EPA Review of Standards for Uranium and Thorium Milling Facilities @ 40 CFR Parts
61 and 192.

Comments by Steven H Brown, CHP
Revised November 7 , 2010

I am Steven Brown from Centennial Colorado. I appreciate the opportunity to provide these

comments for EPA’s consideration regards to review of EPA standards for Uranium and Thorium Milling Facilities @ 40 CFR Parts 61 and 192.

I have been a practicing hea lth physicist for over 40 years. I am certified by the America n Board of Health Physics and a Diplo mat of the American Academy of Health Physics. I am a past president of Central Rocky Mountain Chapter of the Health Physics Society.

The Health Physics Society, formed in 1956, is a scientific organization of professionals who specialize in radiation safe ty. Its mission is to support its members in the practice of their profession and to promote excellence in the science and practice of radiation safety. Today its nearly 6,000 members represent all scientific and technical areas related to radiation safety including academia, government, medicine, research and development, analytical services, consulting, and industry in all 50 states and the District of Columbia.

I would like to provide EPA with some broad scientific perspectives related to the adequacy

o f existing public exposure standards for uranium mills and in situ recovery facilities that are promulgated in 40 CFR Parts 61, 190 and 192. Specifically, these are the 20 picocuries per meter squared per second (pCi / m2

‐ sec) radon flux criteria for urani um mill tailings impoundments specified in Part 61 Subpart W and Part 192, Subpart D as well as the 25 mrem /year public exposure standard in Part 190 as referenced in Part 192.Page 2

My remarks will address the following seven questions:

1. Are the existing rad iation dose limits in the regulations (Federal and Agreement
States ) for uranium milling facilities (including in situ recovery plants) adequate to protect the public from additional radiation exposure above our natural background exposure?
2. Is the existing 20 picocuries per meter squared per second (pCi/meter 2

– sec) radon flux (emission) standard in 40 CFR Parts 61 , Subpart W and 192 , Subpart D adequate to protect the public from additional radiation exposure above our natural background exposure ?
3. What do we know about radon releases from water impoundments?
4. What do we k now about radon emissions from ISR s? 5. What are current practices and results in estimating doses to the public f rom uranium recovery facilities?
6. What is known about the potential health effec ts to populations living in the vici nity of uranium mines and mills?
7. What is known about the health impacts (e.g., lung cancer) to many uranium miners who worked underground in the 1950s and 1960s?

1. Are the existi ng regulations (Federal or USNRC Agreem ent States ) for uranium milling facilities (including in situ recovery plants) adequate to protect the public from additional radiation exposure above our natural background exposure?

Our lifestyles, where we choose to live, what we eat and drink, has a m uch larger impact on
our  radiation exposure  than  exposure  at  current regulatory  limits.  The  basic  regulatory limits that operating uranium mills and ISRs must comply with are 100 millirem* per year from  all  sources  including  radon  and  25  millirem  /  year  ex cluding  radon**  (US  Nuclear Regulatory  Commission:  10  CFR  20  and  10  CFR  40  Appendix  A;  US  Environmental Protection Agency: 40 CFR 190; Texas Department of State Health Services , Title 30 of the
Tex as  Administrative  Code, Chapter  336 ;  Colorado  Department  He alth  of  Public  and Environment, 6 CCR 1007

‐ 1, Part 4)

*NOTE: a millirem is a unit of effective radiation dose. It is related to the amount of energy absorbed by human tissue and other factors. 1,000 millirem = one rem.

** Radon is a naturally occurring radioactive gas, which is released into the atmosphere at the Earth’s surface from the decay of radium. Both radium and radon are daughter products of uranium

.

Now lets compare these numbers to the annual radiation doses we receive as ci tizens of planet E arth. Figure 1 below depicts the typical components of human exposure in the US to ionizing radiation.Page 3

Figure 1:  Percent contribution of various sources of exposure to the total radiation dose of a typical

r esident in the US. Reproduced from Nation al Council on Radiation Protection and Measurements. Report No. 160 , Ionizing Radiation Exposure of the Population in the United States. 2009

.

As can be seen from figure 1, background radiation exposure is about 50% of the total exposure; the other 50% is primarily from med ical exposures. Consumer products we use everyday that contain radioactive materials (e.g., smoke detectors, luminous watches, etc) contribute about 2 % of our dose. Other man made sources of radiation, including the nuclear industry, contribute < 0.1% of our annual dose.

