5

Potential Human Health Effects of
Uranium Mining, Processing, and
Reclamation

Key Points

• Uranium mining and processing are associated with a wide range of potential adverse human health risks. Some of these risks arise out of aspects of uranium mining and processing specific to that enterprise, whereas other risks apply to the mining sector generally and still others are linked more broadly to large-scale industrial or construction activities. These health risks typically are most relevant to individuals occupationally exposed in this industry but certain exposures and their associated risks can extend via environmental pathways to the general population.

• Protracted exposure to radon decay products generally represents the greatest radiation-related health risk from uranium-related mining and processing operations. Radon’s alpha-emitting radioactive decay products are strongly and causally linked to lung cancer in humans. Indeed, the populations in which this has been most clearly established are uranium miners that were occupationally exposed to radon.

• In 1987, the National Institute for Occupational Safety and Health (NIOSH) recognized that current occupational standards for radon exposure in the United States do not provide adequate protection for workers at risk of lung cancer from protracted radon



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5 Potential Human Health Effects of Uranium Mining, Processing, and Reclamation Key Points • Uranium mining and processing are associated with a wide range of potential adverse human health risks. Some of these risks arise out of aspects of uranium mining and processing specific to that enterprise, whereas other risks apply to the min- ing sector generally, and still others are linked more broadly to large-scale industrial or construction activities. These health risks typically are most relevant to individuals occupationally exposed in this industry, but certain exposures and their associated risks can extend via environmental pathways to the general population. • Protracted exposure to radon decay products generally rep- resents the greatest radiation-related health risk from uranium- related mining and processing operations. Radon’s alpha-emitting radioactive decay products are strongly and causally linked to lung cancer in humans. Indeed, the populations in which this has been most clearly established are uranium miners that were occu- pationally exposed to radon. • In 1987, the National Institute for Occupational Safety and Health (NIOSH) recognized that current occupational standards for radon exposure in the United States do not provide adequate protection for workers at risk of lung cancer from protracted radon 123

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124 URANIUM MINING IN VIRGINIA decay exposure, recommending that the occupational exposure limit for radon decay products should be reduced substantially. To date, this recommendation by NIOSH has not been incorporated into an enforceable standard by the Department of Labor’s Mine Safety and Health Administration or the Occupational Safety and Health Administration. • Radon and its alpha-emitting radioactive decay products are generally the most important, but are not the only radionuclides of health concern associated with uranium mining and processing. Workers are also at risk from exposure to other radionuclides, in- cluding uranium itself, which undergo radioactive decay by alpha, beta, or gamma emission. In particular, radium-226 and its decay products (e.g., bismuth-214 and lead-214) present alpha and gamma radiation hazards to uranium miners and processors. • Radiation exposures to the general population resulting from off-site releases of radionuclides (e.g., airborne radon decay products, airborne thorium-230 (230Th) or radium-226 (226Ra) par- ticles, 226Ra in water supplies) present some risk. The potential for adverse health effects increases if there are uncontrolled releases as a result of extreme events (e.g., floods, fires, earthquakes) or human error. The potential for adverse health effects related to releases of radionuclides is directly related to the population density near the mine or processing facility. • Internal exposure to radioactive materials during uranium mining and processing can take place through inhalation, inges- tion, or through a cut in the skin. External radiation exposure (e.g., exposure to beta, gamma, and to a lesser extent, alpha radiation) can also present a health risk. • Because 230Th and 226Ra are present in mine tailings, these radionuclides and their decay products can—if not controlled adequately—contaminate the local environment under certain conditions, in particular by seeping into water sources and thereby increasing radionuclide concentrations. This, in turn, can lead to a risk of cancer from drinking water (e.g., cancer of the bone) that is higher than the risk of cancer that would have existed had there been no radionuclide release from tailings. • A large proportion of the epidemiological studies performed in the United States, exploring adverse health effects from potential off-site radionuclide releases from uranium mining and processing facilities, have lacked the ability to evaluate causal relationships

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125 POTENTIAL HUMAN HEALTH EFFECTS (e.g., to test study hypotheses) because of their ecological study design. • The decay products of uranium (e.g., 230Th, 226Ra) provide a constant source of radiation in uranium tailings for thousands of years, substantially outlasting the current U.S. regulations for oversight of processing facility tailings. • Radionuclides are not the only uranium mining- and processing-associated occupational exposures with potential adverse human health effects; two other notable inhalation risks are posed by silica dust and diesel exhaust. Neither of these is specific to uranium mining, but both have been prevalent historically in the uranium mining and processing industry. Of particular importance is the body of evidence from occupational studies showing that both silica and diesel exhaust exposure increase the risk of lung cancer, the main risk also associated with radon decay product exposure. To the extent that cigarette smoking poses further risk in absolute terms, there is potential for increased disease, including combined effects that are more than just additive. • Although uranium mining-specific injury data for the United States were not available for review, work-related physical trauma risk (including electrical injury) is particularly high in the mining sector overall and this could be anticipated to also apply to ura- nium mining. In addition, hearing loss has been a major problem in the mining sector generally, and based on limited data from overseas studies, may also be a problem for uranium mining. • A number of other exposures associated with uranium min- ing or processing, including waste management, also could carry the potential for adverse human health effects, although in many cases the detailed studies that might better elucidate such risks are not available. • Assessing the potential risks of multiple combined exposures from uranium mining and processing activities is not possible in practical terms, even though the example of multiple potential lung carcinogen exposures in uranium mining and processing under- scores that this is more than a theoretical concern.

