But oftentimes the effects of these chemicals can linger for decades, as is the case with polychlorinated biphenyls (PCBs), a class of chemicals that was banned in the 1970s, but that has been found to still be causing cases of breast cancer today.

A recent study published in the journal Breast Cancer Research and Treatment explains how persistent PCBs, which used to be added to coolant fluids, electric motors, capacitors and other industrial equipment prior to being banned, are continuing to show up in the bloodstreams of humans today. According to the paper, one in four women today are afflicted by high levels of PCBs, and these same women are three times more likely to develop breast cancer by the age of 50 than others with lower levels.