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Occupational exposure during production of wood pellets in Sweden
Örebro University, Department of Natural Sciences.
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The aims of the studies underlying this thesis were to assess workers’ air exposure to wood dust and various chemicals, and to evaluate the variability in exposure and occupational dermal exposure to resin acids during the production of wood pellets in Sweden. Personal air measurements of wood dust, monoterpenes, resin acids and nitrogen dioxide (as a marker of diesel exhaust), accompanied by area measurements of these substances, VOCs and carbon monoxide, were performed at up to ten plants. Repeated measurements were also performed to evaluate within- and between-worker variability, determinants of exposure, the probability that a worker’s mean exposure exceeded the occupational exposure limit, OEL (overexposure), and the bias in the exposure-response relationship (attenuation).

Dermal exposure was measured at the forehead, neck, forearm and hand using a tape-stripping method, in which a strip of adhesive tape is applied to the skin and then removed along with the outermost layer of the skin and chemicals adsorbed to this layer. The workers’ exposure to wood dust was high (mean: 2.4 mg/m3), with 35−42 % of the measurements above the Swedish OEL of 2 mg/m3. The exposure is also classified as unacceptable due to the calculated levels of overexposure. Exposure to resin acids like 7-oxodehydroabietic acid and dehydroabietic acid was identified, which has not been previously observed in the wood industry, with mean sum levels of 2.4 _g/m3. Levels of monoterpenes, nitrogen dioxide, VOCs and carbon monoxide were all below their Swedish OELs. A factor that influenced the level of exposure to wood dust and resin acids was the nature of the work done, notably cleaning operations, like sweeping, which increased the exposure slightly. The attenuation was high for the individual-based model, and at least 12 repeated measurements were needed to yield a bias in the exposureresponse relationship of _10 %. The results also showed that dermal exposure to resin acids occurs in these plants, which has not been shown before, and provided indications of both increased exposure during a work shift and diffusion into the skin. The main conclusion is that wood dust exposure at these levels is likely to have implications for the workers’ health in the long run, and, therefore, it is important to reduce exposure to wood dust in this industry.

Place, publisher, year, edition, pages
Örebro: Örebro universitet , 2008. , p. 75
Series
Örebro Studies in Environmental Science, ISSN 1650-6278 ; 11
Keywords [en]
Occupational hygiene, wood dust, resin acids, VOC, variability, determinant of exposure, overexposure, dermal exposure
National Category
Occupational Health and Environmental Health
Research subject
Enviromental Science
Identifiers
URN: urn:nbn:se:oru:diva-1726ISBN: 978-91-7668-571-6 (print)OAI: oai:DiVA.org:oru-1726DiVA, id: diva2:135368
Public defence
2008-02-22, Wilandersalen, M-huset, Universitetssjukhuset, Örebro, 13:00
Opponent
Supervisors
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2018-01-13Bibliographically approved
List of papers
1. Exposure assessment to alpha- and beta-pinene, delta(3)-carene and wood dust in industrial production of wood pellets
Open this publication in new window or tab >>Exposure assessment to alpha- and beta-pinene, delta(3)-carene and wood dust in industrial production of wood pellets
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2003 (English)In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 47, no 3, p. 219-226Article in journal (Refereed) Published
Abstract [en]

The main aim of the study was to measure the exposure to monoterpenes (alpha- and beta-pinene and Delta(3)-carene) and wood dust during industrial production of wood pellets and briquettes. Additional aims were to compare the results from wood dust sampled on a filter with real time measurements using a direct reading instrument and to identify peak exposures to dust. Twenty-four men working at six companies involved in industrial production of wood pellets and briquettes participated in the study. Monoterpenes were measured by diffusive sampling and wood dust was measured as total dust. A data logger (DataRAM) was used for continuous monitoring of dust concentration for 18 of the participants. The sampling time was approximately 8 h. The personal exposure to monoterpenes ranged from 0.64 to 28 mg/m(3) and a statistically significant (Kruskal-Wallis test, P = 0.0002) difference in levels of monoterpenes for workers at different companies was seen. In the companies the personal exposure to wood dust varied between 0.16 and 19 mg/m(3) and for 10 participants the levels exceeded the present Swedish occupational exposure limit (OEL) of 2 mg/m(3). The levels of wood dust during the morning shift were significantly (Mann-Whitney test, P = 0.04) higher compared with the afternoon shift. Continuous registration of dust concentration showed peak values for several working operations, especially cleaning of truck engines with compressed air. For 24 workers in six companies involved in industrial production of wood pellets the personal exposure to monoterpenes was low and to wood dust high compared with the present Swedish OEL and previous studies in Swedish wood industries. Since the DataRAM can identify critical working tasks with high wood dust exposure a reduction in exposure levels could probably be achieved by changes in working routines and by the use of protective equipment

