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R. William Field, Ph.D., M.S. Associate Professor

Residential Radon Exposure – A Leading Environmental Health Risk: Why we need to take action in (insert your region)?. Top 10 List. R. William Field, Ph.D., M.S. Associate Professor Department of Occupational and Environmental Health Department of Epidemiology College of Public Health

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R. William Field, Ph.D., M.S. Associate Professor

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  1. Residential Radon Exposure – A Leading Environmental Health Risk: Why we need to take action in (insert your region)? Top 10 List R. William Field, Ph.D., M.S. Associate Professor Department of Occupational and Environmental Health Department of Epidemiology College of Public Health 104 IREH University of Iowa Iowa City, IA 52242 Bill-field@uiowa.edu

  2. Why is the evidence ignored or not accepted ?? • Invisible, odorless, colorless • Naturally occurring (no villains) • Can not link deaths to radon exposure • Long latency period • Not a dread hazard • Cancers occur one at a time • Voluntary risk • Lack of press – no sensational story • No sensory reminders to repetitively stimulate us to think about it • Lung cancer does not occur in children

  3. Radon Mines

  4. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #1 There is widespread potential for radon exposure in homes coast to coast as well as workplaces!

  5. U.S. Radon Potential Many parts of the country have elevated radon concentrations. Map developed as basis for radon control techniques in new construction.

  6. Insert slide here describing radon occurrence in year area of interest Radon maps can be found here: http://www.epa.gov/radon/zonemap.html

  7. Radon Radium Uranium What Is Radon –222 (radon)? • Radon is a gas • It is naturally occurring • You can not see or smell it • It enters buildings from the soil beneath them 3.8 days 1,600 years 4.5 billion years

  8. Emanation 2 - 5% Water < 1% Soil Gas 85 - 90% Diffusion 1 - 4% Radium Containing Soil Radium Containing Soil Average Contributions From Radon Sources In U.S. Homes • The movement of soil gas into a home is the predominant entry route. • These are averages - a particular home can be different!

  9. < 5 5-6 10 Radon Gas Spatial Distribution • Radon enters from beneath foundation and travels upward. • Diluted with outdoor air infiltrating building • If radon is less than 4 pCi/L in lower level, one can say with reasonable confidence that upper floors are also less than 4 pCi/L.

  10. Occupational Exposure to Radon – Very Common • Mine workers, including uranium, hard rock, and vanadium • Workers remediating radioactive contaminated sites, including uranium mill sites and mill tailings • Workers at underground nuclear waste repositories • Radon mitigation contractors and testers • Employees of natural caves • Phosphate fertilizer plant workers • Oil refinery workers • Utility tunnel workers

  11. Subway tunnel workers • Construction excavators • Power plant workers, including geothermal power and coal • Employees of radon health mines • Employees of radon balneotherapy spas (waterborne 222Rn source) • Water plant operators (waterborne 222Rn source) • Fish hatchery attendants (waterborne 222Rn source) • Employees who come in contact with technologically enhanced sources of naturally occurring radioactive materials • Incidental exposure in almost any occupation from local geologic 222Rn sources • Plowing?

  12. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #2 Outdoor radon exposure can be significant!

  13. Outdoor 222Rn Concentrations

  14. Outdoor Radon in Iowa National INDOOR Average 1.4 pCi/L

  15. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #3 Alpha particles are very effective at causing DNA damage!

  16. Radon Decay Products Radon Radon Why Is Radon A Concern? • Radon decays into radioactive particles known as radon decay products. • These particles are easily inhaled and deposited in the lungs where they can damage sensitive lung tissue.

  17. Radon Radon What Happens When Radon-222 Enters a House? • Radon enters home. • Radon radioactively decays into RDPs in the air. • Some RDPs remain in the air. • Some RDPs plate out on surfaces. RDPs RDPs

  18. 4 day Radon-222 a,g 3 min Polonium-218 a,g 27 min Lead-214 b,g 20 min Bismuth-214 b,g 0.2 ms Polonium-214 a,g Lead-210 22 yrs b,g Bismuth-210 5 day b,g Polonium-210 138 day a,g Lead-206 Stable 218Po and 214Po deliver the radiologically significant dose to the respiratory epithelium. Radon Progeny

  19. + + + +2 + + + + + + 4He + 218Po Radon - 222 Alpha  Decay 4He Nucleus Ejected from 222Rn Nucleus

  20. What Happens When Radon Decay Products Are Inhaled? • Highly radioactive particles adhere to lung tissue, where they can irradiate sensitive cells. • Radiation can alter the cells, increasing the potential for cancer. Double Strand Breaks

  21. Ionizing radiation can directly and indirectly damage DNA Free radical formation Alpha Particle Double –strand DNA breaks Defects in tumor suppressor genes – p53 At risk individuals–GSTM1 (glutathione S-transferase M1)

  22. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #4 For the average individual in the United States – Radon decay products (radon) deliver over 50% of our average radiation dose! For the average, Iowan it represents well over 75%!!

  23. Annual Effective Dose Equivalent to Member of the U.S. Population NCRP 93 (1987) Natural(mrem) Radon 200 Cosmic 27 Terrestrial: -external 28 -internal 39 Artificial (mrem) -Diag. X-rays 39 -Nuc. Med. 14 -Consumer Pro. 10 -Other ~1 TOTAL ~360

  24. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #5 Waterborne radon also contributes to our overall radon exposure!

