TOXICITY OF DIVINYLBENZENE-55 FOR B6C3F1 MICE IN A 2-WEEK INHALATION STUDY

Divinylbenzene (DVB) is a crosslinking monomer used primarily for copo lymerization with styrene to produce ion-exchange resins. The toxicity of inhaled DVB was investigated because of the potential for worker e xposure and the structural similarity of DVB to styrene, a potential c arcinogen. Male and female B6C3F1 mice were exposed to 0, 25, 50, or 7 5 ppm DVB for 6 hr/day, 5 days/week for up to 2 weeks. Six mice/sex/do se group were killed after 3, 5, and 10 exposures and six mice/sex in the 75 ppm group were killed 7 days after 10 exposures. The most sever e effects occurred in the nasal cavity and liver, with less severe eff ects occurring in the kidneys. In the nasal cavity olfactory epitheliu m acute necrosis and inflammation were present at early time points fo llowed by regeneration, architectural reorganization, and focal respir atory metaplasia by 7 days after the last exposure. Olfactory epitheli al changes were concentration-dependent with extensive involvement at 75 ppm and peripheral sparing at 25 ppm. There was also necrosis and r egeneration of olfactory-associated Bowman's glands as well as the lat eral nasal (Steno's) glands. Hepatocellular centrilobular (CL) necrosi s was observed only in the 75 ppm dose group and was similar to that c aused by styrene. A time-dependent progression was observed, character ized by CL degeneration after 1 exposure, necrosis after 3 and 5 expos ures, and chronic inflammation with CL karyomegaly after 10 exposures and 7 days after the 10th exposure. Hepatic GSH levels were decreased in a dose-dependent manner. In the kidneys, transient tubular damage w as observed in some male mice exposed to 75 ppm, and appeared to be a response to DVB-induced tubular epithelial injury.