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What happens to painkillers, antibiotics and other medicines after their work is done, and they end up in the wastewater stream? The National Institute of Standards and Technology (NIST) is 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 byproducts of those drugs created during chlorine treatment or time spent in the environment. The topic drew a large audience at the American Chemical Society annual meeting last month, where NIST chemist Mary Bedner was one of several presenters. Among the concerns is possible damage to the environment, animals or people from bioactive compounds.
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 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.
"We have unique measurement capabilities here at NIST, which help to confirm the presence of products that are difficult to identify," says chemist William MacCrehan. Measurement techniques and data collected throughout the project should help other laboratories further investigate possible health or environmental effects.