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Assessment of farmers' exposure to aflatoxin B1 and other natural toxins in grain and grain dust.

Selim MI
NIOSH 2001 Mar; :1-19
Epidemiological studies from around the world provide evidence for an association between the incidence of lung and other cancers and exposure to airborne aflatoxins in contaminated grain and/or grain dust. Exposure data to assess the potential risk of cancer in farmers and grain workers due to the inhalation of aflatoxin contaminated grain dust are limited by the high cost and poor detection limits of current analytical methods. Exposure data to other mycotoxins (e.g., fumonisins, ochratoxins, vomatoxin, and zearalenones) which are commonly found in grain and grain dust, is virtually nonexistent. Past analysis of grain dust samples from the Midwest and Southeast corn growing belt has demonstrated the presence of aflatoxins in high volume air samples of airborne dust. Our preliminary studies indicated that if aflatoxin B1 is present in airborne dust samples during harvest, it continues to be present and may in fact increase throughout subsequent grain handling and animal feeding operations; over 75% of our test farms had detectable airborne aflatoxin by the time the grain bins are cleaned out. Airborne levels in these bins were found in excess of those associated with a historic cohort exposed to airborne aflatoxin currently experiencing excess cancer. The completed project (5R01OH02857-3) was an extension of an earlier grant limited largely to laboratory method development (1R01OH02857-1) which demonstrated the high sensitivity, efficiency, and reliability of the supercritical fluid extraction technique for the extraction of aflatoxin B1 and fumonisin B1 from grains and grain dust. In this project we proposed to investigate potential correlation between the level of aflatoxin B1 (and other mycotoxins) in grain and its level in airborne dust. Such correlation provides a means by which the health risk of farmers' exposure to airborne aflatoxin B1 (and other mycotoxins) can be predicted from the analysis of an appropriately processed sample of bulk corn. Such correlation will then be used to determine the exposure levels needed to conduct future epidemiologic assessments over a wide geographical area throughout the corn growing belt in the U.S. (including South Carolina, North Carolina, IIlinois, Iowa, Kansas, Missouri, and Oklahoma). The first phase of this project tested and optimized two methods for processing grain dust from bulk corn samples. These methods were then used to characterize the variability of aflatoxin B1 and other mycotoxins in samples collected during on-farm grain handling activities within the state of Iowa. The data obtained provide information on the prevalence, activity mean exposure level, and the variability within the study area. During the second phase we have achieved significant improvements in the speed and sensitivity of our multitoxins analysis methods, using the upgraded ES-API/HPLC/MS system. In addition, the project examined the effect of intra-farm, intra-year variability (change) in the aflatoxin content of the grain over time as affected by the grain moisture content at storage and grain handling history. Obtained correlation for aflatoxin B1 in aerosolized dust and bulk corn provides means to estimate farmers' exposure to aflatoxin in airborne dust from its measurement in a processed bulk sample. The prevalence of other mycotoxins such as fumonisin, ochratoxin, vomatoxin, and zearalenone in bulk and prepared grain dust in these same on-farm activities was investigated. Correlations for other mycotoxins in bulk corn and aerosolized dust were also investigated. The correlations obtained, extend the utility of the new bulk processing methods as means to estimate farmers' exposure to other mycotoxins in aerosolized grain dust based on its measurement in bulk samples. In addition to achieving the above project objectives, we have studied the fate and distribution of aflatoxin B1 and its transformation products in soil and aerosolized soil dust. The data obtained provide information on the stability and prevalence of aflatoxin B1 and its breakdown products in soil and soil dust. Such information is important for estimating the overall level of farmer's exposure to aflatoxin B1 from various farming activities. The possibility of climatic patterns of repeated hot and humid growing seasons creates an increasing need to define the possible role of aflatoxins in the etiology of lung or other cancers. We intend to use the results and methodology developed in this project to establish the exposure database and exposure model needed to initiate and/or participate in an epidemiologic assessment of the occupational risk to farmers resulting from their exposure to aflatoxin B1 and other mycotoxins throughout the agricultural belt in the U.S.
Exposure methods; Mycotoxins; Grain dusts; Agricultural industry; Agricultural workers; Sampling; Sampling methods; Air sampling; Airborne particles; Analytical methods; Laboratory techniques; Dust analysis; Dust exposure; Dust inhalation; Soil sampling; Pulmonary cancer; Microorganisms
University of Iowa, Department of Preventive Medicine and Environmental Health, 100 Oakdale Campus, 137 IREH, Iowa City, IA 52242-5000
Publication Date
Document Type
Final Grant Report
Funding Amount
Funding Type
Fiscal Year
Identifying No.
NIOSH Division
Priority Area
Research Tools and Approaches; Exposure Assessment Methods
Source Name
National Institute for Occupational Safety and Health
Performing Organization
University of Iowa, Department of Preventive Medicine and Environmental Health, Iowa City, Iowa
Page last reviewed: April 9, 2021
Content source: National Institute for Occupational Safety and Health Education and Information Division