The Purdue University study suggests recreational swimmers, water-fitness buffs, and aqua aerobics fans may be putting themselves at risk from thousands of chemicals in pools.
 

"The whole motivation for examining pharmaceuticals and personal care products is that there is this unknown potential for them to bring about undesired or unexpected effects in an exposed population," said Ernest R. Blatchley III, a professor in Purdue’s Lyles School of Civil Engineering and the Division of Environmental & Ecological Engineering. "There are literally thousands of chemicals from pharmaceuticals and personal care products that could be getting into swimming pool water."
 

Chlorination is used primarily to prevent pathogenic microorganisms from growing. But previous research has shown that many chemicals — including such constituents of urine as urea, uric acid, and amino acids — interact with chlorine to produce potentially hazardous byproducts in swimming pools.
 

The latest study suggests chemicals from drugs and consumer products products are adding to that potential toxic mix.
 

The findings, detailed in a research paper published in the journal Environmental Science and Technology Letters, flagged 32 chemicals including three — N,N-diethyl-m-toluamide, known as DEET, the active ingredient in insect repellants; caffeine; and tri(2-chloroethyl)-phosphate (TCEP), a flame retardant — that could be harmful at low concentrations.
 

"Because there are literally thousands of pharmaceuticals, this is just a small subset of compounds that could be present in swimming pools,” Blatchley said. “The main issue is that the release of chemicals into a place like a swimming pool is completely uncontrolled and unknown. I don't want to be an alarmist. We haven't discovered anything that would be cause for alarm right now, but the bottom line is we just don't know."
 

Some chemicals are volatile, which means they can escape into the air to be inhaled. Others can be ingested or absorbed through the skin.