RECREATIONAL drugs could become a major source of Australian urban water contamination, scientists warn.
With tens of thousands of Australians using illicit drugs, researchers are concerned these drugs could be making their way back into the nation's water supplies and food chain, a conference will be told on Monday.
Pandian Govindarasu of the CRC for Contamination Assessment and Remediation of the Environment said cannabis was the most widely used illicit drug in Australia, followed by amphetamine-type drugs such as methamphetamine, ecstasy and cocaine.
"These drugs, when taken, are eliminated from the body in urine and flushed down the toilet," he said.
"People who manufacture these drugs also illegally get rid of the waste in sewers and stormwater drains."
While most of the drugs go through wastewater treatment plants, some of them escape the treatment process, Mr Govindarasu explains.
Also, drugs that are thrown out with domestic waste end up in landfills, and can leach into the soil or groundwater underneath when it rains.
Mr Govindarasu and his colleagues at The University of South Australia are currently investigating the extent to which drugs have escaped into Adelaide's urban water system in order to get a handle on the scale of the problem nationally.
The CRC CARE team is also testing how long drugs can stay in the soil and how they affect insects that live in water, soil bacteria, earthworms and microalgae.
Principal supervisor of the research Megh Mallavarapu of CRC CARE and UniSA said it was crucial to find out how these illicit drugs affected the environment.
"They're very similar in nature to chemicals called endocrine disruptors that have been shown to have harmful effects on fish, soil, insects and plants as well as humans. In other words they may add to the overall toxic burden in society," he said.
Prof Mallavarapu said there were rising concerns about the presence of legitimate drugs such as antibiotics, antidepressants, antihistamines, steroids and contraceptives in water both in Australia and around the world.
The widespread use of chemically similar illegal drugs could be greatly amplifying the overall contamination problem, he said.
Mr Govindarasu said the contamination of water from legal drugs was linked with effects such as the increase in antibiotic-resistant bacteria and 'intersex' fish that have both male and female sex organs.
"They are also suspected of causing reproductive disorders in humans," he said.
"With the high intensity of illicit drug abuse in Australia, we need to find out what happens when more of these things find their way back to us.
"They could be very harmful to fish and soil - and also to the humans who eat fish and vegetables grown with contaminated soil and water.
"Although the concentration of these drugs is probably at low levels, it's still a persistent exposure for the rest of the population."
Mr Govindarasu said the study would also help researchers find out the level of illicit drug abuse in different states.
"We can then identify what bacteria we can use to degrade the drugs and prevent them from going into our food and drinking water," he said.
Mr Govindarasu is delivering his presentation Occurrence of illicit drugs in Adelaide environment at 3pm at the CleanUp 2013 conference in Melbourne.
For more details, visit www.cleanupconference.com.