Metals (e.g., lead, arsenic, cadmium) and other impurities (e.g., pesticides, petroleum hydrocarbons, solvents) are found in the environment due to natural deposits and/or human activities. Consequently, detectable levels of some impurities have been documented in foods. Specifically, plants can uptake impurities from the soil they grow in, animals can bioaccumulate impurities from plant feed consumed, and fish can uptake and bioaccumulate impurities from the water and food sources. Impurities can also be introduced into food during the addition of spices, water, and other ingredients. It is often not possible to produce a food product with non-detectable concentrations of certain impurities, like metals.

When impurities in foods are brought to light—whether by internal testing, a third party, or the media—consumers often react with concern, confusion, and even fear. They want to know: Is this food safe? Should children avoid it? Could this have been prevented? Without clear, science-based answers, these concerns can quickly turn into reputational and regulatory risk. In many instances, consumers are familiar with a hazard, i.e., something that has the potential to be "dangerous." But often, the public needs more information to accurately assess health risk, which is a function of the severity of the hazard, as well as the magnitude and likelihood of exposure to the hazard.

Expansion of Reporting and Regulating Impurities in Foods

In recent years, there has been a notable expansion in both the reporting and regulation of impurities in foods—particularly metals and impurities consumed by infants and young children—driven by growing public awareness and scientific advancements. For example, in 2021, the U.S. Food and Drug Administration (FDA) launched the "Closer to Zero" initiative, which aims to reduce dietary exposure to arsenic, lead, cadmium, and mercury to as low a level as possible. In 2025, FDA launched "Operation Stork Speed," which includes the goal of increasing testing for metals in infant formula and foods consumed by young children.

Several states have also begun implementing their own regulations to address metals in baby food. In California (Assembly Bill 899) and Maryland (House Bill 97), manufacturers of baby food sold in these states are required to test for and disclose concentrations of arsenic, lead, cadmium, and mercury. The testing information must be publicly available and reported on the manufacturer's website.

Other states have passed or are considering regulations that require the use of warning language in certain instances when select impurities or ingredients are present in a product. For example, per California's Proposition 65 (i.e., the Safe Drinking Water and Toxic Enforcement Act of 1986), businesses that sell products in California may need to provide exposure warnings for approximately 900 substances that have the potential to cause cancer, birth defects, or other reproductive harms, if exposures are anticipated to exceed a maximum level. Some of these substances are detectable in foods and beverages.

Monitoring impurities in foods is an important tool for protecting vulnerable populations, especially infants, children, and pregnant women. However, as consumers encounter more reports of detectable impurities in everyday foods, concern is likely to grow unless these findings are clearly communicated in the context of potential health risk.

Risk Assessment as a Tool for Interpreting Exposures in Foods

Applying a risk assessment framework to evaluate and communicate exposures can help consumers better understand and interpret findings of detectable impurities in foods. This approach involves:

1. Identifying the potential hazard
2. Assessing how the body is expected to respond across different levels of exposure (dose-response) or relying on health-based guidance values established by governmental agencies
3. Estimating the actual exposure for the relevant scenario
4. Characterizing the risk by comparing the estimated exposure to known dose-response relationships and/or health-based guidance values.

Estimates of exposure via ingestion depend on three key factors:

1. The concentration of the element in the food
2. The amount of element consumed via food (and, importantly, the fraction absorbed)
3. The body weight of the individual.

Higher exposures can occur from consuming a food containing higher concentrations of the impurity, consuming large quantities of a food, or consuming the impacted food frequently. Moreover, exposure to the same amount of an impurity would result in a higher dose in individuals with lower body weights compared to individuals with higher body weights. Populations with exposures to higher doses often include those with a limited diet or lower body weight, such as infants and young children.

Once an exposure dose has been estimated, a screening level risk characterization can be performed by comparing the dose to an appropriate health-based guidance value—typically an estimate of the exposure that can occur on a daily basis for a lifetime yet is unlikely to cause an adverse health effect.

For non-cancer health effects, the difference between the estimated element-specific exposure from the ingested food and the health-based guidance value can be used to conclude whether there is a sufficient margin of safety or if additional research is needed to evaluate the product. Further evaluation may include exploring potential interventions or opportunities for exposure reductions.

For cancer health endpoints, the assessment typically focuses on estimating the increased lifetime risk associated with the exposure. If a risk is identified at a screening level, then a more nuanced assessment can be performed to more precisely estimate anticipated risk. Benefits specific to the product of concern (e.g., essential nutrition, access, cost) and risks associated with alternatives should also be considered.

Approaches for Characterizing Exposures to Impurities in Foods

Estimated dietary exposures to an impurity can be compared to regulations and health-based guidance values to understand whether they exceed recommended limits. For example, FDA monitors and regulates impurities in some foods and in dietary supplements, and the U.S. Environmental Protection Agency (EPA) monitors and regulates impurities in drinking water. California's Office of Environmental Health Hazard Assessment (OEHHA) has established "safe harbor" levels for the exposure to many of the contaminants regulated under Proposition 65. On a more global scale, the Codex Alimentarius Commission is a joint Food and Agriculture Organization of the United Nations (FAO) and World Health Organization (WHO) program that establishes international food standards to facilitate trade. A subset of these standards includes maximum levels for food contaminants and naturally occurring toxicants.

An alternative approach for contextualizing the presence of impurities is to compare the estimated dietary exposure to what is expected from other foods that are considered acceptable. For example, lead has been detected in some chocolate products. However, reported estimates of lead exposure from chocolate are generally similar to lead exposures from other commonly consumed foods and markedly lower than environmental (e.g., soil and dust) exposures to lead. This approach can help consumers understand that, while a detectable exposure will occur, the associated risk may be something that they are already familiar and comfortable with.

