Screening-level assessment of cancer risk associated with ambient air exposure in Aamjiwnaang First Nation.

The manuscript reports findings from a screening-level assessment of cancer risk from outdoor air in Aamjiwnaang First Nation. Ambient air pollution can contribute to cardiovascular/respiratory diseases, and certain types of cancer. Certain communities may be at higher risk to the negative health impacts due to their geographical proximity to pollution sources. Outdoor air concentrations were mapped and the Lifetime Excess Cancer Risks (LECR) associated with long-term exposure to known carcinogens were estimated. LECR results for both benzene and 1,3-butadiene were above one per million. The LECR for benzene was 6.4 per million when the Health Canada slope factor was applied and 12.0 when using the US EPA. For 1,3-butadiene the LECR estimate was 8.8 per million. This work provides a better understanding of environmental exposures and potential associated cancer risks for residents in the Aamjiwnaang community and highlights the need for further air monitoring and a more detailed risk assessment.

Improving Post-Release Care Engagement for People Living with HIV Involved in the Criminal Justice System: A Systematic Review.

Given sub-optimal HIV care outcomes for people living with HIV (PLWH) post-release from incarceration, we systematically searched peer-reviewed literature (2010-2021) describing controlled trial interventions aimed at improving Antiretroviral Therapy (ART) adherence and care linkage following release from correctional facilities for PLWH. Of 392 studies, 16 (4%) met the inclusion criteria. All studies were conducted in the United States and involved some form of intensive case management. Trials that scored highest in terms of study quality provided cell phones for engagement, reported sustained viral load suppression as a measurable outcome to infer ART adherence, and measured longitudinal data collected for at least 3-to-6 months following release. The two trials that demonstrated improved HIV viral load suppression involved Peer Navigators, and incentivized undetectable viral load, respectively. Facilitating support for addictions and addressing other social and structural barriers to achieving optimal health is also of vital importance in bridging care gaps for PLWH.

RESUMEN: Debido a los resultados suboptimos en los cuidados de las personas que viven con VIH después de su liberación del encarcelamiento, nosotros realizamos una revisión sistemática de la literatura (2010­2021) que describe ensayos control de intervenciones para mejorar la adherencia a la terapia antiretrovirales (TAR) y el vinculo con la atención medica después de la liberación del encarcelamiento de las personas que viven con VIH. De los 392 estudios, 16 (4%) cumplieron con los criterios de inclusión. Todos los estudios fueron realizados en los Estados Unidos e incluyen alguna forma de cuidados con manejo intensivo. Los ensayos que tenían los puntajes mas altos en términos de calidad proveían teléfonos celulares para la vinculación, reportaban supresión de la carga viral sostenida como medida indirecta de adherencia al TAR, y han medido datos longitudinales por lo menos de tres a seis meses después de la liberación carcelaria. Los dos ensayos que demostraron mejora en la supresión de la carga viral del VIH involucraban a los pares navegadores e incentivaban la carga viral no detectable, respectivamente. Facilitando el soporte para la adicción y el entendimiento de otras barreras sociales y estructurales para alcanzar una salud optima, es de vital importancia para superar las brechas en la atención de las personas que viven con VIH.

Using geographic information systems to estimate potential pesticide exposure at the population level in Canada.

Residents in close proximity to agricultural land are at risk of higher pesticide exposures. The purpose of this study was to generate national population-level exposure estimates for Canada for three commonly applied pesticides that are suspected carcinogens (2,4-dichlorophenoxyacetic acid (2,4-D), glyphosate and chlorothalonil). Using geographic information systems, pesticide exposure was estimated for every - census subdivision (CSD) in Canada (n = 5054) by combining raster-based surfaces for the distribution of crops with average crop-specific pesticide application rates data. Analyses examined all identified crops in combination with different pesticide application rates to obtain a cumulative potential total exposure. Specifically, the number of acres of particular crops were calculated for each CSD and then multiplied by the average pesticide application rates data, summed across crops, and combined with population data by CSD to provide a potential pesticide exposure estimate for each CSD. Results demonstrate that the population exposure varies greatly depending on agricultural production by CSD region. For example, in Ontario, the 2,4-D application rate was an average of 361 kg/km2, while in Saskatchewan, which primarily grows field/cereal crops, 2,4-D application rates were much higher (3810 kg/km2). The highest potential exposures to all three pesticides were in the prairie provinces (Alberta, Saskatchewan, Manitoba) along with Prince Edward Island, Southern Quebec and British Columbia. This work can be used in conjunction with other exposure assessment approaches to better understand overall pesticide exposure among Canada's general population.

