Food processing happens anytime you take fresh food and change it into a cooked dish or food product. Whether you are cooking food at home or a manufacturer is preparing food in a facility, food processing can help ensure food safety and quality. It is also a way to make food taste better and last longer.

Process contaminants are undesired chemical by-products that can form during food processing, especially when heating, drying, or fermenting foods. They can form during home cooking and in manufacturing facilities, and in some cases, low levels may be unavoidable. Not all are harmful, but some process contaminants have been linked to potential health effects.

In order to protect public health, the FDA researches how process contaminants form, develops measurement methods, and surveys levels of process contaminants in foods. When we determine that the levels of contaminants in a food are unsafe, we take measures to reduce their presence in the food supply. We also work with the food industry and international organizations to help reduce process contaminants in foods as well as provide guidance and information to industry and consumers.

Examples of Process Contaminants

Process contaminants can be found in plant-based and animal-based foods. Examples of process contaminants include acrylamide, ethyl carbamate, furan, 3-monochloropropane-1,2-diol esters (3-MCPDE), glycidyl esters (GE), nitrosamines, heterocyclic amines, 4-methylimidazole (4-MEI), and polycyclic aromatic hydrocarbons (PAHs).

We engage in research on process contaminants in the food supply. Studies show that high doses of these contaminants or their breakdown products can cause cancer in laboratory animals, but the levels used in these studies were much higher than those typically found in human food. For additional information on each of these process contaminants, please visit the individual webpage links.

• Acrylamide is a substance that can form in plant-based foods, including potato and cereal-grain-based foods, during high-temperature cooking such as frying, roasting, and baking. The FDA measures acrylamide in foods and developed Guidance for Industry on Acrylamide in Foods that outlines strategies for growers, manufacturers, and food service operators to reduce acrylamide in the food supply. For consumers, we have resources for reducing acrylamide exposure in food prepared at home.
• Ethyl carbamate can form during fermentation of beverages and other foods. We have developed analytical methods that industry and we can use to measure ethyl carbamate in foods, evaluated levels in foods and beverages, and shared resources from academia and industry on ways to control ethyl carbamate in wine.
• Furan can form in some foods during heating, such as cooking, jarring, and canning. We developed a method to measure furan, surveyed furan levels in food, and published toxicology studies on furan.
• 4-Methylimidazole (4-MEI) can form at low levels in some foods during cooking, including roasting coffee beans, roasting or grilling meats, and during manufacture of certain types of caramel coloring used in foods. As part of an ongoing review of color additive safety, we published an assessment in 2018 of consumer exposure to 4-MEI from certain caramel colors as well as from heat-treated foods.
• 3-Monochloropropane-1,2-diol (3-MCPDE) and Glycidyl Esters (GE) can form in edible oils, such as vegetable oils, during industrial refining when these oils are heated at high temperatures to remove unwanted tastes, colors, and odors. The FDA has developed methods to measure 3-MCPDE and GE in foods, conducted surveys of edible oils and other foods containing edible oils (such as infant formula), and researched the potential adverse health effects of 3-MCPDE and GE. We also continue to engage with the food industry to exchange information on mitigation methods and helped develop an international code of practice outlining how industry can reduce levels of 3-MCPDE and GE in refined oils and foods made from refined oils.

3-monochloropropane-1,2-diol esters (3-MCPDE) and glycidyl esters (GE) are contaminants that can occur in edible oils, such as vegetable oils, and foods made from these oils. Both food manufacturers and consumers use edible oils as an ingredient in foods and for cooking. During industrial refining, 3-MCPDE and GE can form in edible oils when the oils are heated at very high temperatures to remove unwanted tastes, colors, or odors. The highest concentrations typically occur in refined palm oil and palm olein oil, but 3-MCPDE and GE also are found in other refined vegetable oils (such as safflower, coconut, sunflower, and soybean oils) and refined marine oils (such as fish oils).

During digestion, 3-MCPDE and GE break down to the organic chemicals 3-monochloropropane-1,2-diol (3-MCPD) and glycidol. In studies of rodents, 3-MCPD caused adverse effects on kidneys and male reproductive organs, and both 3-MCPD and glycidol caused cancer. To better understand the potential risks of 3-MCPDE and GE in foods for humans, the FDA has developed methods to measure these contaminants in foods, conducted surveys of edible oils and other foods containing edible oils, and researched the potential adverse health effects of 3-MPCDE and GE.

Refined vegetable oils are a major component of infant formula, because fats from added oils are important for infant nutrition. Since infants are a vulnerable population, FDA work has focused on measuring levels of 3-MCPDE and GE in infant formulas to ensure the safety of infant formula. The FDA has also engaged with industry to share information on the health effects of 3-MCPDE and GE and the availability of mitigation methods for refined edible oils and infant formula to help reduce the levels of these contaminants.

