The metabolism of styrene in the rat and the stimulatory effect of phenobarbital

Induction of sister chromatid exchanges by styrene and its presumed metabolite styrene oxide in the presence of rat liver homogenate

Styrene and its metabolite styrene oxide were tested for their ability to induce sister chromatid exchanges (SCE) in CHO cells. Styrene oxide appeared to be a potent inducer of SCE. Styrene itself did not increase the number of SCE per metaphase, even in the presence of a metabolic activation system. The metabolic activation system decreased the SCE induction caused by styrene oxide. Induction of SCE by styrene in the presence of metabolic activation occurred when cyclohexene oxide was used as an inhibitor of the enzyme epoxide hydrase.

Mutagenicity and chromosomal aberrations as an analytical tool for in vitro detection of mammalian enzyme-mediated formation of reactive metabolites

1. Incubation of trichloroethylene, 1,1-dichloroethylene, vinylchloride, tetra-chlorocyclopentadiene, the nitroso derivatives of the pesticides Carbaryl, Prometryn, and Dodin in the presence of metabolically active mouse liver microsomes and bacteria as target cells were mutagenic, whereas tetrachloroethylene, 1,2 cis- and transdichloroethylene, hexachlorocyclopentadiene, carbontetrachloride, chloroform, halothane, trichlorofluoromethane and styrene were not activated to mutagenic species. 2. In a similar in vitro test system using freshly isolated human lymphocytes as target cells dimethylnitrosamine induced chromosomal aberrations. 3. It is concluded from the experiments that submammalian or mammalian in vitro cell systems with metabolically active liver microsomes are not only suitable to screen for chemical mutagens but to demonstrate formation of reactive intermediates, which are short lived and cannot be detected by chemical procedure.

Pharmacokinetics and distribution of styrene monomer in rats after intravenous administration

An interest in the pharmacokinetics of styrene monomer in the rat, arising from the presence of the monomer in the industrial work place and in foods, necessitated an investigation of the dose dependency of the kinetics of styrene monomer when administered by the iv route. A rapid distribution of the monomer to the major organs was observed, and all of the rate coefficients describing the rates of distribution and elimination decreased with increasing dose. No change in the apparent volume of distribution with dose was observed. Some evidence for the involvement of saturable metabolic pathways was obtained.

Toxicity of styrene and styrene oxide on chick embryos

Styrene and styrene oxide were injected into the air space of fertilized chicken eggs at different times during an incubation period of 14 days. The toxicity of styrene and styrene oxide when injected on the fourth day of incubation revealed an LD50 of 40 mumol/egg and 1.5 mumol/egg, respectively. Malformations were found in 0-20% of the embryos, but never in the controls. The results obtained point to a need for further experimental, and possibly epidemiologic, studies on the consequences of styrene exposure.