Co-administration of a Rhododendron tomentosum extract does not affect mercury tissue concentrations and excretion rate in methylmercury-treated adult male rats.

OBJECTIVES: Consumption of fish/seafood is clearly linked to higher mercury levels in human tissue samples. However, correlations between methylmercury (MeHg) intakes calculated from dietary surveys and mercury body burdens are usually weak and can vary across populations. Different factors may affect MeHg absorption, distribution, metabolism and excretion, including co-exposures to phytochemicals and antibiotics, which were shown to affect mercury body burdens in rodents. Based on the observation that rat pups developmentally exposed to MeHg and a Rhododendron tomentosum extract (Labrador Tea) presented significantly higher blood mercury levels at weaning compared to pups exposed to MeHg alone, the modulation of MeHg toxicokinetics by Labrador Tea was further investigated in adult rats. RESULTS: Total mercury levels were quantified in the blood, liver, kidney and feces of adult male rats exposed to MeHg (1.2 mg/kg bodyweight/day, for 3 weeks) administered either alone or in combination with Labrador Tea (100 mg/kg bodyweight/day) or with an antibiotics cocktail (to inhibit MeHg demethylation by gut bacteria). While the reduced fecal excretion and higher blood mercury levels expected from antibiotics-treated rats were observed, mercury levels in samples from Labrador Tea-treated rats were not significantly different from those measured in samples from rats exposed to MeHg alone.

Assessing occupational mercury exposures and behaviours of artisanal and small-scale gold miners in Burkina Faso using passive mercury vapour badges.

Artisanal and small-scale gold mining (ASGM) is a crucial economic activity in Burkina Faso, however it is associated with significant mercury exposure and health concerns. The aim of the present study was to assess the level of mercury (Hg) vapour exposures and occupational behaviours at a representative site using Hg vapour monitor badges and questionnaires. To our knowledge this is the first time that personal exposure to Hg vapour during ASGM activities has been reported. The study population were ASGM workers who completed a questionnaire (n=100) or participated with an occupational exposure assessment using commercially available passive Hg vapour samplers (n=44). Occupational exposure to Hg was high during open-air burn events with a time weighted average (TWA) exposure of 7026±6857µg/m3 for burners, and 1412±2870µg/m3 for bystanders. Most (82%) of the people present at the burn exceeded the Permissible Exposure Limit (PEL) of 100µg/m3, and 11% exceeded the level considered to be Immediately Dangerous to Life and Health (IDLH) of 10,000µg/m3. Even control workers who were not present at the burn exceeded the PEL (24%), likely due to legacy Hg contamination producing latent Hg releases to the atmosphere. Similarly, 86% of the miners at the burn and 59% of control workers had an 8-h TWA that exceeded the Recommended Exposures Limit (REL). Several occupational behaviours that may contribute to Hg exposures were documented. This study corroborates previous studies suggesting that Hg exposure during amalgam burning is very high, and demonstrates the plausibility of using passive vapour monitoring badges rather than costly and logistically difficult biomonitoring methods. Mercury reduction and elimination interventions are strongly needed to reduce Hg exposure in ASGM communities, particularly as countries come into compliance with the Minamata Convention.

Modulation of the effects of methylmercury on rat neurodevelopment by co-exposure with Labrador Tea (Rhododendron tomentosum ssp. subarcticum).

