News from CRIS: In the News - Heavy Metals in Food

January 24, 2023

What do the headlines say?

These are a few headlines of the many stories making their way through our newsfeeds over the past couple of weeks. While we know heavy metals can adversely impact our health at unsafe levels, let’s look at the exposure to these contaminants.

What types of contaminants exist? 

There are three main contaminant categories:

  1. Natural: primarily of plants, fungi, insects, bacteria, viruses, naturally-occurring metals, and more
  2. Human-made: can include pesticides, unwanted by-products like acrylamides (naturally formed when cooking), and pollutants such as polybrominated biphenyls (PCBs) in certain fish
  3. Human-introduced natural contaminant: can describe metals or other elements like arsenic, an ingredient farmers regularly used as a natural pesticide in apple orchards decades ago but can still be found in some soils and can make their way onto or in foods and water.

How do contaminants generally make their way into our food and water system?

Food and water can be contaminated at any stage of the food web and supply chain. It can occur:

  • in nature from the environment.
  • from farming methods.
  • during processing on an industrial scale.
  • during food distribution.
  • on our plates at home or in a restaurant.

How do heavy metals get into our food?

Manufacturers do not add heavy metals to foods as an ingredient. Often, heavy metals are found naturally in soil, air, and water where plants grow (1).
While many articles focus on arsenic, lead, cadmium, and mercury, other heavy metals found in soil can have adverse health impacts if consumed in sufficient quantities, such as zinc and copper (1,2). Additionally, there can be elevated amounts of heavy metals if the growing or processing environment is near a mine or where there is specific industrial activity (1).
Certain fruits, vegetables, and grains can and do absorb heavy metals during their natural growing process. Even organically grown, non-GMO crops can contain these heavy metals (1,2).

Why do crops absorb heavy metals?

Crops grow in soil, utilize carbon from air, and consume water to thrive. Since soil, air, and water can contain heavy metals both naturally and from industrial activity, the crops are exposed to heavy metals, and the crop takes up the metals during the growing process.
Some crops are more prone to absorbing specific metals than other plants. For example, rice naturally absorbs more arsenic, lettuce and onions accumulate lead more readily, and spinach and carrots accumulate cadmium more easily (1,2).
It does not mean all fruits, vegetables, and grains are harmful, and we should avoid eating them—quite the opposite, as fruits and vegetables are essential to a healthy diet. Remember, the presence of a hazard does not necessarily mean there is a risk (1). Heavy metals can be present but at such a low level that it doesn’t cause harm.
Additionally, we typically consume various fruits, vegetables, and grains grown in different areas, which helps limit our exposure to metals.


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