Biomedical subjects

N Goyer

Publications and source records attributed to N Goyer.

3 recordsLinked to original sources

PubMed1992

Workers' exposure to isocyanates.

A model of exposure to isocyanates, based on knowledge of industrial processes and starting materials and the results of industrial hygiene surveys, is proposed. This model of exposure suggests the concentration and physical form of airborne isocyanate monomers and oligomers. A new sampling and analytical system was developed that is capable of determining the physical and chemical characteristics of occupational exposure to a variety of aliphatic and aromatic isocyanates as required by the exposure model. The sampling system consisted of a dual-filter 37-mm cassette, in which the first filter captured aerosol phase contaminants and the second captured vapor phase isocyanates through derivatization with 9-(N-methylaminomethyl) anthracene (MAMA). Urea derivative recovery by the sampling system, isocyanate-MAMA reactivity, and linearity of the calibration curve were evaluated in the laboratory. The practicality of the system was evaluated during field trials. Sampling times are reduced to 15 min, and the detection limit for TDI, HDI, and MDI was 1.0 micrograms/m3. A partial validation of the new sampling system was performed for HDI vapor by comparison to a standard method in field trials and for TDI vapor in a controlled test atmosphere. The analytical system may also be used to measure the concentration of oligomeric isocyanates. Airborne concentrations of isocyanates were measured in two foam plants, nine paint shops, and two foundries to verify the usefulness of the model. Exposure in foam plants was predominantly to gaseous monomeric isocyanates. Exposure to oligomer isocyanates was higher than expected in paint shops. Both monomer and oligomer isocyanates were undetectable in foundries.

Air Pollutants, Occupational↗

PubMed1990

Evaluation of occupational exposure to sulfur compounds in paper pulp kraft mills.

A study was carried out to provide a comprehensive profile of sulfur gas concentrations to which workers are exposed during the manufacture of paper pulp by the kraft process. Methods currently available--including colorimetric tubes, direct-reading monitors, and gas chromatographic methods--were compared. Gas chromatography is the only technique able to reliably measure individual sulfur gases. However, the necessity of using a gas sampling bag renders this technique inappropriate for personal monitoring. A strategy to evaluate occupational exposure was developed, based on fluctuations in workplace concentrations and the time profile of worker activities. In most samples, only three sulfur products were detected: dimethyl sulfide, methyl mercaptan, and hydrogen sulfide. Concentrations varied as a function of time and location and are correlated to process and equipment-operation variables. Using the proposed strategy, it was demonstrated that workers in the pulp and paper industry can be exposed to significant concentrations of sulfur compounds.

Chromatography, Gas↗

PubMedDate not supplied

Emissions of chemical compounds and bioaerosols during the secondary treatment of paper mill effluents.

This study identified and quantified the main chemical compounds--the substances responsible for the disagreeable odors--and the bioaerosols emitted during the biological treatment of paper mill effluents. It also identified the characteristics of the process that effects the generation or diffusion of these substances. All treatment stages were evaluated. Measuring sites were located as closely as possible to the potential emission sources. Measurements were taken in the summer in 11 paper mills during a 2- to 3-day period in each mill. Chemical compounds were evaluated by direct-reading instruments; bioaerosols were sampled by impaction and counted. Sulfur compounds, emitted into the air when the effluent or the sludge is stirred, had the highest concentrations; their presence was attributable to such things as kraft-type paper pulp. Next in concentration were the carbon and nitrogen oxides, ammonia, and some organic acids, produced by the action of microorganisms. These acids are found mainly in the sludge environment. Terpenes, which come from wood, are present at various locations in paper mills. Odor perception thresholds for most of these substances are much lower than those established to protect the health of workers. Significant concentrations of total bacteria, total molds, and endotoxins were measured at several sites. Gram-negative bacteria were high at only one site, whereas the mold Aspergillus fumigatus was occasionally present at low concentration. No actinomycetes bacteria were detected. The highest concentrations were measured where there was water or dust aerosolization. Emissions are therefore controlled by controlling the operations that lead to the dispersion of water and particles into the air.

Air Pollutants, Occupational↗