Toxicity of Ambient Particulate Matter II. Acute toxicity study in asthmatic mice following 3-day exposure to fine ammonium ferrosulfate, a model compound for secondary aerosol of PM10

In this second report on acute inhalation studies with model compounds for secondary particulate matter, results are presented of a study with fine ammonium ferrosulfate aerosol in asthmatic animals. We hypothesised that an aerosol with a transitional metal could produce enhanced symptoms of asthma. We exposed healthy and 'asthmatic' mice to fine (MMD = 459 nm; 4.1 x 10 exp 3 particles per cm3) ammonium ferrosulfate. The mean actual mass concentration was 250 mug/m3. The pulmonary response in mice was determined using bronchoalveolar lavage fluid (BALF) analysis, airway reactivity measurements and histopathology. The results suggest that ammonium ferrosulfate as a model compound for the secondary fraction of ambient PM 10 at concentrations near ambient levels and using short-term exposures exert no pulmonary effects in healthy mice and in a asthma mouse model. In comparison with a previous experiment in which animals were exposed to ammonium bisulfate, no additional effect of the transitional metal, iron, could be established.