RADON TOXICITY. Case Studies in Environmental Medicine

Transcription

1 Case Studies in Environmental Mediine Course: SS3045 Revision Date: Marh 2000 Original Date: September 1995 Expiration Date: June 30, 2003 RADON TOXICITY Environmental Alert In the United States, indoor radon exposure might result in 7,000 30,000 lung aner deaths annually. Radon might be seond only to smoking as a ause of lung aner, and the ombination of smoking and radon exposure results in an espeially serious health risk. Using urrent tehnology, the risk of lung aner due to indoor radon exposure an be dereased. This monograph is one in a series of self-instrutional publiations designed to inrease the primary are provider s knowledge of hazardous substanes in the environment and to aid in the evaluation of potentially exposed patients. This ourse is also available on the ATSDR Web site, atsdr.d.gov/hec/csem/. See page 3 for more information about ontinuing medial eduation redits, ontinuing nursing eduation units, and ontinuing eduation units. U.S. DEPARTMENT OF HEALTH AND HUMAN SERVICES Ageny for Toxi Substanes and Disease Registry Division of Health Eduation and Promotion

2 Revision Content Experts: Darlene Johnson, RN, BSN, MA; Ralph O Connor Jr, PhD; Osar Tarrago, MD, MPH; Pamela Tuker, MD Revision Planners: William Carter, MD; Diane Dennis-Flagler, MPH; Patriia Drehobl, RN, BSN; Kim Gehle, MD, MPH; Darlene Johnson, RN, BSN, MA Revision Edited By: Pamela S. Wigington, Beverly Harris Original Contributor: Mark Upfal, MD, MPH Original Peer Reviewers: Charles Beker, MD; Jonathan Borak, MD; Bernard Goldstein, MD; Alan Hall, MD; Rihard J. Jakson, MD, MPH; Jonathan Rodnik, MD; Linda Rosenstok, MD, MPH; Robert Wheater, MS; Brian Wummer, MD Dislaimer The state of knowledge regarding the treatment of patients potentially exposed to hazardous substanes in the environment is onstantly evolving and is often unertain. In this monograph, ATSDR has made diligent effort to ensure the auray and urreny of the information presented, but makes no laim that the doument omprehensively addresses all possible situations related to this substane. This monograph is intended as an additional resoure for physiians and other health professionals in assessing the ondition and managing the treatment of patients potentially exposed to hazardous substanes. It is not, however, a substitute for the professional judgment of a health are provider. The doument must be interpreted in light of speifi information regarding the patient and in onjuntion with other soures of authority. Use of trade names and ommerial soures is for identifiation only and does not signify endorsement by the Ageny for Toxi Substanes and Disease Registry or the U.S. Department of Health and Human Servies. Table of Contents Case Study... 5 Pretest... 5 Who s at Risk... 5 Exposure Pathways... 8 Physiologi Effets Treatment and Management Radon Detetion Radon Abatement Standards and Regulations Suggested Reading Answers to Pretest and Challenge Questions Soures of Information Posttest Tables and Figures Table 1. Radon Risk Evaluation if You Smoke Table 2. Radon Risk Evaluation if You Have Never Smoked Table 3. Residential Standards and Regulations for Radon Table 4. Oupational Standards and Regulations for Radon Figure 1. Soures of Radon and Common Entry Points... 8 Figure 2. Subslab Depressurization ATSDR Publiation No.: ATSDR-HE-CS

3 Case Studies in Environmental Mediine (CSEM): Radon Toxiity Radon Toxiity Goals and Objetives The goal of the CSEM is to inrease the primary are provider s knowledge of hazardous substanes in the environment and to aid in the evaluation of potentially exposed patients. Instrutions See page 4 After ompletion of this eduational ativity, the reader should be able to disuss the major exposure route for radon, desribe two potential environmental and oupational soures of exposure to radon, state two reasons why radon is a health hazard, desribe three fators that ontribute to radon toxiity, identify evaluation and treatment protools for persons exposed to radon, and list two soures of information on radon. Areditation Continuing Medial Eduation (CME) AMA: The Centers for Disease Control and Prevention (CDC) is aredited by the Areditation Counil for Continuing Medial Eduation (ACCME) to provide ontinuing medial eduation for physiians. CDC designates this eduational ativity for a maximum of 1.5 hours in ategory 1 redit toward the Amerian Medial Assoiation (AMA) Physiian s Reognition Award. Eah physiian should laim only those hours of redit that he/she atually spent in the eduational ativity. AAFP: This ativity has been reviewed and is aeptable for 1.5 presribed hours by the Amerian Aademy of Family Physiians (AAFP). ACEP: This ativity has been approved by the Amerian College of Emergeny Physiians (ACEP) for 1.5 hours per issue of ACEP ategory 1 redit. AOA: This issue has been approved by the Amerian Osteopathi Assoiation (AOA) for 1.5 redit hours of ategory 2-B redit. Continuing Nursing Eduation (CNE) This ativity for 1.6 ontat hours is provided by CDC, whih is aredited as a provider of ontinuing eduation in nursing by the Amerian Nurses Credentialing Center s Commission on Areditation. Continuing Eduation Units (CEU) CDC has been approved as an Authorized Provider of ontinuing eduation and training programs by the International Assoiation for Continuing Eduation and Training and awards 0.1 ontinuing eduation units (CEUs). 3

