Occupational biohazards in agricultural dusts from India

Sixteen samples of settled dusts deposited during handling of various granular plant materials (green gram, red gram, amaranth, rice, pearl millet, sorghum, wheat, maize) in small food storing and processing facilities (godowns) were collected in the region of Aurangabad (Southern India). The samples were examined by the dilution plating method for the concentration and species composition of Gram-positive mesophilic bacteria, Gram-negative mesophilic bacteria, thermophilic actinomycetes and fungi. They were also examined by Limulus test for the concentration of bacterial endotoxin. The total concentration of microorganisms (bacteria + fungi) in examined samples varied within a wide range of 1.4 x 10(5) - 8.45 x 10(8) cfu/g (median 8.36 x 10(6) cfu/g). On average, the most common were Gram-positive bacteria (87.84% of all isolates) followed by Gram-negative bacteria (11.12%). Less common were fungi (1.24%) and thermophilic actinomycetes (0.01%). Among isolated bacteria and fungi, there were many species known as causative agents of allergic alveolitis, asthma and organic dust toxic syndrome. The concentration of bacterial endotoxin in the examined samples ranged between 12.5 - 62500 microg/g (median 781.25 microg/g), being particularly large in the samples of dust from maize (6250 microg/g and 62500 microg/g) and pearl millet (6250 microg/g and 12500 microg/g). The results of the present work indicate that the agricultural dusts from India represent a potential hazard for the workers because of high concentrations of allergenic microorganisms and bacterial endotoxin. The particular risk is associated with handing of maize and pearl millet. Further studies on this subject with the use of aerobiological methods are highly desirable