship them to a central FDA laboratory for preparation and analysis. For each kind of food, we combine samples from each of the three separate cities of the region to form one composite sample of that particular food.

For each TDS food, the samples from each of the three cities
in a region are formed into a composite.

Numerous FDA units participate in the operation of the TDS. The Center for Food Safety and Applied Nutrition (College Park, MD) provides overall management of the program and summarizes the laboratory results. FDA District Offices from across the U.S., under the Office of Regional Affairs, collect the foods and ship them to the FDA Kansas City District Laboratory (Lenexa, KS), which prepares and analyzes them for toxic elements, nutrient elements, and pesticides. Portions of the prepared composites from two market baskets per year are sent to FDA's Winchester Engineering and Analytical Center (Winchester, MA) for radionuclide analyses. After we have reviewed and finalized the results of the analyses, we post them on this website.

Where samples are prepared and analyzed.

Each of the approximately 10-year iterations of the TDS is based not only on an updated food list, but also on updated consumption amounts. To estimate dietary exposure to each TDS analyte, we: 

• determine the average level of that analyte in each TDS food.
• estimate the average amount the U.S. population (or age / gender subpopulation) consumes of each TDS food.
• for each TDS food, multiply the average level of that analyte in that food by the average amount the U.S. population (or age / gender subpopulation) consumes of that food.
• combine the results to arrive at the estimated total dietary exposure to the analyte among the U.S. population (or age / gender subpopulation).

Age and gender groups for whom we have calculated TDS consumption amounts

Age	Males	Females	Males & Females, Combined
6 - 11 months
2 yrs
6 yrs
10 yrs
14 - 16 yrs
25 - 30 yrs
40 - 45 yrs
60 - 65 yrs
70+ yrs

To calculate average per-capita daily consumption amounts for a given food on the TDS Food List, we first go back to the group of foods from the surveys; that is, the multiple foods that the TDS food represents. We calculate per-capita consumption amounts for each of the foods within that group and combine them into a single figure. We use that single figure as the per-capita consumption amount for that TDS food. (See graphic below.)

You can use a mapping file we created to map any of the more-than 7,900 food codes in the 2003-2014 National Health and Nutrition Examination Survey (NHANES), What We Eat In America (WWEIA) to the TDS Foods (i.e., the TDS Foods List) we analyzed in 2014, to find their representative chemical concentrations. To request the file, contact [email protected]. As noted earlier, each of the TDS Foods represents a large group of similar foods. The concentrations of chemicals in each of the TDS Foods applies to all of the foods in the group the TDS Food represents (a limitation that should be noted when reporting chemical concentrations estimated via the TDS and the TDS mapping file). Data on the TDS Foods’ chemical concentrations can be downloaded from the TDS Website. Please see the Analytical Results page.