Natural background can vary considerable from place to place across the United States or over relatively small areas within a region. This is due to effects of elevation (higher cosmic radiation exposure at higher elevations), greater lev els of naturally occurring radioactive elements in soil and water in mineralized areas (e.g., igneous formations in Rocky Mountains) and other factors like local geology and chemistry. This is depicted in Table 1, which compares average annual background r adiation exposure for the US, all of Colorado

a nd Leadville, CO . (high elevation and in mineralized area) as contrasted to coastal areas like Virginia and Oregon

. This table shows the major components of natural background radiation including terrestrial radiation (uranium, radium, thorium and a naturally radioactive form of potassium in soil, rocks and water), cosmic radiation (high energy particles and rays from space) and internal radiation (from food, water and radon gas fromPage 4

natural uranium decaying i n the ground).

The data in Table 1 demonstrates that the differences in annual background exposure based on where one chooses to live, what one chooses to eat and drink have a much greater impact on public exposure than the regulatory dose limits we discu ssed above.

Source US Avg. 1 Colorado 2 Leadville

, CO. 2 Virginia 3 Oregon 3

Cosmic Radiation 31 50 85 28 28

Terrestrial
Radiation 19 49 97 20 27

Radon and
Other Internal 260 301 344 182 102

Totals 310 400 526 230 157

TABLE 1: Compar ison of average radiatio n backgrounds in US (units of millirem / yr)

1 National Council on Radiation Protection and Measurements.  Report No. 160 , Ionizing Radiation Exposure of the Population in the United States. 2009.

2 Moeller D, Sun LSC . Comparison o f Natural Background Dose Rates for Residents of the Amargosa Valley, NV, to those in Leadville, CO, and the States of Colorado and Nevada. Health Physics 91:338

‐ 353; 2006

3 USEPA.  Assessment of Variations in Radiation Exposure in the United States.  Cont ract Number EP

‐ D

‐ 05

‐ 002 (Revision 1).  Washington, DC.  2006

Because background radiation varies significantly across the U.S., it follows that population exposure varies accordingly. As indicated in Table 1, if for example, one chooses to live in
Colorad o vs. Oregon, the difference in his or her annual radiation dose is more than 240 mrem /yr which is more than twice the Federal public exposure limit for uranium mills of 100 mrem /yr. In other words, if you are a resident of Colorado and leave to visit y our sister for a month in Oregon, you could “save” 20

– 30 mrem of exposure, which is about equal to the EPA 40 CFR 190 limit of 25 mrem /year excluding radon.

2. Is the existing 20 picocurie/meter 2

– second ( pCi/m2

­ sec) radon flux /emission
standard in 40 CFR Parts 61, Subpart W and 192, Subpart D adequate to protect the public from additional radiation exposure above our natural background exposure ?

Specifically regarding natural background exposure to radon, note that Figure 1 and Table
1 demonstrate that radon can contribute much more than 50 % of our total background exposure and almost 300 mrem / yr in the Rocky Mountain States (due to higher levels of natural uranium and radium in the soil and rocks than, e.g., the coastal plains of the US).

It

is recognized that EPA’s public exposure criteria for radon in 40 CFR 61, Subpart W and Part 192, Subpart D is expressed as a “flux” (emission rate from a surface) of 20 pCi/m2

‐Page 5

sec. This limit however includes natural background, which is typically 1

‐ 2 pC i/m 2

‐ sec almost anywhere on the earth’s surface and can be several times higher than this in mineralized areas. So in some places, the EPA radon flux limit could be just a few times the existing background rate.

It is also recognized that 40 CFR Subpart W also imposes work practice requirements @ 61.252(b)(1) limiting the operator to two tailings impoundments of no more than 40 acres each . Accordingly, if it is assumed that the entire 80

‐ acres are emitting radon at the limit of 20pCi/m2

‐ sec, the annual “source term” can be directly calculated to be about 200 Curies. This is approximately equal to the “source term” from 2

‐ 3 square miles of the earth, almost anywhere, at a typical planet wide background flux of 1

‐ 2 pCi/m2

‐ sec.

However, the quantity or emission rate of a radionuclide from a source within the restricted area of a licensed facility is not the primary criteria for public radiation protection. This is routinely achieved by demonstrating compliance with the fundamental public dose limit of 100 mrem /year including radon (e.g., @ 10 CFR 20.1301 and commensurate sections of Agreement State regulations) and in demonstrating compliance to concentrations of radionuclides permitted to be released to unrestricted areas (e.g., at the site boundary) specified in 10 CFR 20, Appendix B, Table 2 (for radon = 1 X 10

‐ 8 uCi/ml w/o progeny; 1 X 10

‐ 10 with progeny).

