[Pharmwaste] Water treatment turns common chemicals toxic, says report

DeBiasi, Deborah (DEQ) Deborah.DeBiasi at deq.virginia.gov
Wed Dec 7 13:46:50 EST 2011



Water treatment turns common chemicals toxic, says report 

Ben Cubby

December 2, 2011 


"There are hundreds and thousands of drugs out there, and so it is a
pretty fair assumption that some of the things emerging from treatment
are a lot more toxic than we thought" ... Stuart Khan, one of the
study's authors. 

TRACES of common pain-killing drugs are being transformed into toxic
forms by waste water treatment plants, a new report from researchers at
the University of NSW shows.

The study, which used samples from water treatment plants across Sydney
and some interstate plants, showed that the organic sludge used to help
destroy household chemicals can actually transform them into something

The altered chemicals from three widely-used household drugs were
detected at very low levels, meaning that there is minimal risk to human
health. But the consequences could be much larger for some aquatic
environments where treated water is reused.

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''There are hundreds and thousands of different drugs out there, and so
it is a pretty fair assumption that some of the things emerging from
treatment are a lot more toxic than we thought,'' said one of the
study's authors, Stuart Khan, from the water research centre at the
University of NSW.

Some drugs occur in two forms, called ''enantiomers'', which are very
similar but not quite identical. ''Chemically, they are like a mirror
image of each other; different in the same way a right hand and a left
hand are different from each other,'' Dr Khan said.

Sometimes pairs of enantiomers have different effects on living
organisms, and when this happens, the enantiomer with a beneficial
effect is separated from its toxic mirror image, and turned into a safe

The key to the new findings is that careful testing of water samples
from treatment plants were compared with fresh water and water
containing raw sewage, including samples from the heavily-polluted Cooks
River. The sewage contained the enantiomers associated with ordinary
pharmaceuticals that are flushed down toilets or sinks across the city.
But the treated waste water samples showed that the organic
''scrubbing'' by bacteria in treatment plants had restored some of the
toxic enantiomers.

The most infamous case of a chemical being transformed into a toxic
chemical took place in the 1950s, when the drug thalidomide was
administered to pregnant women but was changed to a toxic form in the
human gut, causing birth defects.

''What this research means is that we really need to think about this
question of measuring toxins a lot more broadly,'' Dr Khan said.

The study was published in the peer-reviewed journal Water Research, and
follow-up work is now being done on the effects of waste water treatment
on other chemicals.

Read more: 


Deborah L. DeBiasi
Email:   Deborah.DeBiasi at deq.virginia.gov
WEB site address:  www.deq.virginia.gov <http://www.deq.virginia.gov/> 
Virginia Department of Environmental Quality
Office of Water Permit and Compliance Assistance Programs
Industrial Pretreatment/Whole Effluent Toxicity (WET) Program
PPCPs, EDCs, and Microconstituents 

Mail:          P.O. Box 1105, Richmond, VA  23218
Location:  629 E. Main Street, Richmond, VA  23219
PH:         804-698-4028      FAX:      804-698-4032


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