[ RadSafe ] Silent, Invisible, and Deadly, Radon Gas Accumulates in Many Houses

[Susan Gawarecki]

Bill and Bernie duke it out on MedPage Today website.

--Susan Gawarecki

Silent, Invisible, and Deadly, Radon Gas Accumulates in Many Houses
     
By Michael Smith, MedPage Today Staff Writer
Reviewed by Robert Jasmer, MD; Assistant Professor of Medicine, 
University of California, San Francisco
August 22, 2005
http://www.medpagetoday.com/Pulmonary/LungCancer/tb1/1578

Review
WASHINGTON-An invisible silent killer stalks the nation, causing a 
plague of lung cancer, but most people are only dimly aware of the 
deadly hazard. People can take precautions without much effort although 
relatively few do.

That, according to many authorities, is the status in America of radon, 
a colorless, odorless, radioactive gas that seeps into people's houses 
from the soil beneath and causes occupants to die of lung cancer many 
years later. The annual toll may top out at 21,000 deaths a year, 
according to the Environmental Protection Agency.

Of course, that pales next to the 150,000 lung cancer deaths caused by 
smoking. Yet it's enough to make radon the second leading cause of lung 
cancer deaths in the country, says Phil Jalbert, acting director of the 
EPA's center for radon and air toxics.

Radon is a major risk, he said, even compared with other common causes 
of death, such as drunk driving (about 18,000 deaths a year), accidental 
falls in the home (8,000), and fires in the home (3,000).

The scientific consensus is that radon "represents a major environmental 
health hazard," says Bill Field, Ph.D., of the University of Iowa's 
College of Public Health. That consensus has been strengthened by 
several recent developments, Dr. Field says:

    * A pooled analysis of seven different North American residential 
radon studies, published in the journal Epidemiology in January, showed 
an 11% to 21% increase in lung cancer risk for those exposed to the gas. 
The risk grew with increasing radon exposure.

    * A similar study in Europe, published in the British Medical 
Journal in January, concluded that radon in European homes accounts for 
about 9% of deaths from lung cancer.

    * The World Health Organization launched a radon program, after 
concluding that the gas causes between 6% and 15% of all cases of lung 
cancer in the world. "Radon poses an easily reducible health risk to 
populations all over the world, but has not up to now received 
widespread attention," says Mike Repacholi, coordinator of WHO's 
Radiation and Environmental Health Unit.

    * U.S. Surgeon General Richard H. Carmona issued a national health 
advisory in January, urging citizens to take action against radon.

Radon comes from the radioactive decay of uranium in the soil. It has no 
immediate health effects, but it in turn gives rise to so-called 
"daughter products." Among them are two radioactive isotopes of polonium 
that can lodge in the lungs and cause cancer.

In the outside air, the concentration of radon is low - about 0.4 
picoCuries per liter on average - but when it seeps into houses from 
soil, it can build up to higher levels.

The EPA argues that householders should have their houses tested for 
radon and take steps to reduce it if the average concentration is 
greater than the co-called "action level" of 4 picoCuries per liter of air.

Because uranium is not uniformly distributed, some places have less 
radon than others. In the U.S., for instance, Iowa has the highest radon 
concentrations, while states like Florida are relatively low.

But, Jalbert said, even in areas where radon is generally low, it can 
still build up to the action level in any given house, depending on how 
it is built and ventilated. "It's impossible to predict," he said.

Radon has not always been the bad guy. After its discovery in 1900, it 
was regarded as having curative powers and was added to everything from 
toothpaste to hair cream.

The link between lung cancer and radon was first shown in uranium 
miners, exposed to high levels of the gas during their work. Based on 
theoretical models, the EPA and many researchers argue that there's no 
safe threshold. What kills miners at high levels will also kill average 
citizens at lower levels.

And indeed, many studies seem to show just that. The European pooled 
analysis in January, for instance, concluded that the dose-response 
curve was linear, with no evidence of a threshold of safety.

The contrary view is championed by Bernard Cohen, Ph.D., a physicist at 
the University of Pittsburgh, who has argued for years that such studies 
are based on a flawed model -- the so-called linear, no-threshold model 
-- and buttressed by weak statistics.

The model essentially says that there's no safe threshold below which 
exposure to radon is safe. "We do not know at what level there might not 
be a cancer effect," said the EPA's Jalbert.

With colleagues, Dr. Cohen looked at average radon levels in 1,600 
counties in the U.S., containing more than 90% of the nation's 
population, and plotted them against lung cancer deaths.

If the model were correct, he argues, counties with the highest average 
radon levels should have the highest rates of lung cancer -- but they 
don't. "It's just the other way around," he said.

To Dr. Cohen, the EPA's action level is a waste of time. "To worry about 
4 picoCuries is really not justified," he says.

But if you are worried, says Dr. Field, the hazard can be banished 
without much effort.

In fact, the EPA's action level was set not because the agency thinks 
it's a safe level but because if the radon is at 4 picoCuries, it is 
relatively easy and inexpensive to reduce it sharply, says Jalbert.

The standard way of reducing radon levels is called sub-slab 
depressurization. Dr. Field says.

It works like this. A homeowner hires someone to drill through the 
basement floor (the "slab"), dig out some of the soil to create a hole, 
and insert a piece of plastic pipe. Attach a fan to the pipe and run the 
other end through the wall of the house into the open.

The idea is that the fan will create an area of low pressure in the 
small hole under the slab; soil gas, including any radon, will seep into 
that area, rather than the house itself, and be vented harmlessly into 
the atmosphere.

"It costs anywhere from $700 on up," Dr. Field says. Testing radon 
levels costs between $5 and $15 and should be done every few years, even 
if a radon mitigation system is installed in the house, he said.

The EPA says millions of American homes have been tested and about 
575,000 have had mitigation systems installed.

People aren't worried about radon because there are "no sensory 
reminders," Dr. Field says - the gas is colorless, tasteless and 
odorless. "Because people don't see it, they don't think about it," he says.

"If radon were purple, people would be testing like crazy."

Primary source: British Medical Journal
Source reference:
Darby S et al. Radon in Homes and Risk of Lung Cancer: Collaborative 
Analysis of Individual Data from 13 European Case-control Studies. BMJ 
2005 January 29, 330 (7485): 223.

Additional source: Epidemiology
Source reference:
Krewski D et al. Residential radon and risk of lung cancer: a combined 
analysis of 7 North American case-control studies. Epidemiology. 2005 
Mar;16(2):137-45.

Additional source: Health Physics
Source reference:
Cohen BL. Lung cancer rate vs. mean radon level in U.S. counties of 
various characteristics. Health Phys. 1997 Jan;72(1):114-9.