Radon Facts You Should Know

Radon is the most potent carcinogen in our homes

You cannot see radon gas. And you cannot smell it or taste it. But it may be a problem in your home. That is because whenever you breathe air containing radon, you increase your risk of getting lung cancer. The primary site of radioactive exposure to most people is their home. "Radon in homes causes more deaths than fire, drowning and airplane crashes combined." (EPA)

Radon is a proven and very potent "Class A" carcinogen. Safety limits on toxins or carcinogens are set at levels thousand times less lethal than what is the risk from radon in an average American home. As the only gas in the decay chains of radioactive heavy metals, radon and its floating radioactive products can easily get into human body by inhalation. Radiation is called the "complete carcinogen" because, unlike chemical carcinogens, radiation alone can initiate, promote and propagate cancer.

The average person receives a higher radiation dose from radon at home than from all other natural or man-made sources combined. The National Academy of Sciences estimates that radon causes 19,000 cancer deaths in the U.S. each year, and the recent "Annual Report on Carcinogens 2000" attributes to radon 20,000 lung cancer deaths per year.

The lung cancer crises

After smoking, "radon is the second leading cause of lung cancer." (Surgeon General) Among non-smokers, radon is the No. 1 cause of lung cancer deaths.

Lung cancer has become the leading cancer killer of all Americans, both men and women, claiming 160,000 lives every year - more than breast cancer, prostate cancer, and colorectal cancer combined. Over 171,000 new lung cancers are diagnosed in the U.S. each year.

There is a lung cancer crises, particularly among women. Lung cancer deaths have increased by 20% among men during the past two decades, but by 150% among women, and in the 1990's alone, lung cancer deaths of white females have increased 60%.

Children are more susceptible to radon

Children are known to be more radiosensitive than adults. Analysis of Hiroshima victims showed a higher incidence of lung cancer among those who were exposed to the radiation blast as children. A single x-ray to the abdomen of a pregnant woman in the first six weeks of pregnancy leads to a 50 percent increase in cancer and leukemia risks to the child. The gamma rays emitted by radon progeny are far more energetic than x-rays, but the emitted alpha and beta particles are even more harmful.

Radiation risk to embryos is higher than to children, which in turn is higher than to adults. This increased sensitivity of children to radiation-induced cancers may be caused by their rapidly dividing cells and higher breathing rates. It is compounded by their heavier exposure to radon by spending more time inside the house and/or in the basement.
(Source: Dr. Gordon Edwards - Estimating Lung Cancers)

Recent research in Europe confirms that radon is much more harmful to children than to adults. Lung cancer incidence as a result of radon exposure is estimated to be about ten times higher for people exposed at the age of about 15 than at about 50.

A single radon atom can cause lung cancer

Carcinogens cause random damage to the chromosomes and DNA molecules contained in the nucleus of the cell. Most of these cells are either killed or sterilized. However, in a very few cases, one of these damaged cells may survive the injury and still be capable of reproducing. Such a cell may begin to proliferate in an undifferentiated or "cancerous" manner. Most cancers are of monoclonal origin, that is, they originate from damage to a single cell.

Even a single alpha particle can cause major genomic changes to the cell's DNA, including mutation and transformation. Since these effects take place in a random manner at the cellular level, there is no such thing as a "harmless" dose. Even allowing for a substantial degree of repair, the passage of a single alpha particle has the potential to trigger cancerous growth of cells, which it does not kill outright.

The problem is not radon, but rather the radioactive particles it produces. As radon atoms undergo radioactive decay, they disintegrate into radiation and radon progeny ("daughters") - solid heavy metal particles of lead, polonium, and bismuth. These minute electrically-charged and chemically active particles float in the air, and when breathed in, some of the particles (less than 1%) get trapped permanently in the airways. The accumulated radioactivity in the airways is proportional to the radon level: At the 4 pCi/L level, about 600,000 radioactive particles get trapped in the lungs every hour.

The deposition in lungs depends on whether the particles are attached to airborne dust or smoke, or unattached. Unattached daughters lodge deeper in the lung, which explains the severity and the type of deep-lung cancers in non-smokers.

The radon daughter particles are not dispersed throughout the body, but accumulate in the lungs and tracheobronchial tree, particularly in bifurcations. Since the bulky alpha particles cannot penetrate more than a fraction of a millimeter into the lung tissue before smashing into an atom, the damage is concentrated on the cells in the immediate area. The result of such concentrated radiation is much more severe than if the radioactivity was distributed throughout the body.

Alpha particles from radon do not even have to hit the cell

The Los Alamos National Laboratory researchers discovered in 1997 that alpha particles emitted by radon do not have to hit the nucleus of a cell to damage the cell's DNA, which resides in the nucleus. Moreover, the alpha particles do not even have to hit the cell; a bombardment of the surrounding medium produces chemical radicals inside the cells which cause DNA damage.

This negates the widely-held assumption that alpha particles cause genetic changes only through direct traversals of cell nuclei. Merely the interaction of alpha particles with the fluids that line the lungs damages the DNA of nearby cells. Exposure even to the lowest doses of alpha emission produces the very reactive chemicals within cells, and their production increases with the alpha-particle dose. This confirms that radon is dangerous even at very low levels - there is no "safe" threshold. The research also suggests that radon may be disproportionately more harmful at lower concentrations.

Minimize the radon level in your home!

Many of the 20,000 lung cancer deaths caused by radon in the U.S. each year are preventable. EPA has warned the public: "Any radon exposure has some risk of causing lung cancer. The lower the radon level in your home, the lower your family's risk of lung cancer." The 4 or 2 pCi/L "action" and "consider action" limits are merely cost/benefit guidelines for the population at large - EPA has left the radon mitigation decision and responsibility up to the individual homeowner.

You should always try to reduce the radon level in you home to a practical minimum. The target of the U.S. Radon Abatement Act is the natural level outdoors (average 0.4 pCi/L). Whether you current level is 30 or 3 pCi/L, also if a mitigation system is already installed, reducing radon in your home by 90 or 50 percent will reduce the risk to your family by 90 or 50 percent.