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Hydrogen Sulfide (H2S) is produced in manure storage facilities and released during manure agitation. Exposure to this gas presents health risks to workers at daily exposure of greater than 10 parts per million (ppm). Exposure levels on BC dairy farms are unknown. The aim of this study was to document peak H2S exposure levels to operators and bystanders during manure agitation on British Columbia dairy farms to determine if action levels were exceeded. Farms were evaluated at two time points during manure agitation. Both operator exposure and potential exposure sampling were undertaken. Peak hydrogen sulfide levels were measured and categorized as greater than or less than the ceiling level (10 ppm) and action level (5 ppm). Associations between H2S levels above the ceiling level and farm factors were assessed. Measures were recorded at 43 dairy farms with 91 total measures recorded. Action levels were exceeded in 30% of operator measures and 64% of potential exposure measures while 20% of operator and 53% of potential peak H2S measures exceeded 10 ppm. Manure storage facilities were evenly distributed between indoor and outdoor locations with under-barn (43%) and outdoor storage (47%) most common. Sawdust was the most prominent bedding type (65%). Tractor operated propeller was the most common type of agitation equipment (62%). Manure temperature remained a significant predictor in the multivariate model for operator peak exposure. Exposure to H2S above the action level commonly occurs on BC Dairy farms. Given that Worksafe BC requires exposure control plans for H2S levels above 5 ppm, and that on dairy farms, measures of operator and potential H2S exposures were recorded above these levels, best practices to reduce potential H2S exposure are necessary to reduce possible operator and bystander exposure. [ABSTRACT FROM AUTHOR]

Background: Fipronil is an insecticide that acts at the gamma-aminobutyric acid receptor and glutamate-gated chloride channels in the central nervous systems of target organisms. The use of fipronil is increasing across the globe. Presently, very little data exist on the potential impact of exposure to fipronil on the lungs., Methods: We studied effects of intranasal (N = 8) and oral (N = 8) treatment with fipronil (10 mg/kg) on lungs of mice. Control mice were given groundnut oil orally (N = 7) or ethanol intranasally (N = 7) as these were the vehicles for respective treatments., Results: Hematoxylin-eosin stained lung sections showed normal histology in the control lungs compared to the thickened alveolar septa, disruption of the airways epithelium and damage to vascular endothelium in the intranasal and the oral groups. Mice exposed to fipronil either orally or intranasally showed increased von Willebrand factor staining in the endothelium and septal capillaries. Compared to the control mice, TLR4 expression in airway epithelium was increased in mice treated intranasally but not orally with fipronil. Oral fipronil reduced TLR9 staining in the airway epithelium but intranasal exposure caused intense staining in the alveolar septa and airway epithelium. There were higher numbers of TLR4 positive cells in alveolar septa in lungs of mice treated intranasally (P = 0.010) compared to the respective control and orally treated mice but no significant differences between treatments for TLR9 positive stained cells (P = 0.226). The U937 macrophage cells exposed to fipronil at concentrations of 0.29 μm to 5.72 μm/ml over 3- or 24-hour showed significant increase in cell death at higher concentrations of fipronil (P < 0.0001). Western blots revealed no effect of fipronil on TLR4 (P = 0.49) or TLR9 (P = 0.94) expression on macrophage cell line., Conclusion: While both oral or intranasal fipronil treatments induced signs of lung inflammation, the number TLR4-positive septal cells was increased only following intranasal treatment. Fipronil causes macrophage cell death without altering TLR4 and TLR9 expression in vitro.