4 The questionnaire and posttest must be ompleted and returned eletronially, by fax, or by mail for eligibility to reeive ontinuing eduation redit. Instrutions for Completing CSEM Online 1. Read this CSEM, Radon Toxiity; all answers are in the text. 2. Link to the online learner support system, CDC/ATSDR Training and Continuing Eduation Online, at 3. One you aess the PHTN online system, reate a partiipant profile and login to the system. 4. Searh the atalog and find this ourse, Case Studies in Environmental Mediine: Radon Toxiity. 5. Follow instrutions to selet the type of ontinuing eduation redit you want and register for the ourse. 6. Complete the ourse evaluation and posttest no later than June 29, If you sore 70% or better on the posttest, you will be able to immediately print your ontinuing eduation ertifiate from your personal transript. Note: Even if you are not interested in reeiving ontinuing eduation redit, please omplete the ourse evaluation. To only evaluate the ourse, selet 0 Audit when presented with the redit seletion list. We will appreiate reeiving your input. Instrutions for Completing CSEM On Paper 1. Read this CSEM, Radon Toxiity; all answers are in the text. 2. Complete the evaluation questionnaire and posttest, inluding your name, mailing address, phone number, and address, if available. 3. Cirle your answers to the questions. To reeive your ontinuing eduation redit, you must answer all of the questions. 4. Sign and date the posttest. 5. Return the evaluation questionnaire and posttest, no later than June 1, 2003, to CDC by one of the following methods: Mail or Fax Continuing Eduation Coordinator Division of Health Eduation and ATTN: Continuing Eduation Coordinator Promotion, ATSDR MS E-33, 1600 Clifton Road, NE Atlanta, GA If you sore 70% or better on the posttest, you will reeive an award ertifiate within 90 days of submitting your redit forms. No fees are harged for partiipating in this ontinuing eduation ativity. 4

5 Case Study A 56-year-old housewife seen at your offie has a 3-month history of hroni, nonprodutive ough, whih has reently beome unresponsive to over-the-ounter liquid ough suppressants. She denies having shortness of breath, wheezing, hest pain, hemoptysis, fever, hills, sore throat, hoarseness, or postnasal drip. Her ough is independent of time of day, physial ativity, weather onditions, and exposure to dust or household leaning agents. Furthermore, her daughter s igarette smoke does not seem to aggravate the ough. She notes that she has been feeling fatigued and, without dieting, has lost 18 pounds over the past 6 months. Her past medial history is nonontributory. She does not smoke or drink alohol and does not ome in ontat with any known hemial substanes or irritants other than typial household leaning agents. Her father died at age 65 of a myoardial infartion, and her mother had breast aner at age 71. Her first husband died of a erebrovasular aident 3 years ago. Newly remarried to a retired shipyard worker, she and her urrent husband live with her 28-year-old daughter and 9-year-old grandson in their New Hampshire home. She has not been outside the New England area for the last 5 years. Results of the physial examination, inluding head, eyes, ears, nose, throat (HEENT) and hest examination, were normal. There is no yanosis or lubbing of the extremities, and no palpable lymph nodes. Blood tests, inluding a omplete blood ount and hemistry panel, are normal, with the exeption of a total serum alium level of 12.7 milligrams per deiliter (mg/ dl) (normal range: 9.2 to 11.0 mg/dl). However, a hest radiograph reveals a nonalified, nonavitary 3.5-entimeter mass within the parenhyma adjaent to the right hilum. There are no other radiographi abnormalities. Results of a purified protein derivative (PPD) skin test for tuberulosis are negative. Urinalysis results are normal. A nonsmoking 56-year-old woman has weight loss and a hroni ough Pretest (a) What is the differential diagnosis for this woman s ondition? (b) What further testing might you order? () List several environmental auses that have been assoiated with this patient s probable disorder. (d) What treatment options might you onsider? Who s at Risk As early as the 16th entury, Paraelsus and Agriola desribed a wasting disease of miners. In 1879, this ondition was identified as lung aner by Herting and Hesse in their investigation of miners from Shneeberg, Germany. Radon itself was disovered some 20 years later by Rutherford. Subsequently, an inrease in the inidene of lung aner among miners was linked to radon daughter exposure in mines. Underground uranium mines found throughout the world, inluding the western United States and Canada, pose the greatest risk beause of their high onentration of radon daughters in ombination with silia dust, diesel fumes, and, typially, igarette smoke. Iron ore, potash, tin, fluorspar, gold, zin, and lead mines also have signifiant levels of radon, often beause of radium in the Miners in uranium and other types of underground mines are at risk of inreased radon exposure. 5

6 Approximately 6 million homes in the United States have radon onentrations above 4 pci/l. surrounding rok. In the past, it was not unommon to use the tailings from these mines as fill on whih to build homes, shools, and other strutures. Indoor radon daughters have been widely reognized as a potential problem in Europe and the Sandinavian ountries sine the 1970s. Publi awareness in the United States was heightened in Deember 1984, when Worker A at the Limerik nulear plant in Pennsylvania began setting off radiation alarms when he entered the plant. The ause was traed to levels of exessive radon daughters in his home 500 times the level at whih the U.S. Environmental Protetion Ageny (EPA) reommends remediation [i.e., 4 piouries per liter (pci/l)]. Radon daughters attah to dust partiles in the air that are attrated to items suh as lothing, espeially when the air is old and dry. In 1987, the federal government allotted $10 million to the states to determine the extent of radon ontamination in homes and shools, and subsequently amended the Toxi Substanes Control At to assist the states in responding to the threat to human health posed by exposure to radon. In 1988, EPA and the Offie of the Surgeon General jointly reommended that all US homes below the third floor be tested for radon. In 1990, Congress appropriated $8.7 million for grants to states to develop and enhane programs to redue radon risk in homes and shools. It has beome standard pratie in some states to measure radon levels in homes at the time of real estate transations. Radon testing is required for all government buildings. The amount of radon emanating from the earth and onentrating inside homes varies onsiderably by region and loality, and is greatly affeted by the residential struture as well as soil and atmospheri onditions. Nearly every state in the United States has dwellings with measured radon levels above aeptable limits. EPA estimates that 6% of Amerian homes (approximately 6 million) have onentrations of radon above 4 pci/l. In Clinton, New Jersey, near a geologi formation (the Reading Prong) that is high in radium, all 105 homes tested were above the reommended guidelines; the levels in 40 homes exeeded 200 pci/l. In the Worker A home, levels of 2,700 pci/l were found in the basement. Areas of the ountry that are likely to have homes with elevated radon levels are those with signifiant deposits of granite, uranium, shale, and phosphate, whih are all high in radium ontent and, therefore, potential soures of radon gas. Some homes in these areas, however, might not have elevated levels of radon. Beause of the many determinants of indoor radon levels, loal geology alone is an inadequate preditor of risk. 6

