Abstract
Agricultural burning is a worldwide practice performed to reduce trash and pest infestation after the crops are harvested. Although this function is economically beneficial, the large quantities of smoke potentially expose not only the farm workers but also any surrounding communities. Characterization of this smoke is difficult, and there are few published reports on this topic.
Unique to the sugar cane industry is the practice of burning the crop before harvesting. This not only produces smoke but also creates a considerable potential for worker exposure to the ash during the harvesting operations.
A previous study had characterized workers' exposures to biogenic silicate fibers during manual harvesting of sugar cane in Florida. In Hawaii, contrary to practice in Florida, all cane is mechanically harvested. An exploratory survey was performed in Hawaii for the purpose of evaluating the feasibility of using gravimetric particulates, organic and elemental carbon, total elemental profiles, polycyclic aromatic hydrocarbons, and biogenic silica fibers to characterize smoke. In addition, personal air sampling was performed to characterize exposure to biogenic silicate fibers and total particulate mass. Results of this assessment indicate that among the above indices evaluated, organic carbon and total elemental analysis of air samples present the most promising means of characterizing smoke.
In addition, it was concluded that harvest workers in Hawaii are exposed to respirable silica fibers which are physically similar to those fibers found previously in Florida. Compared to the National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) for asbestos of 100,000 fibers/m3, or the NIOSH REL for fibrous glass of 3 million fibers/m3 time-weighted average (fibers ≤ 3.5 μm in diameter and ≥ 10 μm in length), the highest partial period air concentration of biogenic silica fibers was 56,000 fibers/m3 obtained among the harvest workers, and 8,350 fibers/m3 obtained among the mill workers. The predominant diameters of these fibers ranged from 0.5 to 2 μm with lengths ranging from 10 to 40 μm. Total dust exposures for both the field harvesting and mill workers were below accepted criteria for unclassified particulates.
