Epoxidation of 1,3-butadiene in liver and lung tissue of mouse, rat, monkey and man

When 1,3-butadiene is incubated with liver postmitochondrial fractions from mouse, rat, monkey or man and a NADPH-regenerating system the formation rate of butadiene monoxide is different in the four species. With the exception of rhesus monkey the amount of epoxide is proportional to the monooxygenase activity. The sequence of epoxide formation is B6C3F1-mouse, Sprague Dawley rat, man, rhesus monkey. The relation between mouse and monkey was about 7:1. When 1,3-butadiene is incubated with homogenates from lung tissue, only tissues from mouse and rat produces measurable butadiene monoxide concentrations. The monooxygenase activity in lung tissue of the mouse was only 1/30 that in mouse liver. By contrast, lung tissue formed the epoxide concentrations comparable to those formed by liver tissue, whereas monkey and human lung tissue did not produce any measurable levels of butadiene monoxide. The data might suggest that the results of recent rodent inhalation studies with 1,3-butadiene could not automatically be extrapolated to man.