Twelve of the initial 49 workers (24.5%) in this inception cohort were no longer available for follow-up by the end of their first 12-months of employment, as shown in Tables I and andII.II. Six of these 49 workers (12.2 %) had resigned and were no longer working at the plant at the time of follow-up, 4 workers were still employed by the company but not available for follow-up, and two workers refused subsequent participation. There were no differences in demographics or exposure risk group, comparing the lost to follow-up group to the other workers.