Correlation of Lethal Doses of Industrial Chemicals between Oral or Intraperitoneal Administration and Inhalation Exposure

抄録

Correlations of lethal doses of industrial chemicals between oral or intraperitoneal administration and inhalation exposure in rats and mice were investigated. LC₅₀ values for inhalation exposure and LD₅₀ values for oral and intraperitoneal administration were obtained from the Registry of Toxic Effects of Chemical Substances. LC₅₀ and LD₅₀ values were plotted on ordinate and abscissa, respectively, using logarithmic scales. A correlation coefficient of r=0.624 (n=146, p<0.001) was obtained for LC₅₀ (ppm) and LD₅₀ (mg/kg) values with oral administration (oral LD₅₀) in rats. This correlation was improved by converting the units of LC₅₀ from ppm to ppm h (cumulative dose), and by converting the units of LD₅₀ from mg/kg to mmol/kg. The correlation coefficient was r=0.742 when ppm*hr and mmol/kg were adopted for LC₅₀ and LD₅₀, respectively. A similar improvement in correlation coefficients by the same unit conversion was also observed between LC₅₀ and LD₅₀ with intraperitoneal (i.p.) administration (i.p. LD₅₀) in rats. Correlations between LC₅₀ and oral LD₅₀ in mice were also improved by the same unit conversion. The correlations between LC₅₀ and i.p. LD₅₀ were higher than those between LC₅₀ and oral LD₅₀ both in rats and mice. In these correlations, coefficients obtained in rats were greater than corresponding coefficients in mice. We calculated equations to estimate LC₅₀ values accompanied by confidence limits from oral or i.p. LD₅₀ values.