Seafood is an important source of nutrients for many populations worldwide. Unfortunately the contamination of seafood with methylmercury (MeHg) has raised health concerns, particularly for developing infants. The modification of MeHg toxicity by nutrients, including antioxidants, has been reported in both epidemiological and animal exposure studies. We used a rat perinatal exposure model to investigate the modulation of developmental MeHg toxicity by an extract of Rhododendron tomentosum ssp. subarcticum, a plant rich in antioxidants traditionally consumed by Inuit. Sprague-Dawley rat dams were exposed daily to 2 mg MeHg/kg bw and 100 mg R. tomemtosum extract/kg bw administered either separately or jointly, from the first day of gestation until weaning. MeHg exposure was associated with impaired pup growth and survival, decreased grip strength, hyperactivity and altered exploratory behaviour, delayed acoustic startle response, elevated brain N-methyl-D-aspartate receptor (NMDA-R) levels, and increased serum lipid peroxidation. R. tomemtosum extract co-exposure modulated MeHg's effects on oxidative stress and brain NMDA-R levels and may have affected MeHg pharmacokinetic. However, modulation of these molecular endpoints did not lead to significant alterations of MeHg's effects on rat neurobehaviour.

Seasonal variation of phenolic constituents and medicinal activities of Northern Labrador tea, Rhododendron tomentosum ssp. subarcticum, an Inuit and cree First Nations traditional medicine.

Northern Labrador tea, Rhododendron tomentosum ssp. subarcticum, is one of the most commonly used medicinal plants by Inuit and other First Nations peoples of Canada. The phenolic profile and seasonal variation of this commonly used medicinal plant remains largely unknown. To assess optimal harvesting time, R. tomentosum was collected in accordance with traditional knowledge practices bimonthly throughout the snow-free summer in Iqaluit, Nunavut. The antioxidant potency was measured in a DPPH radical scavenging assay, and the anti-inflammatory activity was determined with a TNF-α production assay. The seasonal variation of phenolic content was assessed with HPLC-DAD for fifteen of the most abundant phenolic compounds; (+)-catechin, chlorogenic acid, PARA-coumaric acid, quercetin 3-O-galactoside (hyperoside), quercetin 3-O-glucoside (isoquercitrin), quercetin 3-O-rhamnoside (quercitrin), quercetin pentoside, myricetin, quercetin, 3 procyanidins, and 3 caffeic acid derivatives. The most abundant constituent was (+)-catechin, which made up 19 % of the total weight of characterized phenolics. There was significant seasonal variation in the quantity of all fifteen constituents assessed, whereas there was no seasonal variation of their total sum. The antioxidant activity was positively correlated with phenolic content and negatively correlated with daylight hours. The anti-inflammatory activity was negatively correlated with caffeic acid derivative 1 and daylight hours. Together these results demonstrate that the timing of harvest of R. tomentosum impacts the plant's phenolic content and its antioxidant and anti-inflammatory activities.

Contribution of methylmercury, polychlorinated biphenyls and organochlorine pesticides to the toxicity of a contaminant mixture based on Canadian Arctic population blood profiles.

Human populations are simultaneously exposed to a variety of anthropogenic contaminants. However, despite extensive literature on animal exposure to single compounds, data on the toxicity of complex mixtures are scarce. The Northern Contaminant Mixture (NCM) was formulated to contain the 27 most abundant contaminants in the same relative proportions found in the blood of Canadian Arctic populations. Sprague-Dawley rat dams were dosed from the first day of gestation until weaning with methylmercury (MeHg), polychlorinated biphenyls (PCBs) or organochlorines pesticides (OCs) administered either separately or together in the NCM. An additional control group for hypothyroxinemia was included by dosing dams with the goitrogen 6-propyl-2-thiouracil (PTU). Offspring growth, survival, serum thyroxine and Thyroid Stimulating Hormone (TSH) levels, thyroid gland morphology, brain taurine content and cerebellum and hippocampus protein expression patterns resulting from such exposures were monitored. Pups' increased mortality rate and impaired growth observed in the NCM treatment group were attributed to MeHg, while decreased circulating thyroxine levels and perturbations of thyroid gland morphology were mostly attributable to PCBs. Interestingly, despite comparable reduction in serum thyroxine levels, PCBs and PTU exposures produced markedly different effects on pup's growth, serum TSH level and brain taurine content. Analysis of cerebellum and hippocampus protein expression patterns corroborated previous cerebellum gene expression data, as contaminant co-exposure in the NCM significantly masked the effects of individual components on protein two-dimensional electrophoresis patterns. Identification by MALDI-TOF/TOF MS of differentially expressed proteins involved notably in neuronal and mitochondrial functions provided clues on the cellular and molecular processes affected by these contaminant mixtures.