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126 URANIUM MINING IN VIRGINIA M any of the findings related to occupational exposures and adverse health outcomes presented in this chapter are based on studies of uranium and hard-rock miners (e.g., worker-based radon studies) for periods of disease risk when the magnitude of the exposures was much greater than the exposures reported at most mines and processing facilities in North America today. Nevertheless, although current exposures are generally much lower, con - temporary uranium workers and processors in the United States continue to express work-related health concerns. For example, in 2008 the National Institute of Occupational Safety and Health (NIOSH) organized stakeholder meetings that included uranium miners and processors in Wyoming, Texas, Colorado, and Utah. The stakeholders expressed numerous health-related concerns, including concerns about exposure to alpha radiation via inhalation or ingestion of dust particles containing radon decay products, exposure to both radiation and particu- late uranium via inhalation, ingestion and inhalation of ore dust, and exposure to diesel particulate matter (Miller et al., 2008). This chapter describes some of the major human health effects related to occupational and public (i.e., off-site) health and safety as they pertain to ura - nium mining, processing, and reclamation in the Commonwealth of Virginia. Specifically, the chapter discusses the well-documented human health effects arising from the radioactive constituents of uranium mining that are of primary health concern, including uranium and its decay products (e.g., radium, radon). In addition, the chapter provides an overview of other, nonradioactive hazards related to mining and processing. This includes both a group of major exposures (i.e., silica, diesel, and physical exposure hazards) as well as a group of miscel - laneous potential hazards related to mining in general and to uranium processing in particular. Epidemiological and other human health data derived from previ - ous studies of uranium mining and processing were examined, as well as other relevant biomedical data pertaining to the potential exposures of interest. It was not the Committee’s charge to develop a quantitative risk assess- ment, or to characterize uranium mining- and processing-associated risks scaled and ranked against various occupational and nonoccupational hazards (such as risks quantified for activities such as travel, hobby activities, or military ser- vice). Although such information might be of interest to various stakeholders in Virginia, and would undoubtedly be required for a site-specific analysis, it is beyond the resources, scope, and capabilities of the Committee as constituted to carry out the extensive research that would be required to undertake such a Virginia-wide analysis. RADIONUCLIDE-RELATED HEALTH HAZARDS For many of its aspects, the potential adverse health effects associated with uranium mining are no different than the risks identified in other types of non- radiation-related mining activities (Laurence, 2011). Uranium mining, however,

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127 POTENTIAL HUMAN HEALTH EFFECTS adds another dimension of risk because of the potential for exposure to elevated concentrations of radionuclides. Internal exposure to radioactive materials during uranium mining and processing can take place through inhalation, ingestion, or absorption through an open cut or wound. External radiation exposure from beta particles or gamma rays can also present a health risk. Radiation typically encountered in uranium mining or processing facility operations includes alpha (α), beta (β), and gamma (γ) radiation. All three are types of ionizing radiation—energy in the form of particles or waves that has sufficient force to remove electrons from atoms. Alpha particles consist of two neutrons and two protons, travel only a few centimeters in air, and can cause a high density of ionizations along their path. In some cases, alpha particles can penetrate the dead layer of skin. If radionuclides that decay by alpha emission (e.g., polonium-218, polonium-214) are inhaled, they have the potential to impart a significant dose to the pulmonary epithelium. The dose of alpha energy deliv - ered by an alpha particle to the DNA in a cell in the respiratory epithelium is fixed and not dependent on concentration or duration of exposure. Although alpha particles can travel only a short distance, they impart a much greater effective dose than beta particles or gamma rays (NRC, 1988, 2008b). The high effec- tive doses from alpha particles, as compared with beta particles or gamma rays, result from their relatively high energies combined with their very short ranges in tissue. Alpha particles are notable among environmental carcinogens because of their potent ability to produce a high proportion of double-strand DNA breaks per particle. Double-strand DNA breaks are more difficult for the body to repair. Compared with alpha particles, beta particles are light and fast electrons with a mass of about 1/2000th of a proton. Beta particles have greater penetrat - ing power than alpha particles, but have much less ability than alpha particles to ionize tissues and cause disruptions of the DNA. Beta particles present both an external and an internal radiation hazard. Beta particles can travel over 50 cm in air and, if an individual is externally exposed, beta particles can penetrate the dead layer of the skin and reach the germinal layer of the skin. In most exposure scenarios related to uranium mining and processing, beta radiation presents a greater external than internal radiation hazard. For example, the beta dose rate from uranium decay products is negligible immediately after separation of ura - nium, but can produce a beta dose rate on contact of about 150 mrem/hr several months after separation because of the buildup of 234Th (USNRC, 2002). Gamma rays are not particles, but rather are highly penetrating electromagnetic radiation traveling at the speed of light. Gamma rays do not have a charge or mass; they are highly penetrating radiation that can ionize atoms in the body directly or cause “secondary ionizations” when their energy is transferred to atomic particles such as electrons. In most exposure scenarios related to uranium mining and pro- cessing, gamma rays present a greater external than internal radiation hazard. The energy deposited by alpha, beta, or gamma radiation can damage or kill cells. The impact of radiation on a cell depends on the duration of radiation

