TORONTO - Detectable levels of cholesterol and high blood pressure medications have been found in the St. Lawrence River downstream from Montreal's sewage treatment facility, researchers from the University of Montreal reported Monday.
The team found quantities of the two drugs in water samples taken half a kilometre from the point where the treated wastewater flowed into the St. Lawrence, said Sebastien Sauve, the professor of environmental chemistry who led the work.
"All in all, these quantities are minimal, yet we don't yet know their effects on the fauna and flora of the St. Lawrence," Sauve said.
A Toronto-based environmentalist suggested the findings point to a problem -- the potential buildup in the environment of compounds or pathogens that aren't neutralized by sewage processing systems.
"I think it has to be said that sewage treatment plants are 19th century technology trying to deal with 21st century pollutants," said Maureen Reilly, who edits an online environmental mailing list called Sludge Watch.
Sauve and his colleagues set out to see if they could find five different drugs -- two chemotherapy drugs, which are highly toxic and carcinogenic, a statin drug used to treat high cholesterol, another cholesterol lowering medication, bezafibrate and enalapril, a drug taken to control hypertension.
They looked for all five in sewage entering the treatment facility, in treated water leaving the treatment facility and in water samples taken in the river 500 metres downstream.
They did not see evidence of the statin anywhere, though they did find detectable levels of the other four drugs entering the treatment plant.
They were unable to detect the chemotherapy drugs in the water flowing out of the treatment facility. Sauve cautioned, though, that they might have been present but at levels the tests could not pick up.
As for the other two drugs, they were found both in water coming out of the treatment plant and in the river. He acknowledged the concentrations were low, but said it is unclear whether that is safe for marine life.
"There's virtually no information in the scientific literature for me to tell you whether this is too much and this is a cause of concern for fish and the biology in the river or whether this is very safe. I don't know," Sauve said, adding studies should be done to determine safe thresholds for fish.
He suggested communities downstream that draw on the St. Lawrence for drinking water probably treat the water sufficiently to remove any traces of these medications if they hadn't already dispersed.
Other studies have found residues of antidepressants, estrogen and antibiotics in bodies of fresh water.
"I think that any medication that we go and look for, if it is consumed in significant quantities, is going to be appearing in the wastewater and potentially in the waters released into rivers," Sauve said.
The study, which was published in the Journal of Environmental Monitoring, was funded by the Natural Sciences and Engineering Research Council of Canada, the National Council for Science and Technology of Mexico, the Canada Foundation for Innovation, the St. Lawrence Action Plan and Health Canada's Chemicals Management Plan.
