Samples of airborne grain dust representing a variety of grains were examined for the presence of aflatoxins. Although aflatoxins could not be detected in most of the samples, one corn sample contained 130 ppb aflatoxin B1. When the components of this sample were separated according to aerodynamic diameter and analyzed for aflatoxins, it was found that particles with diameters 7-11 micrometers and less than 7 micrometers had much higher levels of aflatoxins than the sample as a whole. These findings suggest that measurements of aflatoxin in whole corn might underestimate aflatoxin levels in corn dust aerosols.

Environmental surveys were conducted in 85 barns, predominantly dairy, in central Wisconsin to characterize exposures to organic dusts and dust constituents from routine barn work. Environmental analytes included airborne dusts (total, inhalable inlet, and respirable), particle size distributions, endotoxins, total spore and bacteria counts, viable bacteria and fungi, histamine, cow urine antigen, mite antigen, ammonia, carbon dioxide, and hydrogen sulfide. The geometric mean (GM) concentration of airborne dusts include area total, 0.74 mg/m3; personal inhalable inlet, 1.78 mg/m3, and area respirable, 0.07 mg/m3. Viable bacteria and fungi, spores, endotoxins, histamine, cow urine antigen, and mite antigen were quantifiable constituents of these organic dusts and potential respiratory exposure hazards from routine dairy barn work. Endotoxin concentrations from the inhalable inlet samples ranged from 25.4 endotoxin units per cubic meter of air (EU/m3) to 34,800 EU/m3. The GM endotoxin concentration from these samples, 647 EU/m3, exceeds estimated threshold exposure levels for respiratory health effects. Ammonia was a common irritant quantified in most dairy barns. There were significant correlations between the concentrations of organic dusts and certain dust constituents, although in most instances these correlations were not strong. These sampling results demonstrate the complex nature of organic dusts and provide quantitative description of the exposures to toxic and immunogenic dust constituents during routine barn work.

Thirty volunteer subjects were exposed to controlled amounts of respirable dust generated by the carding of cotton in an experimental cardroom. Eighteen exposures each lasting six hours were performed while carding unwashed and washed cottons from the three major growing regions of the United States. Elutriated dust was analysed gravimetrically and was comparable (059 mg/mi3 + 004) for all exposures. Spirometry was recorded before and after each exposure. California cotton resulted in a significantly smaller fall in FEV, than cotton of the same grade from Texas or Mississippi. All washed cottons resulted in reduced declines when compared with unwashed cottons. For 17 subjects breathing zone personal total dust samples were analysed for airborne endotoxin and compared with the individual's pulmonary function response. A significant correlation between endotoxin exposure and acute decrease in FEV, was seen. The effect on FEV, per nanogram of airborne endotoxin was greater for Mississippi cotton than for cotton from the other regions. Airborne endotoxin appears to be an important determinant of acute pulmonary effects of cotton dust. Water washing of cotton results in reduced airborne endotoxin and less bronchoconstriction.Certain workers employed in the processing of cotton, flax, and hemp fibres develop acute and chronic respiratory symptoms generically called byssinosis.'In different reports the prevalence rates of byssinosis range from 2% to 90%.2 In addition to typical symptoms, acute and chronic ventilatory declines have been shown in people exposed to cotton dust.2 The variability of human responses to the inhalation of textile dusts has been related both to constitutional (individual susceptibility) and environmental factors. Increased responses to cotton dust and cotton dust extracts have been reported in cigarette smokers3 and individuals with atopy.4 Epidemiological and experimental studies have related symptom prevalence and ventilatory declines to airborne respirable dust levels.5'-Even after accounting for dust levels, pronounced differences exist between mills,5 and within mills at different work areas.

Bulk cotton samples and airborne vertical elutriated cotton dusts were obtained from textile mills in Shanghai, People's Republic of China. Analyses of endotoxin contents revealed that baled cottons which were grown in different countries varied in endotoxin contamination. The two textile mills, which operated at similar overall airborne dust levels, differed markedly in the levels of airborne endotoxins. The data suggest that the biological activity or "toxicity" of airborne cotton dusts may not be correlated directly with gravimetric dust levels.