Section 1 - CHEMICAL PRODUCT AND COMPANY IDENTIFICATION

PRODUCT NAME

RADON-220

NFPA

PRODUCT USE

For the initiation of chemical reactions. Surface label for study of surface reactions. In
the determination of radium and thorium. In the study of the behaviour of filters. As a
source of neutrons in combination with beryllium and other light materials.
Antineoplastic. One of three isotopes formed by alpha- disintegration of radium and its
isotopes. Eighteen additional isotopes of radon (mass numbers 202- 224) have been produced
by various means. All the isotopes are radioactivity and possess short half- lives. With
the exception of Rn223 and Rn224, they are all beta- emitters which then decay by alpha-
emission or alpha- emission and e- capture in the case of the lightest isotopes. Although
considered as a " noble " chemically inert gas the preparation of radon fluoride has been
described.

SYNONYMS

Rn, "Nt (obsolete)", "Em (obsolete)", "radon gas", alphatron, niton, "radium emanation",
thoron

Section 2 - HAZARDS IDENTIFICATION

CANADIAN WHMIS SYMBOLS

EMERGENCY OVERVIEW

RISK

May cause CANCER.

POTENTIAL HEALTH EFFECTS

ACUTE HEALTH EFFECTS

SWALLOWED

  Considered an unlikely route of entry in commercial/industrial environments.  

EYE

  alpha-Radiation produces severe inflammation of eyelid tissue and eye surface. There may be a delay of years before symptoms develop. Cataracts can develop an are progressive, but their growth may stop at any stage.  The eye is particularly sensitive to radioactivity. A single dose of 1 Gy can cause inflammation of the conjunctiva and cornea. It is unlikely that a dose sufficient to cause radiation sickness would occur if only the eyes were involved. However, if eye damage caused by ionizing radiation occurs, it should be assumed that other parts of the body are involved.  

SKIN

  Considered an unlikely route of entry in commercial/industrial environments.  

INHALED

  Inhalation may produce health damage*.  alpha-Radiation kills cells immediately adjacent to the source of contact. Damage may be irreversible. Generally, soluble compounds are more easily absorbed. Smaller particles can lodge and remain in the alveoli (air sacs); larger ones are more easily swallowed. Damage depends on the speed of elimination, susceptibility of tissue, and radioactive damage. Even a single dose may produce radiation sickness.  A whole body dose of 2-10 Gray may cause loss of appetite, tiredness, nausea and vomiting,  most severe after 6-12 hours. After this subsides a gross disturbance in blood cell distribution occurs with loss of white blood cells and platelets over weeks. The activity of bone marrow may become so depressed that overwhelming infections can occur and cause death. A dose of 4 Gray can lead to damage of the bowel lining, causing untreatable nausea, vomiting and diarrhea, which may result in severe dehydration, collapse and death. Although repair of the damage may occur, failure of blood cell production can ensue. At 6 Gray, damage to the blood cell production and digestive systems can be fatal. Whole body doses of 30 Gray can cause nausea, vomiting, listlessness, drowsiness, weakness, tremors, convulsions, inco-ordination and death within hours. The reproductive organs are particularly sensitive to radiation. A does of 0.3 Gray can cause temporary loss of fertility in men; there may be cessation of periods in women.  

CHRONIC HEALTH EFFECTS

  There is sufficient evidence to suggest that this materialdirectly causes cancer in humans.  

