RESUMEN
As industrial development is increasing near northern Canadian communities, human health risk assessments (HHRA) are conducted to assess the predicted magnitude of impacts of chemical emissions on human health. One exposure pathway assessed for First Nations communities is the consumption of traditional plants, such as muskeg tea (Labrador tea) (Ledum/Rhododendron groenlandicum) and mint (Mentha arvensis). These plants are used to make tea and are not typically consumed in their raw form. Traditional practices were used to harvest muskeg tea leaves and mint leaves by two First Nations communities in northern Alberta, Canada. Under the direction of community elders, community youth collected and dried plants to make tea. Soil, plant, and tea decoction samples were analyzed for inorganic elements using inductively coupled plasma-mass spectrometry. Concentrations of inorganic elements in the tea decoctions were orders of magnitude lower than in the vegetation (e.g., manganese 0.107 mg/L in tea, 753 mg/kg in leaves). For barium, the practice of assessing ingestion of raw vegetation would have resulted in a hazard quotient (HQ) greater than the benchmark of 0.2. Using measured tea concentrations it was determined that exposure would result in risk estimates orders of magnitude below the HQ benchmark of 0.2 (HQ = 0.0049 and 0.017 for muskeg and mint tea, respectively). An HHRA calculating exposure to tea vegetation through direct ingestion of the leaves may overestimate risk. The results emphasize that food preparation methods must be considered when conducting an HHRA. This study illustrates how collaboration between Western scientists and First Nations communities can add greater clarity to risk assessments.
RESUMEN
Arsonous wildfires are complex investigations due to the high abundance of natural background compounds and subsequent pyrolysis by-products formed during combustion. These interfering compounds can be present in large concentrations and overwhelm the marker compounds used to identify ignitable liquid residue (ILR). Complex matrix effects often interfere with the identification of ILR, providing ambiguous results. The use of comprehensive two-dimensional gas chromatography with time of flight mass spectrometry (GC×GC-TOFMS) separates natural compounds from interfering with ILR compounds of interest. When compared to standard gas chromatography-mass spectrometry (GC-MS) analysis, GC×GC was able to reduce the number of tentative results by 20%. Certain compounds were determined to be unusable for the identification of ILR in wildfire debris samples, in particular the Three Musketeer Group (ethylbenzene, m,p-xylene, and o-xylene), which are ubiquitous in all samples, as well as long chain n-alkylbenzenes, which are formed in the pyrolysis of organic matter. Conversely, the presence of C1- and C2-alkylnaphthalenes were excellent indicators of the presence of gasoline-type ILR. A sizeable number of background samples were collected that helped to provide additional lines of evidence when classifying samples for ILR. Given the complicated matrices encountered in arsonous wildfires, it is evident that GC×GC provides better capabilities at identifying ILR than the standard GC-MS analytical technique.
RESUMEN
The illicit manufacture of methamphetamine (MAP) produces substantial amounts of hazardous waste that is dumped illegally. This study presents the first environmental evaluation of waste produced from illicit MAP manufacture. Chemical oxygen demand (COD) was measured to assess immediate oxygen depletion effects. A mixture of five waste components (10mg/L/chemical) was found to have a COD (130 mg/L) higher than the European Union wastewater discharge regulations (125 mg/L). Two environmental partition coefficients, K(OW) and K(OC), were measured for several chemicals identified in MAP waste. Experimental values were input into a computer fugacity model (EPI Suite™) to estimate environmental fate. Experimental log K(OW) values ranged from -0.98 to 4.91, which were in accordance with computer estimated values. Experimental K(OC) values ranged from 11 to 72, which were much lower than the default computer values. The experimental fugacity model for discharge to water estimates that waste components will remain in the water compartment for 15 to 37 days. Using a combination of laboratory experimentation and computer modelling, the environmental fate of MAP waste products was estimated. While fugacity models using experimental and computational values were very similar, default computer models should not take the place of laboratory experimentation.