Health effects of subchronic exposure to diesel-water-methanol emulsion emission

Abstract

The U.S. Environmental Protection Agency's National Ambient Air Quality Standards for ozone and particulate matter (PM) require urban non-attainment areas to implement pollution-reduction strategies for anthropogenic source emissions. The type of fuel shown to decrease combustion emissions components versus traditional diesel fuel, is the diesel emulsion. The Lubrizol Corporation, in conjunction with Lovelace Respiratory Research Institute and several subcontracting laboratories, recently conducted a health assessment of the combustion emissions of PuriNOx diesel fuel emulsion (diesel-water-methanol) in rodents. Combustion emissions from either of two, 2002 model Cummins 5.9L ISB engines, were diluted with charcoal-filtered air to exposure concentrations of 125, 250 and 500 microg total PM/m3. The engines were operated on a continuous, repeating, heavy-duty certification cycle (U.S. Code of Federal Regulations, Title 40, Chapter I) using Rotella-T 15W-40 engine oil. Nitrogen oxide (NO) and PM were reduced when engines were operated on PuriNOx versus California Air Resources Board diesel fuel under these conditions. Male and female F344 rats were housed in Hazleton H2000 exposure chambers and exposed to exhaust atmospheres 6 h/day, five days/week for the first 11 weeks and seven days/week thereafter. Exposures ranged from 61 to 73 days depending on the treatment group. Indicators of general toxicity (body weight, organ weight, clinical pathology and histopathology), neurotoxicity (glial fibrillary acidic protein assay), genotoxicity (Ames assay, micronucleus, sister chromatid exchange), and reproduction and development were measured. Overall, effects observed were mild. Emulsion combustion emissions were not associated with neurotoxicity, reproductive/developmental toxicity, or in vivo genotoxicity. Small decreases in serum cholesterol in the 500-microg/m3 exposure group were observed. PM accumulation within alveolar macrophages was evident in all exposure groups. The latter findings are consistent with normal physiological responses to particle inhalation. Other statistically significant effects were present in some measured parameters of other exposed groups, but were not clearly attributed to emissions exposure. Positive mutagenic responses in several strains of Salmonella typhimurium were observed subsequent to treatment with emulsion emissions subfractions. Based on the cholesterol results, it can be concluded that the 250-microg/m3 exposure level was the no observed effect level. In general, biological findings in exposed rats and bacteria were consistent with exposure to petroleum diesel exhaust in the F344 rat and Ames assays.

Cardiopulmonary response to inhalation of secondary organic aerosol derived from gas-phase oxidation of toluene

“…Because of this, SOA has rarely been considered by health scientists who, in large part, have focused research efforts on concentrated ambient particles (that contain SOA in part), diesel exhaust (EPA, 2002), sulfate (Schlesinger, 2007), and to a lesser extent, gasoline engine emissions and wood smoke (Reed et al, 2006). SOA is also difficult to study directly.…”

“…EPA, 2002;McDonald et al, 2007), wood smoke (e.g. Reed et al, 2006) and inorganic ions such as sulfate (Reiss et al, 2007;Schlesinger, 2007). The epidemiological literature is scant on this subject, although a recent study revealed a stronger association between daily mortality and fine particulate air pollution in summer than in winter, suggesting that SOA may substantially contribute to the observed effect on mortality owing to high PM levels in summer being typically associated with the production of SOA (Nawrot et al, 2007).…”

Exhaust Emissions and Combustion Characteristics of a Direct Injection (DI) Diesel Engine Fueled with Methanol−Diesel Fuel Blends at Different Injection Timings

“…NO and PM were reduced when engines were operated on Puri NO x versus California Air Resources Board diesel fuel under these conditions. 18 In a different study, 19 a stabilized methanol-diesel blend was developed and combustion characteristics and heat release analysis were carried out in a CI engine. According to the experimental results, increasing the methanol mass fraction in the methanol-diesel fuel blends resulted in an increase in the heat release rate at the premixed burning phase and shortened the combustion duration at the diffusive burning phase.…”

Non-cancer health effects of diesel exhaust: A critical assessment of recent human and animal toxicological literature

“…The investigators concluded that "comparisons of the biological responses to these two fresh combustion emissions at levels relevant to potential human exposure levels suggest relatively little overt toxicity" . Corroborating these findings are several recent subchronic inhalation studies of alternative diesel fuels, also conducted at Lovelace Respiratory Research Institute, that have similarly reported evidence of only mild health effects for diesel-water-methanol emulsions (Reed et al, 2005(Reed et al, , 2006 and soybean oil-derived biodiesel fuel (Finch et al, 2002).…”