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Drug cocktail in the St. Lawrence River offers no relief to aquatic organisms

The research findings of Environment Canada scientists reveal that medications contained in municipal wastewater discharges are present in the waters of the St. Lawrence River. Some of these medicines could pose a threat to aquatic biota.

At water quality monitoring stations along the St. Lawrence River, 17 pharmaceutical, and personal care products (PPCPs), and other substances were detected among the 30-odd contaminants analyzed in 2006. Where do these products come from? Old medications flushed down toilets and medications ingested and eliminated by the human body are the main sources. Thus, wastewater discharged into the St. Lawrence River contains traces of medications which, ironically, you thought were safely stored in your medicine cabinet: analgesics, anti-inflammatory drugs, contraceptives, and so on.

Detection frequency of PPCPs and other substances in the St. Lawrence River and its tributaries in 2006
ProductUseSamples containing
PPCPs (%)
Salicylic acidAnalgesic10
Bisphenol APlasticizer100
CholesterolFatty liver97
CoprostanolBy-product of cholesterol39
Coprostanol-3-olBy-product of cholesterol85
Coprostanol-3-oneBy-product of cholesterol51
Estradiol-17bHormone therapy18
TestosteroneHormone therapy5
4-ter-octylphenolSurfactant degradation product97

Source: Rondeau, 2008.

Concentrations of medications detected in water (ng/L)
Yamaska River1 to 202 to 79
Detroit River64 to 14194 to 207

The Yamaska River has lower concentrations of ibuprofen and naproxen than the Detroit River.
Source: Hale et al., 2003.

Concentrations of PPCPs and other substances measured in the St. Lawrence River and tributaries in 2006
Concentrations of pharmaceutical and personal care products measured in the St. Lawrence River and tributaries in 2006 at the stations of Carillon, Lavaltrie, Richelieu, Trois-Rivières, Bécancour and Québec.
Source: Rondeau, 2008.

Do these medications threaten the health of aquatic organisms?

Most of these substances are considered toxic, but their measured concentrations are generally too low to be acutely toxic to aquatic organisms. However, longer-term effects could occur. Moreover, some substances that are considered non-toxic or not highly toxic, such as caffeine, may cause oxidative damage in the tissues of some aquatic organisms such as mussels and fish. When these organisms absorb caffeine, through the process of biotransformation metabolites are released that are even more toxic than the initial substance.

The effects of anti-inflammatory drugs on mussels exposed to them in the laboratory or municipal wastewater have not been demonstrated to date. However, scientists have recently observed that naproxen and ibuprofen produce toxic effects at concentrations ten times lower or less than the values measured in municipal effluents (Blaise et al., 2006). Other medications, such as novobiocin and morphine, respectively used as an antibiotic and an analgesic, cause reduced phagocytosis in freshwater mussels (Elliptio complanata) in the St. Lawrence River (Gagné et al., 2006). Other research findings show that estrogens present in the St. Lawrence River affect the reproductive system of male spottail shiners (Notropis hudsonius), a fish of the minnow family (Cyprinidae), which serves as prey for many freshwater predatory fish (Aravindakshan et al., 2004). Similar results have been observed among E. complanata musselsexposed to water from the St. Lawrence River.

Did You Know? Up to 66% of male mussels living near the Montréal municipal outfall had become females, whereas the proportion was only 41% upstream from the point of discharge, which is the normal rate of frequency for females of this species (Gagné et al., 2004).

Canadian water quality guidelines are intended to provide protection of freshwater and marine life from anthropogenic stressors such as chemical inputs […].” Among other things, these guidelines identify the lowest concentrations of a substance that produce effects on organisms. There are no recommendations yet for several emerging or newly detected substances. However, regulations are being developed governing environmental risks related to pharmaceutical and personal care products contemplated by the Food and Drug Act.

To Know More

Aravindakshan, J., V. Paquet, M. Gregory, J. Dufresne, M. Fournier, D.J. Marcogliese, and D.G. Cyr. 2004. Consequences of xenoestrogen exposure on male reproductive function in spottail shiners (Notropis hudsonius). Toxicological Sciences 78: 156–165.

Blaise, C., F. Gagné, P. Eullaffroy, and J.-F. Férard. 2006. Ecotoxicity of selected pharmaceuticals of urban origin discharged to the St. Lawrence River (Quebec, Canada): A review. Brazilian Journal of Aquatic Science and Technology 10(2): 29–51.

Gagné, F., C. Blaise, M. Fournier, and P.D. Hansen. 2006. Effects of selected pharmaceutical products on phagocytic activity in Elliptio complanata mussels. Comparative Biochemistry and Physiology, Part C 143(2): 179–186.

Gagné, F., C. Blaise, and J. Hellou. 2004. Endocrine disruption and health effects of caged mussels, Elliptio complanata, placed downstream from a primary-treated municipal effluent plume for one year.Comparative Biochemistry and Physiology, Part C, 138: 33–44.

Hale, R.C., M. Alaee, J.B. Manchester-Neesvig, H.M. Stapleton, and M.G. Ikonomoun. 2003. Polybrominated diphenyl ether flame retardants in the North American environment. Environment International 29: 771–779.

Rondeau, B. 2008. Monitoring and Surveillance of Water Quality – Quebec, Water Science and Technology Branch, Environment Canada. Personal communication.

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