Comparison of personal diesel and biodiesel exhaust exposures in an underground mine.

This study aimed to compare personal exposures to diesel fuel and a biodiesel blend exhaust in an underground mine. Personal exposure monitoring was performed in a non-operational, hard rock underground mine during use of a load-haul-dump vehicle. Eight-hour time-weighted average (TWA8) exposure concentrations of ultra-low sulfur diesel and 75% biodiesel/25% diesel blend (B75) fuels were compared. Compared to diesel, use of B75 was associated with relative percent reductions of 22 and 28% in median respirable (r) diesel particulate matter (DPM) and nitrogen dioxide and 25 and 23% increases in median total DPM and nitric oxide TWA8 exposure concentrations, respectively. Diesel was associated with a slightly greater total geometric mean mass concentration and lower mean surface area concentration. Although further testing is needed, B75 has the potential to reduce rDPM exposures.

Occupational exposures to emissions from combustion of diesel and alternative fuels in underground mining--a simulated pilot study.

Diesel fuel is commonly used for underground mining equipment, yet diesel engine exhaust is a known human carcinogen. Alternative fuels, including biodiesel, and a natural gas/diesel blend, offer the potential to reduce engine emissions and associated health effects. For this pilot study, exposure monitoring was performed in an underground mine during operation of a load-haul-dump vehicle. Use of low-sulfur diesel, 75% biodiesel/25% diesel blend (B75), and natural gas/diesel blend (GD) fuels were compared. Personal samples were collected for total and respirable diesel particulate matter (tDPM and rDPM, respectively) and total and respirable elemental and organic carbon (tEC, rEC, tOC, rOC, respectively), as well as carbon monoxide (CO), formaldehyde, acetaldehyde, naphthalene, nitric oxide (NO), and nitrogen dioxide (NO2). Compared to diesel, B75 use was associated with a 33% reduction in rDPM, reductions in rEC, tEC, and naphthalene, increased tDPM, tOC, and NO, and no change in rOC, CO, and NO2. Compared to diesel, GD was associated with a 66% reduction in rDPM and a reduction in all other exposures except CO. The alternative fuels tested both resulted in reduced rDPM, which is the basis for the current Mine Safety and Health Administration (MSHA) occupational exposure standard. Although additional study is needed with a wider variety of equipment, use of alternative fuels have the promise of reducing exposures from vehicular exhaust in underground mining settings.

Evaluation of CBRN Respirator Protection in Simulated Fire Overhaul Settings.

Overhaul is the phase of firefighting after flames have been extinguished but when products of combustion are still being released. While positive pressure self-contained breathing apparatus (SCBA) provide the highest level of respiratory protection during overhaul, use of air-purifying respirators (APRs) with suitable filters could potentially provide a lower weight, longer duration option for first responders. The objective of this study was to assess whether an APR with a chemical, biological, radiological, and nuclear (CBRN) canister could be recommended as substitution for SCBA during overhaul. A total of 15 simulated standard overhaul environments were created by burning household materials. Sampling was conducted using mannequin heads fitted with full facepiece respirators with either a CBRN canister or SCBA. In-mask and personal samples were collected for aldehydes, polynuclear aromatic hydrocarbons, inorganic acids, aromatic hydrocarbons, nitrogen dioxide, and particulate matter. An additional six simulated high-exposure overhaul environments were created in a flashover chamber by continuously adding household materials to a smoldering fire. The sampling train was the same for both the standard and high-exposure environments; however, the facepiece was sealed to the mannequin head in the high-exposure environments. In the standard overhaul environment, the CBRN canister effectively reduced the level of exposure for most contaminants, while in the high-exposure overhaul exposure setting in-mask acetaldehyde and formaldehyde were detected. In both exposure settings, the SCBA prevented almost all exposure, and therefore remains the recommended respiratory protection during overhaul.

Comparison of Acute Health Effects From Exposures to Diesel and Biodiesel Fuel Emissions.

OBJECTIVE: To investigate the comparative acute health effects associated with exposures to diesel and 75% biodiesel/25% diesel (B75) blend fuel emissions. METHODS: We analyzed multiple health endpoints in 48 healthy adults before and after exposures to diesel and B75 emissions in an underground mine setting-lung function, lung and systemic inflammation, novel biomarkers of exposure, and oxidative stress were assessed. RESULTS: B75 reduced respirable diesel particulate matter by 20%. Lung function declined significantly more after exposure to diesel emissions. Lung inflammatory cells along with sputum and plasma inflammatory mediators increased significantly to similar levels with both exposures. Urinary 8-hydroxydeoxyguanosine, a marker of oxidative stress, was not significantly changed after either exposure. CONCLUSIONS: Use of B75 lowered respirable diesel particulate matter exposure and some associated acute health effects, although lung and systemic inflammation were not reduced compared with diesel use.

Schistosoma mansoni: assessment of effects of oleic acid, cercarial age and water temperature on parasite-host attraction.

Although the lifecycle of Schistosoma spp. and pathophysiology of schistosomiasis have been established, the mechanism by which cercariae find their host is not well understood. Speculatively, host infection by random and accidental host contact is not as biologically plausible as a biochemical mechanism of mammalian attraction. A few studies have indicated that biochemical cues and temperature gradients may play a role in host identification, attraction and attachment triggers. This study aimed to elucidate these mechanisms more specifically through evaluation of biochemical, age and temperature influences leading to Schistosoma mansoni cercariae attraction and attachment behaviors. Oleic acid, a common unsaturated free fatty acid in the outer layer of human skin, was tested for cercariae attraction across biologically relevant concentrations. Influence of media type (beeswax, nail varnish and agar), age-dependent behavior variability and environmentally appropriate temperatures (22 and 30 °C) were also evaluated. Results indicated that oleic acid at concentrations of 0.3, 0.9 and 1.8 g/mL in beeswax significantly increased median attachment to media (median attachment of 7.50%, 4.20% and 3.71%, respectively, P<0.001), compared with plain beeswax, with maximal attachment of 30.30% at 0.3g/mL of oleic acid. In media containing 0.3 g/mL of oleic acid, cercarial attachment was highest for freshly emerged cercariae to 5h post-emergence, with a significant decrease in attachment behavior at 10h post-emergence (P<0.01). Aquatic temperature at which cercariae were exposed to media did not yield significant results (P value >0.05). Biochemical, age and environmental factors influencing cercarial host attraction and attachment behavior have been elucidated by this study. This information will inform further development of devices for environmental surveillance and potentially improve cercarial exposure prevention strategies.