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128 URANIUM MINING IN VIRGINIA exposure, the dose rate of the exposure, the total amount of energy absorbed, and the tissue or organ exposed. If radiation damages a cell’s genetic material (DNA) and the cell survives, this damage can initiate cancer. The risk of cell dam- age increases with increasing dose. Although radiation-induced heritable muta - tions have not been documented in the children of uranium mine or processing workers, or in the children of Japanese atomic bomb survivors, there is some very limited evidence (lacking consistent findings of exposure-response) suggesting that radiation-induced heritable mutations may occur in humans (NRC, 2006; Kodaira et al., 2010; Bunin et al., 2011; Tawn et al., 2011). The radionuclides of greatest health-related concern in uranium mining and processing are those present in the uranium-238 (238U) (Figure 5.1), uranium-235 (235U) (Figure 5.2), and thorium-232 (232Th) decay series. The potential for occu- pational exposure to uranium or thorium and their decay products can vary greatly depending on numerous factors, including the type of ore deposit, uranium grade, mineralogy of deposit, production capacity, uranium mining method, production rate, variation in process methods (e.g., types of crushers or grinders), reagents used in the chemical dissolution of uranium-bearing mineral species, solid-liquid separation method, purification method, precipitation, packaging, transportation, waste treatment (e.g., effluent treatment, or water treatment), storage of tailings, environmental conditions around the plant (e.g., hydrological balance and local geology), and engineering controls and safeguards. Although 232Th sometimes occurs in high concentrations in uranium deposits, limited data suggest that pres - ently known commercially viable uranium occurrences in Virginia (see Chapter 3) are unlikely to contain high 232Th concentrations. In addition to 238U, the radionuclides of greatest health concern in this decay series are uranium-234 (234U) with a 240,000-year half-life, thorium-230 (230Th) with its 77,000-year half-life, radium-226 (226Ra) with a 1,600-year half-life, and the short-lived radon-222 (222Rn) decay products—polonium-218 (218Po), polonium-214 (214Po), and polonium-210 (210Po). In modern uranium processing facilities, over 97 percent of the uranium in the ore can be extracted. However, other radionuclides with potential adverse health effects, including 230Th, 226Ra, 222Rn, and 210Po, and their decay products, remain in the tailings and other waste materials generated by the extraction. In fact, about 85 percent of the original radioactivity in the ore remains after the uranium is extracted. Of particular note, the 77,000-year radioactive half-life of 230Th provides a constant source of 226Ra. Both radionuclides (230Th and 226Ra) are common components of leached mate- rials and airborne dusts from uranium ore tailings and waste piles, and 230Th and 226Ra can pose a health hazard if inhaled or ingested. Radium-226 and its decay products present both an alpha (e.g., internal exposure hazard) and a gamma (e.g., external exposure hazard from the decay products bismuth-214 and lead-214) radiation hazard to miners as well as to uranium processors. A summary of the major radon and uranium series occupational exposure standards is presented in Table 5.1; note that this table is not intended to be an

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129 POTENTIAL HUMAN HEALTH EFFECTS FIGURE 5.1 Uranium-238 decay series. SOURCE: Modified from Argonne National Laboratory, Environmental Science Division (available at http://www.ead.anl.gov/pub/ doc/natural-decay-series.pdf). exhaustive compilation of all recommendations regarding radon and uranium occupational exposure limits, but rather is intended to highlight the complexity and the differences among the guidelines as context for ensuing descriptions of dose and exposure standards and regulations both in this chapter and in Chapter 7. For additional background, Box 5.1 presents a summary of the rather confusing

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130 URANIUM MINING IN VIRGINIA FIGURE 5.2 Uranium-235 decay series. SOURCE: Argonne National Laboratory, Envi- Uranium-235 Envi - ronmental Science Division (available at http://www.ead.anl.gov/pub/doc/natural-decay- series.pdf). terms and units used for radiation activity, exposure, and dose. Additional infor- mation on current regulations and guidelines applicable to uranium is available in ATSDR (2011). The type of radiation exposure that may be encountered in uranium min - ing and processing varies by source material and work process (Table 5.3). For example, uranium miners working in underground mines generally have a much greater potential for exposure to radon and radon decay products during the min -

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131 POTENTIAL HUMAN HEALTH EFFECTS ing process as compared with miners working in open-pit mines (UNSCEAR, 2000). In addition to radon and its short-lived alpha-emitting decay products (i.e., 218Po, 214Po), other important sources of airborne radioactivity in the mine include the longer-lived radioactive decay products of 238U and 235U (e.g., 234U, 230Th, 226Ra, 210Po) (Ahmed, 1981). Work with processed uranium (e.g., yellow- cake) generally only increases the potential for alpha exposure. However, drums containing yellowcake that have been stored for several months can lead to increased exposure to x-rays as a result of the interaction of beta particles from aged yellowcake with the steel drums; the beta surface dose is about 150 mrem/hr after a few months (USNRC, 2002) (this potential beta and x-ray exposure is not included in Table 5.3). Work with materials that have undergone uranium separation (e.g., mine or processing plant tailings) primarily presents an alpha and gamma radiation hazard. Process workers in proximity to materials that are being tipped into comminution equipment (grinder) are often at greater risk from airborne exposure to radioactive materials, while those performing maintenance on such equipment may be at higher risk of gamma radiation exposure. Worker radiation exposures most often occur from inhaling or ingesting radioactive materials or through external radiation exposure. Generally, the high - est potential radiation-related health risk for uranium mining or processing facil - ity workers is lung cancer associated with inhaling uranium decay products (more specifically, radon decay products), as well as other non-lung-cancer risks associated with gamma radiation exposure on-site. Nonoccupational radiation exposures to the general population can occur from airborne dispersal of radioac- tive particulates to off-site locations, including subsequent resuspension, or gases from mining operations, processing facility exhausts, waste rock, wastewater impoundments, or tailings. Exposures may also occur by release of contaminated water or leaching of radioactive materials into surface or groundwater sources where they may eventually end up in potable water supplies. Radon and its decay products can also be transported off-site, especially from tailings or waste areas, in the form of radon gas or radon decay products. The potential for internal radia- tion exposure from drinking water contaminated with radionuclides (e.g., 226Ra, 228Ra, 230Th, uranium) that have been leached or otherwise released from tailings or other wastes is a common health concern for the public (Landa and Gray, 1995; Baker, 2010). Another health concern for people living near mines and process - ing facilities is the potential for off-site radiation exposure from atmospheric deposition of “fugitive” ore or tailings dust (e.g., dust containing uranium, 226Ra, 230Th, 210Pb, 210Po, and other radionuclides). Even though such fugitive dusts are extensively diluted once they leave the plant or mine boundaries (Thomas, 2000), accumulation in the food chain can occur with subsequent human consumption of wild or domestic animal meat, fish, or milk. Additional information concerning a selection of the major radionuclides of health interest (222Rn, 238U, 226Ra) is presented below.

