Center for Research on Ingredient Safety

What do the headlines say?

• Dark chocolate might have health perks, but should you worry about lead in your bar?
• Hershey sued in U.S. over metal in dark chocolate claim
• 5 brands—including Trader” Joe’s—whose dark chocolate tested high for lead, cadmium
• Heartland study finds spices second only to paint for the lead poisoning of children

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.

How do food and beverage manufacturers ensure these contaminants aren’t in our products at harmful levels?

As discussed in a prior post, Current Good Manufacturing Practices help keep our food and water systems safe from many harmful substances. However, sometimes levels are exceeded.

We have also noticed that articles refer to the levels of metals in food products by the percentage of change.  Scientists use this term to describe how much something has changed, compared to the standard. The percentage is not a measurement of safety. 
 
Percentages in the proper context help us understand a situation, but they can also cause confusion and be misleading when dealing with small numbers like those found in foods and beverages. 

For instance, if a product usually contains zinc at three parts per billion and a new batch of that product contains zinc at four parts per billion, it’s a 33% increase or 133% from the standard. The percentages seem like we are now being exposed to significant amounts of zinc, but if we look at the actual number (amount), an increase of one part per billion is not a risk.  

While billion sounds like a big number, it's 1 part per billion of 1.
 
For example:
1 part per million = 0.000001 of 1
1 part per billion = 0.000000001 of 1

If a contaminant like a heavy metal is found, does that automatically make the consumable harmful?

No, in fact, emerging technology and fields of study like non-targeted analytical chemistry can detect hundreds to thousands of contaminants at harmless, minuscule levels. Researchers are learning more about the application of non-targeted analysis and how they can apply it to our food system.
 
One important note is that detecting a contaminant or heavy metal does not mean it’s harmful. We must always consider the contaminant, the amount, and the duration of exposure before we can determine if something will cause an adverse health impact.

Does the government regulate contaminants like heavy metals in food and beverages?

For many contaminants, the United States Food and Drug Administration (FDA), Environmental Protection Agency (EPA) (1,2), and the Department of Agriculture (USDA) have strict guidelines regarding allowable limits in or on foods and water. 
 
Typically, agencies work with scientists to establish contaminant thresholds many magnitudes lower than what is known to cause harm based on the current state of the science. So, even a slightly elevated level may not cause harm to most individuals because it’s still magnitudes lower than what’s known to cause harm. 
 
However, the U.S. regulatory systems lack robust guidance on many heavy metals in final food products. 

Does this mean heavy metals are safe to consume?

No, we are not advocates for the consumption of heavy metals at harmful levels. However, we think it’s important to share all the facts so you can more accurately consider the risks.

The good news.