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NORA Manufacturing Sector Strategic Goals

927Z6RS - Validation of appropriate wood dust sampling and analysis procedures

Start Date: 10/1/2006
End Date: 9/30/2010

Principal Investigator (PI)
Name: Martin Harper
Phone: 304-285-6034
Organization: NIOSH
Sub-Unit: HELD
Funded By: NIOSH

Primary Goal Addressed

Secondary Goals Addressed
6.0, 8.0

Attributed to Manufacturing


Project Description

Short Summary

This study will form part of an international initiative to develop improved sampling and analytical procedures for wood dust in support of Manufacturing Sector Strategic Goal #5 and Agriculture Sector Strategic Goal #7. It has been estimated that at least two million people are occupationally exposed worldwide. Wood dust exposure has been implicated in upper airways diseases, including sino-nasal adenocarcinoma. Current procedures for assessing exposure to dust are not optimal. Different commercially available sampling technologies will be evaluated, along with a novel method of discriminating wood dust from other environmental dust. Research to practice will involve the development of recommendations for nationally and internationally harmonized exposure assessment procedures for wood dusts, which will be presented to relevant organizations, published in journals, and translated into standard methods.


The current NIOSH and OSHA exposure assessment sampling methods for wood dust are to collect particles on a filter from a metered amount of air. The filter is housed in a plastic cassette, and the filter is weighed to determine the amount collected. OSHA utilizes an internal filter capsule to ensure all dust entering the cassette is accounted in the analysis. The NIOSH procedure does not specify this capsule so that potentially large amounts of material may be lost to the internal walls of the cassette. Thus the result will depend on the procedure followed. There is, in any case, a strong objection to this sampler in that its entry characteristics do not match the ISO inhalable convention. In many studies it has been found to sample much less, particularly in the 40 – 100 µm range in which most of the mass in typical wood dusts is concentrated. Samplers that match the ISO inhalable convention have been developed. The Comité Européen de Normalisation (CEN) is currently considering a technical document with recommendations for their selection and use. However, wood dust is not a typical aerosol. The size distribution covers much larger sizes, and often includes particles greater than 100 µm, whose inhalability is in doubt, but which can remain airborne as a result of unusual aerodynamic properties conferred by extreme physical dimensions (i.e. "frizbee's"). These particles have a disproportionate effect on the total mass of the air sample as a result of the cube relationship between volume (mass) and diameter. The result is that many so-called "inhalable" samplers grossly over-sample wood dusts leading to non-compliance with limit values.

Since the OSHA/NIOSH cassette has entry and wall losses, and many inhalable samplers are prone to bias by large non-inhalable particles, there is a need for recommending a more appropriate sampling device. The French INRS (equivalent to NIOSH) has begun a program of side-by-side assessment of two samplers: the plastic cassette with internal capsule, and the CIP-10, a rotary sampler developed in France. This study is parochial, in that it does not include samplers developed in other countries. The INRS has invited NIOSH to collaborate on this study, to increase the range of samplers which can be tested. The proposed Project Officer has previously evaluated three other samplers in wood-working situations in the USA. The first aim therefore is to cross-correlate results from the INRS study and previous US studies through additional side-by-side field evaluations. The second aim is to validate the results through determining the particle size distributions of the samples using a microscopic imaging technique developed by the proposed Project Officer. The third aim is to evaluate the performance of a technique developed through a NIOSH RO1 grant to Tulane University for discriminating wood dust from other environmental dust using the samples collected in this study. This technique of Diffuse Reflectance Infra-Red Fourier Transform Spectroscopy (DRIFTS) was developed by Dr. Roy Rando and will be replicated in our laboratory. Samples will be shared with Dr. Rando for quality assurance purposes.

Successful completion of this project will allow the development of recommendations for nationally and internationally harmonized exposure assessment procedures for wood dusts.



- Organize collaborations with wood-working companies and Universities to collect samples

- Collect wood dust samples and compare to INRS data

- Validate collected samples through microscopic evaluation

- Transfer DRIFTS technique to our laboratory

- Assess the contribution of non-wood dust to samples collected as above

- Write up results as journal articles, methods and standards.


