Radon gas is a naturally occurring by-product of uranium. It actually seeps from the ground and is present all around us, such that all people are exposed to naturally occurring radioactivity in our soil, water, air, and food. Radon may also be present in drinking water, which presents two concerns: ingestion of waterborne radioactive particles and inhalation of radioactive particles. Drinking water with concentrations of uranium above the USEPA’s maximum contaminant level (MCL) of 30 μg/L and over an extended period of time (70 years) may increase one’s lifetime risk of developing certain types of cancer, e.g., renal, and may present a theoretical risk of developing stomach cancer; however, no human study evidence has ever supported such a causal relationship in humans.
The main exposure concern from radon stems from its volatile release from tap water into household air which thus adds to the ambient radon already present in the indoor environment. According to the USEPA, in sufficient quantities, breathing radon released to the air from tap water increases the risk of lung cancer over the course of one’s lifetime.
Radon is ubiquitous and every person is exposed to it in potentially cancer-causing levels.
Radiation is a natural part of the environment. All people receive exposure from naturally occurring radioactivity in soil, water, air and food. The largest fraction of natural radiation comes from a radioactive gas, radon. Radon is emitted from uranium, a naturally occurring mineral in rocks and soil. Low levels of radon are present in all the air we breathe. Radon gas has no taste or odor and cannot be detected by a person’s senses. Most of the radon gas that enters a building comes directly from soil that is in contact with or beneath the basement or foundation of the building.
Radon is also found in well water and will enter a home whenever water is used. Approximately half of the drinking water in the United States comes from ground water that is tapped by wells. Despite this, the primary exposure route and public health risk from radon is not from drinking, but rather through breathing.
The National Academy of Sciences (NAS) concluded that radon can cause lung cancer when inhaled over many years. In fact, breathing radon in the indoor air of homes contributes to about 20,000 lung cancer deaths each year in the United States. By contrast, the USEPA estimates that radon in drinking water causes only about 168 cancer deaths per year. In short, radon in the air is approximately 120 times more significant than radon in water with respect to inducing a cancer risk.
In recognition of these risks, the USEPA proposed new regulations to reduce the public health risks from radon on November 2, 1999, in the Federal Register (64 FR 59246). Under these proposed regulations, states could then choose to develop enhanced state programs to address the health risks from radon in indoor-air, known as Multimedia Mitigation (MMM) programs, while individual water systems would have to reduce radon levels in drinking water to the proposed upper limit of 4,000 pCi/L or lower.
If a state chose not to develop an MMM program, individual water systems in that state would be required to either reduce radon in their system’s drinking water to 300 pCi/L or develop individual local MMM programs and reduce levels in drinking water to the 4,000 pCi/L limit. Water systems already at or below the 300 pCi/L standard would not be required to treat their water for radon. The purpose of the proposed regulation is to encourage states to educate community members of the full scope of risk, that is, to indoor air and water, not just water.
Radon gas exposure medical expert witness specialties include oncology, toxicology, pulmonology, occupational medicine, internal medicine, and radiology.