Is Our Water Drugged?

CAMERON SMITH / Toronto Star 29may04

Are we breeding superbugs in the waste we flush down toilets?

It's a question that professor Chris Metcalfe has been asking. He's dean of research and graduate studies at Trent University in Peterborough. As yet, he has no answer.

In a study soon to be published in Environmental Science And Technology, he and three other researchers conclude there's a possibility that bacteria and other micro-organisms will become drug-resistant as a result of exposure to medications.

Only 30 to 70 per cent of the medications people take is absorbed in their bodies. The rest is excreted, usually flushed down toilets, and wends it way through sewage treatment plants into rivers and lakes.

Some of it, such as penicillin, degrades rapidly and is not considered a problem. Other drugs, especially tetracycline, have been found in effluent from eight sewage treatment plants in five Canadian cities — Vancouver, Calgary, Burlington, Peterborough and Windsor.

The research team — Metcalfe, Xiu-Sheng Miao from Trent University, Farida Bishay from the Greater Vancouver Regional District and Mei Chen from the City of Calgary — were looking at "antimicrobials," compounds that kill viruses and harmful bacteria.

They found that those that survived the sewage treatment process were in concentrations too low to harm fish, and it was unlikely they would affect the survival of plants and bacteria.

But since they're always present, because people on medication keep flushing toilets, they're constantly in contact with bacteria and viruses in water bodies.

That raises the possibility of bacteria and viruses developing resistance to them.

Once resistant, they could multiply and travel. Should they invade a hospital — perhaps in a person who had eaten fish containing drug-resistant microbes — they could become a real threat.

"(It's) an emerging issue," the researchers say.

In addition, they express concern about possible long-term effects from medications in the environment. As Metcalfe puts it in an interview: "It's okay to treat a 60-year-old man with a drug to lower cholesterol. But what happens if it finds its way to a 6-year-old?"

That's the kind of question that's going to require more research. This study looked at exposure — the level of drugs in rivers and lakes near sewage effluents.

New research will need to look at what effect these levels have on organisms over the long term. "So far, we've got nothing on chronic, long-term effects," Metcalfe says.

The object of the research is to gather information that can be used to design future studies, including the consequences of antibiotic and antiviral drugs reaching groundwater. Translation: What happens if drug-resistant bacteria and viruses get into drinking water?

The question becomes even more serious when you realize this study deals only with drugs reaching water bodies after passing through sewage treatment plants. The level of antibiotic and antiviral drugs left behind in the plants' sewage sludge would be much higher. And municipal sewage sludge is routinely spread on farmers' fields across Ontario. It's a perfect formula for introducing drugs into groundwater and for superbugs to evolve in drinking water.

The study is waving a big red flag, and Queen's Park should be paying attention. Technology is available for neutralizing drugs in the sewage treatment process. What's needed is the political will to see that it's installed.

Cameron Smith is an author and environmentalist living near Gananoque, Ont.

source: http://www.thestar.com/NASApp/cs/ContentServer?pagename=thestar/Layout/Article_PrintFriendly&c=Article&cid=1085782209586&call_pageid=968332188774 29may04