National Category
Occupational Health and Environmental Health
Research subject
Enviromental Science
Identifiers
urn:nbn:se:oru:diva-2859 (URN)12639835 (PubMedID)
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2018-01-13Bibliographically approved
2. Exposure to wood dust, resin acids and volatile organic compounds during production of wood pellets
Open this publication in new window or tab >>Exposure to wood dust, resin acids and volatile organic compounds during production of wood pellets
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2008 (English)In: Journal of Occupational and Environmental Hygiene, ISSN 1545-9624, E-ISSN 1545-9632, Vol. 5, no 5, p. 296-304Article in journal (Refereed) Published
Abstract [en]

The main aim of this study was to investigate exposure to airborne substances that are potentially harmful to health during the production of wood pellets, including wood dust, monoterpenes, and resin acids, and as an indicator of diesel exhaust nitrogen dioxide. In addition, area measurements were taken to assess background exposure levels of these substances, volatile organic compounds (VOCs), and carbon monoxide. Measurements were taken at four wood pellet production plants from May 2004 to April 2005. Forty-four workers participated in the study, and a total of 68 personal measurements were taken to determine personal exposure to wood dust (inhalable and total dust), resin acids, monoterpenes, and nitrogen dioxide. In addition, 42 measurements of nitrogen dioxide and 71 measurements of total dust, resin acids, monoterpenes, VOCs, and carbon monoxide were taken to quantify their indoor area concentrations. Personal exposure levels to wood dust were high, and a third of the measured levels of inhalable dust exceeded the Swedish occupational exposure limit (OEL) of 2 mg/m3. Parallel measurements of inhalable and total dust indicated that the former were, on average, 3.2 times higher than the latter. The data indicate that workers at the plants are exposed to significant amounts of the resin acid 7-oxodehydroabietic acid in the air, an observation that has not been recorded previously at wood processing and handling plants. The study also found evidence of exposure to dehydroabietic acid, and exposure levels for resin acids approached 74% of the British OEL for colophony, set at 50 microg/m3. Personal exposure levels to monoterpenes and nitrogen dioxide were low. Area sampling measurements indicated that aldehydes and terpenes were the most abundant VOCs, suggesting that measuring personal exposure to aldehydes might be of interest. Carbon monoxide levels were under the detection limit in all area measurements. High wood dust exposure levels are likely to have implications for worker health; therefore, it is important to reduce exposure to wood dust in this industry.

Place, publisher, year, edition, pages
Philadelphia, PA: Taylor and Francis, 2008
National Category
Occupational Health and Environmental Health Medical and Health Sciences
Research subject
Occupational and Environmental Medicine
Identifiers
urn:nbn:se:oru:diva-2860 (URN)10.1080/15459620801957225 (DOI)
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2018-01-13Bibliographically approved
3. Variability and determinants of wood dust and resin acid exposure during wood pellet production: measurement strategies and bias in assessing exposure-response relationships
Open this publication in new window or tab >>Variability and determinants of wood dust and resin acid exposure during wood pellet production: measurement strategies and bias in assessing exposure-response relationships
2008 (English)In: Annals of Occupational Hygiene, ISSN 0003-4878, E-ISSN 1475-3162, Vol. 52, no 8, p. 685-694Article in journal (Refereed) Published
Abstract [en]

Production of wood pellets is a relatively new and expanding industry in which the exposure profiles differ from those in other wood-processing industries like carpentries and sawmills where there are lower levels of wood dust. Sixty-eight personal exposure measurements of wood dust (inhalable and total dust) and resin acids were collected for 44 participants at four production plants located in Sweden. Results were used to estimate within- and between-worker variability and to identify uniformly exposed groups and determinants of exposure. In addition, overexposure, whether the risk of the long-term mean exposure of a randomly selected worker exceeding the occupational exposure limit is acceptably low, was calculated as well as the underestimation of the exposure–response relationship (attenuation). Greater variability in exposure between work shifts than between workers was observed with the within-worker variation accounting for 57–99% of the total variance in the individual-based model. Several uniformly exposed groups were detected but were mostly associated with a between-worker variation of zero which is an underestimation of the between-worker variation but an indication of uniformly exposed groups. Cleaning was identified as a work task that increases exposure slightly; so reducing workers’ exposure during this operation is advisable. The levels of wood dust were high and were found to pose unacceptable risks of overexposure at all plants for inhalable dust and at three out of four plants for total dust. These findings show that exposure to dust needs to be reduced in this industry. For resin acids, the exposure was classed as acceptable at all plants. According to an individual-based model constructed from the data, the level of attenuation was high, and thus there would be substantial bias in derived dose–response relationships.

National Category
Occupational Health and Environmental Health
Research subject
Enviromental Science
Identifiers
urn:nbn:se:oru:diva-2861 (URN)10.1093/annhyg/men052 (DOI)
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2018-01-13Bibliographically approved
4. Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet production
Open this publication in new window or tab >>Tape-stripping as a method for measuring dermal exposure to resin acids during wood pellet production
(English)Manuscript (preprint) (Other academic)
National Category
Occupational Health and Environmental Health
Research subject
Occupational and Environmental Medicine; Enviromental Science
Identifiers
urn:nbn:se:oru:diva-2862 (URN)
Available from: 2008-02-01 Created: 2008-02-01 Last updated: 2018-01-13Bibliographically approved

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