Calgary — Canadian rivers and streams are contaminated with a range of pharmaceutical drugs that present unknown dangers to people and wildlife, a study currently being considered by the federal government has found.

Painkillers, anti-inflammatories and prescription drugs used to treat epilepsy and blood cholesterol were found in waters near sewage-treatment plants across the country, according to the first nationwide Canadian study of the problem, paid for in part by Environment Canada and obtained under the Access to Information Act.

The study, which confirms suspicions held by some Canadian scientists for many years, was based on tests of water samples taken near sewage-treatment plants in 14 different cities as well as in open water at various points along the Great Lakes. Although European and U.S. research has documented the problem in those jurisdictions, this is the first study to verify its existence in Canada and determine its extent.

"[It proves] drug contamination does occur in the Canadian environment and North America context," said Chris Metcalfe, a professor of environment and resource studies at Trent University in Peterborough, Ont., who headed the research team that conducted the study.

"In some cases, we're actually getting higher concentrations of these drugs than what we see in Europe."

Among the other drugs discovered by Mr. Metcalfe and scientists at Environment Canada's National Water Research Institute in Burlington, Ont., but not included in the study, were antibiotics, Prozac and drugs common in birth-control pills.

All of the pharmaceuticals have been found in extremely low concentrations, in some cases one part per billion and one part per trillion. But it is unclear what impact they are having on people and wildlife — in laboratory tests, even small traces of drugs have disrupted hormones and turned male fish into females.

Scientists worry that people with allergies to drugs may be at particular risk. They are also concerned about what kind of pharmaceutical soup is being created by mixing all of these chemicals together in the waterways. And there is a fear that their presence in water systems will increase resistance to antibiotics.

"I don't think we really know what the impacts are," Mr. Metcalfe said.

"But what we're concerned about is that these drugs are designed to have certain effects at low concentrations."

Scientists stress the importance of the fact that the drugs have been found near sewage-treatment plants, not in drinking water, so people are not necessarily consuming them. But they also point out that no Canadian studies have yet examined whether the drugs are in drinking water, either in wells or out of the tap.

Mark Servos, a scientist at the National Water Research Institute, says Environment Canada is setting up studies to look at drinking water, adding that that technology has become available only recently to test for trace amounts of drugs in water.

"We don't really have enough data to answer those kinds of questions yet," Mr. Servos said. "It's a really new issue. People have not thought of drugs as environmental contaminants until the last four or five years."

The study, which was conducted in 2000 and 2001, has been submitted for peer review and has not yet been published. But scientists at the National Water Research Institute have duplicated its results, Mr. Servos said.

"We're pretty sure if you go to a sewage-treatment plant anywhere in Canada you're going to find prescription and non-prescription drugs."

That's because sewage-treatment plants were not designed to cope with pharmaceutical drugs, which have been found in waters surrounding cities such as Calgary, which boasts some of the most advanced treatment facilities in North America.

John Jagorinec, a lab-operations supervisor with the city, said he was not surprised by the results, adding that Calgary is working with researchers to test for other drugs.

"Everyone uses pharmaceuticals from time to time," Mr. Jagorinec said.

"Inevitably, we end up flushing those drugs down the toilet in one form or another."

Governments must crank up research and testing for the drugs while updating sewage-treatment plants to ensure pharmaceuticals do not end up in the drinking water, Mr. Metcalfe said.

With a growing and aging population, he says the amount of drugs in the water will only get worse.

"Things aren't going to get better in terms of the concentrations of drugs and other contaminants in the environment unless we take steps now."