Nanoplastics Raise Heavy Metal Levels in Lettuce

New research from Texas A&M University finds that nanoplastics may significantly increase the accumulation of toxic heavy metals in food crops. In a controlled hydroponic study, lettuce exposed to both nanoplastics and cadmium absorbed up to 61 percent more cadmium in edible leaf tissue compared to plants exposed to cadmium alone.

Cadmium is a toxic heavy metal naturally present in the Earth’s crust and commonly introduced into agricultural systems through fertilizers, irrigation water, and industrial pollution. The study also found that when nanoplastics were present alongside cadmium, concentrations of nanoplastics in lettuce leaves were 67 percent higher than when plants were exposed to nanoplastics alone.

Under typical conditions, plants can limit heavy metal uptake by keeping more of these substances in their roots or by growing roots toward less contaminated areas. However, nanoplastics are small enough to pass through filtration systems and enter water supplies, and once taken up by plants, they trigger oxidative stress that weakens natural defense processes. This makes it easier for cadmium to move from roots into the leaves that are consumed.

The findings suggest that combined exposure to emerging and existing pollutants may increase risks beyond current regulatory assumptions. “This means that current safety thresholds for cadmium in agricultural systems may need to be reassessed,” said Dr. Bingjie Ma, one of the study’s researchers. The authors note that further research is needed to understand how these interactions occur under field conditions.

Sources: Texas A&M University College of Engineering. “What’s in your salad? Crops exposed to nanoplastics may boost heavy metal intake.” March 17, 2026. Bryant, M.T. et al. “Synergistic Effects of Polystyrene Nanoplastics and Cadmium on Hydroponically Grown Lettuce.” Journal of Agricultural and Food Chemistry, 2025.

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