Breathing wood dust does not pose an adverse health risk to respiratory functions, concludes the six-year, $1.9 million study of 1,100 workers conducted by the Tulane University Medical Center.
The study's much-anticipated release was delayed for several months, first by the shear workload created by analyzing the more than 3,000 samples that were collected and then by Hurricane Katrina. The savage Aug. 29 storm caused an estimated $200 million in damage to the university's campus in New Orleans and forced it to cancel more than two dozen PhD programs.
The study was commissioned by the Inter Industry Wood Dust Coordinating Committee, a consortium of 19 wood products trade associations led by the American Forest & Paper Assn. It involved periodically collecting personal air samples of 1,100 employees working at 10 manufacturing plants, representing a cross-section of the U.S. wood products industry. In addition, each of the employees who volunteered for the study participated in dust monitoring and lung function testing, and answered health questionnaires.
While the study was specifically looking at potential effects of exposure to wood dust, the researchers noted pulmonary effects unrelated to wood dust at two of the 10 facilities, a milling plant and a sawmill-planing-plywood plant. The Tulane study authors suggested the results from the milling plant may be due to a "masked smoking effect," that the workers under-reported their smoking habits. The results from the sawmill-planing-plywood plant are harder to explain, but did not appear to be related to wood dust and are subject to further investigation.
In the Nov. 8, 2005 press release announcing the completion of the study, Sharon Kneiss, vice president of regulatory affairs for the AF&PA, said, "We are happy to learn the researchers found no statistically significant adverse effects from wood dust at the facilities participating in the study. This is good news for our employees and our industry."
Wood & Wood Products contacted the American Forest & Paper Assn. to learn more about the Tulane study, including its implications for woodworkers and the industry at large. Following is our Q&A with Kneiss.
Wood & Wood Products: How does this study compare with any previous study done on the human health effects of wood dust exposure?
Sharon Kneiss: The Tulane Study is the first longitudinal (multi-year) study to examine the respiratory health of workers in the wood and wood processing industry. It is also the only study that has assayed (quantified) the wood solids portion of the personal dust samples collected at the study plant sites. This was made possible by Tulane's development of an innovative analytical method specifically for this purpose.
The study addresses many of the limitations of previous studies, which have generally included small populations, limited exposure sampling and inadequate assessment of lung function.
W&WP: Why was Tulane University chosen for this study? What special qualifications did the university bring to the table?
Kneiss: The Tulane University Medical Center was selected based on recognition of its excellence in respiratory research. The research team at Tulane has many years of experience in studying the potential effects of airborne substances on respiratory health. Tulane has conducted studies of cotton textile workers, of workers in spray-painting operations and of workers in man-made mineral fiber plants, among other studies.
W&WP: The wood dust report was originally scheduled to be released at the end of 2004, then rescheduled for release in the first quarter of 2005. What delayed it?
Participating Wood Dust Study Sponsors
The groups funding the wood dust study include:
American Forest & Paper Assn.
American Home Furnishings Alliance
APA-The Engineered Wood Assn.
Appalachian Hardwood Manufacturers
Architectural Woodwork Institute
Assn. of Woodworking & Furnishings Suppliers
Composite Panel Assn.
Hardwood Manufacturers Assn.
Hardwood Plywood & Veneer Assn.
Kitchen Cabinet Manufacturers Assn.
National Hardwood Lumber Assn.
National Wooden Pallet & Container Assn.
NOFMA: The Wood Flooring Manufacturers Assn.
Northeastern Lumber Manufacturers Assn.
Southern Forest Products Assn.
Western Wood Products Assn.
Wood Machinery Manufacturers of America
Wood Moulding & Millwork Producers Assn.
Woodworking Machinery Industry Assn.
Kneiss: The researchers needed more time to complete their work. This was a very large study with a very large data set to be analyzed. The Tulane researchers conducted rigorous analysis of the data, and it is not at all unusual in studies of this size and depth for researchers to require additional time to complete analysis.
