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Consumers are increasingly worried about heavy metals. A 2024 survey by the International Food Information Council found that around 70% of American consumers are concerned about heavy metals in foods such as chocolate, baby food and seafood. This not surprising, given recent high-profile contamination recalls stemming from lead in applesauce and arsenic in apple juice.

With consumers on high alert about lead, arsenic, mercury and cadmium exposure, what can food companies do to limit heavy metal contamination in their products? Anna Rosales, senior director of government affairs and nutrition at the Institute of Food Technologists (IFT) elaborates.

Unfortunately, heavy metal exposure is a complicated issue. Heavy metals are ubiquitous in nature, and unlike the recent applesauce incident, most contamination happens through natural paths due to inherent levels in air, water and soil. While the route of contaminations varies there are ways to limit heavy metal levels in products.  

Ingredients matter

First, some ingredients have inherently higher levels of heavy metals. Research suggest that root, leaf and stem tissues of plants tend to easily accumulate heavy metals, resulting in crops like potatoes, carrots and collard greens posing the highest risk of contamination. Fruiting vegetables such as tomatoes, beans and peppers tend to accumulate less heavy metals. 

The United States Food and Drug Administration’s (FDA) 2022 Total Diet Study Report showed similar findings, indicating that crops like rice, wheat, leafy greens and sweet potatoes may be more prone to heavy metal contamination. Conversely, corn and oats do not have significant levels of heavy metals. Testing ingredients for heavy metals and adjusting formulations to substitute crops with naturally lower levels can help lower final concentrations, which is especially important in few-ingredient foods meant for vulnerable populations like baby food. Additionally, including a variety of crops in a product – such as multigrain bread for a pre-made sandwich product instead of single grain – can also help mitigate heavy metal exposure.

Seafood also poses a risk for heavy metals contamination, but some varieties pose a lower risk than others. The FDA advises that some common species of fish, such as marlin, tilefish and swordfish, contain high levels of mercury, and urges consumers to opt for seafood with low concentrations of mercury such as catfish, cod and salmon.

Mercury levels may also vary within different types of the same fish: for instance, the FDA reports that bigeye tuna contains high levels of mercury, yellowfin and albacore/white tuna contains medium levels and canned light tuna such as skipjack contains low levels. Similarly, the FDA recommends avoiding king mackerel and choosing Atlantic or Pacific chub mackerel, both of which contain low levels of mercury. Manufacturers looking to decrease potential heavy metal contamination in seafood products may want to consider substituting higher risk varieties with lower risk varieties. 

Tech forward

New processing technologies have also shown promise in lowering and identifying levels of heavy metals. For example, two rounds of industrial washing with an alkaline solution have been shown to remove more than 95% of cadmium in rice. 

Adsorption has also been shown to filter out heavy metals in contaminated water as well as peanut skins by capturing heavy metal ions. Novel detection technologies like electrochemical and optical biosensors can help identify heavy metal ions and show promise for creating improved low-cost and portable tools for on-site detection. Though these technologies may not be ready to be scaled to an industrial level and must be further studied for disadvantages – adsorption may also remove nutritionally necessary heavy metals like zinc – keeping an eye out for future applications is beneficial.  

It's also important for manufacturers to stay aware of what types of processing technologies can increase concentrations of heavy metals. Processing techniques that remove water from the finished product such as frying, baking and dehydrating can increase concentration. For example, the Total Diet Study found differences in lead and cadmium between three different preparations of potatoes: peeled and boiled potatoes had the lowest concentration with no lead detected and an average 25 ppb cadmium; French fries had averages of .56 ppb lead and 58 ppb cadmium; and potato chips had the highest concentration with averages of 2.1 ppb lead and 130 ppb cadmium.

While completely eliminating food contamination is unlikely due to the ubiquitous nature of heavy metals, manufacturers can take steps from partnering with their suppliers in testing and mitigation to ingredient substitution and shifts in processing methods to reduce risk and avoid becoming the focus of a nationwide recall.