Flow Control - Jan 2012
research development Study Finds Bacteria Convert Wastewater Chemicals into Toxic Form While traces of pharmaceutical compounds are commonly present in wastewater interactions with bacteria during the treatment process could transform them from non toxic to toxic forms a new study from the University of New South Wales UNSW unsw edu au suggests Some drugs can occur in two forms known as enantiomers While they are chemically very similar pairs of enantiomers can have drastically different effects on the human body ranging from medically beneficial to highly toxic In cases where both parts are known to be safe drugs are manufactured and dispensed as mixtures of the two forms However some drugs are dispensed as single enantiomers since the other form is known to be toxic In the study published in the International Water Association IWA iwahq org journal Water Research UNSW researchers monitored three common pharmaceuticals during wastewater treatment These included the antiinflammatory drug naproxen which is manufactured and dispensed as a single enantiomer known as S naproxen Its counterpart R naproxen is known to be highly toxic to the liver and is not publicly available Through the treatment process researchers observed that some of the safe versions of naproxen had been converted to the unsafe form which could have negative environmental implications It is the first time that enantiomeric inversion during the wastewater treatment process has been reported We found that some of the S naproxen had turned into R naproxen so even though were measuring a major reduction in the concentration of naproxen the overall toxicity could be increasing says study supervisor Stuart Khan Ph D an environmental engineer at the UNSW Water Research Centre in a prepared statement Researchers note the process mimics a similar transformation that can be seen in the human gut where drugs believed to be safe can be inverted during metabolism into their toxic forms Many international studies have reported on the effectiveness of wastewater treatment processes for removing various pharmaceuticals however the vast majority of these studies use analytical methods that dont differentiate between the two enantiomers Its not well understood how this transformation is occurring in wastewater but it is believed to be enzyme driven says Khan and is being caused by microorganisms in the treatment plant converting the non toxic form into the toxic form Circle 7 or Request Info Instantly at www FlowControlNetwork com www FlowControlNetwork com January 2012 9
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