Leafy greens are known to absorb toxic heavy metals, such as cadmium and lead, from soil. However, crops take up various metals differently, and the distribution of metals across different parts of the plant also varies.

A recent study published in GeoHealth has exemplified the differences in how cadmium and lead are absorbed and accumulate in spinach. The research was led by Angelia Seyfferth, Ph.D. of the University of Delaware, and was supported by Institute for the Advancement of Food and Nutrition Sciences’ (IAFNS’) Food and Chemical Safety Committee.

Practical pre- and post-harvest techniques that could help reduce dietary exposure to harmful metals were described in the paper. Noted was the importance of reducing chloride inputs into crops like spinach, kale, and lettuce to lower cadmium uptake. At the same time, the study acknowledges that chloride-based sanitizers are essential for preventing pathogenic contamination, requiring a balance between reducing metal absorption and maintaining microbial food safety.

The study also underscores the need to better understand soil and plant interactions that affect metal accumulation in edible plants. The authors recommend that action be taken during cultivation and after harvesting to mitigate risks. Pre-harvest mitigation strategies described in the paper include proper soil preparation, irrigation practices, and selecting appropriate plant varieties. Post-harvest strategies, such as proper handling, washing, and consumer choices, also play a role in minimizing exposure.

The researchers call for further in-field research exploring cost-effective mitigation strategies for crop uptake of heavy metals. As growers often operate on slim profit margins, policy efforts should focus on incentivizing safe practices without burdening farmers with additional costs.

Dr. Seyfferth noted that stakeholders in the spinach industry are generally open to adopting mitigation measures but are seeking more data to determine the necessity and extent of these strategies. Regulatory bodies must therefore balance the need for safer food with the financial challenges faced by producers in the competitive global market.