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.