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INDUSTRIAL HEALTH 1991,29,11-21
Evaluation of Methyl Bromide Exposure on the
Plant Quarantine Fumigators by Environmental
and Biological Monitoring
Sanjay TANAK, Shin-ichi ABUKU, Yukio SEKI and
Shun-ichiro IMAMIYA
School of Hygienic Sciences, Kitasato University,
1-15-1, Kitasato, Sagamihara-shi, Kanagawa 224 Japan
(Received September 26, 1990 and in revised form December 11, 1990)
Abstract: The study was undertaken to assess the potential risk of exposure to methyl bromide (MB) gas of plant quarantine fumigators who wore full facepiece gas masks with respirator canisters. The mean ambient concentrations of MB determined by a personal sampling device exceeded the TLV-ACGIH level of 5 ppm in the degassing processes at three fumigation sites except at the silos. The mean urinary bromine concentration of 379 non-MB workers was 6.3[+-]2.5 mg/l with 95% confidence limits of 10 mg/l. There were 44.6% of 251 MB workers whose urinary bromine levels exceeded the 10 mg/l. Thre was a significantly positive correlation between the urinary bromine concentrations of the MB workers and the ambient MB concentrations in the degassing process. The MB levels in the workers' exhalation were positive in the degassing process, while those were below the detection limit in the dispersion process. Three possible routes through which the workers are exposed to MB gas are considered to exist: leakage through the interstice between the facepiece of a gas mask and the wearer's face, breakthrough of MB gas in the respirator canister, and percutaneous absorption of MB gas. Biological monitoring of urinary bromine and exhalatory MB as well as environmental monitoring of the ambient MB provided useful information for evaluating exposure of workers to MB.
Key words: Plant quarantine fumigator-Methyl bromide-Urinary bromine-Biological exposure index-Leakage from facepiece-Respirator canister-Percutaneous absorption
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