  An excess of lung cancers have been reported in uranium, iron-ore and  other underground miners exposed to radon and its various decay products.  Cigarette smoking appears to synergise the effect. Increased incidence of  lung cancer have also been reported in individuals whose homes are in  high radon regions. The carcinogen in the case of radon is actually the  alpha-emitting short-lived daughters of radon, polonium 218 and 214.  these daughters are solids and deposit on the bronchial airway during  inhalation and exhalation according to the laws of diffusion. As the  airway lining (the bronchial epithelium) is only 40um thick, the alpha  particles emitted are able to transfer a significant amount of energy to  all the cells implicated in lung cancer induction. Some 8-15% of the solid  daughters do not attach to aerosol particles and this ultrafine species is  deposited with high efficiency in the upper bronchial airways. The rest  attach to aerosols of about 100 um average diameter and only a few percent  of these deposit on the airways. Lung cancers appear only on the first  few branching airways of the bronchial tree.  Occupationally exposed individuals or those resident in areas of high  natural radiation show an increased incidence of chromosomal aberration.  In 1992 the US EPA estimated that the number of deaths resulting from  radon exposure in the US was somewhere between 7000 and 30000. In 1994,  the results of a large Swedish survey yielded further evidence to support  the conclusion that "residential exposure to radon is an important cause  of lung cancer in the general population". Radon was measured in homes  occupied by cancer patients and controls since 1947 - the risk of lung  cancer increased in relation to estimated cumulative exposure to radon.  Elevated radon levels were estimated to be responsible for between 300 and  1500 lung cancer cases per year out of a population of only 8.5 million.  Swedens' radon problem may be due to high levels of uranium in the  countries rocks (eg granitic) and soil. Hong Kong also has high indoor  radon levels - mean levels in many high rise buildings are about 178  Bq/m3. At first sight this appears strange because very little is  encountered above the second floor level. In Hong Kong however the  main building materials have the highest average radon 226 levels in the  world. Local researchers have concluded that the most effective and  inexpensive way of reducing radon entry is to use wall-paper thus reducing  radon levels by as much as 80%. This is twice as effective as paint or  plaster depending on the type used.  In a further study unusually high levels of radon (up to 274000 Bq/m3) in  the village of Umhausen in the Austrian Tyrol, were identified. Houses  were built on a giant rock slide of granitic material that occurred 8700  years ago. The material in the rock was heavily fractured and has a large  diffusion coefficient for soil radon - the gas escapes very easily after  it forms. In this region the mean on the ground floor is 1868 Bq/m3 and in  the rest of the village 182 Bq/m3. The researchers were able to correlate  these remarkably high levels of radon with a statistically significant  increase in lung cancer mortality in the village. It is not clear however  whether the lower concentration found in most homes (20 Bq/m3) is a  significant threat to health. Indeed one study in the US reveals a  negative correlation between lung cancer and radon levels (the results  were confounded by the fact that a much greater risk exists from smoking).  Areas in the UK where 1% or more of house exceed an action level of  200 Bq/m3 are classified as "affected areas". Where more than 10% of  houses in an affected area exceed this level new houses are required to be  built with primary (radon-proof barrier) and secondary (radon sump and  extract pipe from ventilated sub-floor voids) protection measures.  Action levels have also been established, in the UK, for workplaces  (400 Bq/m3). However local National Service Health buildings in the UK  were consistently found to be above this level*. Hotspots were generally  restricted to smaller offices rather than wards or store rooms and  included several rooms no larger than 2m by 3m. A pilot study of four  locations above 400 Bq/m3 revealed that staff were receiving annual doses  of 5 mSv or more - greater than the occupational exposure of many  radiographers, radiotherapists and other health workers. Radon levels  appeared to be higher at night than in the day. Radon enters a building  from the ground because of reduced pressure in the building compared to  outside (the stack effect). At night, with doors shut and ventilation  reduced, the radon level rises. In the day, human activity results in open  doors and windows, and as a consequence, reduced radon levels. There are  no general rules to predict radon levels. A building, for example which is  on a sloping site, and which might have basement rooms at one end might be  expected to have high radon levels in these rooms. Measurements, however,  have shown that radon levels are high at the other end. Another study has  shown that radon progeny are less common in air-conditioned rooms  Some studies have suggested that radon might also be implicated in  leukaemia and in motor neuron disease. Other studies suggest that radon  progeny may be deposited on surfaces such as mains wires leading to  speculation that electromagnetic fields may cause cancer.  Radon-222 is a natural contaminant of ground waters and as such the  stomach is a critical organ exposed to radon and its daughters. After  about 4 hours only a few percent of ingested radon remains in the body;  this is located in adipose (fatty) tissues and is eliminated slowly.  Studies have suggested that there is a connection between high radon  levels in drinking water and gastric cancer mortality. The US EPA has a  proposed limit for drinking water is 11 Bq/l. Many parts of the world  using well water exceed this limit.  Very high levels of radon are also found in limestone caves. Mean levels  range between 450 to 155000 Bq/m3. The potential dose from a single  four-hour exposure might exceed the average annual dose of 1.25 mSv.  The effects of exposure to internally deposited alpha-emitters largely depends on the dose and target organs. Sufficiently high doses may produce radiation sickness. Possible disorders may include lung cancer, problems of sterility, anemia, leukemia or bone-  cancer. Leukemia and cataracts have been observed at doses lower than those which produce skin scarring and cancer or bone tumors. The lens of the eye should be considered as critical.  A single large or prolonged low exposure to radiation can cause delayed effects, including blood cancers, genetic disorders, shortened lifespan and cataracts. Leukemia is the most common cancer caused; cancers of the thyroid, bone, lung (due to radioactive particle deposits) and skin are also seen. Many and varied genetic changes can occur; if they affect cells of the reproductive system, they may only display themselves after being inherited.  P. Phillips et al: Chemistry in Britain pp 35-38, January 1997