Toxins in Everyday Life - Radiation
radon water exposure energy
Radiation is energy that travels in waves or particles. Radiation exposure comes from natural and human-made sources. People are exposed to natural radiation from outer space (cosmic radiation), the Earth (terrestrial radiation and radon), and their own bodies. According to the U.S. Nuclear Regulatory Commission, these sources account for about 82 percent of the average person's radiation exposure. (See Figure 8.7.) Radon is, by far, the largest source of radiation exposure, at 55 percent. Human-made sources, mostly medical devices and electromagnetic equipment, account for 18 percent of a person's average radiation exposure.
In 1984 a worker in a nuclear plant triggered a radiation contamination alarm as he entered the plant to work. Since the alarms were intended to check for contamination as workers left the plant, plant officials were amazed. Investigations discovered the source of the worker's contamination was radon present in extraordinarily high amounts in his home.
Radon is an invisible, odorless radioactive gas formed by the decay of uranium in rocks and soil. This gas seeps from underground rock into the basements and foundations of structures via cracks in foundations, pipes, and sometimes through the water supply. Because it is naturally occurring, it cannot be entirely eliminated from homes.
Although there is no federal regulation addressing radon in indoor air, the EPA recommends that a resident take action if levels reach or exceed four picocuries per liter (pCi/L). The average indoor radon level is 1.25 pCi/L; the average outdoor level is 0.4 pCi/L. The EPA estimates that there are at least six million homes—one in 15 nationwide—with levels greater than four pCi/L, and 100,000 with levels greater than 20 pCi/L. The radon content in most homes can be reduced to 2 pCi/L or less by using devices such as specially designed fans that prevent radon from seeping into a house.
Radon inhaled into the lungs undergoes radioactive decay, releasing particles that damage the DNA in lung tissue. In June 2003 the EPA published its latest estimates of radon-related deaths in EPA Assessment of Risks from Radon in Homes. The report estimates that radon causes an estimated 21,000 deaths from lung cancer each year—the second leading cause of lung cancer after smoking. A synergistic effect has been noted: when radon levels are high in a home where a smoker resides, the likelihood of that person contracting lung cancer is greatly increased.
The EPA has proposed voluntary guidelines calling for builders to install protective measures in hundreds of thousands of new houses across the country to prevent radon from seeping in. The EPA recommends the testing of homes, which is generally quite inexpensive; home test kits are also available to homeowners. Radon contamination is addressed under the Superfund Amendments and Reauthorization Act of 1986 (PL 99-499).
The Indoor Radon Abatement Act of 1988 directed the EPA to identify areas of the country with the potential for elevated levels of indoor radon. The EPA assessed 3,141 counties in terms of geology, aerial radioactivity, soil permeability, foundation type, and indoor radon measurements. Each county was assigned to one of three zones based on its predicted average indoor radon screening level:
- Zone 1—predicted level greater than four pCi/L
- Zone 2—predicted level of two to four pCi/L
- Zone 3—predicted level less than two pCi/L
The EPA map of radon zones is shown in Figure 8.8. The map is not intended to indicate which homeowners should test their homes for radon, but to provide a general guide to state and local organizations dealing with radon abatement. The EPA cautions that homes with elevated levels of radon have been found in all three zones.
RADON IN DRINKING WATER.
In addition to exposure through the air, humans can also contact radon in drinking water. Radon gas can dissolve and accumulate in groundwater such as that found in wells. The EPA estimates that only about 1 to 2 percent of radon comes from drinking water. However, ingesting radon-contaminated drinking water can lead to the development of internal-organ cancers, primarily stomach cancer—although the risk is smaller than that of developing lung cancer from radon released to the air from tap water. The National Academy of Sciences report Risk Assessment of Radon in Drinking Water (1999), a study mandated by the Safe Drinking Water Act Amendments, estimates that radon in drinking water causes about 169 cancer deaths a year; 89 percent of those are caused by breathing radon released into the air from tap water while 11 percent are caused by consuming water that contains radon.
