MEDICAL SURVEILLANCE FOR HEMATOLOGICAL DISORDERS AMONG ACTIVE AND RETIRED OIL REFINERY WORKERS

Ten-year (1985-1995) results of an expanded medical surveillance progr am of 2475 active employees and retirees of an oil refinery and petroc hemical complex in Illinois are presented, At the end of the program 1 16 participants with persistent abnormalities of complete blood cell c ount had been referred for hematologic evaluation, and most were found to have benign conditions. Fifteen of the 116 were referred for bone marrow and cytogenetic studies, All of the referred active employees ( seven) were Sound to have completely normal bone marrows with no evide nce of any myelopathic process. Among the eight retirees, two had norm al bone marrows, one was diagnosed with Philadelphia chromosome-positi ve chronic myelogenous leukemia, one declined to participate and fours were diagnosed to have myelodysplastic syndrome (MDS) of various subt ypes. A total of eight cases of MDS were identified, including six cas es among program participants and two cases among nonparticipants. The MDS standardized incidence ratio of 1.26 (95 % confidence interval = 0.54 -2.47) was not statistically significant, and there was virtually no increase of MDS in, persons less than 80 years of age (4 observed and 3.8 expected). This MDS increase was entirely from program partici pants, probably because of intensive follow-up and diagnostic screenin g. Routine surveillance of complete blood cell count information did n ot identify any new cases of leukemia or MDS in active employees. Thes e findings suggest that the utility of expanded medical surveillance p rogram in this population is very limited.