In addition, the Codex Alimentarius Commission, in which FDA participates, developed recommendations for industry on reducing 3-MCPDE and GE in refined oils and foods. As chair of a Codex working group, the U.S. helped to develop a code of practice that outlines agricultural, refining, post-refining, and processing measures that industry can use to reduce levels of 3-MCPDE and GE in refined oils and foods made from refined oils.

Health Effects from 3-MCPDE and GE Exposures

In laboratory studies, 3-MCPDE and GE break down in the digestive tract to 3-MCPD and glycidol. Research studies in rodents show that 3-MCPD primarily affects the kidney and the testes and can cause cancer. There is clear evidence that glycidol is a carcinogen in rodents from research by the U.S. National Toxicology Program. The International Agency for Research on Cancer classifies 3-MCPD and glycidol as possible and probable human carcinogens, respectively.

In 2016, the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) conducted an evaluation of 3-MCPDE/3-MCPD and GE/glycidol and the evaluation included participation by FDA scientists. JECFA derived a provisional maximum tolerable daily intake (PMTDI) of 4 µg/kg bw/day for 3-MCPDE/3-MCPD. For GE, JECFA determined that the lower end margins of exposure (MOEs) for infants, children, and adults may be a health concern. Based on this assessment, JECFA recommended reducing 3-MCPDE and 3-MCPD in infant formula and GE and glycidol in fats and oils, particularly when used in infant formula.

As new research on 3-MCPDE and GE becomes available, FDA experts will consider the research in their continued evaluation of the effects of 3-MCPDE and GE on human health.

FDA Monitoring and Testing of 3-MCPDE and GE in Food, including Infant Formula and Vegetable Oils

As part of the FDA research program on 3-MCPDE and GE, FDA scientists have developed and validated analytical methods to measure 3-MCPDE and GE and used the methods to conduct surveys of refined vegetable oils and infant formulas. FDA scientists also conducted an exposure assessment of 3-MCPDE and GE from consumption of infant formula. Research publications of the FDA’s methods and results are presented in the subsequent section.

The FDA has focused its testing efforts on infant formula because infants are a vulnerable population, infant formula contains relatively large amounts of oil (about 25-30%) to support infants’ nutritional needs, and for some infants, infant formula is a sole food source. Because of the combined efforts of industry and the FDA, average 3-MCPDE and GE levels in infant formula in the U.S. have declined over the last several years.

Between 2013-2016, FDA scientists surveyed 98 infant formula samples including both milk- and plant-based formulas. Using the data collected, the FDA conducted an exposure assessment estimating the average 3-MCPDE and GE exposures to infants (0-6 months), considering all types and brands of formula, as 7-10 µg/kg bw/day for 3-MCPDE and 2 µg/kg bw/day for GE, with the 3-MCPDE levels exceeding the 4 µg/kg bw/day recommended JECFA level. Following this finding, FDA scientists initiated conversations with the infant formula industry and brought concerns about the elevated levels in the 2013-2016 sample set to industry’s attention.

Between 2017-2019, to determine if infant formula manufacturers had reduced 3-MCPDE and GE levels in infant formulas, FDA scientists surveyed and analyzed an additional 222 samples of infant formula from the four largest U.S. infant formula manufacturers. Based on FDA’s testing of products on the market from 2017-2019, three U.S. manufacturers successfully reduced 3-MCPDE and GE levels in their infant formula products to levels consistent with levels seen in infant formulas internationally.

The FDA continued its dialogue with infant formula manufacturers, followed by testing in 2021 and 2023. Between 2021-2023, the FDA scientists surveyed and analyzed an additional 206 samples of infant formula from the four largest U.S. infant formula manufacturers. These testing results indicate that all four manufacturers have successfully reduced 3-MCPDE and GE in their infant formula products to levels consistent with levels seen in infant formulas internationally.

The FDA will continue to monitor the levels of 3-MCPDE and GE in infant formulas in the marketplace.

Acrylamide is a substance that forms through a natural chemical reaction between sugars and asparagine, an amino acid, in plant-based foods – including potato and cereal-grain-based foods. Acrylamide forms during high-temperature cooking, such as frying, roasting, and baking. In research studies, high levels of acrylamide caused cancer in laboratory animals, but the levels of acrylamide used in these studies were much greater than those found in human food. The FDA monitors levels of this contaminant in certain foods because of its potential to affect human health.

Although it's not clear exactly what risk acrylamide poses to humans, the FDA has recommendations for both consumers and industry about how to reduce acrylamide formation in foods. In 2016, the FDA developed a Guidance for Industry that outlines strategies to help growers, manufacturers, and food service operators reduce acrylamide in the food supply. And for consumers, the FDA has developed resources that contain information about acrylamide and ways to reduce exposure from foods prepared at home. See the More Information for Consumers section below.

