Effects of exposure to sulfuric acid-aerosol on airway responsiveness in guinea pigs: concentration and time dependency

The health impact of common inorganic components of fine particulate matter (PM2.5) in ambient air: a critical review

Ambient air particulate matter (PM) originates as either primary particles emitted directly into the atmosphere from a specific source or as secondary particles produced from atmospheric chemical reactions between precursor gases or between these gases and primary particles. PM can derive from both natural and anthropogenic sources, resulting in a complex chemical mix. The "fine" size mode of ambient PM, designated as PM(2.5), is defined as comprising those particles having aerodynamic diameters below 2.5 microm. While the total mass of PM(2.5) has been associated with adverse human health outcomes, the relationship between these and specific chemical components has not been resolved. This article provides a perspective on the current state of the science concerning health effects from a major group of chemical species found within PM(2.5), namely common inorganic constituents. The specific chemical classes discussed herein are secondary inorganic species, namely, sulfate, nitrate, and acidity, and generally crustal-derived species, namely, phosphate, sodium, potassium, calcium, magnesium, silicon, and aluminum. The article discusses evidence for adverse health effects from inorganic PM(2.5) components within the framework of various caveats surrounding both epidemiology and toxicology assessments. The largest database exists for sulfate, but conclusions that attribute sulfate to health outcomes have not been consistent across all epidemiology studies, and there is a lack of coherence with toxicology studies, which show biological responses only at high levels of exposure. Limited epidemiological and toxicological data for nitrate suggests little or no adverse health effects at current levels. Epidemiological studies specifically identifying crustal components of PM(2.5) suggest that they are not likely, by themselves, to produce a significant health risk, and these components do not have unequivocal biological plausibility from toxicological studies for being significant contributors to adverse health outcomes.

Exposure to diesel exhaust aggravates nasal allergic reaction in guinea pigs

Diesel exhaust particulates (DEP) () and exposure to diesel exhaust (DE) induce nasal mucosal hyperresponsiveness to histamine. Therefore, in the present study, we investigated whether or not exposing guinea pigs to DE aggravates the nasal allergic reaction induced by repeated nasal administration of ovalbumin (OVA). Guinea pigs were exposed to filtered air or to DE (DE containing 0.3 or 1.0 mg/m(3) of DEP) for 5 wk. During exposure to filtered air or to DE, guinea pigs were administered 1% of OVA in saline into the nasal cavities once a week. Sneezes were counted and nasal secretions were measured as indices of sneezing responses and rhinorrhea for 20 min after OVA administration. Titers of specific anti-OVA-IgG and anti-OVA-IgE and the number of eosinophils infiltrated into both nasal epithelium and subepithelium were measured at the end of the exposure to DE. Exposure to DE enhanced the number of sneezes and the amount of nasal secretions induced by OVA. Titers of specific anti-OVA-IgG and anti-OVA-IgE also significantly increased in DE-exposed animals. Exposure to DE also augmented the number of eosinophils that infiltrated both the nasal epithelium and the subepithelium induced by OVA. These results suggest that exposure to DE enhances the nasal allergic reaction induced by repeated antigen administration in guinea pigs.