7 The only way to determine indoor radon onentration is by testing. A home 100 feet away from the Worker A home did not have measured radon onentrations that required remediation, yet both houses were on the same geologi formation. Other fators that predispose homes to elevated levels of radon inlude soil porosity, foundation type, loation, building materials used, entry points for soil gas, building ventilation rates, and soure of water supply. Further researh is being onduted on ways to predit whih homes are most likely to have signifiant levels of radon. Several studies have shown that smokers exposed to radon are at greater risk for lung aner than are similarly exposed nonsmokers. It is generally believed that exposure to radon and igarette smoking are synergisti; that is, that the ombined effet exeeds the sum of their independent effets. The risk of lung aner from radon exposure is estimated to be 10 times greater for persons who smoke igarettes in omparison with those who have never smoked. Aording to the National Aademy of Sienes Committee on the Biologial Effets of Ionizing Radiation (BEIR VI), a breakdown of the ontribution of smoking and radon exposure to lung aner deaths in the United States illustrates that of every 100 persons who died of lung aner, approximately 93 were urrent or former smokers, whereas 7 had never smoked. Data on the effets of radiation in hildren are limited, and even less is known about the effets of radon exposure in this age group. Caner development in Japanese atomi bomb survivors suggests an inreased suseptibility to radiation in hildren ompared to that in adults. Children also have different lung arhiteture, resulting in a somewhat larger dose of radiation to the respiratory trat, and hildren have longer lateny periods in whih to develop aner. However, no onlusive data exist on whether hildren are at greater risk than adults from radon. Challenge (1) Who else in the home of the patient disussed in the ase study ould be at risk for lung aner as a result of elevated radon levels? (2) Would your patient s neighbors be equally at risk of exposure to radon? Explain. (3) How are the risks of radon exposure inreased for your patient s daughter, who is a smoker? How does the daughter s smoking affet the risk for other members of the family? Exposure to exessive radon levels inreases the already elevated risk of lung aner for smokers. The primary adverse health effet of exposure to radon is lung aner. 7

8 Radioative deay of uranium through radium produes radon, whih an move from soil into the air. It deays into a series of progeny, some of whih are short-lived and emit alpha and beta partiles and gamma rays. Radon, a olorless, odorless gas, is both hemially inert and impereptible to the senses. Its infiltration into buildings is the main soure of indoor radon; however, building materials and the water supply an also be soures. Exposure Pathways Soures of Radon Exposure Radon gas is derived from the radioative deay of radium, a ubiquitous element found in rok and soil. The deay series begins with uranium-238 and goes through four intermediates to form radium-226, whih has a halflife of 1,600 years. Radium-226 then deays to form radon-222 gas. Radon s half-life, 3.8 days, provides suffiient time for it to diffuse through soil and into homes, where further disintegration produes the more radiologially ative radon progeny ( radon daughters ). These radon progeny, whih inlude four isotopes with half-lives of less than 30 minutes, are the major soure of human exposure to alpha radiation (high-energy, high-mass partiles, eah onsisting of two protons and two neutrons). This alpha radiation produes damage that, if not repaired, results in ellular transformation in the respiratory trat, whih an lead to radon-indued lung diseases or aner. Radon itself is impereptible by odor, taste, and olor, and auses no symptoms of irritation or disomfort. There are no early signs of exposure. Only by measuring atual radon or progeny levels an people know whether they are being exposed to exessive levels of radon. Radon seeps from the soil into buildings primarily through sump holes, dirt floors, floor drains, and inder blok walls, and through raks in foundations and onrete floors (Figure 1). When trapped indoors, espeially during a temperature inversion that redues its esape from the building, radon an beome onentrated to unaeptable levels. When radon esapes from the soil to the outdoor air, it is diluted to levels that offer relatively little health risk. Radon gas an enter a building by diffusion, but pressure-driven flow is a more important mehanism. Negative pressure in the home relative to the soil is aused by exhaust fans (kithen and bathroom), and by rising warm air reated by fireplaes, lothes dryers, and furnaes. In addition to pressure differenes, the type of building foundation an affet Figure 1. Soures of Radon and Common Entry Points 8

