Exposure to and Acute Effects of Medium-Density Fiber Board Dust

Abstract

The goals of this study were (1) to investigate workers' exposure to medium-density fiber (MDF) dust (inhalable dust, particle size), formaldehyde, and volatile organic compounds; (2) to study the possible inflammatory nasal reactions caused by exposure to MDF board dust; and (3) to determine the occurrence of irritative symptoms among exposed workers. Nasal lavage fluid was analyzed for cytokines and nitric oxide/nitrite, and inflammatory cells were counted. The time-weighted average of MDF dust was 1.4 mg/m ³ in the workers' breathing zones. MDF board dust was composed mainly of particles exceeding 10 μm in diameter. The MDF board dust released formaldehyde in concentration of about 1000 μ g/g when extracted with water for 6 hours at 37°C. The cell counts and cytokine levels of the nasal lavage fluid samples did not show statistically significant differences between the workers exposed to MDF board dust and those exposed to other wood dusts. Nevertheless, two MDF-exposed workers had a considerable increase in the proportion of eosinophils and cytokine levels. Several workers exposed to MDF and wood dusts experienced nasal, eye, and skin symptoms at the end of a work shift. Both exposed groups had significantly more nasal symptoms, although the median dust level was only 1.2 mg/m ³ , considerably less than the occupational exposure limit for wood dust in Finland. Nasal symptoms were more frequent among workers exposed to MDF board dust and did not correlate with smoking. Our results suggest that the occupational exposure limit of 5 mg/m ³ is probably too high for MDF board dust.

Keywords:

• cytokines
• dust exposure
• exposure limit
• formaldehyde
• irritation
• MDF board

ACKNOWLEDGMENTS

We wish to thank Mats Holmström, from Huddinge Sjukhus, Stockholm, for providing his questionnaire for our use. We are especially grateful to Kirsi Immonen for carrying out the nasal lavage sampling and the cytologic analyses. We also wish to thank Aija Jalkanen and Juhani Rautiainen from the Tampere and the Kuopio regional institutes of occupational health for their assistance with the field measurements. We thank Jouni Räisänen, from the Finnish Institute of Occupational Health, for carrying out the particle size analyses. We are grateful to Dr. Antti Tossavainen and Reima Kämppi, both from the aerosol laboratory of the Finnish Institute of Occupational Health, for the electron microscopic analyses. We thank Pirjo Palmroos for her statistical advice in the analysis of the results. We also wish to thank J.-P. Kasanen, Professor A.-L. Pasanen, and Professor Pertti Pasanen from the University of Kuopio, Department of Environmental Sciences, for their cooperation with the wood dust research.

We are grateful to the Finnish Work Environment Fund for funding the study.

Notes

^A GM = geometric mean.

^B GSD = geometric standard deviation.

^C SD = standard deviation.

^D No data available.

^A Difference significant at p = 0.05 level, compared with controls.

^B Difference significant between pre- and postwork shift samples.

^A Difference statistically significant, p < 0.05, compared with unexposed controls.