National Pollutant Release Inventory use in environmental research

Background

Since 1993, the National Pollutant Release Inventory (NPRI) is Canada’s legislated registry of pollutant releases reported by commercial, institutional and other facilities across Canada. The data is publicly accessible, and comprises information on pollutant releases to air, water and land, as well as disposals and transfers of pollutants. Different levels of government use this data to set priorities for environmental management and public health, and to inform Canadians about pollutant releases.

This fact sheet summarizes the use of the NPRI in environmental research based on a scoping review that was conducted to better understand future opportunities for using NPRI data in relevant research areas. The French version of the article can be obtained by submitting a request to the following email address: inrp-npri@ec.gc.ca. This fact sheet gives an overview of NPRI use in environmental research, particularly peer-reviewed literature, from the creation of the program to 2019.

The literature review was undertaken using a set of criteria to select journal articles. Particularly, the articles had to:

  1. contain the words “National Pollutant Release Inventory”
  2. be publicly available
  3. be peer-reviewed
  4. be written in French or English
  5. be published between 1994 and 2019

The articles meeting those criteria were then filtered, and 225 relevant articles that substantially used NPRI information were included in the scoping review.

Brief history of NPRI use in environmental research

Based on an analysis of the number of articles by year of publication, NPRI-related research first began appearing in the literature in 1997, three years after the first NPRI dataset was published. The number of articles published each year remained fairly low (fewer than four articles per year) until 2002, when an upward trend began, peaking at 31 articles in 2019. Most of the NPRI-related articles were published in English. The analysis also showed that NPRI-related articles were published in 90 different peer-reviewed journals, meaning that the work was reviewed by academic peers prior to publication to limit the risk of errors.

Graph showing the annual number of research articles using the NPRI.
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Graph showing the annual number of research articles using the NPRI.

This graph is taken from the scoping review of the use of the NPRI in research and is available in interactive format.

Graph showing the number of research articles using the NPRI by the peer-reviewed journal in which they are published.
Long description

Graph showing the number of research articles using the NPRI by the peer-reviewed journal in which they are published.

This graph is taken from the scoping review of the use of the NPRI in research and is available in interactive format.

The scoping review also revealed that the NPRI is increasingly being used as a data source for research in a variety of areas from environmental monitoring to socio-economic issues.

The upward trend in NPRI-related articles coincides with changes in the NPRI reporting requirements. For example:

To learn more about the history of NPRI reporting requirements, visit the NPRI history of reporting requirements.

In addition to changes in reporting requirements, other factors may have played a role in the increased use of the NPRI in research, including:

What NPRI data is used in research

For more information on the use of NPRI data in research, readers can consult the interactive figures available online in the scoping review.

Environmental compartments of the NPRI

The NPRI collects a large amount of data on pollutant releases, which are categorized according to environmental compartments

Infographic showing industry information collected by the NPRI categorized into environmental compartments.
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Infographic showing industry information collected by the NPRI categorized into environmental compartments.

NPRI data on pollutant releases to the air, the main environmental compartment studied, account for 89% of all articles. Data on pollutants released to water and land as well as disposals were used in the other articles (11%). Some articles (3%) used NPRI data encompassing all the environmental compartments. Data on off-site transfers were not used in any of the studies included in the review.

number of articles broken down by the NPRI environmental compartment studied
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Graph showing the number of research papers using the NPRI by the NPRI environmental compartment studied

This graph is taken from the scoping review of the use of the NPRI in research and is available in interactive format.

Substances monitored by the NPRI

Another aspect that distinguishes the studies examined relates to the various substances monitored by the NPRI. CACs, such as volatile organic compounds, sulphur oxides and nitrogen oxides, were among the most widely studied substances. Metals (for example, mercury), polycyclic aromatic hydrocarbons (PAHs), organic substances, polychlorinated dioxins and furans, and hexachlorobenzene (HCB) were also examined.

Graph showing the proportion of substances groups studied among research papers using the NPRI.
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Graph showing the proportion of substances groups studied among research papers using the NPRI.

This graph is taken from the scoping review of the use of the NPRI in research and is available in interactive format.

NPRI data formats

NPRI data are accessible online, and are published in various formats

The NPRI annual data (single year data tables) were the most commonly used format before 2012. After that, longer NPRI data time series were the most widely used format (for example five to fifteen years). Data from 2005 to 2010 and from 2013 were used most often, in 65 articles.