In addition, Hurricane Katrina probably caused a three- to four-week delay. The university was shut down and some of the researchers had to relocate.
W&WP: Because the 10 factories participating in the study were under such close scrutiny, did they upgrade their dust collection systems or take extraordinary precautions to safeguard their employees from wood dust exposure exceeding the industry's norm?
Kneiss: Given that the study took place over six years, it is possible that a facility participating in the study may have made a scheduled upgrade to its dust collection systems. However, the point of this study was to test for a range of wood dust exposures to test exposure responses. It was not to find "clean" facilities, but rather to examine potential exposure-response relationships between wood dust and respiratory effects.
This is why Tulane conducted dust measurements three to fours times at each facility over the study period, collecting over 3,000 samples. They obtained a range of average exposure measurements across the 10 facilities which permitted the researchers to achieve their study objective.
W&WP: How does the information from this study benefit the wood products industry? How should employers of wood products companies react to the study's findings?
Kneiss: The results of the Tulane study will aid in the development of a sound scientific basis for a safe wood dust exposure level. The study speaks for itself; the researchers found no adverse health effects from wood dust at the studied exposure levels.
W&WP: Do the results have any potential implications on the National Toxicology Program's listing of wood dust as a "known human carcinogen?"
Kneiss: No. The Tulane study's focus was on non-cancer respiratory health.
W&WP: What will the Industry Wood Dust Coordinating Committee do with the study? Will it be forwarded to any government agencies or private groups like the American Conference of Industrial Hygienists and International Agency on Cancer Research for comment?
Kneiss: We will share the report with ACGIH and OSHA, and have already sent it to the U.S. Environmental Protection Agency.
W&WP: Why was it initially sent to the EPA? Is that agency developing an indoor air-quality standard that would include wood dust?
Kneiss: While we had no obligation to report this information to the EPA, we did so out of an abundance of caution. The U.S. EPA is not developing an indoor air-quality standard.
W&WP: Considering that the industry sponsored this study, are you concerned that its merits will be diminished in the eyes of government agencies and/or private health-based organizations?
Kneiss: No. The Tulane study was conducted in a scientifically independent manner by the university's medical center, which is widely recognized for its integrity and excellence in respiratory research. The researchers will publish their results in a peer-reviewed scientific journal.
W&WP: What most surprised you about the study's results?
Kneiss: We were pleased the researchers found no association between wood dust exposure and health effects at the levels encountered in the study. However, scientific research by its very nature will often generate new hypotheses. The reported health effects at the sawmill-planing-plywood facility raise hypotheses that await further evaluation of the data. Additional analysis of that facility is underway.
W&WP: What specifically is being reviewed at that facility? How might this review impact the initial findings of the Tulane study?
Kneiss: The sawmill-planing-plywood facility is conducting industrial hygiene surveys and employee pulmonary function testing in an effort to help clarify the reported findings at the facility. We will not know how that might affect the Tulane findings until it is completed and data has been evaluated.
W&WP: Two years ago, Steven Witt, director of OSHA's Directorate of Standards and Guidance, told W&WP that OSHA had nothing in the works to develop a wood dust standard. Have you heard any word or hint that OSHA might initiate the regulatory process to create a wood dust rule?
Kneiss: No, we have not heard anything.
W&WP: Any special advice for W&WP readers on what measures they might take to better safeguard their employees from wood dust exposure?
Kneiss: We have no special advice; the study's results on wood dust speak for themselves. Clarification of the findings at the sawmill-planing-plywood facility requires further analysis of the data, which is in progress.
W&WP: The Tulane Wood Dust Study is the topic of a technical seminar planned for the International Woodworking Machinery & Furniture Supply Fair this August. What will woodworkers learn by attending this program? How else can they find out more about the Tulane study?
Kneiss: They will learn about the study, how it was conducted and the findings. They can get more information by contacting AF&PA's Regulatory Affairs Department at (202) 463-2435.
W&WP: Anything you would like to add?
Kneiss: The wood and wood products industry is proud of having sponsored this study, and of its commitment to worker health and safety.
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