Health Risks from Acrylamide Exposure

Acrylamide has been shown to cause cancer in animals exposed to very high doses, and although there is no consistent epidemiological evidence on the effect of acrylamide from food consumption on cancer in humans, both the U.S. National Toxicology Program and the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) consider acrylamide to be a human health concern.

Acrylamide exposure can be detected by testing for the presence of acrylamide markers in the blood. According to scientists at the Centers for Disease Control and Prevention, markers of acrylamide exposure can be found in the blood of 99.9% of the U.S. population; however, finding these markers does not imply that their presence will result in adverse health effects.

As new research on the effect of acrylamide exposure becomes available, FDA experts will consider it in their continued evaluation of the risk that acrylamide may pose to human health.

Ethyl carbamate is a process contaminant that is sometimes found in fermented foods and alcoholic beverages. Ethyl carbamate (also called urethane) can form during the fermentation and storage of foods and beverages that naturally contain nitrogen-rich compounds such as urea, citrulline, and cyanate. Low levels of ethyl carbamate can be found in breads, soy sauce, beer, and wine. In the case of beer, wine, and bread, ethyl carbamate can form when there is a reaction between ethanol and nitrogen-rich compounds produced by yeast during brewing and fermenting. Higher levels of ethyl carbamate can occur in distilled alcoholic spirits, especially those made from sugar cane and stone fruits, due to the presence of ethyl carbamate precursors in the raw materials and the high temperatures used during distillation. Industry practices can reduce the levels of ethyl carbamate in finished products.

The FDA has worked with domestic manufacturers and other government agencies to set voluntary limits for ethyl carbamate in wines and distilled spirits and to share information on reducing ethyl carbamate exposure.

Health Risks from Ethyl Carbamate Exposure

In laboratory studies, high doses of ethyl carbamate have been shown to cause cancer in animals. The United States National Toxicology Program lists ethyl carbamate in the 15th Report on Carcinogens as “reasonably anticipated to be a human carcinogen” based on data from animal studies.

In 2005, the 64th Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA) estimated exposure to ethyl carbamate from foods and alcoholic beverages and determined that the dietary risk from foods, excluding alcoholic beverages, was of low concern. FDA experts participated in this session. However, ethyl carbamate exposure for consumers of alcoholic beverages was significantly higher, leading JECFA to suggest that mitigation measures to reduce ethyl carbamate in some alcoholic beverages are needed. Other government agencies, including the FDA, have reached similar conclusions, and there have been worldwide efforts to reduce ethyl carbamate levels in alcoholic beverages.

Monitoring data from JECFA, Canada, and the United States suggest that ethyl carbamate levels in alcoholic beverages have decreased since the 1990s. Therefore, exposure estimates from the 1990s may be higher than current dietary exposure to ethyl carbamate from alcoholic beverages. As new data on ethyl carbamate levels becomes available, FDA experts will consider these data in their continued evaluation of exposure and potential risk.

Monitoring and Testing of Ethyl Carbamate in Fermented Foods and Alcoholic Beverages

The FDA’s Center for Food Safety and Applied Nutrition (CFSAN) monitors contaminant levels in foods and beverages, including ethyl carbamate, to inform FDA actions and protect public health.

In 1988, the FDA developed a method to detect and quantify ethyl carbamate and conducted surveys to determine the amount of ethyl carbamate that naturally occurs in alcoholic beverages, bread and other fermented foods. See Publications by the FDA on Ethyl Carbamate for sampling data on foods other than alcoholic beverages.

The FDA shares responsibility for alcoholic beverage regulation with the U.S. Department of Treasury Alcohol and Tobacco Tax and Trade Bureau (TTB). TTB monitored levels of ethyl carbamate in distilled spirits, wine, and malt beverages between 1988-1998. TTB published their method for detecting ethyl carbamate in alcoholic beverages in the Journal of AOAC International.

In FY2020-21, the FDA and TTB cooperated on the sampling and analysis of 278 additional alcoholic beverages. Survey results showed that average ethyl carbamate levels in distilled spirits and wine decreased in 2021 from levels reported in 1988, and overall ethyl carbamate levels in malt beverages remained low. This decrease in ethyl carbamate concentrations in distilled spirits and wine over time suggests that industry mitigation efforts have been effective. See the FDA’s presentation for further details on this survey of alcoholic beverages.

Furan is a chemical contaminant that forms in some foods during traditional heat treatment techniques, such as cooking, jarring, and canning. FDA has developed a method for quantitative furan measurements, surveyed furan levels in food, and conducted toxicology studies of furan in rodents.