Graph showing the annual number of research articles using the NPRI according to the years of NPRI data used.
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Graph showing the annual number of research articles using the NPRI according to the years of NPRI data used.

This graph is taken from the scoping review of the use of the NPRI in research.

Users of NPRI data in research

Map showing the location of the authors of research papers using the NPRI.
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Map showing the location of the authors of research papers using the NPRI.

Graph showing the number of authors by type of affiliation.

This graph is taken from the scoping review of the use of the NPRI in research and is available in interactive format.

 

The selected peer-reviewed articles included over 800 authors and co-authors, the majority of whom were affiliated with universities, as well as the Government of Canada and the Government of the Untited-States.  Canadian universities, such as the University of Alberta, the University of Toronto, the University of British Columbia and McGill University, represented 38% (over 480 authors) of the publications associated with universities. A total of 40 post-secondary educational institutions in Canada were represented in the NPRI-related publications. The programs of study involved included engineering, biology, chemistry, health sciences, medicine, environmental sciences, geography and forestry.

The Government of Canada and the Government of the United-States were also well represented: Environment and Climate Change Canada (ECCC) and the United States Environmental Protection Agency accounted for the largest number of authors (185 researchers for a total of 81 articles). Some of these authors were affiliated with:

Recent publications show that interest in the NPRI is increasing, particularly among universities, federal governments and international organizations in Mexico, Europe and Asia. The broadening of study topics and author affiliations, from a small group of universities and Government of Canada scientists to a broad range of researchers, including those from hospitals, non-government organizations, Indigenous groups and international organizations, indicates that the reach of the NPRI is increasing as well (from a local to a global scale).

Interactive figures are available online and provide further details on authors using NPRI data in their research.

Research topics associated with the NPRI

Figure showing the proportion of study themes found among the articles used in this scoping review.
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Figure showing the proportion of study themes found among the articles used in this scoping review.

This graph is taken from the scoping review of the use of the NPRI in research and is available in interactive format.

The most popular environmental research topic is geospatial analysis, which accounts for more than 80% of studies analysed in this scoping review. For example, NPRI geospatial information has been used to:

The topic of environmental monitoring was covered in over 60% of studies examined, and was often linked to geospatial analysis, including in situ and satellite observations. Some of the studies that used NPRI data from an environmental monitoring perspective involved:

Predictive modelling is another popular avenue of research (39%): NPRI data were integrated with multiple information sources in predictive models to obtain a variety of findings related to the environment and human health. Predictive modelling was often combined with geospatial analysis and environmental monitoring, as shown by the following examples:

Approximately one third of the studies (34%) dealt with specific industrial sectors; the majority concerned the Athabasca oil sands.

Other research topics identified include:

Interactive figures are available online and provide further details on the research topics and scientific articles identified in the scoping review.

Benefits and limitations

The use of NPRI data in research has several benefits, including:

However, the literature covered in the scoping review mentions certain limitations that should be considered when using NPRI data in environmental research, particularly data quality issues and inventory comprehensiveness. For example:

It is important to consider these limitations when using the NPRI for research. The NPRI takes them into account in its efforts to continuously improve the program. For example, since the inventory was created, a number of changes have been made to increase the comprehensiveness of the substance list and the level of detail for reporting thresholds. Despite the increased complexity of data interpretation, the various changes made have helped increase user interest, as shown by the results of the scoping review.

To learn more about factors to consider in your analyses, visit the guide of using and interpreting data from the National Pollutant Release Inventory.

If you have any questions or suggestions for changes, you can contact us at inrp-npri@ec.gc.ca.

Future environmental research using NPRI data

The scoping review revealed that some NPRI data are under-used in environmental research. New research topics using NPRI data could be considered, such as:

More in-depth analysis of these data would help us better understand how to improve them for users.

The analysis also suggested other opportunities for projects of interest, such as:

What can you do now

The NPRI is seeking to encourage broader use of its data. You can help improve the program by sharing your ideas with us at inrp-npri@ec.gc.ca or by collaborating on NPRI awareness and promotion initiatives. The NPRI is also seeking to encourage larger numbers of educational institutions to use its data through the NPRI Academic Challenge, a mentoring opportunity for students which involves working with ECCC pollutant data experts.

For more information, visit our web page named “Partnering and collaborating with the National Pollutant Release Inventory”.

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