A Newton-based laboratory recently found that 75 percent of the Cape Cod drinking-water sources it tested had contaminants like over-the-counter drugs, insect repellent and flame retardants.

Silent Spring Institute, which focuses on women's health issues like breast cancer and receives funding from the EPA and the CDC, reported that septic systems are the main cause of the contamination. 

WGBH News science editor Heather Goldstone joined Greater Boston to talk about the lack of regulations on the amount of pharmaceuticals that can be in drinking water, and the fact that there's no evidence yet that they harm humans. See what she had to say below: