Radiation and Human Beings

A study commissioned by Tehelka newspaper found that four-fifths of the Capital’s area is exposed to “unsafe” radiation levels. While this is genuine cause for concern, such radiation only constitutes the tip of the proverbial iceberg.  Far more dangerous radiation sources surround us night and day: bricks, and other building materials.

Radiation and cell phone radiation: the picture

There are two types or radiation:
  (1) ionizing which knocks electrons from atoms producing ions, ex. x-rays, and (2) nonionizing, which usually does not dislodge the electron and is considered not as hazardous as ionizing radiation, for it only heats the surface layers of its target. The radiation from mobile phones and cell towers is believed to be of the second, less harmful kind.

Tests on animals showed  no harmful effects of radiation from cell phones. WHO in 2005 based upon the consensus view of the scientific and medical communities, stated that cancer is unlikely to be caused by cellular phones or their base stations and that reviews have found no convincing evidence for other health effects. European Commission in 2009 echoed that exposure to radio frequency fields is unlikely to lead to an increase in cancer in humans. Studies in other countries like Britain, Germany, Swedan shows similar findings.

There is however another problem. The heat created by impinging radiation can indeed damage cells by overheating them. Since radio waves from a mobile telephone handset are absorbed  by the part of the body adjacent to the phone, this causes heating of the tissue. While normal blood flow easily takes care of small amounts of heat, there is concern that prolonged use could cause headaches, fatigue, tissue swelling, tingling and, potentially, long-term damages.

The bigger worry: ionizing radiation

A greater worry is the ionizing radiation which is constantly present in the environment and is emitted from a variety of natural and artificial sources. This is called background radiation and one of its primary contributions is  from the atmosphere, in form of radon gas which is released from the Earth's crust and subsequently decays into radioactive atoms that become attached to airborne dust and particulates. Other radioactive materials such as thorium are present in significant amounts in many sorts of rocks, other building materials and in the soil.

Listed below are a few of common building materials and their estimated levels of uranium, thorium and potassium.

Material Uranium Thorium Potassium
ppm mBq/g (pCi/g) ppm mBq/g (pCi/g) ppm mBq/g (pCi/g)
Granite 4.7 63 (1.7) 2 8 (0.22) 4.0 1184 (32)
Sandstone 0.45 6 (0.2) 1.7 7 (0.19) 1.4 414 (11.2)
Cement 3.4 46 (1.2) 5.1 21 (0.57) 0.8 237 (6.4)
Limestone concrete 2.3 31 (0.8) 2.1 8.5 (0.23) 0.3 89 (2.4)
Sandstone concrete 0.8 11 (0.3) 2.1 8.5 (0.23) 1.3 385 (10.4)
Dry wallboard 1.0 14 (0.4) 3 12 (0.32) 0.3 89 (2.4)
By-product gypsum 13.7 186 (5.0) 16.1 66 (1.78) 0.02 5.9 (0.2)
Natural gypsum 1.1 15 (0.4) 1.8 7.4 (0.2) 0.5 148 (4)
Wood - - - - 11.3 3330 (90)
Clay Brick 8.2 111 (3) 10.8 44 (1.2) 2.3 666 (18)
ppm- Part Per Million; mBq/g- Megabecquerel Per Gram (One Bq is the activity of a quantity of radioactive material in which one nucleus decays per second); pCi/g- Picocuries Per Gram (Picocurie is the amount of radioactivity in a particular solid substance.)

Other sources of ionizing radiation

Other natural and man-made sources of this ionizing radiation are
  • Radioactive material in earth. These include sources in food and water, which are incorporated in the body, and in building materials and other products that incorporate those radioactive sources
  • From space, in form of cosmic rays: flight crew are at particular risk, because of the reduced filtering by our atmosphere at cruising altitudes.
  • From the radioactive atoms produced in the bombardment of atoms in the upper atmosphere by high-energy cosmic rays.

Naturally occurring sources are responsible for the vast majority of radiation exposure. About 3% of background radiation comes from man-made sources such as:

  • Self-luminous dials and signs
  • Global radioactive contamination due to historical nuclear weapons testing
  • Nuclear power station or nuclear fuel reprocessing accidents (though these are rare)
  • Normal operation of facilities used for nuclear power and scientific research
  • Emissions from burning fossil fuels, such as coal fired power plants
  • Emissions from nuclear medicine facilities and patients

Damage ionizing radiation can cause

The body has repair mechanisms against damage induced by radiation as well as by chemical carcinogens. Consequently, biological effects of radiation on living cells may result in three outcomes: (1) injured or damaged cells repair themselves, resulting in no residual damage; (2) cells die, much like millions of body cells do every day, being replaced through normal biological processes; or (3) cells incorrectly repair themselves resulting in a biophysical change.

The degree of damage caused by radiation depends on many factors - dose, dose rate, type of radiation, the part of the body exposed, age and health. Some of the symptoms of radiation sickness -- the result of extreme exposure, as for instance faced by atom bomb victims -- include actual burns to the skin, nausea, vomiting, and diarrhea, and can cause death.

Radiation and Cancer

The correlations between radiation exposure and the development of cancer are mostly based on populations exposed to relatively high levels of ionizing radiation (e.g., Japanese atomic bomb survivors, and recipients of selected diagnostic or therapeutic medical procedures). Cancers associated with high dose exposure (greater than 50,000 mrem) include leukemia, breast, bladder, colon, liver, lung, esophagus, ovarian, multiple myeloma, and stomach cancers.

The US Department of Health and Human Services literature also suggests a possible association between ionizing radiation exposure and prostate, nasal cavity/sinuses, pharyngeal and laryngeal, and pancreatic cancer.

Although radiation may cause cancers at high doses and high dose rates, currently there are no data to unequivocally establish the occurrence of cancer following exposure to low doses and dose rates -- below about 10,000 mrem (100 mSv). Those people living in areas having high levels of background radiation -- above 1,000 mrem (10 mSv) per year-- such as Denver, Colorado have shown no adverse biological effects.

How to reduce ionizing radiation?
  • Do not sleep with your head near a wall.
  • Ventilate well, particularly basements
  • Be selective in use of construction materials
How to avoid cell phone radiation?
  • Use hands-free to decrease the EMR radiation to the head, and ensure that a ferrite bead is clipped to the headset to absorb radiation.
  • Keep the mobile phone away from the body, and use a speaker phone.
  • Do not use telephone in a car without an external antenna.
  • Use a landline for longer telephone calls.
  • Avoid using your cell phone in metallic enclosures such as elevators, where radiation has nowhere to go but into your body.
  • Use a cell phone radiation shield. Many companies offer such shields.
  • Look for the SAR number of the mobile phone before buying it. SAR, Specific Absorption Rate is the measurement rate at which radiation absorbed by the human body is measured. Lower number indicates a lower radiation exposure risk. Every cell phone model sold in the US has  SAR information in its manual.