9 radon entry. Basements allow more opportunity for soil gas entry, but slabon-grade foundations (no basement) allow for less. In most ases, the inrease of indoor radon due to home tightening for energy onservation is slight ompared to the amount of radon oming from the soil. Typial building materials, suh as onrete blok, brik, granite, and sheet rok, ontain some radium and are soures of indoor radium. Normally, these onstrution materials do not ontribute signifiantly to elevated indoor radon levels. In rare ases, however, building materials themselves have been the main soure of radioative gas. Building materials ontaminated with uranium and vanadium mill tailings in Montiello, Utah, and uranium mill tailings in Grand Juntion, Colorado, were an important soure of radon beause they ontained elevated onentrations of radium. (Tailings are the sandlike material remaining after minerals are removed from ore.) Also, onrete made from phosphate slag in Idaho and Montana and insulation made from radium-ontaining phosphate waste from the state of Washington have been found to emit high levels of radon. Radon might enter into homes via the water supply. With muniipal water or surfae reservoirs, most of the radon volatilizes to air or deays before the water reahes homes, leaving only a small amount from deay of uranium and radium. However, water from private wells might be another matter. Groundwater that omes from deep subterranean soures and passes over rok rih in uranium and radium, suh as that found in northern New England, might dissolve some of the radon gas produed from radium deay. As the water splashes during showering, toilet flushing, dishwashing, and laundering, radon is released into the air and an result in inhalation exposure. Radon an also be present in natural gas supplies. Challenge (4) Your loal newspaper reently featured an artile on radon and urged that all homes in your ommunity be tested. Your patient tests her home and finds that the living spae averages 35 pci/l. Disuss how onstrution of the patient s house an affet this level. Hazard Assessment Respiratory Dose and Units of Measure Beause the health effets of radon are insidious and have a long lateny period, it is important to measure exposure to the gas empirially. Tehniques for measuring radon are disussed in the Radon Detetion setion. Inluded here is a review of the basi unit of radon measurement and the fators that are used to estimate radiation dose from air onentration information and physial parameters. (Note that this subsetion is on dose and units, and not on risk.) Although onrete slab basements allow for less soil gas entry than do unfinished dirt-floor basements, both types of surfaes ould permit entry of radon. Radon and its progeny an be deteted only by testing. 9

10 EPA reommends remediation for homes with airborne radon levels at or above 4 pci/l. In early 2000, EPA proposed muniipal drinking water levels tied to state plans to remediate radon in indoor air. The relationship between exposure to radon and the dose of radiation from deay produts that reahes target ells in the respiratory trat is omplex. Some fators that influene the pulmonary radiation dose inlude the following: Charateristis of inhaled air radon. Progeny that are attahed to dust partiles (the attahed fration) deposit muh more effiiently than free or unattahed progeny; of the attahed progeny, only those adhering to the smallest partiles are likely to reah the alveoli. Amount of air inhaled. The amount and deposition of inhaled radon deay produts vary with the flow rate in eah airway segment. Breathing pattern. The proportion of oral to nasal breathing will affet the number of partiles reahing the airways. Oral breathing deposits more of the larger partiles in the nasopharyngeal region. Regardless of the breathing pattern, the smaller the partile, the deeper it penetrates into the lung and the more likely it is to deposit there. Arhiteture of the lungs. Sizes and branhing pattern of the airways affet deposition; these patterns may differ between hildren and adults and between males and females. Preferential deposition of larger partiles ours at all branh points beause of inertial impation. Biologi harateristis of the lungs. The radiation dose ours in those areas where muoiliary ation is either absent or ineffetive in removing the partiles. Partiles moving with the muous flow ause essentially no radiation dose to tissue beause of the short range of alpha partiles in fluids. It is possible, therefore, that two environments with the same radon measurement (e.g., a dusty mine and a home environment) might ause different deposition patterns and, therefore, deliver different doses of alpha radiation to a person s lungs. Likewise, two persons in the same environment might reeive differing doses of alpha radiation to the target ells in the upper portion of their lungs beause of differing breathing patterns and pulmonary arhiteture. If partile size distribution is not known, an assumed distribution, along with the average measured air onentration, is used to estimate deposition within the lung and the resulting radiation dose. The higher the average radon level a person experienes, the higher the radiation dose. Radon gas an be olleted on ativated haroal filter media, or the attahed progeny an be olleted on mesh filters. Radon measurements are expressed in piouries per liter of air, where a piourie is equivalent to the amount of progeny in whih atoms disintegrate per seond. EPA has reommended that remedial ation be taken to lower the amount of radon in homes if the level measured in air is 4 pci/l or greater. 10

