Personal exposure to dust, endotoxin and crystalline silica in California agriculture

Aims: The aim of this study was to measure personal exposure to dust, endot oxin and crystalline silica during various agricultural operations in Calif ornia over a period of one gear. Methods: Ten farms were randomly selected in Yolo and Solano counties and w orkers were invited to wear personal sampling equipment to measure inhalabl e and respirable dust levels during various operations. The samples were an alysed for endotoxin using the Limulus Amebocyte Lysate assay and crystalli ne silica content using X-ray diffraction, In total 142 inhalable samples a nd 144 respirable samples were collected. Results: The measurements show ed considerable difference in exposure level s between various operations, in particular for the inhalable fraction of t he dust and the endotoxin, Machine harvesting of tree crops (Geometric mean (GM) = 45.1 mg/m(3)) and vegetables (GM = 7.9 mg/m(3)), and cleaning of po ultry houses (GM = 6.7 mg/m(3)) showed the highest inhalable dust levels. C leaning of poultry houses also showed the highest inhalable endotoxin level s (GM = 1861 EU/m(3)). Respirable dust levels were generally low, except fo r machine harvesting of tree crops (GM = 2.8 mg/m(3)) and vegetables (GM = 0.9 mg/m(3)), Respirable endotoxin levels were also low. For the inhalable dust fraction, levels mere reduced considerably when an enclosed cabin was present. The percentage of crystalline silica was overall higher in the res pirable dust samples than the inhalable dust samples. Conclusions: Considerable differences exist in personal exposure levels to dust, endotoxin and crystalline silica during various agricultural operatio ns in California agriculture with some operations showing very high levels. (C) 1999 British Occupational Hygiene Society, Published by Elsevier Scien ce Ltd.