A new study conducted on roundworms finds that a common plastic ingredient causes breaks in DNA strands, resulting in egg cells with the wrong number of chromosomes. Monica Colaiácovo of Harvard Medical School led the study, which was published October 24 in the journal PLOS Genetics.

Benzyl butyl phthalate (BBP) is a chemical that makes plastic more flexible and durable, and is found in many consumer products, including food packaging, personal care products and children’s toys. Previous studies have shown that BBP interferes with the body’s hormones and affects human reproduction and development, but the details of how it impacts reproduction have been unclear.