11 Risk Estimates Even onservative estimates based on urrent knowledge suggest that radon is one of the most important environmental auses of death. EPA and the National Caner Institute estimate that approximately 15,000 deaths annually in the United States are due to lung aner aused by indoor radon exposure. It has also been estimated that approximately 14% of the 164,100 ases of lung aner diagnosed annually are attributable to radon. For a lifetime exposure at the EPA reommended guideline of 4 pci/l, EPA estimates that the risk of developing lung aner is 1 to 5%, depending on whether a person is a nonsmoker, former smoker, or smoker. The National Researh Counil estimates the risk as 0.8 to 1.4%. Many fators influene the risk of lung aner due to radon exposure; among these are age, duration of exposure, time sine initiation of exposure, igarette smoking, and other arinogen exposures (Tables 1 and 2). In assessing the risk of radon in a home or offie, it is important to onsider not only the average level of radon, but also the oupants and their lifestyles. Are there any smokers? Any hildren? How muh time is spent in the home? Where do oupants sleep? The highest radon levels are typially found in the lowest level of the house. If well water is the major soure of radon, upper floors an be affeted more than lower floors. In older limates, radon levels are often higher in the winter and lower in the summer. Physiologi Effets Radon exposure auses no aute or subaute health effets, no irritating effets, and has no warning signs at levels normally enountered in the environment. The only established human health effet assoiated with residential radon exposure is lung aner. Epidemiologi studies of miner ohorts have reported inreased frequenies of hroni, nonmalignant lung diseases suh as emphysema, pulmonary fibrosis, and hroni interstitial pneumonia, all of whih inreased with inreasing umulative exposure to radiation and with igarette smoking. Epidemiologi studies and a reent study of groundwater radon and aner mortality have found no assoiation with extrapulmonary aners, suh as leukemias and gastrointestinal aners. This is expeted on the basis of studies of the radium-dial painter population. Evidene is also laking that environmental radon exposure is ausally assoiated with adverse reprodutive effets. Beause of their harged state and solid nature, radon progeny rapidly attah to most available surfaes, inluding walls, floors, lothing (as in the ase of Worker A ), and airborne partiulates. Radon progeny an be For a lifetime exposure at the EPA reommended guideline of 4 pci/l, EPA estimates that the risk of developing lung aner is 1 to 5%, depending on whether a person is a nonsmoker, former smoker, or smoker. The overall risk of radon exposure is related not only to its level in the home, but also to the oupants and their lifestyles. The primary adverse health effet of exposure to radon daughters is lung aner. The synergisti mehanism(s) of igarette smoking and radon exposure are not known, although the adverse health effets of the ombination are lear. 11

12 Table 1. Radon Risk Evaluation Chart if You Smoke If 1,000 People Who Smoked The Risk of Caner What To Do: Were Exposed to This Level From Radon Exposure STOP SMOKING Radon Level Over a Lifetime... Compares to... and pci/l About 250 men or 143 women > 100 times the risk of drowning Consider fixing between ould die of lung aner 2 and 4 pci/l 8 pci/l About 132 men or 66 women > 100 times the risk of dying Consider fixing between ould die of lung aner in a home fire 2 and 4 pci/l 4 pci/l About 66 men or 33 women > 100 times the risk of dying Consider fixing between ould die of lung aner in an airplane rash 2 and 4 pci/l 2 pci/l About 33 men or 16 women > 2 times the risk of dying Consider fixing between ould die of lung aner in a ar rash 2 and 4 pci/l 1.0 pci/l About 16 men or 8 women (Average indoor radon level) (Reduing radon levels ould die of lung aner below 2 pci/l is diffiult) 0.4 pci/l About 8 men or 4 women (Average outdoor radon level) ould die of lung aner *pci/l: piouries per liter. If you are a former smoker, your risk might be lower. Table 2. Radon Risk Evaluation Chart if You Have Never Smoked If 1,000 People Who Never The Risk of Caner Smoked Were Exposed to From Radon Exposure Radon Level This Level Over a Lifetime... Compares to... What To Do: 20 pci/l About 33 men or 20 women > 2 times the risk of being Consider fixing between ould die of lung aner killed in a violent rime 2 and 4 pci/l 8 pci/l About 13 men or 8 women Consider fixing between ould die of lung aner 2 and 4 pci/l 4 pci/l About 6.4 men or 4 women > 10 times the risk of dying Consider fixing between ould die of lung aner in an airplane 2 and 4 pci/l 1.0 pci/l About 1.6 men or 1 woman The risk of dying in a home fire (Reduing radon levels ould die of lung aner (Average indoor radon level) below 2 pci/l is diffiult) 0.4 pci/l Less than 1 person ould (Average outdoor radon level) die of lung aner *pci/l: piouries per liter. If you are a former smoker, your risk might be higher. 12

13 inhaled, therefore, either as free, unattahed partiles or attahed to airborne dust. Smaller dust partiles an deposit radon progeny deep in the lungs. Beause they are ionized, the progeny tend to attah to the respiratory epithelium. Through muoiliary ation, the progeny are eventually leared from the respiratory trat, but beause of their short half-life, they an release alpha partiles before being removed. The total amount of energy deposited by the progeny is several hundred times that produed in the initial deay of radon. When these emissions our within the lungs, the geneti material of ells lining the airways an be damaged, resulting in lung aner. The risk of lung aner due to radon exposure is thought to be seond only to that of smoking. The synergism between igarette smoking and radon plaes the large population of urrent and former smokers at partiularly high risk for lung aner. Although the net onsequene of igarette smoking and exposure to radon deay produts has been learly demonstrated in smokers, the mehanism of interation is still unlear. Most of the lung aners assoiated with radon are bronhogeni, with all histologi types represented. However, small-ell arinoma ours at a higher frequeny among both smoking and nonsmoking populations of underground miners in the initial years after exposure, ompared to the pattern of histologi types in the general population. Other types of lung aners seen in radon-exposed miners are squamous ell arinoma, adenoarinoma, and large-ell arinoma. Challenge (5) If the patient s daughter desribed in the ase study were pregnant, would the fetus be at risk from maternal exposure to airborne radon? (6) The patient s husband developed mesothelioma as a result of asbestos exposure when he worked in the shipyards. What role might radon have played in the development of this ondition? Treatment and Management No effetive ommunity-wide sreening methods are available for medial prevention or early diagnosis and treatment of lung aner (radon-indued or otherwise). Routine hest radiographs and sputum ytology are ineffetive for sreening lung aner assoiated with igarette smoking and would presumably be ineffetive for sreening lung aner assoiated with radon as well. The most effetive methods of prevention are redution of radon exposure and modifiation of other simultaneous risk fators for lung aner, suh as smoking. The only long-term solution for reduing the risk of Radon progeny an be inhaled either as free partiles or attahed to dust. Attahed progeny preferentially deposit in the bronhi, the site of most lung aners. Generally, the most effetive methods to redue the risk of lung aner are smoking essation and radon mitigation. 13

