"“There really have been no studies that have associated the [pharmaceutical] residues in our water with human health problems,” says Ilene Ruhoy, a pediatric neurologist and environmental toxicologist who has studied the issue. That could be a sign that they pose no threat, but like Wilson, Ruhoy stresses how difficult it is to do these types of studies. “You’re talking about exposure to parts per million, parts per billion. And it’s a combination of drugs. It’s not just one drug in the water, it’s multitudes of. It’s exposure to these very, very minute amounts of these drugs, but many drugs over decades—ten, 20, 30, 40, 50, 60 years.”"