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Rx for Action

A blog devoted to helping people find local medicine take-back programs and highlighting current research findings and pending legislation.

Researchers identify high-risk chemicals for Great Lakes region

A review of 5-years of pharmaceutical pollution studies in the Great Lakes region has identified six chemicals that pose the highest risk to wildlife in area rivers and lakes. At the top of the list is esterone, a synthetic form of estrogen commonly used to treat disorders associated with menopause. The hormone is joined by an anticonvulsant, an antidepressant, and three antibiotics used to treat sinus infections, tonsillitis, and pneumonia.

The comparatively high risk of these chemicals was discovered by researchers in Ontario while reviewing pharmaceutical data collected in the Great Lakes region from 2007-2012. The review included studies on wastewater effluent, surface water, groundwater, and drinking water. Taken together, these studies found over 50 pharmaceutical compounds in wastewater effluent and nearby waterways, although not all chemicals were found in both locations. Many of those same chemicals were also found in treated drinking water.

Researchers used the maximum concentrations reported and the chemical's known toxicity to calculate the risk of each pharmaceutical compound found in surface water. Six chemicals–esterone, erythromycin, sulfamethoxazole, carbamazepine, clarithromycin, and venlafaxine–stood out with levels high enough to impact the growth and development of fish and other aquatic wildlife. The individual risk posed by these six chemicals varies greatly. Results suggest that esterone is almost 37 times as risky as the antidepressant venlafaxine, the least harmful of the six.

Similar processes were used to calculate the environmental and health risks posed by chemicals found in groundwater and drinking water. Researchers found that both ibuprofen and gemfibrozil, a chemical used to regulate lipids, pose high environmental risks in groundwater. However, none of the chemicals detected over the years were at concentrations high enough to threaten human health.

These results, though, do not consider the potential impacts of long-term exposure to chemicals at lower concentrations, or what happens when wildlife are exposed to a mixture of these pharmaceuticals.

In addition to calculating risks, researchers also complied data on the effectiveness of different wastewater treatment processes in removing specific chemicals. Their results join a growing number of studies showing that current wastewater treatment methods are ineffective at removing most pharmaceutical chemicals.

Uslu M.O., Jasim, S., Arvai, A., Bewtra, J., and Biswas, N. 2013. A survey of occurrence and risk assessment of pharmaceutical substance in the Great Lakes Basin. Ozone: Science & Engineering Journal. Retrieved from:

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Posted by Anjanette Riley at 2:00PM on 5/24/2013
Categories: Latest Research