The FDA Total Diet Study - Lead, Mercury, and Other Toxicants Reported

The FDA periodically updates their Total Diet Study with information on heavy metals and pesticides found in foods.  As a parent concerned about reducing the likelihood of lead in our family’s diet, I was intrigued by the study and interested in where lead is lurking in my produce and other foods. 

What is the Total Diet Study?

The Total Diet Study (TDS) is an FDA program that measures and reports levels of various contaminants and nutrients in foods. It began in 1961 and initially focused on radioactive contaminants and eventually grew to include pesticide residues, industrial chemicals and toxic and nutrient elements.  Foods are prepared as they would be prepared and eaten at home prior to analysis.  This is done to provide realistic results and estimates of the dietary intake for the U.S. population[1]

Food samples, also referred to as market baskets, are collected four times a year, once in each geographic region - West, North Central, South, and Northeast.[2]  The samples are purchased by FDA employees from supermarkets, grocery stores, and fast food restaurants and are shipped to a central FDA lab for analysis.  There is not a focus on a particular brand, but rather getting a sample of what is available to consumers and then the information is aggregated and updated on their site.  Therefore, you will not notice brand specific information in this article or in the Total Diet Study report.  

The most recent update occurred in July of 2008.  Following are some results for the lead, mercury, arsenic, and nickel.  To view additional information, such as pesticides, nutritional information, chemicals, moisture, or other toxicants, visit the FDA market study.

Lead

There were literally hundreds of items tested and we simply wanted to bring this study to your attention; not cut and paste information that is available on the FDA’s site.  If you would like to see specifics on each items tested and their results, visit the FDA’s site. 

What is an acceptable level of lead in food?  The report doesn’t detail that information, but as a benchmark, we can tell you that the FDA lowered the acceptable level of lead in candy from .5 ppm to .1 ppm in November of 2006[3].  This would mean that the plain milk chocolate candy bar that tested at the maximum level would be in violation of the standard.  In addition, if collard greens were considered candy, the maximum value tested would also be in violation of the FDA standard.  If we use the EPA’s actionable water safety standard of 15 ppb for lead[4], the fruit cocktail, dill pickles, and chocolate syrup would be considered excessive as well.

Following are a few select items from the lead category.  The left hand column provides a food description.  The middle column provides information on the number of samples that detected lead.  An interesting side note is that sometimes, the numbers did not add up.  For instance the report would state that 38 items would be detected with lead out of a possible 52.  However, the next column would state that 6 items had no detectable levels of lead.  There was not an explanation for the missing 8 (52-38 = 14 not 6).  We only included the actual number of detected samples. 

The last column provides the information in parts per billion (ppb) and parts per million (ppm).  We picked a random sample of items, so you will see some that demonstrated they contained lead a majority of the time, while others barely showed any or none. 

Source:  FDA Total Diet Study

So how does lead end up in food?  There are a number of ways.

1. Crops grown in contaminated soil. Root vegetables such as beets, carrots, turnips, radishes and potatoes easily absorb lead through their roots and there is also the possibility of lead-contaminated dust falling onto leafy vegetables such as lettuce and spinach[5][6].   The University of Rhode Island recommends washing and peeling fruits and vegetables to reduce this risk and maintaining a soil ph between 6.5 and 7.0[7].
2. The Tennessee Department of Health states that some insecticides being sprayed on plants can also contaminate crops[8]. 
3. Lead-bearing equipment used in the manufacture or processing of foods including bronze and brass fittings[9].  Scientists have found it difficult to isolate the source of lead contamination in chocolate, but suspect it happens during the manufacturing process[10].
4. The way food is cooked can also cause contamination.  If food is heated with lead contaminated dinnerware or cookware, the lead can leach out into the food – particularly if the food is acidic.

Arsenic

This table was put together in the same manner as lead.  We intentionally did not pick all high testing items, rather we wanted to give you an idea of the scope and range of items that tested positive for arsenic.  For compete information, please visit the FDA’s Total Diet Study.

There is not an actionable level for arsenic in food, however, the EPA’s actionable level for arsenic in water is 10 ppb[11]. 

Source:  FDA Total Diet Study

Where does the arsenic come from?  Contaminated water[12] and poultry feed[13] are cited as factors.  Arsenic is an approved additive in poultry feed because it helps to kill parasites. 

The Institute for Agriculture and Trade Policy states that about 70% of all chickens receive arsenic in their feed during their lifespan[14].  Arsenic was more than twice as prevalent in conventional brands of supermarket chicken as in certified organic and other “premium” brands.

According to the Virginia Department of Health, most arsenic leaves the human body within several days[15].

Mercury

This table was put together in the same manner as lead and arsenic.  Again, we intentionally did not pick all high testing items, rather we wanted to give you an idea of the scope and range of items that tested positive for mercury.

The EPA has set a limit of 2 ppb of mercury for drinking water. The FDA has set a maximum level of 1 ppm of methylmercury for seafood[16].

Source:  FDA Total Diet Study

According to Consumer Reports, emissions from coal-burning power plants and waste incinerators are the main way mercury gets into the environment[17].

Nickel

The EPA recommends that drinking water should contain no more than 0.1 milligrams (or .1 ppm[18]) of nickel per liter of water and cites food as the major source of nickel exposure[19]. According to the CDC, approximately 10-20% of the population is sensitive to nickel[20].  

According to the National Skin Center, nickel can be released into food if anything acidic (rhubarb, apples, citrus fruit) is cooked in a saucepan that contains nickel. Canned foods also contain nickel[21][22].  Stainless steel cookware contains nickel and the amount is usually noted on the pan.  For instance if the pan is marked 18/10, the first number stands for the amount of chromium and the second number stands for the amount of nickel[23].   Silit Vision Cookware does not contain any nickel, however it is pricey.

What You Can Do

If you are trying to reduce your exposure to these and other toxins, visit the FDA’s Total Diet Study to see which foods scored the lowest and prepare those foods at home Thoroughly wash your produce and use lead-free dinnerware.

Eating organic is another way to minimize exposure.  Even thought farmers are not required to “clean” their soil[24], farmer’s fields should be treated organically for three years prior to obtaining certification[25][26].   Organic fruits and vegetables are farmed with botanical and natural pest controls that are quickly broken down by sunlight and oxygen, instead of long-lasting synthetic chemicals[27]. As mentioned earlier, arsenic was twice as prevalent in conventional chickens than organic chickens.  Organic foods were found to contain 40% less aluminum, 29% less lead, and 25% less mercury than conventional foods[28].

Eating fish that are lower in mercury such as tilapia and salmon is one way to limit mercury exposure from fish consumption. Tilefish, shark, swordfish, and king mackerel have higher levels of mercury[29].

The Total Diet Study has a number of pesticides and nutrition information listed and is worth reviewing.