Correlation between different measures of exposure in a cohort of bakery workers and flour millers.

This paper describes the relationship between continuous and 'grouped' variables for several measures of exposure in a longitudinal study of bakery workers and flour millers. Average shift and peak levels, both for dust and for flour aeroallergen were measured, duration of exposure obtained from questionnaire and cumulative exposure both for dust and for flour aeroallergen calculated. Neither for dust nor for flour aeroallergen was there a correlation between duration of exposure and intensity measures of exposure (peak and average). Moderate to good correlation existed between the various intensity measures of exposures both for dust and for flour aeroallergen. Good correlations existed between measures of exposure of dust and measures of exposure for flour aeroallergen. The degree of correlation was reflected by the fact that the number of workers changing categories depended on which measure of exposure was considered. The higher the correlation coefficient between various measures of exposure the fewer workers changed category. This information provides important information for a better understanding of the exposure-response relationship amongst bakery workers and flour millers.