Industrial Contaminant Concentration Variations in Traditional Medicinal Plants Utilized

Pollution of local environment and associated health risks for residents has been an ongoing politicized issue since the inception of the Chemical Valley. The industrial complex hosts numerous petrochemical refineries and other facilities which release harmful contaminants. Due to Aamjiwnaang First Nation (AFN)’s close vicinity to the complex, their local environment and residents have been subjected to high exposure risks. This study examined concentrations of contaminants of potential concern (COPCs) in traditional medicinal plants used by AFN, with the goal of providing residents reliable empirical data to make informed decisions on maintaining, reducing, or abandoning traditional practices of using these plants. Paired plant and soil samples of plant species of interest were collected in AFN and Kettle and Stoney Point First Nation (KSP), which served as a reference site. A suite of metals and polycyclic aromatic hydrocarbons (PAHs) were quantified in laboratory settings. A systematic review was conducted to examine the potential for uptake, biotransformation, and bioaccumulation of VOCs in the indicated plants. Metal concentrations assessed via Inductively Coupled Plasma Mass Spectrometry (ICP-MS) or Inductively Coupled Plasma Optical Emission Spectrometry (ICPOES), while PAHs were analyzed by Gas Chromatography/Mass Spectrometry (GC/MS). In addition, lipid content was analyzed for plant samples while pH and loss on ignition (LOI) were examined for soil samples. Study findings indicated significant contaminant concentration differences in several plants. Notably, cadmium (Cd) concentrations were significantly higher (p < 0.05) in A. Canadense plants from AFN, and tungsten (W) concentrations in H. virginiana (p < 0.05) and (unwashed) T. occidentalis (p < 0.01) were also observed to be higher in AFN plants. For soil samples, Benzo [bkj] fluoranthene (B[bkj]F) concentrations were found to be significantly higher in Prunella vulgaris (p < 0.001), Thuja occidentalis (p < 0.05), and Sanguinaria canadensis (p < 0.05) in AFN. Although B[bkj]F mean concentrations were nearly 20 times below provincial guidelines. In addition, Cd and lead (Pb) concentrations in most plants from both communities exceeded European Commission maximum levels (MLs) for comparable food items. However, when contextualized with the relative infrequency of consumption of medicinal plants, reported concentrations were well below Health Canada oral total daily intake (TDI) levels on a yearly basis. Although it should be noted Pb is a non-threshold contaminant. To conclude, the present study found significant differences in COPC concentrations in plant and soil samples, although they were generally below provincial or Health Canada standards when contextualized in estimated yearly consumption rates. However, high usage or consumption rate of traditional medicinal plants found in the area should proceed with caution, due to detected presence of lead.