Samples of total blood and unstimulated mixed saliva were obtained from 5 male workers occupationally exposed to lead at various time intervals after removal from their work environment. Initial blood lead concentrations were elevated in all workers and then slowly decreased upon removal. Lead concentrations in saliva fell much more abruptly than those in blood, the saliva half-lives being estimated at 5-7 days. Temporary return to work in 2 workers resulted in relatively marked increases of salivary lead concentrations. These results suggest that salivary lead is closely related to recent lead exposure.

Environmental Exposure↗

PubMedDate not supplied

Metabolism and acute hepatotoxicity of styrene oxide in rats.

The metabolism and acute hepatotoxicity of styrene oxide were studied after ip administration of a high dose of 375 mg/kg to adult male rats. Liver glutathione was significantly depleted at 2 h, but became normal at 6 h. The activity of serum glutamic-oxaloacetic transaminase was increased during the entire period (24 h) of study, while the activities of alkaline phosphatase and serum glutamic-pyruvic transaminase were elevated at 2 and 24 h, respectively, after administration of the dose. Decreased body weights and increased liver weights were observed at 24 h. Both prothrombin time and urinary urobilinogen concentration were temporarily increased. While urinary mandelic and phenylglyoxylic acids were increased during the entire time period, urinary (but no fecal) nonprotein sulfhydryl contents were increased at 2 and 6 h. The results of biochemical tests of liver function suggest a mild liver pattern in rats treated acutely with styrene oxide.

Alanine Transaminase↗

PubMedDate not supplied

Adjustment of permissible exposure values to unusual work schedules.

Research activities sought development of a method to adjust exposure limits for 694 substances for unusual work schedules. A consensus was established on the basic toxicological principle for adjustment; criteria for adjustment were selected by a panel of scientists coordinated by a committee of international experts and supported by toxicokinetic modeling; and a group of toxicologists attributed primary health effects and related adjustment category to each substance. A consensus among scientists and employers' and workers' representatives was established on the protocol of the application, in the field, of the adjusted exposure limits. The guiding toxicological principle for adjusting exposure standards to unusual work schedules is to guarantee an equivalent degree of protection for workers with unusual schedules as for workers with a conventional schedule of 8 hours per day, 5 days per week. The process of the adjustment is inspired from the Occupational Safety and Health Administration logic for attribution of primary health effects and adjustment categories ranging from no adjustment to daily or weekly adjustments. The adjusted exposure limits are calculated according to Haber's rule. Decisions on attribution of adjustment categories for the following toxicological effects were reached: respiratory sensitizers (asthma); skin sensitizers; tissue irritants versus tissue toxicants; methemoglobinenia-causing agents; cholinesterase inhibitors; and reproductive system toxicants and teratogens. A simple procedure is presented to facilitate the calculation, application, and interpretation of the adjusted exposure limits.

Guideline Adherence↗

PubMedDate not supplied

Simultaneous high-performance liquid chromatographic analysis of hippuric acid and ortho-, meta-, and para-methylhippuric acids in urine.

A high-performance liquid chromatographic assay for the simultaneous analysis of hippuric and methylhippuric acids in urine is described. Compounds are first extracted from acidified urines after addition of o-methylbenzoylalanine (internal standard), using methyl-t-butyl ether. The organic phase is evaporated under nitrogen flow and the residue dissolved in the mobile phase which consisted of 91% potassium phosphate buffer (12.0mM, pH: 2.0), 4.5% methanol, and 4.5% tetrahydrofuran. The method described allows complete separation of meta- and para-methylhippuric acids in less than 20 min using a stainless steel column packed with octadecyl-dimethysilyl silica. The authors used this method to determine the urinary excretion of hippuric and methylhippuric acids in rabbits following exposure to a mixture of toluene and isomers of xylene. Data indicated that under the actual experimental conditions of exposure o-xylene is excreted to a lesser extent as a methylhippuric acid than the meta- and para-xylenes.

Animals↗

PubMedDate not supplied

Simultaneous determination of urinary mandelic, phenylglyoxylic, and mercapturic acids of styrene by high-performance liquid chromatography.

We have developed a relatively simple and reproducible HPLC procedure for the determination of urinary metabolites of styrene. Urine samples (pH 2) are extracted with ethyl acetate, the organic layer is evaporated to dryness, and the residues are dissolved in water-methanol (1:1). Samples are analyzed by HPLC with a C18 reversed-phase column and a water (pH 6, 5mM tetrabutylammonium dihydrogen phosphate)-acetonitrile gradient and ultraviolet detection at 225 nm. Using this method, it is possible to determine simultaneously mandelic and phenylglyoxylic acids, N-acetyl-S-(1-phenyl-2-hydroxyethyl)-L-cysteine (M1), and N-acetyl-S-(2-phenyl-2-hydroxyethyl)-L-cysteine (M2). The internal standard is p-hydroxybenzoic acid. Additional validation data are obtained by analysis of urine samples obtained from rats treated with a wide range of styrene doses.

Acetylcysteine↗

PubMedDate not supplied

Assessment of occupational health risk from multiple exposure: review of industrial solvent interaction and implication for biological monitoring of exposure.

This review is a critical survey and evaluation of recent literature on solvent interactions for the assessment of health risk. It addresses the implications of multiple solvent exposures 1) by examining the influence of solvent-solvent and ethanol-solvent interactions on the biological indices of chemical exposure, and 2) by indicating how the eventual modifying effects can be considered in the biological monitoring of mixed exposure. Reviewed studies reveal the effects of toxicokinetic interactions on the biological parameters, and the gaps in our knowledge. The measurement of potentially toxic molecular species is suggested for the biological monitoring of multiple chemical exposure. This approach appears to be important for drawing better quantitative conclusions on the internal exposure to biologically active chemical species. Finally, research needs arising from the critical analysis of the literature are briefly described.

Biotransformation↗

PubMedDate not supplied

Assessment of occupational health risk during unusual workshifts: review of the needs and solutions for modifying environmental and biological limit values for volatile organic solvents.

Aspects of occupational health risk assessment for unusual workshifts are discussed in relation to the question of: 1) using a suitable model for adjusting occupational exposure limits, and 2) assessing the influence of altered work schedules on biological exposure limits. The relative importance of two separate approaches, i.e., mathematical and pharmacokinetic, for the adjustment of exposure limits is discussed. Emphasis is placed on the usefulness of a physiologically based pharmacokinetic model for the exposure limits adjustments during prolonged work hours. The influence of prolonged work schedules on biological exposure limits is discussed and it is concluded that the latter do not have to be adjusted for unusual workshifts. Research needs arising as a result of unusual workshifts and pertaining to the practice of industrial hygiene and biological monitoring are suggested.

Humans↗