Drugs in wastewater: what consequences?

Sewage is known to contain varying levels of pharmaceutical and personal care products (PPCPs), and while wastewater treatment is effective in stripping them out, a study​ reported last year found alarming differences in the effectiveness of the various technologies used.

At the ACS, researchers from the US National Institute of Standards and Technology (NIST) reported that they are using laboratory experiments to help answer this question by studying what happens to pharmaceuticals when they react with chlorine - a disinfectant commonly used in wastewater treatment.

"Scientists around the world often find drugs in water samples taken from streams and other waterways, but little is known about by-products of those drugs created during chlorine treatment or time spent in the environment,"​ said the researchers, headed by NIST chemist Mary Bedner.

Among the concerns is possible damage to the environment, animals or people from bioactive compounds.

The NIST chemists selected four pharmaceuticals sometimes found in the environment, studied their reactions with chlorine over an hour (a timescale during which significant wastewater treatment occurs) and identified the resulting products using multiple techniques.

Scientists found that the reactions are complicated and often produce several products, some unexpected. For instance, acetaminophen (paracetamol) forms multiple products, two of which are highly toxic. All the drugs were transformed significantly, and their products were generally more hydrophobic than the parent pharmaceuticals. Hydrophobic compounds are more likely to build up in the body.

"It is not known whether these reaction products pose any health or environmental hazards,"​ concluded the researchers, but they suggested that further study is warranted to gauge the impact.