1,6-Hexamethylene diisocyanate (HDI) is an aliphatic diisocyanate used in t
he manufacture of higher molecular weight biuret and trimer polyisocyanate
resins. These resins are commonly used in polyurethane paints, resulting in
potential occupational, and to a lesser extent consumer exposures. Because
some isocyanates have been reported to be mutagenic, HDI was tested in the
bacterial reverse mutation assay (Ames test), CHO/HGPRT gene mutation assa
y, and in the mouse micronucleus test, using vapor-phase exposures. Althoug
h indicators of toxicity were observed in each test, HDI did not induce mut
agenic or clastogenic effects in any of the three assays.