Best practices for reducing cadmium in food: New review from FDA scientists

Tom Neltner, J.D.Chemicals Policy Director and Maricel Maffini, Ph.D., Consultant

Note to readers: As we all grapple with the grave global health challenge from COVID19, we want to acknowledge the essential services that the professionals at the Food and Drug Administration and in the food production, processing and retail industries provide in continuing to deliver food. In the meantime, we are continuing to work towards improved health protections – including reducing chemicals in food. We’ll plan to keep sharing developments that may be useful to you. In the meantime, please stay safe and healthy.

Two years ago, the Food and Drug Administration (FDA) put cadmium on our radar when the Toxic Elements Working Group included cadmium together with arsenic, lead and mercury as metals affecting children’s neurological development. As part of that effort, FDA committed to look at all four metals across all foods instead of one contaminant, one food at a time. Last year, FDA’s scientists published a peer-reviewed article assessing children’s exposure to lead and cadmium in the diet. They found that spinach, lettuce, sunflower seeds, potato chips and wheat cereal were among the top 10 foods with the highest cadmium concentration.

New review of mitigation strategies

This year, FDA’s scientists published in a peer-reviewed journal a review of mitigation strategies to reduce dietary exposure to cadmium. Because plants uptake cadmium from the soil and “70 to 80% of dietary cadmium intake in humans comes from plant-based food,” the article focuses on methods to “reduce or prevent initial uptake by plants.” The authors explained that cadmium enters the food supply through natural and manmade sources, highlighting that cadmium often is a contaminant in phosphate fertilizers. Cadmium is also a contaminant in zinc used to galvanize steel.

The map below (extracted from the study) shows the distribution of cadmium in topsoil (called A Horizon) across the country; ranging from blue (less than 0.1 ppm) to red (greater than 0.5 ppm) with the Southeast have lower levels than the Great Plains and Rocky Mountain regions. However, the scientists warned that the amount of cadmium in the soil is only a starting point to develop a mitigation strategy because identifying soil characteristics, crop genetics and agricultural management techniques is also important. They also noted that some crops that are high in iron and zinc also tend to uptake cadmium and that there is a need to better understand the mechanisms involved in cadmium bioaccumulation in different plant species and various soil environments.

Recommendations to reduce cadmium in food

FDA’s scientists provide useful actions that farmers, manufacturers, and consumers can take to reduce cadmium in food. For farmers, they provided the helpful summary below.

For manufacturers, they recommend:

  • Stopping use of galvanized and cadmium-plated utensils and equipment for food production;
  • Reducing cadmium-bearing stabilizers in plastics; and
  • Removing cadmium-based pottery glazes.

We encourage all manufacturers to adopt these steps through their Food Safety Plans required by the FDA Food Safety Modernization Act of 2011 and the agency’s Preventive Controls for Human Food Rule.

FDA’s scientists’ recommendations for consumers are limited to eating a variety of foods and getting the proper amount of zinc, iron, and calcium to protect against cadmium absorption and toxicity.

For next steps, the scientists identified the following areas that require additional effort including:

  • Conducting field-based experimentation and testing to inform risk modeling and to develop practical farm-specific mitigation strategies.
  • Conducting a risk assessment that quantifies the potential effectiveness of mitigations throughout the food supply chain.
  • Developing commodity-specific Codex Codes of Practices to provide technical guidance to reduce cadmium levels in specific crops.
  • Harmonizing the approach and understanding the limitations of using epidemiological data in dose–response assessment for the use in risk assessment.
  • Developing commodity-specific safe limits and a surveillance system for cadmium in crops.

Summary

FDA’s scientists have provided a valuable review of the evidence and made useful recommendations. In a previous blog, we said that the results for cadmium from FDA’s children’s exposure study are new and worrisome. We also noted that “while FDA has not yet set an [maximum daily intake] limit for cadmium, the average young child exceeds most of the relevant daily exposure limits set by other agencies.” The challenge now is to translate relevant mitigation strategies into actions across the food supply chain to more effectively protect children from cadmium and other heavy metals in food.

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