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132 URANIUM MINING IN VIRGINIA TABLE 5.1 Selected Radon and Uranium Decay Series Occupational Exposure Regulations and Standards Regulation/ Applicable Facilities/ Recommended Radon Agency Recommendation Activities Exposure Level/Limit NIOSH Publication No. 88-101 Underground mines REL = 1 WLM/yr @100% progeny equilibrium = 8.3 pCi/L IAEA Basic Safety Standard All workplaces other than Intervention level: 1,000 Bq/m3 (27 pCi/L) 115 (1996) and Safety mines (includes exposure to Report Series No. 33 naturally occurring radon not related to production Assumes 2,000 hours activities) exposure per year and 0.4 equilibrium factor 14 mJ∙h∙m–3 (20 mSv) IAEA Safety Guide No. Activities involved in the 35 mJ∙h∙m–3 (50 mSv) RS-G-1.6 mining and processing of raw materials MSHA 30 CFR Part 57 Underground mines 4 WLM/yr Max = 1 WL USNRC 10 CFR Part 20 Uranium processing facilities DAC @100% equilibrium: and in situ leaching facilities 30 pCi/L ALI = 4 WLM OSHA 29 CFR § 1910.1090 Processing facilities not DAC@100% equilibrium: regulated by the U.S. Atomic 30 pCi/L Energy Acta ALI = 4 WLMb DOE 10 CFR Part 835 DOE facilities DAC @100% equilibrium: 80 pCi/L ALI= 10 WLM Action Level (Bq/m3): ICRP Publication 103: Workplaces The 2007 1000 Recommendations Occupational Limit: of the International 4 WLM/yr averaged over Commission on 5 years; Radiological Protection 10 WLM in a single year aNote that this is an extremely complicated area of policy, law, and regulation; see discussion in Chapter 7 of the division of responsibilities between the U.S. Nuclear Regulatory Commission (USNRC), the Mine Safety and Health Administration, and the Occupational Safety and Health Administration (OSHA). bWhen OSHA issued its ionizing radiation regulations in 1971, they referenced the 10 CFR Part 20 limits that were currently in existence. When the USNRC revised the 10 CFR Part 20 limits in 1991, this created some uncertainty as to which limits would apply.

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133 POTENTIAL HUMAN HEALTH EFFECTS U and Progeny External Particulate Limit Exposure Limit Total Exposure Limit Workplace Controls Not addressed Not addressed Not addressed Continuous ventilation required to reduce radon to 1/12 WL Respirators to be used if the average concentration cannot be reduced to 1/12 WL Not addressed Not addressed Effective dose of Potential remediation 20 mSv/year averaged measures discussed over 5 years, not to exceed 50 mSV in 1 year ALI for U Ore dust Limits are Effective dose of Respirators recommended = 5,700 Bq (20 governed by the 20 mSv/year averaged only for short-duration tasks mSv) and 14,000 Bq total exposure over 5 years, not to (50 mSv) from internal exceed 50 mSV in and external 1 year None stated 5 rem/yr Not addressed Respiratory protection required at levels ≥10 WL Limits specified in Limits are Total Effective Dose Table 1 of Appendix governed by the Equivalent of 5 rem B of 10 CFR Part 20 total exposure from internal plus external References USNRC 1.25 rem per Posting required at 25% of limits specified quarter the exposure limit above Limits specified in Limits are Total Effective Dose Posting required at 10% of Appendix A of 10 governed by the Equivalent of 5 rem the DAC CFR Part 835 total exposure from internal and external Not addressed Not addressed Effective dose of Not addressed 20 mSv/year averaged over 5 years, not to exceed 50 mSV in one year NOTES: WLM = working level month, DAC = derived air concentration, ALI = annual limit on intake, REL = recommended exposure limit. SOURCE: Courtesy Jim Neton, NIOSH, with modifications.

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167 POTENTIAL HUMAN HEALTH EFFECTS et al., 1990). MSHA has regulations that govern worker noise exposure, codified in 30 CFR Part 62. These regulations parallel OSHA noise regulations and have a permissible exposure level, action level, and hearing conservation program. There are requirements for periodic audiometric testing of workers as well as training. Noise—Public/Off-site Exposure Health effects of noise in a community setting are based upon speech inter- ference and sleep interference, rather than noise-induced hearing loss. When ambient sound levels reach a level of 50 decibels (measured on the A-scale to simulate the human hearing range), they begin to mask normal speech (USEPA, 1974; Peterson, 1980). A speaker will have to raise his/her voice to be heard at a distance greater than 2 ft, and the listener will have to concentrate to understand the speech. Telephone use will be difficult, and consonant sounds will be difficult to distinguish. These speech interference effects may be considered a nuisance in a typical residential setting, but may be more critical in an educational setting. Although studies of noise reduction and its impact on student test scores sug - gest that there is an impact of reducing noise exposure on high school student performance, more study is needed on elementary and middle school children’s performance (Eagan et al., 2004). Sleep interference exhibits significant variability between individuals, and is linked to the subjective nature of the response. Much of the research on sleep interference has been conducted to study the impact of aircraft noise near air- ports (FICAN, 1997), and this indicates that a dose-response relationship can be drawn, despite the high degree of scatter in the data. To address the concern about sleep interference, model ordinances designed to protect the public against sleep interference generally require sound levels after 11 p.m. to be below 50 decibels, with an assumption that there will be 15 decibels of attenuation due to housing construction bringing the sound levels in sleeping rooms to 35 decibels. Although buildings can decrease sound levels by about 15 decibels through use of typical window construction, if the building is not air-conditioned and windows are opened during warm weather, sound is transmitted through open windows with no attenuation. Noise—Physiological Effects Noise can act as an environmental stressor, affecting the autonomic and hormonal systems, and causing elevated heart rate, blood pressure, and vaso - constriction. Prolonged exposure to noise can lead to chronic conditions such as hypertension and heart disease. The World Health Organization has reviewed the literature relating to physiological effects, and published community noise guidelines that cover all sources of noise (WHO, 1999). At the federal level, USEPA or a designated federal agency regulates noise