Not all water contains radon. Surface waters—such as rivers, lakes, or reservoirs—usually do not carry radon because the radon tends to evaporate before it has a chance to reach residences. Underground sources such as groundwater, however, may contain radon. Those who get water from a public water system that serves 25 or more year-round residents may obtain an annual water quality report that tells where the water comes from, what is in that water, and whether or not radon was found.
As of April 2004 there is no federally enforced drinking water standard for radon. The EPA has proposed two alternatives to the states and water agencies. The first is a maximum contaminant level of 300 pCi/L for radon in drinking water. The second alternative is a standard of 4,000 pCi/L if the state or water agency also implements a program to reduce indoor air radon. Neither proposal is popular with drinking water agencies, and the EPA continues to review the radon rule. A final ruling is expected by December 2004.
For homeowners who get their water from private wells—which would not be regulated—radon in the water can be reduced by using a carbon filter or aeration devices that bubble air through the water and carry radon gas out through an exhaust fan.
Earth produces electromagnetic fields (EMFs) naturally, such as during thunderstorms and deep within the planet's molten core. Electricity also occurs naturally in the human body where it can be measured by electroencephalograms of brain wave activity, or electrocardiograms of heart rhythms.
Electric power is a fact of life in America and the developed world. Many consumer and industrial products use some form of electromagnetic energy. While the danger of electric shock is well known, another concern has arisen about electric power—does it cause certain types of cancer, particularly leukemia and cancer of the central nervous system?
One type of electromagnetic energy that is of increasing importance worldwide is radio frequency (RF) energy, which includes radio waves and microwaves. RF energy is used for a wide array of applications including television broadcasting, cellular telephones, pagers, cordless phones, radio communications for police and fire departments, amateur radio, and satellite transmissions. In the United States the Federal Communications Commission (FCC) authorizes or licenses most RF telecommunications activities. Noncommunications uses of RF energy include microwave ovens, radar, and diathermy (the delivery of heat to body tissues for medical or surgical purposes).
The spectrum of electromagnetic waves ranges from extremely low-frequency energy to X-rays and gamma rays, which have very high frequencies. Frequency is the number of waves passing a given point in one second. (See Figure 8.9.) All humans are exposed to EMFs at some time during the course of a day, either from natural sources or sources produced by humans. Human-produced sources include electrical items found in the typical home or office. Most people are exposed to some level of EMF daily and that level can differ at different times of the day. (See Figure 8.10.)
Scientists have known for years that exposure to high levels of RF radiation can be harmful because of the ability of RF energy to heat biological tissue rapidly (this is the principle by which microwave ovens work). Two areas of the body, the eyes and the testes, are known to be particularly vulnerable to RF heating. RF radiation, even in low levels, has caused cataracts and sterility in laboratory rabbits.
In 1996 the U.S. Public Health Service reviewed the scientific data on EMFs and determined the following:
In total, the epidemiological data on both residential and occupational exposures show a moderate risk of cancer, generally between 1.1 and 3.0 times, for adults and children exposed to magnetic fields. This is not extremely large relative to other known risks (for example, the smoking-related risk of approximately 10 or the asbestos-related risk of 5). However, what is unusual about magnetic field exposures is that they are universal. Virtually all of us are exposed.… This means that (a) the observed risk may be underestimated because we cannot identify a truly unexposed comparison group; (b) because of the widespread exposure, even a small risk may result in a large number of individual cancers.
The Public Health Service concluded that "the cost of mitigation [cleanup] already instituted far exceeds the health protection offered, and mitigation of other environmental risks is more important. From a cost-benefit view only limited, low-cost mitigation should be considered."
In its 1999 Questions and Answers about Biological Effects and Potential Hazards of Radiofrequency Electromagnetic Fields, the FCC reported: "Environmental levels of RF energy routinely encountered by the general public are far below levels necessary to produce significant heating and increased body temperature. However, there may be situations, particularly workplace environments near high-powered RF sources, where recommended limits for safe exposure of human beings to RF energy could be exceeded. In such cases, restrictive measures or actions may be necessary to ensure the safe use of RF energy."
