Medications used to treat certain cancers, high cholesterol levels and hypertension have been found in the St. Lawrence River, upstream and downstream from the Montreal wastewater treatment plant, according to researchers at Université de Montréal.

The following have all been detected in wastewater entering the treatment station:

• Bezafibrate — a cholesterol-reducing medication.
• Enalapril — hypertension medication.
• Methotrexate and cyclophosphamide — used in the treatment of certain cancers.

However, the researchers only detected bezafibrate and enalapril in the water leaving the plant and in the surface water of the St. Lawrence, where the treated water is released.

Sébastien Sauvé, a professor of environmental chemistry at the university, said the team suspects the chemotherapy medications are also present in the treated water, but researchers will have to improve their detection methods before they show up.

"Consumption of these medications are quite low, but they are toxic. They kill all cells," he told CBC News.

"As for the chemotherapy products detected in the raw wastewater but not in the treated wastewater, one question remains," he said. "Did we not detect them because the treatment process succeeded in eliminating them or because our detection method is not yet sophisticated enough to detect them?"

The quantities of bezafibrate and enalapril detected in the raw wastewater, treated wastewater and surface water at the treatment station outlet are respectively: 50 nanograms per litre, 35 nanograms per litre, and 8 nanograms per litre for bezafibrate; and 280 nanogram per litre, 240 nanogram per litre and 39 nanogram per litre for enalapril.

"All in all, these quantities are minimal, yet we don't yet know their effects on the fauna and flora of the St. Lawrence," Sauvé said. "It is possible that some species are sensitive to them. Other ecotoxicological studies will be necessary."

The study was conducted due to the sharp rise in drug consumption over the past few years, the researchers said in a release.

In 1999, according to a study by consulting firm IMS Health Global Services, world drug consumption amounted to $342 billion Cdn. In 2006, that figure doubled to $643 billion.

A significant proportion of the drugs consumed are excreted by the human body in urine and end up in municipal wastewater. Sauvé said the same is true for the drugs his research team found in the Montreal area.

Previous studies have detected antibiotics in waterways, as well as the remnants of hormone replace therapy and birth-control pills.

Antibiotics are "barely removed," while a "good portion or three-quarters" of prescribed hormones are gone after they leave the body, Sauvé said. "But one-fourth is still too much," he added.

He said estrogen, for example, affects the endocrinology of fish, and if levels are too high, waterways can end up with mostly female fish, curbing population growth.