New York, March 23 (IANS): Interacting with pharmaceuticals in water, chlorine, a common disinfectant used in water treatment, may encourage the formation of unknown antibiotic compounds that could add to the growing problem of antibiotic resistance, a study warns.

The research was presented at the 249th National Meeting & Exposition of the American Chemical Society (ACS) in Denver.

"Increased antibiotic exposure, even at low levels in the environment, can lead to development of antibiotic-resistant microbes and a general weakening of antibiotics' abilities to fight bacterial infections in humans," said Olya Keen from the University of North Carolina at Charlotte.

Chlorine may be failing to completely eliminate pharmaceuticals from wastes. As a result, trace levels of these substances get discharged from the plants to the nation's waterways.

Chlorine treatment may thus encourage the formation of new, unknown antibiotics that could also enter the environment, potentially contributing to the growing problem of antibiotic resistance, the researchers explained.

"Treated wastewater is one of the major sources of pharmaceuticals and antibiotics in the environment," Keen noted.

For the study, the researchers ran several lab experiments and found that exposing doxycycline, a common antibiotic, to chlorine in wastewater increased the antibiotic properties of their samples.

This research has applications to drinking water treatment systems, most of which also use chlorine as a disinfectant, she added.

To purify drinking water, chlorine must remain in the distribution piping system for hours, which blocks microbes from growing.A

But this also provides ample time for chlorine to interact with pharmaceuticals that may be in the water, encouraging development of new antibiotic compounds, the researchers pointed out.