The concentration in ppm is assumed to be equivalent for the experimental animals and humans. Data from Bond et al. Adequate numbers of mice were treated. The relatively close agreement of quantitative estimates across species for females supports the confidence in the unit risk. An alternate analysis using life-table adjustment for both genders of mice shows results within a factor of 2.
Confidence is rated low.
Estimates of human risk based on sketchy epidemiologic data indicate that the unit risk extrapolation from animal to human is consistent. The 1985 Mutagenicity and Carcinogenicity Document received both Agency and external review. Mortality of rubber workers with reference to work experience. R.F. Henderson, G.S. Dutcher, J.L. Mauderly and L.S. Birnbaum. Species differences in the disposition of inhaled butadiene.