A new study suggests that wastewater treatment plants are the primary source for pharmaceuticals entering the Great Lakes.

The study, Reducing the Impact of Pharmaceuticals in the Great Lakes, by Pollution Probe and the Clean Water Foundation, and supported by Environment and Climate Change Canada, found that the most common pharmaceuticals in the Great Lakes include pain killers, hormones and endocrine disrupting compounds, antibiotics and psychiatric drugs, although the presence of these pharmaceuticals varies by lake and location.

Federal and Ontario wastewater regulations currently have no specific requirements pertaining to managing pharmaceutical pollutants.

“Pharmaceuticals are finding their way into the Great Lakes but our understanding of the sources, pathways and impacts of pharmaceutical pollution is limited and there is no coordinated approach to address the issue in Canada”, says Mariana Eret, a Pollution Probe policy analyst, in a statement to media.

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A variety of pharmaceuticals have been detected in surface water, wastewater plant effluent and fish tissue. Pharmaceuticals typically enter wastewater systems via human excretion or through improper disposal of unused and expired medications. Research done for the report shows that analysts were unable to determine how to differentiate between active pharmaceutical ingredient discharges from these sources.

A secondary source for pharmaceuticals entering the Great Lakes is run-off from agricultural zones. Agriculture is a major user of antimicrobials and could be an important source of these compounds in the lakes, the study states.

pharmaceutical substances in the great lakes
Sources and fate of pharmaceutical substances in the environment. Photo credit: Pollution Probe and The Clean Water Foundation

While the levels of drugs found do not present a human health risk, the highest concentrations are usually found close to wastewater treatment plants.

The new study makes a dozen recommendations to address the issue. Notably, the study suggests monitoring wastewater from healthcare facilities, especially for antimicrobials and cancer-fighting medications, to explore the feasibility of requiring pre-treatment before discharging effluents.

“The recommendations are directed mainly at federal, provincial and municipal governments, as well as at hospitals and healthcare facilities, pharmaceutical manufacturers, pharmacies, agricultural operations and aquaculture,” the study states.

The study also found that outreach and engagement efforts by non-profit organizations have made some inroads to increase awareness and participation in pharmaceutical take-back programs at places such as pharmacies. Ontario’s extended producer responsibility regulation for waste pharmaceuticals has achieved measurable diversions of unused and expired pharmaceuticals from going to landfill and municipal wastewater systems.

Additional recommendations are lake-specific, such as one for Lake Ontario and Lake Erie, that suggest their high population densities and significant agricultural concentrations may benefit from upgraded wastewater plants that have advanced and alternative treatment technologies.


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