Evaluating exposures to inhalable dust among dairy parlor workers

Workers in the agricultural industry exhibit higher rates of respiratory diseases than workers who are not employed in agriculture. Farm workers may be chronically exposed to organic dust, which is composed of molds, fungi, pesticides, herbicides, animal-derived particles, feed and bedding particles, and endotoxin. Exposure to organic dust has been linked to the development of various respiratory diseases. Research evidence has shown that variability in exposure to inhalable dust is present, and no studies have assessed variability in exposures to inhalable dust specifically among dairy parlor workers.

A field-based study was conducted to assess exposures to inhalable dust exposure among individuals working as milkers or pushers on dairy farms in the Midwestern United States. A total of 62 dairy parlor workers participated, and 18 of these workers agreed to participate in repeat measurements and were sampled for two work shifts. Two, bilateral personal breathing zone samples were collected continuously from each worker during one work shift using inhalable samplers, amounting to 160 inhalable dust concentration measurements. The filters were weighed, and the TWA of inhalable airborne dust exposure was calculated for each subject and reported in mg/m3. Statistical analyses were used to examine exposure variability.

The results of the statistical analyses did not indicate any statistically significant differences in the means of exposure to inhalable dust between paired sampler groups, with p-values of 0.793, 0.617, and 0.619. An ANOVA analysis of within-worker variance found no statistically significant differences, with p-values of 0.702 and 0.744 for sampler location and sampling day, respectively. Results of the simple linear regression analyses suggested that temperature and humidity levels contribute to less than ten percent of the variability in inhalable dust concentrations.

Analyses of the study indicate that exposure to inhalable agricultural dust does not vary significantly (p-value of 0.05 or less) between the means of right-side and left-side collected exposures, as well as from day-to-day, among dairy parlor workers. The geometric mean of 0.54 mg/m3 (GSD 2.5 mg/m3) of the inhalable dust concentrations from this study align with geometric means found in previous studies of inhalable dust concentrations among dairy farm workers. These results support the hypothesis that using a sample of the dairy parlor worker population can provide an accurate estimate of exposure to inhalable agricultural dust among the general dairy farm worker population.