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168 URANIUM MINING IN VIRGINIA sources, such as rail and motor carriers, low noise emission products, construc - tion equipment, transport equipment, trucks, motorcycles, and the labeling of hearing protection devices (USEPA, 2012b). Primary responsibility for regulating community noise rests with states or local governments. In Virginia, some local governments have passed noise control ordinances, which are enforced by code enforcement officers. During exploration for uranium, it is likely that there would be limited off- site community impacts. During construction, however, there are likely to be more off-site impacts due to drilling and earthmoving, and transportation of con - struction equipment could affect neighborhoods. The choice of mining technique will affect the noise contour of a mining facility, with open-pit mining having more neighborhood noise impact than underground mining. Processing (grinding of the ore) is a noisy operation, but the off-site impact might be minimal if it is a fully enclosed operation. Vibration—Occupational and Off-site Sound is the transmission of vibration in the audible range—from 20 Hz to 20,000 Hz—but energy present in the range below 20 Hz can still cause adverse health effects. Whereas sound is airborne, vibration is primarily structure- borne. Sources of vibration include construction equipment, drilling equipment, blasting, and processing (crushing/grinding) equipment. The health effects of whole-body vibration include fatigue, insomnia, stomach problems, headache, and “shakiness” shortly after exposure. Vibration reduction can be accomplished by using isolation and by installing suspension systems between the vibrating source and the operator. People who operate hand-held vibrating tools can experi- ence changes in tendons, muscles, bones, and joints, and vibration can also affect the nervous system. These effects are known as “hand-arm vibration syndrome,” and the symptoms are aggravated by exposure to cold. Ergonomic tool designs are available. Proper selection and maintenance of tools, and administrative con - trols, such as job rotation and rest periods, can reduce the adverse health effects (Nyantumbu et al., 2007; California State Compensatory Insurance Fund, 2011; Heaver et al., 2011). Elastic waves emanate from any mining blast, causing ground vibration with potential to cause structural damage off-site. Most commonly, ground vibration causes lengthening of existing cracks. Without a structural failure leading to physical injury, however, this would not be classified as a human health effect. Humans can perceive potentially annoying vibration levels far below legal limits, but existing regulations are not intended to eliminate such annoyances.

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169 POTENTIAL HUMAN HEALTH EFFECTS MISCELLANEOUS HEALTH IMPACTS There are additional potential exposures associated with uranium mining and processing beyond those individually described above. These can be categorized as either exposures arising generically out of mining (or at least the type of larger construction project that subsumes modern mining), or alternatively, exposures that are likely to be more specific to uranium processing and ore purification (although this latter category can overlap with certain related mineral extraction processes). Modern mining practices, in general, can be associated with a variety of hazards including—explosive gases; shotcrete; isocyanates; carbon monoxide; welding, metalworking fluids, and other maintenance-related exposures; and mold-related illness. In uranium processing, uranium extraction is a chemically dependent process, with certain commonly used substances (e.g., sulfuric acid) that are known to be hazardous, whereas other process chemicals have uncertain hazard status. A short description of these miscellaneous potential exposures is presented below. Nitrogen Oxides in Explosive Gases Beyond noise and physical trauma, explosive use produces nitrogen oxides as residues. Nitrogen dioxide inhalation can cause severe acute lung injury and lead to chronic lung sequelae, in particular a syndrome of airway destruction called “bronchiolitis obliterans” (Blanc, 2010). Exposure is likely to be highest in enclosed-space applications (e.g., underground detonations). Shotcrete The term “shotcrete” refers to various formulations of concrete-related mate- rials used in high-pressure spraying applications. Shotcrete can be little more than a simple mix of cement and aggregate, which is associated with skin and eye chemical burns in mine spraying (Scott et al., 2009). In modern underground mining applications, however, shotcrete has evolved into chemical-intensive for- mulations that can include “plasticizers” to facilitate flow, accelerators to promote setting, and retardants to temper the accelerator effects, together with added fiber and finely ground silica fume (alluded to previously in the silica discussion). Shotcrete plasticizers can include ethylenediamine as an active ingredient. This organic chemical is a well-recognized sensitizer associated with asthma and dermatitis (White, 1978; Ng et al., 1991). Shotcrete accelerators can include diethanolamine [2,2′-iminodiethanol], also a sensitizing agent (Piipari et al., 1998; Lessmann et al., 2009).

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170 URANIUM MINING IN VIRGINIA Isocyanates (in Polyurethanes), Epoxies, and Related Reactive Polymer Chemicals These materials are widely used in modern mining and tunneling tech - niques associated with bolt placement and other ceiling- and wall-stabilizing applications (Ulvestad et al., 1999). Exposure to these sensitizing materials can lead to asthma and probably carry risk of dermatitis as well (Nemery and Lenaerts, 1993). Carbon Monoxide Whenever internal combustion engine-powered equipment is used in or near enclosed or semienclosed areas, or with heavy outdoor use, excess carbon mon - oxide inhalation may occur (NIOSH, 1972). Exposure sources can include fork - lifts, gas-powered generators or compressors, gas-powered equipment, and motor vehicles. Air intakes near carbon monoxide sources can entrain the gas, leading to overexposure remote from the source. Motor vehicles can cause elevated ambient exposures to carbon monoxide (as well as diesel vapor and particulates as dis - cussed previously) beyond the worksite itself, especially near heavily trafficked roadways or as a result of idling vehicles. Carbon monoxide can also be present in postexplosive detonation atmospheres, together with oxides of nitrogen (as described above). Welding, Metalworking Fluids, and Other Maintenance-Related Exposures Mining and processing operations require extensive onsite maintenance oper- ations that include welding, machining, and various other equipment and parts maintenance and repair work. Welding exposures are complex, and a detailed summary is beyond the scope of this review. Note, however, that stainless steel and titanium welding (the latter because caustic process solution handling can require titanium alloys in working parts) can carry particular exposure risks, for example, from chromium, nickel, and titanium metal fumes (Antonini et al., 2004). These welding techniques can be routine work practices in uranium pro - cessing plant maintenance. Metalworking coolant fluid exposures are also com - plex, with health effects associated in particular with microbial contamination (Mirer, 2010). Other potential maintenance-related exposures include solvents, lubricants (including under high pressure), paints, and sealants. Arsenic Arsenic can be a common contaminant in uranium, as with many other metal-bearing ores. Based on existing knowledge of the uranium ore-bearing characteristics in Virginia (see Chapter 3), however, this does not appear to be a

