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Industrial emissions and Children’s Environmental Injustice in Canada: Exploring geographical patterns and an example of its relation to Children’s Cancer in Manitoba

  • Author / Creator
    Chan, Emily
  • Background: Environmental Injustice (EI) suggests that socioeconomically disadvantaged citizens/minority groups have a higher than average exposure to environmental contaminants and bear more subsequent health risks than their socioeconomically advantaged/majority group counterparts. In order to investigate EI and adverse health outcomes from environmental contaminants in Canada, a measure of SES is needed. Objective: 1) Construct and validate an index to measure socioeconomic status (SES) and minority status in Canadian children; 2) Examine the co-localization of SES and air pollutants emitted by industry, using the index created in Aim 1. This second aim will provide evidence to support or disprove the existence of EI among Canadian children. 3) Determine if there is a difference in EI in urban versus rural areas of Canada. 4) Examine whether environmental pollutants and SES are related to childhood cancer outcomes in Manitoba. Methods: Variables were examined at dissemination area level (DAs, regions containing 400-700 residents, n = 52970 in Canada): 1) Census data (2006): extracted from CANSIM [2]; 2) chemical data (tonnes, n=201): from National Pollutant Release Inventory (NPRI, 2006) [3]; 3) Carcinogens (International Agency for Research on Cancer class 1) (n=15, tonnes); 4) Distance from the center of DAs to nearest emitting facilities: from available latitude and longitude of each emitting facility; 5) children’s cancer data (n=531) from the Manitoba Cancer Registry (1997-2007); 6) Urban and rural DAs, unique identifiers or “UARAs” (urban and rural area codes) were extracted from GeoSuites. [5] Aim 1: Twenty-two Census items were used with principle component analysis to create a valid SES index. The index was validated by examining its association with preterm birth (gestational age < 37 weeks), term low birth weight (LBW, <2500 g), small for gestational age (SGA, <10 percentile of birth weight for gestational age) and PM2.5 (particulate matter ≤ 2.5 μm) exposures in Edmonton, Alberta (1999-2008). Aim 2: Simple correlations and geographically weighted regressions (GWR) were used to examine the relations between SES indices and 1) proximity to nearest emitting facilities, 2) chemical emissions, 3) children’s population for each province and territory and for Canada as well as for Montreal, Vancouver and Toronto. Results are presented in maps. Aim 3: Simple correlations and GWR between SES indices, children’s population and distances from centroids to nearest emitting facilities were also compared for urban and rural groups. SES indices were divided into quintiles and variables were examined based on each group of SES. Aim 4: t-tests (2 tails) and simple correlations were performed between groups of DAs with and without cancer cases. Negative binomial regression was performed to examine if SES, chemical and carcinogen emissions, and proximity to nearest emitting facilities could explain children’s cancer outcomes. Variables were examined with gender and age at diagnosis using multiple linear regressions. DAs with cancer cases were compared between male and female cases using multiple linear regressions. Results: Aim 1: An index used to measure SES for Canada was created and validated. Aim 2: Potential cases of EI were seen throughout Canada with the strongest indications for Northern territories: Nunavut and Northwest Territories had lowest median SES in Canada, second highest median chemical releases, closer than average proximity to emitting facilities. Aim 3: urban DAs were suggestive of EI, as these DAs contained lower SES and closer proximity to emitting facilities than rural DAs; all urban DAs were located within 3 km of an emitting facility; Aim 4: Although there were no overall links between children’s cancer occurrence and proximity to nearest emitting facilities, there was a slight indication that differences may occur according to gender, being females more likely affected. Conclusion: Our index reflects more dimensions of SES than an earlier index and it performed superiorly in capturing gradients in prevalence of pregnancy outcomes. In general, Canadian children may be experiencing environmental exposures because the majority of the Canadian population live in urban areas and regardless of SES, reside in close proximity to industrial emitting facilities. Additionally, gender-specific results and proximity to emitting facilities as well as certain cancer types, might be explored in future studies.

  • Subjects / Keywords
  • Graduation date
    2015-11
  • Type of Item
    Thesis
  • Degree
    Doctor of Philosophy
  • DOI
    https://doi.org/10.7939/R3DN4067Q
  • License
    This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
  • Language
    English
  • Institution
    University of Alberta
  • Degree level
    Doctoral
  • Department
    • Medical Sciences-Paediatrics
  • Supervisor / co-supervisor and their department(s)
    • Osornio Vargas, Alvaro (Paediatrics)
  • Examining committee members and their departments
    • Lavigne, Eric (Epidemiology)
    • Buka, Irena (Paediatrics)
    • Cheung, Po Yin (Paediatrics)
    • Zaiane, Osmar (Computing Sciences)
    • Bamforth, Fiona (Laboratory Medicine and Pathology)
    • Li, Xing Fang (Laboratory Medicine and Pathology)
    • Osornio Vargas, Alvaro (Pediatrics)