14 The potential risk of aner due to radon is often underestimated by the publi; this bias might disourage assessment and abatement measures in the home. Radon levels annot be predited; they must be measured. The most ommon methods of radon measurement are haroal anisters, haroal liquid sintillation detetors, eletret ion detetors, alphatrak detetors, and ontinuous monitors. lung aner is smoking essation, oupled with detetion and mitigation of high radon levels. Several studies have noted optimisti biases in the publi s assessment of the risk due to radon. A New Jersey study found that this bias might disourage testing and subsequent implementation of ontrol measures. In Maine, homeowners were found to greatly underestimate the potential risk, and abatement behavior was not signifiantly related to potential risk. Primary are physiians and publi health professionals should promote publi awareness so that the radon problem is seen in the proper perspetive, leading to appropriate mitigation ation when indiated. Physiians and publi health offiials should therefore test their own homes and offies to relate their experiene to others and to provide guidane on how to arry out the testing. Radon Detetion Radon levels annot be aurately predited solely on the basis of fators suh as loation, geology, building materials, and ventilation. Measurement is the key to identifying the problem. Radon detetion kits are available in most hardware stores. Short-term testing (lasting a few days to several months) is the quikest way to determine if a potential problem exists. Charoal anisters, liquid sintillation detetors, eletret ion detetors, alpha-trak detetors, and ontinuous monitors are the most ommon short-term testing devies. Short-term testing should be onduted in the lowest inhabited area of the home, with the doors and windows shut. Long-term testing (lasting up to 1 year) will give a better reading of a home s year-round average radon level than will a short-term test. Alpha-trak detetors and eletret ion detetors are the most ommon long-term testing devies. Exposed devies are sent via mail to a ertified laboratory for analysis. These devies measure radon gas levels, rather than radon progeny; thus, the units reported are in piouries of radon per liter of air. The haroal anister is a small an ontaining haroal and a filter to keep out radon progeny. It is inexpensive ($10 to $25) and is generally used for short-term testing (3 to 7 days). The alpha-trak devie ontains a small piee of plasti in a filtered ontainer. As the radon gas that has entered the ontainer deays, the alpha partiles form eth traks. These traks an be ounted using a speial tehnique. The ost of the alpha-trak devie is 14

15 roughly twie that of the haroal anister, and it an be used to measure umulative exposure over a longer period (i.e., several weeks to a year). Congress has mandated that eah state set up an offie to deal with requests for radon assistane. Many states provide radon detetion kits suh as the haroal anister free of harge as a publi servie. A list of state radon ontats an be found in the Soures of Information setion. Radon Abatement How ost-effetive is radon mitigation ompared to other investments in health protetion? The Swedish government plans to spend approximately $1,000 per home reduing high radon levels, resulting in about $10,000 in savings per life spared. EPA estimates that the ost of remediation in most homes is less than $1,500. The ost of radon testing and mitigation per life saved ompares favorably with that of other government programs. If exessive levels of indoor radon are found in a struture, low-ost, quikfix methods should be implemented first. These methods inlude limiting the amount of time spent in ontaminated areas and inreasing ventilation in the areas. It is wise to onsult with the state radiation protetion offie before implementing major abatement projets. Information on methods of redution an be obtained from several soures listed in the Suggested Reading and Soures of Information setions. In addition to inreasing ventilation, radon ontrol measures inlude sealing the foundation, subslab depressurization (reating negative pressure in the soil), pressurizing the home, and using air-leaning devies. Methods of inreasing ventilation inlude opening windows, ventilating basements and rawl spaes, ventilating sump-holes and floor drains to the outside of the house, and inreasing air movement with eiling fans. Ventilation must be modified properly, however, beause inreased ventilation an depressurize the house in some ases, ausing an inrease of soil gas entry to the home. Heat exhangers provide a way of bringing fresh air indoors without major heat loss, but these must be properly balaned or they an worsen the problem. Preventing soil gas entry is more important than inreasing whole-house ventilation. Prevention of soil gas entry involves sealing the foundation and depressurizing the soil. Potentially useful methods for prevention of soil gas entry inlude using vapor barriers around the foundation, sealing raks and holes with epoxies and aulks, and sealing the rawl spae from the rest of the house. Subslab depressurization an redue radon levels by as muh as 99%. Sution puts the soil at a lower pressure than the inside of the home, preventing inward migration of soil gas. Subslab depressurization involves The ost of remediation to redue radon levels in the average home is about $1,200. Available proedures to lower indoor radon levels are, dollar for dollar, very effetive in saving lives. Subslab depressurization is one of the most effetive methods of lowering radon levels in many homes. 15

16 sinking ventilation pipes below the foundation and ontinuously pumping air out (Figure 2). The ost to install subslab depressurization in an existing home is approximately $1,000 to $2,500; annual utility osts are about $100. The state radon offie an be onsulted to obtain a listing of radon mitigation ontrators that have passed the EPA Radon Contrator Profiieny program. If the equipment is installed during onstrution of the home, however, the ost of subslab depressurization is onsiderably less; it is muh easier to install pipes during onstrution than to retrofit later. Physiians and other health professionals an perform a publi servie by beoming aquainted with loal building odes and urging loal jurisditions to inlude the installation of apped pipes terminating in a spae under the foundation to allow for later subslab depressurization if needed. Figure 2. Subslab Depressurization. Pipes, attahed to a sution fan, are inserted into the ground below the basement floor, reating a lowpressure region under the house. Adapted from Brenner (1989). No enforeable regulations exist to ontrol indoor radon levels only guidelines and a national goal. Challenge (7) Where in your patient s home should detetors be plaed for radon sreening? (8) What an you as a health professional do to derease the risk of lung aner among your patients? Standards and Regulations No regulations mandate speifi radon levels for indoor residential and shool environments only guidelines for remediation, suh as the EPA reommendations and a national goal. EPA based its guidelines not only on risk onsiderations, but also on tehnial feasibility. No level at whih the 16

