20 Countries Act to Repel Deadly Radioactive Radon Gas

GENEVA, Switzerland, June 22, 2005 (ENS) - Exposure to a natural radioactive gas in the home and workplace causes tens of thousands of deaths from lung cancer each year, the World Health Organization (WHO) said Tuesday. Recent results from the largest radon studies ever conducted in North America and Europe show six to 15 percent of all lung cancers are caused by exposure to the gas.

Smokers have something else to worry about besides the health effects of tobacco. For them, exposure to the radon that may permeate homes or offices, poses a risk of lung cancer 25 times greater than for non-smokers.

"Radon poses an easily reducible health risk to populations all over the world, but has not up to now received widespread attention," said Dr. Mike Repacholi, coordinator of WHO's Radiation and Environmental Health Unit.

"Radon is all around us. Radon in our homes is the main source of exposure to ionizing radiation, and accounts for 50 percent of the public's exposure to naturally occurring sources of radiation in many countries," Dr. Repacholi said.

To cut the risk of lung cancer for smokers and non-smokers alike, the World Health Organization (WHO) Tuesday announced that 20 countries have joined with the agency in a new project that will identify effective strategies for reducing the health impact of radon.

The project is initially expected to run for three years - 2005-2007. As a first step, the WHO International Radon Project is setting up a global network of radon scientists, regulators and policy makers to collaborate in the project.

Scientists from 20 countries meet to form the WHO International Radon Project. (Photo courtesy WHO)

Based on their findings, WHO will issue guidelines intended to help national authorities develop, promote and strengthen activities at country or regional level.

The WHO fact sheets produced in the course of the project will be uses as communication tools to increase public awareness about radon.

A global radon database and a set of maps for pinpointing radon concentrations will be compiled as part of the project, and improved global estimates of the disease burden associated with radon will be calculated.

Overall, together with global tobacco control activities and initiatives on healthy indoor air, the project is expected to be a key step towards reducing lung cancer risk worldwide, WHO says.

Radon is a chemically inert, naturally occurring radioactive gas without odor, color or taste that emanates from the ground into the air. Radon gas in the air is present worldwide, its concentration depending on the variable uranium content of the soil.

Radon is produced from radium in the decay chain of uranium, an element found in varying amounts in all rocks and soil. Radon gas escapes easily from the ground into the air and emits ionizing radiation called alpha particles. These particles are electrically charged and attach to aerosols, dust and other particles in the air we breathe.

As a result, radon progeny may be deposited on the cells lining the airways where the alpha particles can damage the DNA and potentially cause lung cancer.

Radon exposure is the second most important risk factor for lung cancer, after tobacco smoking, causing between six and 15 percent of all cases. Yet, there is little public awareness of radon as a threat to human health, or the fact that can be mitigated with relatively simple measures.

The increased risk of lung cancer as a result of high radon exposure has been investigated in detail, and substantiated in many studies of uranium miners. Based on these studies, the International Agency for Research on Cancer, a WHO agency specializing in cancer, and the U.S. National Toxicology Programme have classified radon as a human carcinogen.

Pooled analyses of key studies in Europe, North America and China have confirmed that radon in homes "contributes substantially to the occurrence of lung cancers worldwide," WHO said. The pooling studies all agree on the magnitude of the risk estimates that run from six to 15 percent.

Dr. R. William Field is one of six U.S. scientists participating in the WHO International Radon Project. (Photo courtesy UI)

He was part of an international team of researchers who performed the combined analysis of the original residential radon studies, conducted in Connecticut, Iowa, New Jersey, Missouri, and Utah and South Idaho, as well as in Winnipeg, Canada. The original studies were funded from several federal sources, including the National Institute of Environmental Health Sciences and the National Cancer Institute.

The investigators' review of 3,662 cases and 4,966 controls from these combined studies represents the largest analytic radon epidemiologic study ever performed in North America.

"The North American and European pooling provides unambiguous and direct evidence of an increased lung cancer risk even at residential radon exposure levels below the U.S. EPA's action level," Field said in March.

The concentration of radon in a home depends on the amount of uranium producing the radon in the underlying rocks and soils as well as the routes available for its passage into the home and the rate of exchange between indoor and outdoor air.

Radon gas enters houses through openings such as cracks at concrete floor-wall junctions, gaps in the floor, small pores in hollow-block walls, and also sumps and drains. Radon levels are usually higher in basements, cellars or other structural areas in contact with soil, and, WHO says, the radon concentrations in houses directly adjacent to each other can be very different.

Radon exposure in homes can be easily mitigated during the construction of new homes, WHO says, but existing buildings can also be protected from radon. Most measures such as increasing under-floor ventilation and sealing cracks and gaps in the floor require simple alterations to the building, but other approaches may have to be taken in areas with high radon concentrations.

The five main ways of reducing the amount of radon accumulating in a house are:

• Improving the ventilation of the house and avoiding the transport of radon from the basement into living rooms
• Increasing under-floor ventilation
• Installing a radon sump system in the basement
• Sealing floors and walls
• Installing a positive pressurization or positive supply ventilation system

In Europe and the United States, the inclusion of protective measures in new buildings has become routine for some builders and in some countries has become a mandatory procedure. Passive systems of mitigation have been shown to be capable of reducing indoor radon levels by up to 50 percent. When radon ventilation fans are added, radon levels can be reduced further.

The International Radon Project intends to issue detailed recommendations on radon risk reduction that will target:

• The installation of mitigation devices at the time of construction versus retrofitting
• The incorporation of radon prevention and control measures in national building codes
• Radon testing, mitigation and inspection of existing passive/active systems at the time of sale for existing homes
• Control measures designed for medium and low radon exposure levels, which contribute most to the overall radon lung cancer burden
• The role of tobacco smoking in radon risk reduction programmes with a view to the overall goal of healthy indoor air
• The use of both voluntary guidelines and enforceable regulations
• Financial support mechanisms to assist radon mitigation actions in cases where such support is necessary to allow implementation of effective protection from radon health hazards