It is also possible to calculate how much of a food a person must consume to reach an exposure limit. For example, recent research has suggested that a child would have to consume multiple chocolate bars every day to increase their blood lead level to the acceptable health-based guidance value. This methodology can be useful when there is a high level of concern around a hazard, like there is for lead and arsenic, but the amount of the food product typically consumed is very low.

Case Studies

The following case studies illustrate exposures to metals in various foods, typical effects on consumer health, and recommended messaging for these food commodities.

Estimating Cumulative Risk from Exposure to Multiple Metals in One Product: Protein Powder Supplements

Arsenic, cadmium, and mercury have been detected in liquid and powder protein dietary supplement products. Using the concentration of each element detected in the selected products, the average serving size consumed per day, and the typical adult body weight, the chronic daily intake of each metal can be estimated and compared to EPA and Centers for Disease Control and Prevention (CDC) estimates of acceptable exposure. Expected health risk from the consumption of these metals in protein powder supplements can be calculated for each metal individually (i.e., hazard quotient) and for the combined, cumulative risk of these metals collectively (i.e., hazard index) within a product.

Using this approach, while arsenic, cadmium, and mercury are detectable in these products, expected risk (individually, and for the metals combined) is below guidance values. Therefore, typical intake is unlikely to result in adverse health effects due to heavy metals.

Comparing to a Familiar Exposure: Infant Formula and Breastmilk

Recent reports have shown that metals and other non-essential elements are detectable in infant formula. While nearly 75 percent of U.S. infants receive formula before six months of age, breastmilk is considered the ideal infant diet and is recommended. However, breastmilk also contains detectable concentrations of metals and other contaminants.

In addition to comparing expected metals exposures from formula to health-based guidance values, exposures from formula can be compared to likely alternative diets, such as expected metals exposures from consuming breastmilk. In this analysis, formula samples generally contained lower concentrations of beryllium, cadmium, lead, mercury, nickel, and thallium, and higher concentrations of beneficial essential elements than what had been reported in breastmilk. This approach informs consumers that consumption of the same volume of a familiar alternative product may also result in exposure to metals.

Low-Consumption Foods: Potato Chips

Acrylamide can form naturally in foods or during heating. It is often detected in potato chips, cookies, crackers, cereals, coffee, almonds, olives, and asparagus. Studies where animals are exposed to chronic, high doses of acrylamide have resulted in tumor formation. However, using a risk assessment approach, for a person to consume the human equivalent of acrylamide daily exposure in which tumors are seen in the most sensitive animal model, a person would have to regularly eat over 90 large bags of potato chips per day.

Beneficial Trade-Offs: Fruits and Vegetables

Consumers are often confronted with seemingly contrasting reports of the detection of pesticide residues in foods and U.S. government reports that the country's food supply is one of the safest in the world. Data from the U.S. Department of Agriculture (USDA) pesticide residue surveillance program can be used to estimate exposures to pesticide residues in commonly consumed fruits and vegetables. These exposures can then be compared to pesticide-specific EPA dietary health-based guidance values. Under this approach, a child would have to consume pounds (or for some produce varieties, tens of thousands of pounds) of a fruit or vegetable daily, for a lifetime, before exposure at the guidance value is reached.

Even more importantly, fruits and vegetables provide many essential nutrients, which are particularly necessary for children. Avoiding the consumption of fruits and vegetables due to concerns about health risks associated with pesticide residues is unnecessary and could also be harmful if it reduces intake of vital essential elements.

Aligning Customer Risk Perception and Risk Reality

People are often inherently more fearful of certain types of exposures, such as those that are beyond their control, engineered, have no apparent health benefit, and/or experienced by children. In contrast, the public generally perceives exposures that are voluntary, familiar, natural, associated with clear health benefits, and/or experienced by adults as less concerning. Customers will likely be fearful if presented with reports that a hazard has been detected in foods they purchase or consume.

To help customers understand the potential for risk associated with these exposures, both consumer messaging and scientific reports should include information explaining why these impurities are present and how these exposures compare to health-based guidance values and/or exposures from alternative, familiar sources. Just as important, this messaging should come from a trusted and credible source.

Neva Jacobs, Dr.P.H., M.S.P.H., CIH is a Technical Fellow, Toxicology in Washington D.C. She is a board-certified industrial hygienist who holds additional certifications in risk assessment, exposure decision analysis, and HACCP plan development. Dr. Jacobs has characterized occupational and consumer exposures and risks throughout the supply chain, including those associated with pesticides and pesticide residues, flavorings, microbial contamination, leaching from packaging materials, and workplace ergonomic and noise hazards.

Ania Urban, Ph.D., M.P.H. is a Senior Supervising Health Scientist in San Francisco, California. She is a toxicologist with 15 years of professional experience in exposure assessment and human health risk assessment, with a focus on carcinogens. Dr. Urban has been involved with risk assessments related to exposures to chemical constituents in foods and beverages, contaminants or impurities in dietary supplements and pharmaceuticals, and risk assessments related to California's Proposition 65.

Andrey Massarsky, Ph.D. is a Senior Supervising Health Scientist. He has over 15 years of experience in the field of toxicology. At Stantec, he has been involved with safety, toxicology, and potential risks of chemicals to humans (e.g., chemicals on the California Proposition 65 list, PFAS, and microplastics), as well as ecological risk assessment (e.g., pesticides, PFAS). Dr. Massarsky has published more than 40 articles in peer-reviewed scientific journals on various aspects of ecotoxicology, neurotoxicology, environmental toxicology, and risk assessment.