Detecting contaminants in the Canadian Arctic

In the Canadian Arctic, researchers found high concentrations of a group of chemicals called organophosphate esters (OPEs) – frequently used as flame retardants or plasticizers, which make materials more flexible and softer – during yearly sampling. The chemicals had been transported thousands of kilometres from where they could have entered the environment. 

OPE use has increased since being marketed as environmentally friendly alternatives to substances now banned under an international treaty.

Research conducted as part of the first large-scale inventory of these chemicals in the Canadian Arctic collected samples between 2013 and 2018. Chemistry professor Roxana Sühring and her collaborators found that some of these OPEs, which are used in products such as floor polish, aircraft lubricants, electronic equipment and upholstered furniture, are travelling via pathways like rivers. OPEs can enter the environment from a wide range of places, from the water discharged from home washing machines, to leaching from landfills, to household dust. Professor Sühring says cities in particular are large, diffuse sources of OPEs.  

It was previously thought that OPEs would not travel far, and would break down quickly and locally. The team, which includes professor Sühring, professor Miriam Diamond from the University of Toronto, Liisa Jantunen from Environment and Climate Change Canada and others, detected 11 different OPEs in surface water and sediment samples from across the region. 

In that remote area, there are not enough local sources to explain the concentrations of chlorinated OPEs found in the samples, says professor Sühring. She says this shows the issue is not only important for environmental or regulatory reasons; there are also social justice implications. Arctic communities face the potential of OPE-contaminated drinking water even though they are not using the products or engaging in the activities that are the likely sources of the chemicals. There is evidence of environmental toxicity, as well as  epidemiological evidence of potential endocrinological and developmental effects on humans (external link)  from exposure to OPE-based flame retardants, notes professor Sühring.

The OPEs the researchers detected in the Canadian Arctic can be grouped into two categories: chlorinated and non-chlorinated. The concentrations, particularly those from the Mackenzie River plume, indicate that the chlorinated chemicals can travel via pathways such as rivers, says professor Sühring. This type of long-distance, water-borne transport wasn’t predicted when environmental risk assessment models were first used to evaluate OPE chemicals and their potential impacts. 

“Chlorinated OPEs are persistent, mobile contaminants, with high concentrations in water in the Canadian Arctic. This means they can undergo long-range transport which enables them to basically be global contaminants,” said professor Sühring. She says their findings show that chlorinated OPEs are mobile in water and persistent enough to be transported into the Arctic, where the chemicals could conceivably make it into drinking water resources of northern communities. The non-chlorinated OPEs, however, seem to be arriving by air or potentially by attachment to microplastics. 

Professor Sühring says international regulations could help to reduce and restrict the release of chlorinated OPEs and similarly mobile and persistent chemicals. Changing attitudes towards risk assessment criteria, so that the ability of such chemicals to travel and get into drinking water is ranked equivalently with the potential for accumulation in a living organism, would also aid reduction efforts, she says.

Professor Sühring and her collaborators used observational data from samples collected via the Amundsen, a Canadian Coast Guard Arctic research vessel, to estimate an inventory of OPEs in Canada’s Arctic waters. They found a median inventory of 3,500 tonnes of chlorinated OPEs and 620 tonnes of non-chlorinated OPEs. “It’s enormous. The inventory is in the same range as what the inventory of the banned pesticide HCH was at its peak use,” said professor Sühring. Their findings suggest that, unlike many other organic pollutants, sediments do not act as a “sink” for chlorinated OPEs. These contaminants will instead remain in the water.

She continues to research how OPEs and other contaminants are entering the environment, as well as how these chemicals travel and behave. 

Read more about the researchers’ findings in Environmental Science and Technology. (external link) 

Arctic communities face the potential of OPE-contaminated drinking water even though they are not using the products or engaging in the activities that are the likely sources of the chemicals.

This project was supported by the Northern Contaminants Program and ArcticNet.