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For Immediate Release: January 3, 2007

Respected Independent Analysis Deflates Claims of Serious Health Risks Associated with Outdoor Wood Furnaces

Lifetime cancer risk overestimated 10,000-fold
Greenbush, MN – A soon-to-be-published report that criticizes an increasingly popular home heating alternative is so riddled with inaccuracies and scientific flaws that it needs complete, in-depth revision, and should not be published in its current form, according to a respected independent review made public today.
The article in question – accepted for publication in an upcoming issue of the journal Human and Ecological Risk Assessment – makes assertions about health risks associated with outdoor wood furnaces that are blatantly false, woefully inaccurate and seriously misleading, according to a review by Gradient Corporation, a respected independent environmental health consulting firm.
“Due to the magnitude of these errors in both fact and scientific judgment, we have initiated discussions with the journal editors to point out why the manuscript should not be published as it is currently written,” says Christopher M. Long, Sc.D., senior environmental health scientist for Gradient.
“Given the serious nature of the errors and methodological flaws we have identified . . . and scientifically unsupported assumptions, it is clear that a careful re-review is needed,” says Gradient’s Dr. Long.
According to Gradient, the report by Dr. David Brown and his co-authors offers conclusions that dramatically inflate lifetime cancer risk as much as 10,000-fold, a marked overstatement of potential health risks.
The Brown report’s dramatically overestimated conclusions about cancer and other health risks associated with outdoor wood furnaces have been picked up in recent weeks in numerous publications across the U.S., including in The New York Times.
“Clearly erroneous misstatements and major methodological flaws by Brown et al raise such large uncertainties that undermine the entire cancer risk assessment – and any conclusions that can be drawn from it,” Dr. Long says.
“Actual cancer risks computed by Brown et al are on the order of 100 times less than those described in their own conclusions,” says Dr. Long. “The fact that erroneous misstatements are in the conclusions section is especially important given that they have been highlighted by both the press and NESCAUM (Northeast States for Coordinated Air Use Management) as a key finding of the Brown et al analysis.”
According to numerous federal, state and local policy makers, NESCAUM has broadly distributed these inaccurate findings across the country, including to the U.S. Environmental Protection Agency (US EPA). And in doing so, NESCAUM has misrepresented that Dr. Brown is an independent scientist, rather than a member of NESCAUM staff.
“It’s unfortunate that what should be an honest discussion about the values and accurate impacts of outdoor wood furnaces, including responsible regulation, is being clouded by shoddy research and unfounded accusations,” says Rodney Tollefson, vice president of Central Boiler, the leading manufacturer of outdoor wood furnaces. Central Boiler requested Gradient’s independent review of the Brown report.
When tested by the US EPA, Central Boiler’s outdoor wood furnace was found to have similar emissions as wood stoves.
Gradient also found:
  • “The corrected Brown et al methodology yields an actual calculated cancer risk of approximately 1 in 10 million for lifetime average concentrations of six micrograms per cubic meter (6 µg/m3),” according to Dr. Long, referring to excess cancer lifetime risks associated with a 7-month exposure to 6 µg/m3 wood smoke particulate matter each year for 30 years. This is far less than is considered significant by the federal and state agencies charged with protection of public health and the environment, including the US EPA.
  • “Only buried in a footnote is it acknowledged that the conclusions made by Brown et al are based on only 4.3 hours of measured air quality. And nowhere is it clearly acknowledged the extremely limited nature of the dataset collected: measurements made over two days at just one residential property, for one boiler,” Dr. Long said.
  • The Brown et al paper relied on 4.3 hours of measured air quality as an estimate of chronic lifetime exposure (based on a report by Philip Johnson, a NESCAUM staff member). Yet, Johnston stated in his own report: “this pilot study was not intended to quantify 24-hour or longer-term average exposures.”
The number of wood heating appliances is increasing as more Americans choose renewable energy solutions to heat their homes. Currently there are an estimated 200,000 outdoor wood furnaces operating in the U.S., primarily in rural areas. The issue of regulation has come to light as more policy makers become aware of what an outdoor furnace is, and that there are no current regulations in place.
“When properly sited, installed and operated – in accordance with manufacturer’s best use practices – outdoor wood furnaces offer a safe, economical, environmentally responsible alternative to fossil fuels and foreign oil,” Tollefson said.
Central Boiler is working closely with the EPA on testing standards and with state and local governments on the adoption of appropriate outdoor wood furnace regulations.
“Central Boiler supports strict, responsible regulations that prevent and/or correct misuse of outdoor wood furnaces. We clearly tell our customers that they can burn only wood and that they need to install a chimney that is the proper height,” Tollefson said.
Central Boiler’s new generation furnace, which will be available in spring 2007, will meet the anticipated new EPA emission guidelines expected to be announced this month, Tollefson said. These standards are more stringent than those enforced for wood stoves.
“It is in our best interest, and the interest of Americans who want to heat with a safe, clean, renewable energy, to prevent the misuse of a product that when properly sited and operated is an economical, environmentally responsible heating alternative,” Tollefson said.
Central Boiler is the leading manufacturer of outdoor wood furnaces, offering a variety of heating-related products and accessories. Central Boiler’s Classic was the first outdoor wood furnace to be UL and CSA certified and is available from authorized dealers throughout the U.S. and Canada. The company is located in Greenbush, Minnesota.
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