17 risk of exposure to alpha emitters is zero is thought to exist. Many standards and guidelines for radon are being reviewed (Tables 3 and 4), and hanges might our over time. EPA or state health departments should therefore be onsulted for the most up-to-date standards. In Otober 1988, the Indoor Radon Abatement At was passed. This at states that the national long-term goal of the United States with respet to radon levels in buildings is that the air within buildings in the United States should be as free of radon as the ambient air outside of buildings. The at mandates that EPA update its publiation, A Citizen s Guide to Radon, and provide a series of ation levels indiating the health risk assoiated with these various levels. The guide will also provide information on the risk to sensitive populations, testing methods, and the ost and feasibility of mitigation tehniques. EPA reommends remediation for homes and other buildings with levels above 4 pci/l, with the aveat that orretive ation be taken below this level on a ase-by-ase basis. The national goal is for indoor radon levels to be as low as those outdoors. About 0.4 pci/l radon is normally found in outside air. Table 3. Residential Standards and Regulations for Radon Soure Fous Level* Comments Indoor Radon Abatement At Indoor air (residential) Indoor = outdoor (~0.4 pci/l) National goal National Counil for Radon Protetion Indoor air (residential) 8 pci/l Guideline U.S. Environmental Protetion Ageny Indoor air (residential) 4 pci/l Current ation level Shools 4 pci/l Guideline for ation Water 4,000 pci/l with state indoor Proposed air risk redution program regulation 300 pci/l without state indoor air risk redution program *pci/l: piouries per liter. The U.S. Environmental Protetion Ageny reommends ation below 4 pci/l in shools on a ase-by-ase basis. Challenge (9) The loal power ompany has offered free radon detetion devies to all of its ustomers. The average level of radon in the lassrooms of your patient s grandson is found to be 20 pci/l. What should the ommunity s reourse be to protet its hildren? 17

18 Table 4. Oupational Standards and Regulations for Radon Soure Fous Level Comments National Institute for Oupational Oupational (mining) 1 WLM*/year and ALARA Advisory; Safety and Health exposure limit Oupational Safety and Oupational 4 WLM/year Regulation Health Administration Mine Safety and Health Administration Mining 4 WLM/year Regulation Amerian Conferene of Oupational 4 WLM/year Advisory for radon Governmental Industrial Hygienists daughters *WLM (working-level month): a unit of measure ommonly used in oupational environments. (Beause WLM bears a omplex relationship to piouries per liter, physiians with responsibility for mine workers are urged to ontat the National Institute for Oupational Safety and Health or the U.S. Environmental Protetion Ageny for further information.) ALARA: as low as reasonably ahievable. Suggested Reading Anonymous Standard proedures for radon measurement developed by the EPA. J Environ Health 49: Bierma TJ Radon risk fators. J Environ Health 51: Brenner DJ Radon risk and remedy. New York: W.H. Freeman and Co. Counil on Sientifi Affairs Radon in homes. JAMA 258: Kerr RA Indoor radon: the deadliest pollutant. Siene 240: National Researh Counil Health effets of exposure to radon, BEIR VI. Washington (DC): National Aademy Press. Available from URL: books.nap.edu/books/ /html/index.html. National Counil on Radiation Protetion and Measurements Evaluation of oupational and environmental exposures to radon and radon daughters in the United States. Bethesda (MD): National Counil on Radiation Protetion and Measurement. NCRP report no. 78. Nero AV, Shwehr MB, Nazaroff WW, Revzan KL Distribution of airborne radon-222 onentrations in U.S. homes. Siene 234: Nazaroff WW, Nero AV Jr, editors Radon and its deay produts in indoor air. New York: Wiley. Lubin JH Models for the analysis of radon-exposed populations. Yale J Biol Med 61:

19 Health Effets Harley N, Samet JM, Cross FT, Hess T, Muller J, Thomas D Contribution of radon and radon daughters to respiratory aner. Environ Health Perspet 70: Samet JM, Nero AV Jr Sounding board: indoor radon and lung aner. N Engl J Med 320: Related Douments Ageny for Toxi Substanes and Disease Registry Toxiologial profile for radon. Atlanta: US Department of Health and Human Servies. Amerian Conferene of Governmental Industrial Hygienists Threshold limit values for hemial substanes and physial agents and biologial exposure indies. Cininnati (OH): Amerian Conferene of Governmental Industrial Hygienists. Centers for Disease Control Health hazards assoiated with elevated levels of indoor radon Pennsylvania. MMWR 34: Centers for Disease Control A reommended standard for oupational exposure to radon progeny in underground mines. Atlanta: US Department of Health and Human Servies. Report No. (NIOSH): Availa ble from URL: Centers for Disease Control Radon exposure assessment Connetiut. MMWR 38: Centers for Disease Control Lung aner and exposure to radon in women New Jersey. MMWR 38: US Environmental Protetion Ageny Radon redution tehniques for detahed houses: tehnial guidane. 2nd ed. Washington (DC): US Environmental Protetion Ageny, Offie of Researh and Development. Report No. EPA 625/587/019. US Environmental Protetion Ageny Radon referene manual. Washington (DC): US Environmental Protetion Ageny, Offie of Radiation Programs. Report No. EPA 520/ US Environmental Protetion Ageny Removal of radon from household water. Washington: US Environmental Protetion Ageny, Offie of Researh and Development. Report No. OPA US Environmental Protetion Ageny Radon measurements in shools: an interim report. Washington: US Environmental Protetion Ageny, Offie of Radiation Programs. Report No. EPA 520/189/010. US Environmental Protetion Ageny Radon redution methods: a homeowner s guide. 3rd ed. Washington: US Environmental Protetion Ageny, Offie of Researh and Development. Report No. OPA US Environmental Protetion Ageny A itizen s guide to radon: the guide to proteting yourself and your family from radon. 3rd ed. Washington (DC): US Environmental Protetion Ageny, Offie of Air and Radiation. Report No. OPA Available from URL: Also available in Spanish from URL: 19

