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Effects of exercise exposure on toxic interactions between inhaled oxidant and aldehyde air pollutants

  • Author(s): Mautz, WJ
  • Kleinman, A
  • Phalen, RF
  • Crocker, TT
  • et al.
Abstract

Respiratory tract injury resulting from inhalation of mixtures of ozone (O3) and nitrogen dioxide (NO2) and of 03 and formaldehyde (HCHO) was studied in SpragueDawleyrats under exposure conditions of restand exercise. Focal inflammatory injury induced in lung parenchyma by 03 exposure was measured morphometrically and HCHO injury to the nasal respiratory epithelium was measured by cell turnover using tritium-labeled thymidine. Mixtures of 03 (0.35 or 0.6 ppm) with N02 (respectively 0.6 or 2.5 ppm) doubled the level of lung injury produced by 03 alone in resting exposures to the higher concentrations and in exercising exposures to the lower concentrations. Formaldehyde (10 ppm) mixed with 03 (0.6 ppm) resulted in reduced lung injury compared to 03 alone in resting exposures, but exercise exposure to the mixture did not show an antagonistic interaction. Nasal epithelial injury from HCHO exposure was enhanced when 03 was present in a mixture. Mixtures of 03 and N02at high and low concentrations formed respectively 0.73 and 0.02 ppm nitric acid (HNOJ vapor. Chemical interactions among the oxidants, HN03, and other reaction products (N2OS and nitrate radical) and lung tissue may be the basis for the 03-N02 synergism. Increased dose and dose rate associated with exercise exposure may explain the presence of synergistic interaction at lower concentrations than observed in resting exposure. No oxidation products were detected in 03-HCH0 mixtures, and the antagonistic interaction observed in lung tissue during resting exposure may result from irritant breathing pattern interactions. © 1975 Taylor & Francis Group, LLC.

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