Using male ICR mice, the LC50 and acute and subacute inhalation toxicity of dichlorosilane (SiH2Cl2, DCS) and the fate of DCS released into the air were investigated. DCS resolved and minute particles including silicon and chloride were observed, when DCS was released into the air. Most particles were under 1 micron in diameter. The LC50 of DCS at 4-h exposure was 144 ppm (nominal concentration). In the acute inhalation study, ten mice in each group were exposed to 64 ppm (nominal concentration) DCS for 1, 2, 4 or 8 h. Body weight loss, wheezing and piloerection were observed in mice exposed for 2 h or more. Histopathologically, injury to the nasal mucosa and trachea were observed in all exposed mice. Mice exposed to 32 ppm (nominal concentration) DCS for 2 or 4 weeks also exhibited depression of body weight gain, wheezing and piloerection. Squamous metaplasia of the nasal mucosa and tracheal epithelium was observed in both 2- and 4-week exposure groups. Exposure to DCS was irritant or corrosive to the respiratory tract with both acute and subacute inhalation. Apart from silane (SiH4), toxic effects of DCS seem to be characterized by chloride compounds derived from DCS.
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