Sewage Treatment May be Promoting Antibiotic Resistance

Sewage treatment may be causing some unintended side effects. Scientists have found that chlorine, a disinfectant commonly used in most wastewater treatment plants, may be failing to completely eliminate pharmaceuticals from waste; this, in turn, may be helping contribute to antibiotic resistance.

"Pharmaceuticals that get out into the environment can harm aquatic life, making them react slowly in the wild and disrupting their hormone systems," said Olya Keen, one of the researchers, in a news release. "Treated wastewater is one of the major sources of pharmaceuticals and antibiotics in the environment. Wastewater treatment facilities were not designed to remove these drugs. The molecules are typically very stable and do not easily get biodegraded. Instead, most just pass through the treatment facility and into the aquatic environment."

The fact that these treatment plants fail to remove all drugs from wastewater could also have other impacts. It could encourage the formation of other antibiotics in the discharged water. In fact, after conducted several lab experiments, the scientists found that exposing doxycycline, a common antibiotic, to chlorine in wastewater increased the antibiotic properties of their samples.

"Surprisingly, we found that the products formed in the lab sample were even stronger antibiotics than doxycycline, the parent and starting compound," said Keen.

The findings reveal that it may be importance to decrease the amount of these drugs that reach a treatment plant in the first place. Currently, the disposal of pharmaceuticals is not regulated. This means that there should be a great emphasis on collecting and incinerating old pharmaceuticals rather than dumping them down the drain or placing them in the trash, which can lead to harmful environmental exposures.

The findings were presented at the 249^th National Meeting & Exposition of the American Chemical Society (ACS).

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