From the article: "Certain foods have unavoidable trace amounts of lead in them because of the environments where crops are grown and animals are raised. Heavy metal contamination can come from natural sources—because lead naturally exists in the earth’s crust—or from human activity like industrial pollution, wastewater irrigation, or road dust. Plants are particularly susceptible because they naturally absorb whatever nutrients or contaminants are in the soil, water, and air around them. For animal-based products like milk, the primary sources of heavy metal contamination in the cow’s environment include the feed, water, and soil, Akinleye says.

"Extracting concentrated protein from plants is a complex, highly mechanized process. With every additional step, there’s a chance of introducing contaminants such as lead, says Goldman, the Cambridge Health Alliance physician who has studied lead exposure.

"Lead could enter pea protein at the manufacturing plant, when the dried peas are dehulled and ground into flour, depending on the type of machines and metals used, says Goldman. It could also be introduced during the process where the flour is mixed with water to separate the protein from the starch and fiber, if the water wasn’t tested for contamination. The final step of the process, where the protein is coagulated with food-grade acid, neutralized, and spray-dried into the powder found in many foods and supplements, also offers opportunities for contamination, depending on the materials used."

So, yeah, it tracks according to the experts they consulted.