Experiences with task-based exposure assessment in studies of farmers and tunnel workers

Abstract

ABSTRACT

Results are described from exposure assessments in two epidemiological studies of farmers and tunnel

workers. The inter and intra worker variances of exposure were used as a basis for classification of

workers in groups exposed to different levels.

The between worker variability of exposure to

α-quartz showed that tunnel workers were exposed

to different levels (GSD

B = 2.7). Classification by job type showed only 39% higher exposure of concrete

workers compared to excavation workers. The influence of tasks on exposure to

α-quartz among

concrete workers was studied further because the between worker variability was large (GSD

B = 4.3).

Multiple regression of tasks on

α-quartz exposure identified two tasks that explained 51% of the total

variance (R

2

adj

). Further classification of concrete workers will depend on identification of workers that

use different time on these tasks.

As farmers carry out few exposed tasks per day, exposure for each task was measured separately.

The between worker variability of exposure to fungal spores among farmers was high (GSD

B = 4.4).

Classification of measurements into two broad task categories related to plant and livestock production

showed that the tasks within each category were relative homogeneously exposed (GSD

B = 1.1 and 1.4)

and with geometric mean exposures that differed by a factor of 20. It therefore seems likely that

farmers can be divided in groups with different cumulative exposure.

These preliminary results indicate that task-based exposure assessment may improve classification

of workers by exposure.