- Peer review of proposal

- Validation of techniques

- Peer review of publications

Mission Relevance

Workers may be exposed to wood dust in primary processing such as in logging and debarking. However, many more workers are exposed in lumber and pulp mills and in secondary wood industries such as furniture and cabinet manufacturing, wood pattern and model shops, etc., in the Manufacturing sector. NAICS Code 113310 (Logging) covers workers in Forestry and NAICS Codes 321 (Wood Products Manufacturing) and 322 (Paper Manufacturing) cover the workers in Manufacturing. In 1997, the US Bureau of the Census recorded 18,825 workers employed in the wood-products industries in just the State of Alabama, and more than one-half million nationwide. In 1994 the International Agency for Research on Cancer (IARC) estimated that at least two million people are occupationally exposed to wood dust worldwide, many of them in the Manufacturing Sector. Respiratory Disease was one of the topics considered significant for this Sector at a recent NORA Symposium. It has been suggested that wood dust exposure leads to an increased prevalence of certain workplace respiratory symptoms, such as bronchitis, loss of pulmonary function, and nasal mucociliary stasis, nasal obstruction, and cuboidal metaplasia, which may be a precursor lesion for nasal cancer. The most biologically relevant portion of wood aerosol is that which can penetrate the head and thoracic airways regions with a high likelihood of deposition. The International Standards Organization (ISO) recognizes a penetration curve termed the "inhalable" convention. The American Conference of Governmental Industrial Hygienists published an inhalable limit value for wood dust (1 mg/m3) in 2005. In France, Decree No. 2003-1254 also set an inhalable limit value for wood dust in workplaces (1 mg/m3). Research is needed to determine which of the many available coarse-dust samplers is most appropriate for sampling the inhalable fraction of wood dust. In addition, these limit values are also very low, and it may be necessary also to discriminate wood dust from other ambient dust in the sample to avoid overestimation. Wood dust has been a major issue at the Forest Products Industrial Hygiene forum at the American Industrial Hygiene Conference & Exposition for the past several years.

This project contributes to the Agriculture Strategic Goal 5 (09PPAFFSG5): Improve the health and well-being of agricultural workers by reducing occupational causes or contributing factors to acute and chronic illness and disease; Intermediate Goal 5.2 (09PPAFFIG5.2): Reduce acute and chronic respiratory disease caused, or exacerbated by, agricultural exposures including asthma, chronic obstructive pulmonary disease, and interstitial and infectious diseases of the respiratory system; and Agriculture Sector Strategic Goal 7 (09PPAFFSG7): Improve the health and well-being of forestry workers by reducing occupational causes or contributing factors to acute and chronic illness and disease; Intermediate Goal 7.4 (09PPAFFIG7.4): Assess the health conditions of forestry workers to improve work design and work practices for workers entering the sector and at career stages of working life. This project addresses the Manufacturing Sector Strategic Goal 5, Reduce the number of respiratory conditions and diseases due to exposures in the manufacturing sector. In the Cancer, Reproductive and Cardiovascular Diseases (50%) cross-sector program, research results from this project will address Activity/Output Goal 1.2.4. (09PPCRCAOG1.2.4): Build partners' (including employers') capacity to address traditional and emerging hazards by developing or adapting methods for the laboratory and field deployable methods and direct reading devices and also Activity/Output Goal 1.3.1. (09PPCRCAOG1.3.1): Provide world leadership in the development of international standards and documents, and the sharing of study methods and findings, and also Activity/Output Goal 1.3.2. (09PPCRCAOG1.3.2): Address global workplace hazards through information sharing and research collaborations. In the Respiratory Disease (50%) cross-sector program, research results from this project will address Strategic Goal #1, Intermediate Goal #2 (09PPRDRIG1.2): prevent and reduce work-related COPD. In the Exposure Assessment (100%) coordinated emphasis area, research results will address Activity/Output 2.3.1 (09PPEXAAOG2.3.1): Development of new or improved methods to measure chemicals or other occupational hazards in the work environment and Activity/Output 2.3.2 (09PPEXAAOG2.3.2): Validation of these methods to provide and characterize their performance (specificity, sensitivity, accuracy, etc.) including publication in the NIOSH Manual of Analytical Methods.

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