Photo: What a river's health means for our own

(Credit: John McGarvey via Flickr)

Lise Parent is a professor of environmental health at Télé-université in Montreal. Her research focuses on the ecotoxicology of heavy metals in the aquatic environment and on endocrine disrupters in the everyday environment. She is also involved with the "Réseau des femmes en environnement" (Network of Women in Environment) and is a member of CINBIOSE (an interdisciplinary research centre on biology, health, society and the environment) and CIRÉ (Interinstitutional Centre for Ecotoxicology Research). Docs Talk asked Dr. Parent for her opinions on the connection between the health of the St. Lawrence River and our own health.

Docs Talk: How can the state of the St. Lawrence River affect the health of those who live in its vicinity?

Dr. Parent: The St. Lawrence, which flows from the Great Lakes, is a complex ecosystem of fresh and salt water. Its water quality is affected by the tributaries that contribute to its flow, the diverse environments it crosses, climatic and hydrographic changes and the multitude of purposes it serves. Despite such complexity, we can identify three ways in which the St. Lawrence can affect health: drinking water drawn from the river and treated; consumption of fish, molluscs and other organisms; and recreational activities associated with the water, such as swimming, sailing, hunting and fishing.

So, it's possible that some pathogens (virus, bacteria, protozoa) will remain in drinking water after sub-optimal treatment or that persistent and bioaccumulative contaminants will be transferred down the food chain to humans by way of aquatic organisms (fish and molluscs) and their predators (carnivorous fish, birds and mammals).

Sign up for our newsletter

Docs Talk: What are the main sources of contamination in the St. Lawrence River?

Dr. Parent: The main sources of pollution in the river are, ironically, the municipal water treatment facilities. But industrial effluent, deposits from atmospheric discharge, municipal effluents containing complex chemical compounds and agricultural runoff also contribute, and not only to water contamination but also to soil erosion and consequently to the eutrophication (nutrient overload) of the river. There are also the cumulative impacts of other pressures such as invasion by non-native species.

So, we're talking about conventional pollutants like suspended solids, biological oxygen demand and phosphorus that contribute, among other things, to eutrophication and the presence of biotoxins. But we're also talking about so-called toxic pollutants like pesticides and their residues, heavy metals, nonylphenols, polychlorinated biphenyls, PBDEs, etc.

Docs Talk: How can these contaminants have an impact on our health?

Dr. Parent: Certainly, in most cases, we're not talking about acute exposure; and if there were effects, we wouldn't see them immediately. The type of chemical contamination to which we're being exposed is the kind with effects that will only be seen in the long term. When it comes to bioaccumulative contaminants found in the flesh of fish and molluscs, we can expect different kinds of health effects similar to those attributed to some emerging pollutants like endocrine disruptors. These have been linked to chronic illnesses like hyperthyroidism, Type II diabetes, hyperactivity and fertility problems, among others. Possible effects from exposure to these substances, though not directly attributable to exposure from the river itself, include effects on the immune system that lead to increased incidence of infection, some allergies, effects on the nervous system that lead to neurological and developmental delays and cancer.

Docs Talk: Is the situation in the St. Lawrence similar to other river systems in Canada?

Dr. Parent: When it comes to sources of contamination it's about the same as you'd find in other river systems in Canada. However, the St. Lawrence stands out by virtue of receiving one of the largest municipal effluents in North America.

Docs Talk: In your opinion, what are the main challenges that need to be addressed to achieve an effective environmental health policy for the St. Lawrence River?

Dr. Parent: We need to monitor the input of these substances at the source and where they're released, and apply the precautionary principle whenever we have indications of toxicity.

We should also monitor sewer overflows and ensure adequate treatment to avoid releasing toxic substances into the river. Also important is the improvement of municipal and agricultural wastewater treatment to reduce input of pesticides and fertilizers to rivers and streams.

Docs Talk: If you could write a "prescription" for the St. Lawrence River, what would it be?

Dr. Parent: We should continue the activities of the St. Lawrence Plan: to better understand pollutants that change in composition, to evaluate user exposure and to determine health effects in concert with the environmental and public health authorities and civil society. As with the previous question, we must try to act before problems occur. Disinfecting wastewater at purification stations and better management of sewer overflows from combined sewers in times of heavy rain would limit degradation of bacterial quality as well as limit the input of nutrients and metals into the river.

Docs Talk: As individuals, what steps can we take to protect the health of our rivers like the St. Lawrence?

Dr. Parent: We should both reduce and maximize the use of potable water from a quantitative and qualitative point of view. We should always be aware of our consumption and what we throw down the drain, recognizing that these releases will have effects on fauna and flora. That's why it's so important to pay careful attention to the chemical ingredients in products we buy. We need to make good shopping decisions and minimize the use of products that are harmful to the environment. Public education is the key to achieving that and it's encouraging to see an evolution in that direction.

Finally, I think that the best thing for us to do is to demand accountability from our government to ensure safe and enjoyable access to the great treasure that is the St. Lawrence River.

May 22, 2012

Read more