Nonetheless, some scientists have continued to suggest that exposure to electric and magnetic fields generated by electric power is responsible for certain cancers (particularly among children), reproductive dysfunction, birth defects, neurological disorders, and Alzheimer's disease. Some activist groups allege the hazards to be so great that they have called for the closure of schools and other public facilities near power lines, and restructuring of the entire power delivery system. EMFs are even cited as causing decreases in property values. Some utilities, with equally strong beliefs, claim there is no proof of risk.
In response to concern about the risks of EMFs, in 1992, under the Energy Policy Act of 1992 (PL 102-486), Congress authorized the Electric and Magnetic Fields Research and Public Information Dissemination Program. The program mandated that the National Institute of Environmental Health Sciences (NIEHS), the National Institutes of Health (NIH), and the U.S. Department of Energy (DOE) research any possible link between EMFs and health. In 1998 an international panel of 30 scientists met to consider the evidence. In 1999 the panel issued its findings in Health Effects from Exposure to Power-Line Frequency Electric and Magnetic Fields.
The report found that the evidence was lacking to prove EMFs were a "known human carcinogen" or "probable human carcinogen," and thus EMFs did not warrant aggressive regulatory action. However, a majority of the members concluded that exposure to power-line frequencies is a "possible human carcinogen." The NIEHS concluded that EMF exposure cannot be recognized as entirely safe because of weak scientific evidence that exposure may pose a leukemia hazard. However, because virtually everyone in the United States uses electricity and is thus exposed, the panel recommended research into ways to reduce exposure. The researchers found no indication of increased cancer incidence in experimental animal studies. The strongest evidence of any connection between EMF exposure and cancer came from observations of human populations, although the scientists noted that some other factor could explain the findings, especially since the correlation was weak, at best.
In 1998 the FCC studied EMF emission levels of cellular phones, vehicle-mounted antennas, and fixed transmitting antennas used for such devices. In Information on Human Exposure to Radiofrequency Fields from Cellular and PCS Radio Transmitters, the FCC reported that a human would have to remain within a few feet of a main transmitting beam for extremely long periods of time to be exposed to levels of RF energy in excess of recognized safety levels. In addition, the study noted that, regarding vehicle antennas, vehicle occupants are effectively shielded by the metal auto body, especially when the antennas are mounted in the center of the roof or trunk. The study yielded similar results for handheld cellular devices—exposures vary greatly depending on use. Nevertheless researchers continue a number of programs to study EMFs.
As reported in "Exposure to Power-Frequency Magnetic Fields and the Risk of Childhood Cancer," (Journal of the American Medical Association, February 2000) the American Medical Association (AMA), after conducting a study of the possible link between EMFs and childhood leukemia, found no evidence that exposure to EMFs increased the risk for childhood cancer.
In June 2002 researchers at Finland's Radiation and Nuclear Safety Authority announced that exposure to cellular phone radiation had been shown to increase activity in human cell proteins grown in the laboratory. More research was recommended to determine the seriousness of these changes and their possible health effects, particularly in the brain.
The huge growth in cellular phone use has brought renewed attention to the potential dangers of EMF exposure, particularly since the phone is held so close to the brain. More than 140 million Americans were cellular phone subscribers in 2003, compared to only 16 million in 1994. Worldwide subscribership is expected to reach two billion by 2006. In May 2001 the U.S. General Accounting Office (GAO) recommended that the FCC improve cellular phone testing and urged both the FCC and the Food and Drug Administration (FDA) to improve consumer information regarding EMF exposure and related health issues.
The FCC requires wireless phones sold in the United States to demonstrate compliance with human exposure limits for radiofrequency energy. The value used to describe the relative amount of this energy absorbed by a person's head while using a wireless phone is called the Specific Absorption Rate (SAR). The FCC safety limit for wireless phones is 1.6 watts per kilogram. Consumers can look up the SAR for a particular phone model using an FCC identification number printed on the case of the phone. Instructions for using the SAR database are available at http://www.fcc.gov/oet/rfsafety/sar.html.