On December 29, 1987, the Hawaii Department of Health requested that the National Institute for Occupational Safety and Health (NIOSH) investigate chronic health effects of sugarcane smoke among sugarcane workers. Since the smoke contains "biogenic silica" fibers (BSF), chronic respiratory diseases were of particular concern. During March 1988, NIOSH investigators measured BSF in air near the Hawaiian Commercial and Sugar Company (HC&S) Plantation on Maui, and in August 1989 conducted further medical and environmental evaluations at the HC&S Plantation and at the Hamakua Sugar Plantation at Honakaa (Island of Hawaii). In addition, NIOSH investigators conducted a case-control study of mesothelioma and BSF exposure using records of the Hawaii Tumor Registry to identify cases and select controls, and ascertaining employment in the sugarcane industry from union records, death certificates, and a special 1942-43 Hawaii census. At the HC&S mill, equipment operators, who move sugarcane into the mill as it is received from the harvested fields, were exposed to BSF; air concentrations of inorganic fibers ranged from 1200 to 8350 fibers per cubic meter (fibers/m 3). In the fields, rake operators had the highest exposures, ranging from 1,250 to 56,280 fibers/m 3 , with a median of 3,970. Exposures of other employees ranged up to 10,250 fibers/m 3 , with a median of 4480. There are no standards or recommendations for limiting exposures to BSF. Ten air samples, from machinists, mechanics, and planting machinery operators, had detectable asbestos. The highest concentration was 0.77 fibers/cubic centimeter, in a bagasse tractor driver (two-hour sample period). Two subsequent samples from this employee during the same work shift had no detectable asbestos. NIOSH recommends that exposure to asbestos be reduced to the lowest possible concentration. The medical study included 355 sugarcane workers. Neither respiratory symptoms or chest X-ray abnormalities were associated with BSF exposure. The ratio of 1-second forced expiratory volume to forced vital capacity (FEV 1 /FVC, a measure of lung air flow obstruction) was lower among workers with ten or more years in jobs with the highest BSF exposures than among those with less time in such jobs [0.72 vs 0.77, p=0.04 (one-way analysis of variance)], but not significantly different from that among workers who never had such jobs (0.72 vs. 0.75). From 1960 to 1987, 93 cases of mesothelioma in Hawaii residents were listed in the Hawaii Tumor Registry. These were compared to 281 residents with other types of cancer category-matched for age at diagnosis, decade of diagnosis, and sex. After adjusting for exposure This Health Hazard Evaluation (HHE) report and any recommendations made herein are for the specific facility evaluated and may not be universally applicable. Any recommendations made are not to be considered as final statements of NIOSH policy or of any agency or individual involved.