The findings, which have not been published in a peer-reviewed journal, came from testing 530 of the best-selling baby food products as determined by using Nielsen data. Out of this sample, arsenic was the most common contaminate with 65% of products testing positive for the toxin. Exposure to arsenic can lead to developmental defects and other serious health risks including cancer.

Rice-based baby foods, like snack puffs, had the highest levels of arsenic, according to Jaclyn Bowen, a food safety scientist and the executive director of the Clean Label Project.

More than one-third of the products tested positive for lead, 58% for cadmium and 10% for acrylamide.

Cadmium can cause neurological and kidney damage, according to the World Health Organization. Acrymalide can also cause neurological damage and is a likely carcinogen, according to the National Cancer Institute.

This isn’t the first time lead has been found in baby foods. A report published in June that analyzed 11 years of Food and Drug Administration (FDA) data found lead in 20% of baby food samples — higher than other types of food. While no amount of lead is safe, the contaminant is not regulated.

“It is important for consumers to understand that some contaminants, such as heavy metals like lead or arsenic, are in the environment and cannot simply be removed from food,” Peter Cassell, a FDA spokesperson, told USA Today.

Low levels of lead have been linked to lower IQs, slower growth, hearing issues, anemia, and behavioral problems, according to the Environmental Protection Agency.

While Gerber, Mead Johnson, and Plum Organics released statements highlighting the safety standards in place for their products, Bowen called on companies to make changes.

“The baby industry needs to do a better job in protecting America’s most vulnerable population,” she said.