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171 POTENTIAL HUMAN HEALTH EFFECTS relevant uranium processing exposure in handling locally mined ore. Were ura- nium processing to involve feedstock from other sites, the potential for arsenic contamination would require further assessment. In areas of the world where arsenic has been present as a uranium contaminant, exposure has been a major issue of occupational health risk among mining and process workers. Although arsenic is a potent toxin with a myriad of adverse effects, its carcinogenic poten - tial has been particularly salient among uranium miners, in particular because of their concomitant exposure to radon (Taeger et al., 2008; Tomášek et al., 1994). Other Metals—Vanadium, Selenium, Iron Vanadium is commonly used as a catalyst in sulfuric acid manufacturing, which is often carried out on-site at uranium processing facilities. Exposure would be most likely to occur in the context of maintenance or catalyst replace - ment. The primary target organ for vanadium’s adverse health effects in humans appears to be the airway, manifested by a bronchitis syndrome. In addition, IARC classifies vanadium as possibly carcinogenic to humans. Selenium can be a natu - ral contaminant of mined materials and thus be a constituent of waste tailings; in addition to natural sources, iron can enter the waste stream as an intentional process additive. For both selenium and iron, the occupational toxic exposure potential does not constitute a relevant health risk in this industry, although such metals do pose a potential environmental hazard as is noted later (see Chapter 6). Mold-Related Illness Work activities that disturb soil, anticipated in any large-scale construc - tion operation, have been associated with outbreaks of mold-related illness due to histoplasmosis or blastomycosis in areas where these environmental fungi are endemic. This could include parts of Virginia. Outbreaks occur among those directly involved in construction activities, but also among bystanders. In histoplasmosis exposures, bystanders have generally been adjacent (e.g., students attending a university with campus construction); however, at least one recent community-wide blastomycosis outbreak was linked to area-level roadway con- struction (Schlech et al., 1983; Carlos et al., 2010). Sulfuric Acid and Sulfur Dioxide Uranium processing can use either acid or sodium carbonate to dissolve (leach) uranium into an aqueous solution, as noted in the technical discussion of uranium extraction in Chapter 4. Acid extraction generally requires sulfuric acid in large enough quantities to require either onsite production or the transport of substantial quantities of the bulk product to the processing site. Sulfuric acid can also be used later in the processing sequence to “strip” uranium from its solvent

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172 URANIUM MINING IN VIRGINIA carriers (a mix of tertiary amines, decanol, and kerosene; see below), and in the treatment of process wastes and effluents (“effluent polishing”). Sulfuric acid production requires a source of sulfur that is handled through either a contact process or a wet sulfuric acid process. Both are associated with potential expo - sures, including sulfur dioxide, vanadium catalyst (as noted above), and sulfuric acid itself. Sulfuric acid skin contact, as might occur in a chemical spill, would be likely to lead to a chemical burn. Sulfur dioxide and sulfuric acid aerosols are both potent respiratory tract and mucous membrane irritants. Heavy acute expo- sure (e.g., through a leak or other large industrial release—events that can occur either as a result of on-site manufacturing or during transport from off-site) can cause severe lung injury; moderate acute exposure can lead to irritant-induced asthma (Blanc, 2010). Lower-level acute sulfur dioxide exposure—including area-level ambient air pollution, as might occur through inadequately controlled plant emissions—could be anticipated to cause asthma exacerbation, based on the known capacity of sulfur dioxide to induce increased airway resistance among persons with preexisting airway hyper-responsiveness, the basis for the health effects endpoint in U.S. National Ambient Air Quality Standards for this pollut - ant (Johns and Linn, 2011). Occupationally, sulfuric acid aerosol exposure is a known cause of chronic dental erosion. Epidemiological studies of sulfuric acid manufacturing worker cohorts have been limited to production processes in which the source of sulfur is sulfur contained in mineral ore. Acrylamide and Related Polymeric Flocculants These materials are used in uranium refining, together with mechanical sepa- ration techniques (e.g., countercurrent decantation and further clarification steps), to precipitate nonmetallic particulates from the process stream. Human-exposure- related adverse effects from polymeric flocculants, as relatively high-molecular- weight polymers, would not be anticipated among secondary occupational users (e.g., people involved in uranium processing) in contrast to the potential exposure risks among primary polymer manufacturers. Tertiary Amines Tertiary amines are used, with alcohols and kerosene, to chemically extract uranium from the aqueous solution that remains following the flocculation/ decantation process. In this processing step, the uranium partitions into an organic solvent phase, while other metals remain predominantly in the aqueous solution (referred to as raffinate; see Chapter 4). The tertiary amines commonly used are either trioctylamine (which is widely known by the trade name Alamine 336, but also has other synonyms) or tridecylamine (Mackenzie, 1997). Both of these tertiary amines have similar chemical structures, with nitrogen linked to three identical aliphatic side chains of either 8 (octyl) or 10 (decyl) carbon atoms.

