Using male ICR mice, the LC(50) and acute and subacute inhalation toxi
city of dichlorosilane (SiH2Cl2, DCS) and the fate of DCS released int
o the air were investigated. DCS resolved and minute particles includi
ng silicon and chloride were observed, when DCS was released into the
air. Most particles were under 1 micron in diameter. The LC(50) of DCS
at 4-h exposure was 144 ppm (nominal concentration). In the acute inh
alation 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. Histopatho
logically, 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 a
nd piloerection. Squamous metaplasia of the nasal mucosa and tracheal
epithelium was observed in both 2- and 4-week exposure groups. Exposur
e 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 DC
S.