Styrene toxicity

SAN resins themselves appear to pose few health problems in that they have been approved by the EDA for beverage botde use (149). The main concern is that of toxic residuals, eg, acrylonitrile, styrene, or other polymerization components such as emulsifiers, stabilizers, or solvents. Each component must be treated individually for toxic effects and safe exposure level. 

The majority of 2-methylphenol is used in the production of novolak phenoHc resins. High purity novolaks based on 2-methylphenol are used in photoresist appHcations (37). Novolaks based on 2-methylphenol are also epoxidized with epichlorohydrin, yielding epoxy resins after dehydrohalogenation, which are used as encapsulating resins in the electronics industry. Other uses of 2-methylphenol include its conversion to a dinitro compound, 4,6-dinitro-2-methylphenol [534-52-1] (DNOC), which is used as a herbicide (38). DNOC is also used to a limited extent as a polymerization inhibitor in the production of styrene, but this use is expected to decline because of concerns about the toxicity of the dinitro derivative. 

Styrene is mildly toxic, flammable, and can be made to polymerize violently under certain conditions. However, handled according to proper procedures, it is a relatively safe organic chemical. Styrene vapor has an odor threshold of 50—150 ppm (72,73). 

Styrene is Hsted in the U.S. Toxic Substance Control Act (TSCA) Inventory of Chemicals. It is not confirmed as a carcinogen but is considered a suspect carcinogen. The recommended exposure limits are OSHA PEL 50 ppm, ACGIH TLV 50 ppm. For higher concentrations,... 

Superheated water at 100°-240 °C, with its obvious benefits of low cost and low toxicity, was proposed as a solvent for reversed-phase chromatography.59 Hydrophobic compounds such as parabens, sulfonamides, and barbiturates were separated rapidly on poly(styrene-divinyl benzene) and graphitic phases. Elution of simple aromatic compounds with acetonitrile-water heated at 30°-130 °C was studied on coupled colums of zirconia coated with polybutadiene and carbon.60 The retention order on the polybutadiene phase is essentially uncorrelated to that on the carbon phase, so adjusting the temperature of one of the columns allows the resolution of critical pairs of... 

Levin, B.C., A summary of the NBS litterature Reviews on the chemical nature and toxicity of the pyrolysis and combustion from seven plastics acrylonitrite-butadien-styrenes (ABS), nylons, polyesters, polyetylenes, polysterenes, poly(vinyl-chlorides) and rigid polyurethane foams, KB SIR 85-3267, 1986... 

T. Watabe, N. Ozawa, A. Hiratsuka, Studies on Metabolism and Toxicity of Styrene. VI. Regioselectivity in Glutathione 5-Conjugation and Hydrolysis of Racemic, R- and S-Phenyloxiranes in Rat Liver , Biochem. Pharmacol. 1983, 32, 111 - 785. 

The bioconversion was carried out in a two-liquid phase system (Figure 15.12), which was developed at the 2-L level, and scaled up to the 30-L level to produce almost 400 g of product. Several apolar phases were used, of which bis(2-ethylhexyl)phthalate (BEHP) was preferred because it showed a better partitioning of epoxystyrene toward the apolar phase and away from the aqueous phase than did hexadecane. This was important because the product was quite toxic to the recombinant biocatalyst when it appeared in the aqueous phase. This bioconversion illustrates that apolar compounds like styrene and its epoxide, which are quite toxic to microorganisms, can be handled successfully in two-liquid-phase cultures. The toxicity of the substrate and product are not significant issues here. 

The odor of a-methyl styrene is detectable at 50 ppm the odor and irritant properties provide good warning of toxic levels. 

Initiation of a free radical chain takes place by addition of a free radical (R ) to a vinyl monomer (Equation 6.8). Polystyrene (PS) will be used to illustrate the typical reaction sequences. (Styrene, like many aromatic compounds, is toxic, and concentrations that come into contact with us should be severely limited.) It is important to note that the free radical (R ) is a companion of all polymerizing species and is part of the polymer chain acting as an end group and hence should not be called a catalyst even though it is often referred to as such. It is most properly referred to as an initiator. 

Styrene is produced by the catalytic vapor phase dehydrogenation of ethylbenzene. Ethylbenzene is made by the Friedel-Crafts condensation of ethylene and benzene. Styrene is also produced by the palladium acetate-catalyzed condensation of ethylene and benzene and by the dehydration of methylphenylcarbinol obtained by the propylation of ethylbenzene. Because of the toxicity of styrene, its concentration in the atmosphere must be severely limited. 

The first systematic investigations of the catalytic Friedel-Crafts-type reaction with alcohols and olefines were performed by Yamamoto and colleagues. After reporting the development of a Pd-catalyzed method for the allylation of different naphthol derivatives [24], the authors used Mo(CO)g for the Friedel-Crafts-type alkylation of electron-rich arenes with allyl acetates [25], The same molybdenum catalyst was additionally used for a Friedel-Crafts-type alkylation of arenes using 1-phenylethanol and styrene as alkylating reagents [26], However, Mo(CO)g is toxic and must be handled under strictly inert conditions. Thus, more stable Lewis acids were necessary. 

Daston GP, Overmann GJ, Taubeneck MW et al (1991) The role of metallothionein induction and altered zinc status in maternally-mediated developmental toxicity. Comparison of the effects of urethane and styrene in rats. Toxicol Appl Pharmacol 110 450-463... 

A few comments on dibromostyrene Known also as brominated styrene, it has been used as a flame retardant in the manufacture of thermoplastics. Although it does not seem to be toxic for the amounts present in the environment, it might have a teratogenic potential if large amounts of it are orally administered, as developmental studies in rats and rabbits have shown. 

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