Environment Canada researchers have found a dozen different types of toxic drugs in water samples taken from the St. Lawrence River in Quebec.

The drugs include non-prescription anti-inflammatory drugs such as ibuprofen, prescription antibiotics and drugs prescribed to treat epilepsy and Alzheimer's disease. Researchers even found caffeine.

Although the amounts were minuscule, the study raises many questions about the long-term effects of pharmacological pollution in the country's waterways.

The drugs were found in concentrations less than 10 micrograms per litre after sewage treatment — "trace amounts," said researchers.

Our bodies get rid of excess medication through urine, but one of the researchers, Andre Lajeunesse, said current sewage treatment methods aren't built to deal with contaminants that enter the water table through human urine.

Although the study dealt specifically with the St. Lawrence, drug pollution in waterways is widespread, said Francois Gagne, who authored along with two other researchers the study published earlier this year in the journal Ecotoxicology and Environmental Safety.

"When you're near a city, you're going to see it," Gagne said.

Drugs, birth control hormones, Prozac and perfume have all turned up in similar studies in the United Kingdom and the United States in recent years.

With files by Canadian Press