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An occupational epidemiology study on the acute irritant effects due to exposure to borax particulate
Abstract
Acute irritant symptoms can be caused by a variety of airborne environmental agents. Earlier studies on the acute irritant effects by comparison of symptom events at the beginning and end of the work shift or between groups at different exposure levels have been inadequate. This research examines the acute irritant effects of occupational exposure to sodium borate dusts (borax) using the repeated measurement design. The study population was composed of 79 exposed and 29 unexposed employees. The subjects were queried about irritant symptoms at hourly intervals for the first six hours of the shift and four days in a row. They were also provided a means to record the timing of the symptom by pressing an event marker. Acute pulmonary function change measured by peak expiratory flow rate (PEFR) was obtained. Dose-response relationships were examined by computing incidence rates of specific symptoms at increasing exposure levels. Both ordinary and two-stage logistic regression analysis were used in symptom analysis. L-th autoregressive models were applied in the assessment of acute change in PEFR in relation to exposure concentrations. The major findings showed that dose-response relationships were present for each of five acute irritant symptoms. Increased symptom responses were associated with measured exposure across entire exposure range; no clear threshold was indicated. On the other hand, analysis of acute change in PEFR revealed that only a temporary drop of PEFR was associated with an exposure level above 2 mg/m$\sp3$. Although this change in PEFR was of no clinical importance, it provided an objective measurement that was consistent with findings for acute symptoms. The event marker was found to be useful in allowing more precise estimation of the time of symptoms in relation to prior short-term peak exposures. It showed that the symptom response to exposure peaks was very quick, if not nearly instantaneous. It also provided validation that the recalled symptom onset time was satisfactory. However, inconsistent marker use with respect to symptom and marker use recall were not infrequent, suggesting that this event marker may not replace the traditional interview in obtaining subjective symptom events in future epidemiologic studies.
Subject Area
Occupational safety
Recommended Citation
Hu, Xiaohan, "An occupational epidemiology study on the acute irritant effects due to exposure to borax particulate" (1991). Doctoral Dissertations Available from Proquest. AAI9120894.
https://scholarworks.umass.edu/dissertations/AAI9120894