  25. Waterborne Radon Primarily from groundwater sources (wells) rather than rivers Waterborne radon to air ratio 10,000 : 1

  26. Proposed Waterborne Radon Standard • EPA proposed new regulations November 2, 1999 (64 FR 59246). • 300 pCi/L standard for public water supplies • Multimedia Mitigation (MMM) programs -- while individual water systems reduce radon levels in drinking water to 4,000 pCi/L or lower

  27. Pipe scale Highest waterborne radon concentrations (> 10,000 pCi/L) in Iowa have been attributed to radium adsorbed pipe scale.

  28. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #6 National and International Public Health Agencies support the contention that radon is a leading environmental health risk!

  29. EPA & Surgeon General Recommend Take action if a home is at or above 4.0 pCi/L (year long average) 4.0 pCi/L EPA ACTION LEVEL Average indoor: 1.3 – 1.4 pCi/L Average outdoor: 0.4 pCi/L

  30. How Does Radon Rank As A Cancer Causing Agent? • Radon is ranked as a Group A carcinogen • Highest ranking for cancer potential • Known to cause cancer in humans • Tobacco smoke and tobacco products in same category International Agency for Research on Cancer

  31. “Radon Is A Serious National Health Problem” • American Lung Association • American Medical Association • Environmental Protection Agency • National Academy of Sciences • National Council on Radiation Protection and Measurement • U.S. Surgeon General • World Health Organization, and others…..

  32. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #7 Laboratory studies using different species of radon-exposed animals clearly show a linear dose- response relationship between radon and lung cancer.

  33. Animal Studies Confirm carcinogenicity of radon. Exposure to ore dusts and diesel fumes, simultaneously with radon, did not increase incidence of lung cancer above that produced by radon progeny exposures alone. (DOE/OER 1988)

  34. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #8 Studies of occupationally-exposed miners clearly show a linear relationship between radon exposure and lung cancer!

  35. Early Radon Related Epidemiology 1556 Agricola - Miners in Europe 1879 Harting & Hesse - Lung Cancer in Miners 1921 Uhlig - Radium Emanations & Lung Cancer 1950s Peller - First Review of Mining Related Cancers 1970s (ongoing) – Studies of Underground Miners

  36. Original Scientific Basis For Radon Risk Estimates • Studies on miners. • Uranium miners in U.S. and other countries

  37. EPIDEMIOLOGIC MINER STUDIES China (Tin Miners) Czechoslovakia (Uranium) Colorado (Uranium) Ontario (Uranium) Newfoundland (Florspar) Sweden (Iron) New Mexico (Uranium) Beaverlodge (Uranium) Port Radium (Uranium) Radium Hill (Uranium) France (Uranium)

  38. Dose Response Model Linear Non-Threshold Theory Atomic Bomb Survivors Observed Effects Underground Miners Medical Patients Adverse Health Effects ? ? ? Dose (rem)

  39. Occupational Miner Studies • Linear dose response relationship was found for all the occupational studies. • A 1994 NCI pooled analyses of 68,000 miners concluded that about 39% of the lung cancer deaths among smokers and 73% of the lung cancer deaths among never-smokers may have been due to their occupational radon progeny exposure. • Projecting risks to the residential setting they concluded that radon progeny may be responsible for 10 – 12% of lung cancers in smokers and 28 -31% in never-smokers.

  40. National Academy of SciencesBEIR VI 1999 • Risk estimates based primarily on radon-exposed miners • Estimated 18,600 lung cancer deaths each year in the U.S. from residential radon exposure EPA Estimates 21,000

  41. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #9 Case-control studies of individuals exposed to radon in their homes show an increased lung cancer risk even at or below the EPA’s action level of 4 pCi/L (150 Bq/m3).

  42. N. American Pooling ___________________________________________________________ Study Cases Controls ___________________________________________________________ New Jersey 480 442 Winnipeg 738 738 Missouri - I 618 1,402 Missouri – II 697 700 Iowa 413 614 Connecticut 963 949 Utah/S. Idaho 511 862 _______________________________________ Total 4,420 5,707

  43. Basement and Living Area Radon Concentrations for U.S. Residential Radon Studies. 1Summary data represent those homes that were measured with no imputed (values added to replace missing values) values.

  44. International Pooling of Residential Radon Case-Control Studies New Jersey, Missouri I, Canada, Iowa, Missouri II, a combined study from Connecticut, Utah and S. Idaho Shenyang, China, Stockholm, Sweden, Swedish nationwide, Winnipeg, Canada, S. Finland, Finnish nationwide, SW England, W. Germany, Sweden, Czech Republic, Italy-Trento, Spain, Austria, France, China - Gansu Province, E. Germany 10% – 18% 16%

  45. 2.2 2.0 1.8 1.6 Odds Ratio 1.4 WLM20 1st Story 1.2 BR BR/LR LR 1.0 Basement 0.8 Risk Estimates for Alternative Models(live cases and controls) Complete exposure Other location radon concentrations only 20-39% 40-59% 60-79% 80+% JEAEE 12(3): 197-203, 2002

  46. Iowa Study Summary • The findings suggest that prolonged exposure to radon, even at 4 pCi/L, increases lung cancer risk. • These findings indicate that radon is a major environmental carcinogen.

  47. Residential Radon Exposure – A Leading Environmental Health Risk: What is the Evidence?WHAT IS THE EVIDENCE #10 Radon exposure represents a major source of cancer mortality in the United States!

  48. LUNG CANCER DEATHS Per Year Estimated 163,510 Lung Cancer Deaths in 2005* Attributed to Radon Approximately 21,000 EPA 2003 *CA: A Journal for Clinicians - 2005

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