20 US Environmental Protetion Ageny Consumer s guide to radon redution: how to redue radon levels in your home. Washington (DC): US Environmental Protetion Ageny, Offie of Air and Radiation. Available from URL: US Environmental Protetion Ageny Radon - physiian s guide. Washington (DC): US Environmental Protetion Ageny, Offie of Air and Radiation. Available from URL: US Environmental Protetion Ageny Radon in water. Washington: US Environmental Protetion Ageny, Offie of Radiation Programs. Available from URL: US Environmental Protetion Ageny. The national radon measurement profiieny (RMP) program: umulative profiieny report. Washington: US Environmental Protetion Ageny, Offie of Radiation Programs. Report No. EPA 520/188/024. (Published twie annually for various states; lists partiipating vendors of radon detetion equipment and servies.) Publi Health Servie. The health onsequenes of smoking: aner. A report of the Surgeon General. Washington: US Department of Health and Human Servies; DHHS report no. (PHS) Answers to Pretest and Challenge Questions Pretest (a) The differential diagnosis for the patient s radiographi solitary pulmonary nodule would inlude: primary pulmonary malignany metastati malignany granulomatous disease (e.g., tuberulosis, oidioidomyosis, histoplasmosis, noardiosis) AV malformation pulmonary hamartoma bronhial adenoma pulmonary absess pseudonodule (e.g., nipple shadow, superfiial skin lesion) saroidosis. The following fators inrease the likelihood of the patient having a pulmonary malignany: radiographi appearane of the lesion (size and lak of alifiation), age, symptoms of ough and weight loss, hyperalemia, absene of residene in or travel to an area endemi for oidioidomyosis (southwest United States) or histoplasmosis (Ohio/ Mississippi Valley), absene of fever or evidene of infetious disease, and negative PPD skin test. The latter does not rule out tuberulosis, but makes it less likely. (b) Initially, one or more of the following tests might be ordered: searh for previous hest radiographs for omparison sputum studies for ytology and ultures (standard pathogens, fungus, aid-fast bailli) CAT san fiberopti bronhosopy with bronhial brushings and speimens for ytology and ulture. 20

21 Additional tests would follow, depending on results of these initial studies. If a primary lung aner is deteted, a metastati workup (sans of the brain, liver, adrenals, and bones) might be indiated. () Environmental auses of lung aner inlude arseni ionizing radiation (alpha, beta, gamma, or X-radiation) asbestos nikel hloromethyl ethers polyyli aromati hydroarbons hromium radon tobao smoke. (d) The treatment issues for this patient are beyond the sope of this monograph, and treatment would not be reommended until further studies are ompleted. The patient should be referred to an onologist and hest surgeon (if she is a surgial andidate) for evaluation before treatment. Depending on histologi type, loal extension into adjaent anatomial strutures, presene of metastases, and the general health of the patient, treatment options would inlude surgial exision, radiation, hemotherapy, and possibly immunotherapy. Challenge (1) Anyone who spends a signifiant amount of time in the home would be at risk. Data are inadequate to assess individual suseptibility to radon-indued lung aner; however, possible reasons to be onerned about the patient s family members inlude her daughter s smoking habit, her grandson s young age, and possible asbestos and radiation exposure due to her husband s past history of shipyard work. The amount of time spent at home by eah family member should be onsidered. You might be onerned about the patient s husband beause exposures to asbestos, external radiation, and radon might inrease his risk of lung aner signifiantly. Beause he is retired, he might spend more time at home indoors, thus inreasing his duration of exposure to radon. (2) No. Everyone in the ommunity will not be exposed to the same radon level. Regional geologi differenes suh as granite deposits and soil struture are major determinants of indoor radon onentration; however, loal onentrations an vary greatly. Even assuming all homes in the ommunity are built on the same geologi formation, the radon level in eah home annot be predited. The only way to determine a home s radon level is to test the home. The onstrution and ondition of eah house and the soure of water supply an vary. Even if the neighbors were exposed to the same radon levels, the neighbors would not be at equal risk of health effets. The risk of lung aner to eah oupant not only depends on the radon level, but also on the oupants themselves and their lifestyles. (3) The ations of radon and igarette smoke are probably synergisti. For your patient s daughter, who is a smoker, the risk of dying from lung aner is 10 to 20 times greater than if she did not smoke. It is not known how passive exposure to igarette smoke affets the risk of developing lung aner in relation to radon exposure. (4) In addition to building loation, the fators that influene radon gas entry into a home are type and ondition of the foundation pressure differenes between the soil and the inside of the home 21