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Mary Beth Kirkham hadn’t studied microplastics when she was invited to co-edit a new book about microplastics in the environment—but something stood out to her about the existing research.

“I had read in the literature that … cadmium and other toxic trace elements [are] increased when we have these particulate plastics in the soil. So that was of concern to me,” Kirkham, a plant physiologist and distinguished professor of agronomy at Kansas State University, told EHN.

Kirkham’s expertise is in water and plant relations and heavy metal uptake, so she decided to conduct her own research in which she cultivated wheat plants exposed to microplastics, cadmium and both microplastics and cadmium. Then she compared these plants to those grown without either additive. She chose cadmium because it’s poisonous, carcinogenic and ubiquitous in the environment due to human activity — it’s shed from batteries and car tires, and is naturally found in the phosphate rock used to make agricultural fertilizers.

“Cadmium is everywhere,” said Kirkham.

At the end of the experiment she sent her wheat plants off for analysis and, validating previous reports, the plants grown with microplastics were more cadmium-contaminated. “The plastics really were acting as the vector for uptake of the cadmium,” she said.

Her experiment became a chapter in the new book “Particulate Plastics in Terrestrial and Aquatic Environments.”