Metals Contamination and Chemical Exposures in Canada's "Chemical Vally": Implications for the Aamjiwnaang First Nation

Abstract

The Aamjiwnaang First Nation is an Ojibwe Tribe at the junction of Lake Huron and the St. Clair River, and is surrounded by 58 petrochemical facilities collectively known as Canada’s Chemical Valley. To increase understanding of chemical contamination and exposures, this dissertation was conducted in partnership with the Aamjiwnaang First Nation Health and Environment Committee. Aim One was to study metals contamination of stream ecosystems on-Reserve (n=4), within the surrounding Chemical Valley (n=14), and a reference community (n=4) during three seasons (2010-2011). Aluminum (3-fold), cadmium (20-fold), lead (2-fold), and cobalt (1.5-fold) levels in streams on-Reserve were greater than the reference community (as indicated in brackets). Many sites were above screening levels for aluminum. Aim Two focused on mercury, motivated by knowledge of existing legacy and active mercury sources in the region. Mercury concentrations of sediments and soils were assessed at stream sites. Levels on-Reserve were higher than the reference community (soil=2.5-fold; sediment=6-fold). One on-Reserve site exceeded screening values in sediment and soil. Human exposures were assessed in 43 mother-child pairs. Mean hair (mothers=242.1±188.9 µg/kg; children=126.7±112.9 µg/kg) and blood levels (1.7±2.0 µg/L; 1.5±1.9 µg/L) were lower than the general public. This is likely due to low amounts of fish consumption. Urinary mercury (0.8±0.9 µg/L; 0.5±0.9 µg/L) exceeded values seen nationally. Aim Three was to increase understanding of multiple chemical exposures among Aamjiwnaang mothers and children. Blood, serum, and urine were used as biomarkers of metals (n=9 elements), perfluorinated compound (n=6 congeners), polycyclic aromatic hydrocarbon (n=12), organochlorine pesticide (n=2), polychlorinated biphenyl (n=5), and polybrominated biphenyl ether (n=5) exposures. Distributions of multiple chemicals were elevated in Aamjiwnaang participants. The outcome of this dissertation significantly increased understanding of multiple chemical exposures for the Aamjiwnaang First Nation. The disproportionate placement of industrialization depicts an environmental justice issue seen among many Tribes. The data will fill gaps in the literature, since First Nations Tribes are under-represented in environmental health research. In identifying key chemicals, future studies can be molded to better serve the community. The data will empower the Aamjiwnaang First Nation in taking public health actions to reduce exposures and improve health.