Cancer risk to First Nations' people from exposure to polycyclic aromatic hydrocarbons near in-situ bitumen extraction in Cold Lake, Alberta.

BACKGROUND: The Alberta oil sands are an important economic resource in Canada, but there is growing concern over the environmental and health effects as a result of contaminant releases and exposures. Recent studies have shown a temporal and spatial trend of increased polycyclic aromatic hydrocarbon (PAH) concentrations in sediments and snowpack near the Athabasca oil sands operations (i.e., open pit mines), but thus far similar studies have not been done for the Cold Lake region where steam assisted gravity drainage (in situ) extraction is performed. METHODS: Many PAHs are known mutagenic carcinogens, and this study measured soil and atmospheric concentrations of PAHs in the Cold Lake region to assess the excess lifetime cancer risk posed to the First Nations' inhabitants of the region. Using both deterministic and probabilistic risk assessment methods, excess lifetime cancer risks were calculated for exposures from inhalation or inadvertent soil ingestion. RESULTS: The mean excess cancer risk for First Nations' people through ingestion who engage in traditional wilderness activities in the Cold Lake region was 0.02 new cases per 100,000 with an upper 95% risk level of 0.07 cases per 100,000. Exposure to PAHs via inhalation revealed a maximum excess lifetime cancer risk of less than 0.1 cases per 100,000. CONCLUSIONS: Excess lifetime risk values below 1 case per 100,000 is generally considered negligible, thus our analyses did not demonstrate any significant increases in cancer risks associated with PAH exposures for First Nations people inhabiting the Cold Lake region.

Dynamics of uptake and elimination of 17α-ethinylestradiol in male goldfish (Carassius auratus).

We used male goldfish (Carassius auratus) as a model species to determine the uptake, elimination, and bioaccumulation of 17α-ethinylestradiol (EE2). Goldfish were exposed to EE2 via two different routes: water (135ng/L±12.8 standard deviation) for 72h, and food (231ng/g±42 SD) for 120h. We observed a rapid uptake of EE2 in goldfish, reaching 8.4ng/g±1.2 dry weight (dw) after the first hour of exposure with an uptake rate coefficient (k1) of 45h(-1). The elimination rate coefficient (k2) was determined by a depuration experiment to be 0.0786h(-1). In the feeding experiment, EE2 concentrations increased rapidly, reaching an average of 1.4ng/g after 3h following the first dietary exposure with an estimated absorption efficiency (α) of 0.106. An average of 2.66ng/g±0.87 (n=8) was determined in the 24-72h samples, whereas EE2 concentrations in fish fell below our method detection limits (0.67ng/g) for all samples after 72h, suggesting efficient elimination over time. The bioconcentration factor (BCF) for EE2 reached a maximum of 377, similar to BCFs measured for other pharmaceuticals like fluoxetine and sertraline. Our kinetic data were also used to model various scenarios of EE2 uptake in the aquatic environment. To our knowledge, this is the first report to describe aqueous and dietary EE2 uptake and elimination in fish, as well as providing important data to model EE2 kinetics in fish.

Is there widespread metal contamination from in-situ bitumen extraction at Cold Lake, Alberta heavy oil field?

The extraction of oil sands by in-situ methods in Alberta has expanded dramatically in the past two decades and will soon overtake surface mining as the dominant bitumen production process in the province. While concerns regarding regional metal emissions from oil sand mining and bitumen upgrading have arisen, there is a lack of information on emissions from the in-situ industry alone. Here we show using lake sediment records and regionally-distributed soil samples that in the absence of bitumen upgrading and surface mining, there has been no significant metal (As, Cd, Cu, Hg, Ni, Pb, V) enrichment from the Cold Lake in-situ oil field. Sediment records demonstrate post-industrial Cd, Hg and Pb enrichment beginning in the early Twentieth Century, which has leveled off or declined since the onset of commercial in-situ bitumen production at Cold Lake in 1985.

A method to estimate sediment ingestion by fish.

A method is proposed to use naturally occurring radionuclides of the (238)U decay series as mass balance tracers to estimate sediment ingestion by benthic fish. The mass balance tracer method can take two forms: one that does not account for tracers that would be ingested in invertebrate food items (simple mass balance tracer method) and one that does (adjusted mass balance tracer method). The contents of the gastrointestinal (GI) tracts from 17 Shorthead Redhorse Suckers (Moxostoma macrolepidotum) were analyzed using the proposed method to determine the proportion of sediment in the fish gut. The proportion of sediment in the GI tract samples was also determined using a method developed by Beyer et al. (1994), where the percent soil in wildlife is estimated from the acid insoluble residue (AIR) content of their scat and an assumed level of digestibility of their food (AIR method). The mean mass of sediment in the GI tracts of the 17 fish sampled, calculated using the simple mass balance tracer method, was observed to be 1.14g (standard deviation 0.99g) or approximately 46% (standard deviation 16%) of the dry weight of total GI tract contents. A mean of 0.97g (standard deviation 0.85g), or approximately 38% (standard deviation 13%) of the dry weight of total GI tract contents, was observed when the mass of sediment in the GI tract was calculated using the adjusted mass balance tracer method. When using the AIR method, the mean percentage of sediment in the GI tracts was observed to be 30% (standard deviation 16%). The findings in this study support the assertion that direct ingestion of sediment by benthic fish may be an important pathway for contaminants in aquatic food webs.

Mass balance soil ingestion estimating methods and their application to inhabitants of rural and wilderness areas: a critical review.

Quantitative soil ingestion studies employing a mass balance tracer approach have been used to provide a defensible means to estimate soil ingestion for human health risk assessments. Past studies have focused on soil ingestion in populations living in urban/suburban environments. There is a paucity of reliable quantitative soil ingestion data to support human health risk assessments of other lifestyles that may be predisposed to ingesting soil, such as agricultural workers or indigenous populations following traditional lifestyles. The results of a preliminary analysis of sampling and analytical variability that would result from assessing activities typical of populations in rural or wilderness areas and conducted over wide areas show that approximately 225 subject days would be required to detect a difference of 20mg/d in soil ingestion. Given the typically small populations in these areas, future soil ingestion studies should be focused on specific activities with a high potential for soil ingestion.

Surgical approaches to the metacarpophalangeal joint of the thumb for repair and reconstruction of the collateral ligaments and capsule.

Surgical repair and reconstruction of the ulnar and radial collateral ligaments at the thumb metacarpophalangeal joint require an adequate exposure to identify and repair or reconstruct the disrupted collateral ligaments. The authors have used the approach to be described with safety and convenience over a several year period for repair and reconstruction of both the ulnar and radial collateral ligaments at the thumb metacarpophalangeal joint. This dorsal approach gives a comprehensive exposure without significant disruption of the extensor tendons or hood mechanism.