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173 POTENTIAL HUMAN HEALTH EFFECTS Toxicity data specific to these tertiary amine moieties are extremely limited. The Toxnet National Library of Medicine Toxicology Data Network lists only one human exposure study for trioctylamine and none for triodecylamine.7 For the triodecylamine, a Russian study did not observe acute irritation to humans exposed by inhalation, even though mouse toxicity was observed not only when test ani - mals were exposed by inhalation, but also by skin contact (Loyt and Filov, 1964). As opposed to early steps in the uranium processing sequence, which can include open tanks with varying amounts of shielding, depending on the uranium concentration in the ore, solvent extraction typically takes place within a closed- circuit system. When used in such an enclosed system, occupational exposures are likely to be minimal under normal operating conditions, but excess exposure could occur in maintenance or quality control activities or through loss of integrity for an otherwise closed system (e.g., through a leak or other rupture). As solvents, these materials should be presumed to be readily absorbable through the skin, in addi- tion to inhalation of vapor or through droplets suspended in the air. As a chemi - cal group, aliphatic amines have been associated with causation of occupational asthma, indicating a structure–function relationship (Jarvis et al., 2005; Seed and Agius, 2010). Other tertiary amines have been shown to produce adverse ocular effects in exposed humans; the assessment of such endpoints, however, has not been reported for the specific octyl- and decyl-tertiary amines (Page et al., 2003). Decanol Decanol, a 10-carbon aliphatic alcohol, is used with the tertiary amines in the uranium solvent extraction process. Human health data specific to decanol are limited. It does penetrate intact skin and has been studied as a potential absorp - tion enhancer in models of transdermal delivery for pharmaceuticals (Williams and Barry, 2004), even though in another study, it was found to be a human skin irritant (Robinson, 2002). In a rodent study, inhalation of decanol up to vapor saturation levels did not demonstrate sensory irritation (Stadler and Kennedy, 1996). In addition to being a synthetic organic chemical, decanol also falls within the category of microbial volatile organic compounds (MVOCs), pro - duced as metabolites of fungi and detectable environmentally in sites of mold contamination—when 12 such MVOCs were tested in a lung cell-line model of toxicity, decanol proved to be the most toxic by a factor of 5 to 10 (Keja and Seidel, 2002). Decanol, along with other shorter chain aliphatic alcohols, was shown in a rat model to potentiate the liver toxicity of chloroform, even though decanol was not toxic on its own (Ray and Mehendale, 1990). Although ques - tions of potential human toxicity are raised by these studies, the same imitated exposure scenarios in an enclosed system, as noted for the tertiary amines, are also relevant to decanol’s application in uranium processing. 7 See http://toxnet.nlm.nih.gov/; accessed September 14, 2011.

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174 URANIUM MINING IN VIRGINIA Kerosene Kerosene is a hydrocarbon distillate of mixed hydrocarbon composition that is employed in uranium purification at the same process stage as tertiary amines and decanol (see Chapter 4). As noted previously, overexposure would only be likely to occur through perturbations in otherwise enclosed processes. Generi - cally, adverse health effects of kerosene vapor inhalation or skin absorption are associated with higher level exposures, in particular through dermal contact leading to substantial systemic absorption (Bebarta and DeWitt, 2004) . In addi- tion, aspiration of petroleum distillates, as well as inhalation of their combustion products, is linked to acute lung injury (Blanc, 2010). These latter exposure sce - narios, however, are not anticipated from the routine use of kerosene in uranium processing, although the latter is possible if there were to be a fire. Onsite stor- age of inflammable materials can be associated with risk of conflagration, and leaks of material at any stage of use (including stored material prior to use or in recycling systems or waste handling) can lead to groundwater contamination. Sodium Hydroxide, Hydrogen Peroxide, and Ammonia Sodium hydroxide (caustic soda) can be used in an alkaline process for the initial precipitant step after uranium is dissolved into solution, or it can be used to raise the pH of an acid solution in another processing stage (see Chap - ter 4). Industrial process solutions of sodium hydroxide are caustic and corrosive, requiring adequate skin and eye protection when handled and other safeguards against splashes, sprays, or aerosolization of concentrated solutions to prevent caustic eye, skin, or inhalation injury. Similar safety steps are relevant for high pH alkaline solutions (sodium carbonate/bicarbonate) if used in the initial process step of dissolving uranium. Hydrogen peroxide can be used in both early and later uranium processing steps. In the initial leaching step, it facilitates solubilizing uranium by acting as an oxidizing agent (sodium chlorate and ferrous sulfate also can be employed as oxidants; adverse health effects would be limited to unlikely ingestion sce - narios). Hydrogen peroxide can also be used as a reagent (along with magnesia) in the precipitation of aqueous uranium in its final purification as an alternative to sodium hydroxide or ammonia. Hydrogen peroxide at industrial concentrations (e.g., 50 percent or higher) is a powerful oxidant and highly irritating by inhala - tion, eye, or skin contact. Ammonia can be used in uranium processing to neutralize acidified aqueous solutions containing uranium and precipitate the uranium. Concentrated (e.g., anhydrous) ammonia is typically handled in pressurized containers. Ammonia is an acute respiratory tract mucous membrane irritant that in high-level exposures can cause severe lung injury. Because of its high solubility, injury to the upper

