Some food contaminants arise from natural or agricultural environments where crops are grown. Examples include heavy metals which are sometimes present in leafy greens like spinach and grains like rice. If concentrations of these and other heavy metals exceed certain thresholds they can pose risks to public health, especially in younger populations. Both food groups are critical components of nutritious and wholesome diets. But the risks posed by sometimes significant levels of heavy metals are giving health experts pause and prompting new research into how to reduce potential risks in vegetables and grains without reducing or eliminating these healthy foods from diets.

The sensitivity of children to heavy metals/toxic elements has led the U.S. Food and Drug Administration to establish a ‘Closer to Zero’ initiative to reduce them in the food supply. This often involves addressing important food groups like vegetables and rice.

Leafy greens like spinach, kale and lettuce can absorb metals like cadmium and lead which are often naturally found in the soil. But they do so in different ways and in different parts of the plant. And the potential for arsenic to accumulate in rice under certain growing conditions is leading researchers to explore steps both farmers and home cooks can take to reduce the metals’ presence.

One study led by Dr. Angelia Seyfferth at the University of Delaware and supported by the food safety and nutrition research nonprofit IAFNS uses spinach to compare and contrast how cadmium and lead differ in how they move through soil and accumulate in plant foods. The paper also discusses practical pre- and post-harvest techniques to reduce human exposure to these metals that can be adopted by farmers, food processors and consumers.

The study, “Mitigating Toxic Metal Exposure Through Leafy Greens: A Comprehensive Review Contrasting Cadmium and Lead in Spinach,”¹ appears in the peer-reviewed journal GeoHealth. This review highlights differences in the magnitude of exposure, bioavailability, and the practicality of mitigation strategies and calls for more research on cutting chloride inputs to leafy green crops like spinach, kale and lettuce to reduce plant uptake of cadmium.

According to the authors, “It is paramount to understand the soil and plant factors that dictate contaminant accumulation in edible tissues to identify mitigation strategies for metals in foods.”

They recommend action during both crop cultivation and product processing. “Pre-harvest techniques are generally actionable by the grower and include soil preparations and amendments, irrigation practices, and cultivar selection. Post-harvest techniques are further downstream and include spinach handling in the field, washing either by a factory or by the consumer, and other consumer-driven choices regarding diets.” The paper also looks at mitigation steps for lead and other metals in several crops.

Alternative Cultivation

Another study supported by IAFNS in the journal Science of Food finds that alternative cultivation practices that reduce water use may reduce greenhouse gas emissions and arsenic concentrations in rice crops but may inadvertently also boost levels of cadmium in rice plants. That paper, Unintended Food Safety Impacts of Agricultural Circular Economies², with Case Studies in Arsenic and Mycotoxins, makes several findings.

For example, continually flooded rice paddy production — the traditional method of producing rice — boosts arsenic levels in rice. But alternate wetting-drying rice production reduces the risk of arsenic uptake from soil. However, dryer soils may lead to greater uptake of cadmium in crop plants. The authors remind readers that alternative cultivation practices are not all-or-nothing strategies. For example, rice farmers often carefully weigh the specific amount of flooding and dry field management in a manner that optimally reduces both arsenic and cadmium uptake by their crops.

A third IAFNS study, Agronomic Solutions to Decrease Arsenic Concentrations in Rice³, suggests that the most effective treatments for reducing levels of the toxic metal arsenic in rice are cultivar selection, irrigation management, cooking approach and the application of selenium or silicon soil amendments. This research appears in a recent article “Reducing the Risk of Arsenic in Rice” in Food Safety Tech. The article pointed out that both farmers and home cooks can take steps to reduce arsenic.

Postharvest Techniques

Partially cooking and drying the rice is known to reduce arsenic. Rinsing, soaking and disposing of the leftover water are viable methods of reducing arsenic for home cooks. For example, cooking methods that involve briefly parboiling rice (partially cooking in boiling water before finishing by steaming or other methods) and discarding the parboiled water lowered levels of arsenic up to 83%.

The presence of heavy metals in healthy foods like leafy greens and rice pose potential public health challenges and require creative research, analysis, and engagement with stakeholders throughout the supply chain. New research is identifying workable solutions to this issue that can be applied by all stakeholders from growers to consumers. IAFNS is proud to catalyze new science that is mitigating the risks of toxic metals in foods.

References

¹ Seyfferth, A.L., Limmer, M.A., Runkle, B.R.K., Chaney, R.L. (2024). Mitigating toxic metal exposure through leafy greens: A comprehensive review contrasting cadmium and lead in spinach. GeoHealth, 8(6).  https://doi.org/10.1029/2024GH001081

² Scott, C.K., Wu, F. (2024). Unintended food safety impacts of agricultural circular economies, with case studies in arsenic and mycotoxins. Science of Food, 8(52). https://doi.org/10.1038/s41538-024-00293-8

³ Leavitt, M.E., Reba, M.L., Seyfferth, A.L., Runkle, B.R.K. (2025). Agronomic solutions to decrease arsenic concentrations in rice. Environmental Geochemistry & Health, 47(209). https://doi.org/10.1007/s10653-025-02508-7

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