A Study on Risk Assessment of Soil Fumigation with Methyl Bromide in Greenhouses

ABSTRACT

In order to protect farmers from health hazards posed by soil fumigation with methyl bromide in greenhouses, the authors monitored the concentrations of the fumigant inside greenhouses, before and after fumigation and measured occupational exposures. In the meantime, a questionnaire survey was conducted to find out the facts about working conditions, health effects and personal protective equipment in 1996.<BR>As environmental concentrations of methyl bromide decreased from 2200ppm to 1100ppm gradually in three days, two farmers were exposed to 57ppm and 25ppm, in opening up the greenhouses, respectively, which are above ACGIH's TLV-TWA (1ppm) and OSHA's PEL-C (20ppm). The questionnaire survey (n=164) found that about 80% of the respondents have fumigated inside the whole greenhouse without mulch, above 90% have opened up greenhouses within 5 days, and that only 10% have worn effective gas masks and clothes. Regarding subjective symptoms after fumigation, 2%-6% of respondents complained about eye and respiratory tract irritation.<BR>These results suggest that farmers might be exposed to high concentrations of methyl bromide in opening up greenhouses. In order to prevent health hazards of methyl bromide, education programs on toxic information and health effects of methyl bromide, and safety training in soil fumigation should be provided to farmers.