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175 POTENTIAL HUMAN HEALTH EFFECTS airways, including the nasal tract, is particularly associated with ammonia inhala- tion episodes (Blanc, 2010). For three of the agents discussed above (sodium hydroxide solutions, hydro - gen peroxide, and ammonia), overexposure can occur through transportation mishaps if manufactured elsewhere and delivered for use, through storage con - tainment failure, or through unintended release associated with valve or piping failure. Because pressurized ammonia is released as a gas (whereas the others are liquids), of the three, ammonia has the highest potential for inhalation injury in an acute system failure. In addition, unintended contact mixing of these mate- rials, in particular hydrogen peroxide, with certain other reagents on-site can lead to potentially hazardous interactions. Adherence to internationally accepted best practices (see Chapter 8) should seek to minimize the likelihood of adverse events such as transportation mishaps or equipment failure that might lead to unintended releases of irritant or toxic chemicals. FINDINGS AND KEY CONCEPTS The committee’s analysis of potential human health impacts that might apply if uranium mining and processing were to take place in Virginia has produced the following findings: • Uranium mining and processing are associated with a wide range of potential adverse human health risks. Some of these risks arise out of aspects of uranium mining and processing specific to that enterprise, whereas other risks apply to the mining sector generally, and still others are linked more broadly to large-scale industrial or construction activities. These health risks typically are most relevant to individuals occupationally exposed in this industry, but certain exposures and their associated risks can extend via environmental pathways to the general population. • Protracted exposure to radon decay products generally represents the greatest radiation-related health risk from uranium-related mining and pro- cessing operations. Radon’s alpha-emitting radioactive decay products are strongly and causally linked to lung cancer in humans. Indeed, the populations in which this has been most clearly established are uranium miners that were occupationally exposed to radon. The epidemiological data from studies of radon- exposed miners clearly demonstrate that protracted radon decay product exposure causes lung cancer in a dose-dependent manner, and that it can act independently of other known carcinogenic exposures as well as having a greater than additive effect (i.e., synergistic effect) with co-exposures to other lung carcinogens (e.g., cigarette smoking). As protracted radon decay product exposure increases, so do the rates of lung cancer (i.e., a linear dose-response relationship). The existing scientific evidence indicates that even very low exposure to radon decay products

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176 URANIUM MINING IN VIRGINIA carries some risk, so there are incremental excess risks down to the lowest rates of environmental radon decay product exposure. • In 1987, the National Institute for Occupational Safety and Health (NIOSH) in the Centers for Disease Control and Prevention recognized that current occupational standards for radon exposure in the United States do not provide adequate protection for workers at risk of lung cancer from protracted radon decay exposure, recommending that the occupational exposure limit for radon decay products should be reduced substantially. To date, this recom- mendation by NIOSH has not been incorporated into an enforceable standard by the U.S. Department of Labor’s Mine Safety and Health Administration or Occupational Safety and Health Administration. • Radon and its alpha-emitting radioactive decay products are gener- ally the most important, but are not the only radionuclides of health concern associated with uranium mining and processing. Workers are also at risk from exposure to other radionuclides, including uranium itself, which undergo radio - active decay by alpha, beta, or gamma emission. In particular, radium-226 and its decay products (e.g., bismuth-214 and lead-214) present alpha and gamma radiation hazards to uranium miners and processors. • Radiation exposures to the general population resulting from off- site releases of radionuclides (e.g., airborne radon decay products, airborne horium-230 or radium-226 particles, 226Ra in water supplies) present some t risk. The potential for adverse health effects increases if there are uncontrolled releases as a result of extreme events (e.g., floods, fire, earthquakes) or human error. The potential for adverse health effects related to releases of radionuclides is directly related to the population density near the mine or processing facility. • Internal exposure to radioactive materials during uranium mining and processing can take place through inhalation, ingestion, or through a cut in the skin. External radiation exposure (e.g., exposure to beta, gamma, and to a lesser extent, alpha radiation) can also present a health risk. • Because 230Th and 226Ra are present in mine tailings, these radionuclides and their decay products can—if not controlled adequately— ontaminate the c local environment under certain conditions, in particular by seeping into water sources and thereby increasing radionuclide concentrations. This, in turn, can lead to a risk of cancer from drinking water (e.g., cancer of the bone) that is higher than the risk of cancer that would have existed had there been no radionuclide release from tailings. • A large proportion of the epidemiological studies performed in the United States, exploring adverse health effects from potential off-site radionu- clide releases from uranium mining and processing facilities, have lacked the ability to evaluate causal relationships (e.g., to test study hypotheses) because of their ecological study design. • The decay products of uranium (e.g., 230Th, 226Ra) provide a constant source of radiation in uranium tailings for thousands of years, substantially

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177 POTENTIAL HUMAN HEALTH EFFECTS outlasting the current U.S. regulations for oversight of processing facility tailings. • Radionuclides are not the only uranium mining- and processing- associated occupational exposures with potential adverse human health effects; two other notable inhalation risks are posed by silica dust and diesel exhaust. Neither of these is specific to uranium mining, but both have been prevalent historically in the uranium mining and processing industry. Of particular impor- tance is the body of evidence from occupational studies showing that both silica and diesel exhaust exposure increase the risk of lung cancer, the main risk also associated with radon decay product exposure. Thus, workers in the uranium mining and processing industry can be co-exposed to several separate lung carcinogens, including radon decay products, silica, and diesel. To the extent that cigarette smoking poses further risk in absolute terms, there is potential for increased disease, including combined effects that are more than just addi- tive. Moreover, because manual workers and lower socioeconomic status (SES) groups in the United States generally have higher rates of smoking, work-related lung cancer in uranium miners and processors may be related to socioeconomic status such that those with lower SES could comprise a particularly vulnerable subset of the population. • Although uranium mining-specific injury data for the United States were not available for review, work-related physical trauma risk (including electrical injury) is particularly high in the mining sector overall and this could be anticipated to also apply to uranium mining. In addition, hearing loss has been a major problem in the mining sector generally, and based on limited data from overseas studies, may also be a problem for uranium mining. • A number of other exposures associated with uranium mining or pro- cessing, including waste management, also could carry the potential for adverse human health effects, although in many cases the detailed studies that might better elucidate such risks are not available. For example, some of the materials used in this industry may be potential sensitizers that could cause asthma. Many of these exposures have not have been adequately evaluated in animal or human studies. • Assessing the potential risks of multiple combined exposures from uranium mining and processing activities is not possible in practical terms, even though the example of multiple potential lung carcinogen exposures in uranium mining and processing underscores that this is more than a theoreti- cal concern.