It is at the site boundary and/or locations where people actually live, not at a somewhat arbitrary* location within the restricted area inacc essible to the public, that public radiation protection criteria should be applied. Although the historical need is understood for establishment of the radon flux criteria to limit radiological impact to a future public who may have access to formerly deco mmissioned uranium tailings sites, for licensed operating facilities, other mature regulatory controls as referenced here provide much greater assurances that exposure of the public is maintained ALARA in support of optimizing the risk vs. benefit relation ship.

* “Arbitrary” relative to the most likely pathways of exposure to a member of the pubic including
considerations of local meteorolog y and demography

3. What Do We Know About Radon Releases from Water Impoundments ?

In response to concerns regards t o radon releases from the decay of its radium parent contained in water impoundments (e.g., evaporation ponds) associated with uranium recovery facilities, two recent reports provide some valuable insight:

(1) SENES Consultants Ltd, Evaporation Pond Radon Flux Anal ysis, Piñon Ridge Mill Project, Montrose County, Colorado

. August 2010 for Energy Fuels Resources Corporation; included as Appendix D of Energy Fuels’ Application for Approval for Construction , Pinon Ridge Mill,
Montro se County

, Colorado as s ubmi tted to US EPA Region VIII, Denver, Colorado August 31 2010. This report is posted along with the complete application on the EPA Subpart W webPage 6

site under “Applications”, Pinon Ridge Mill: Application for Approval of Construction of Tailings Facility

.

Th is study provided estimates of radon flux from and concentrations above proposed water impoundments (evaporation ponds containing raffinate solution ) with a specified radium concentration and compared results to other existing models. Conservative
estimate s of radon flux indicates that the emissions are low and less than or similar to the

pre

‐ operational average b ackground radon flux of 1.7 pCi m ‐ 2 s ‐ 1 observed at various locations within the proposed tailings areas on the site

. The estimated radon flux le vels from the evaporation ponds is also a small fraction (less than 10%) of the 20 pCi m ‐ 2 s ‐ 1 limit for pre

‐ 1989 uranium tailings that has been assumed here for context.  This conservative estimate was based on the Nielson and Rogers model *

.

* Nielson, K.K. and V.C. Rogers 1986. Surface Water Hydrology Considerations in Predicting Radon Releases from Water

­ Covered Areas of Uranium Tailings Ponds. Proc. Eighth Annual Symposium on Geotechnical & Hydrological Aspects of Waste Management, Geotechnical Eng ineering Program, Colorado State University & A.A. Balkema, Fort Collins, CO, USA, February 507, PP:215

‐ 222.

The model assumes that the emission rates are enhanced by the turbulence at the top layer
of the water column where all the radon in the top one

‐ m eter of water is assumed to be released to air instantaneously.  For comparison purpose s , the same parameters were used to estimate the radon emissions using an on

‐ lin e program that is available on the World Information Services on Energy (WISE) website

. T he on

‐ line model, which is attributed to
the Rogers and Nielson model, produced identical results.

The results of this assessment also indicated that the radon emissions associated with the evaporation of the raffinate solution and the emissions due to the operation of sprinkler system s are extremely low and insignificant compared to the radon flux from the ponds
due  to diffusional and turbulence processes.

Finally, the calculations indicated that the incremental air concentration due to the
emission of ra don from the evaporation ponds is very small (on the order of 3%) relative to the assumed background radon concentration.

(2) K.R. Baker and A.D. Cox 2010. Radon Flux from Evaporation Ponds .  Presented at National Mining Association (NMA) / Nuclear Regul atory Commission (NRC) Uranium Recovery Workshop 2010, Denver, CO, May 26

‐ 27.

A presentation by Baker and Cox at the most recent NMA/NRC workshop in Denver ( May 2010) and subsequently at the National Health Physics Society Annual Meeting in Salt Lake City (June 2010) considers the situation where appreciable concentrations of radon are present in the ponded water, as may arise for example from elevated levels of Ra

‐ 226 dissolved in the pond water.  Baker and Cox

, reporting on a stagnant film model and somePage 7

measurement data *

, suggest a radon flux of the order of 1 pCi m ‐ 2 s ‐ 1 per 100 pCi/L of
dissolved radon in the ponded water.

* A modified version of EPA Method 115 was used to measure radon flux from the pond surface

4. What do we know About Radon Emissions from ISRs?

Regarding radon evolution from in situ uranium recovery facilities, the major ity of r adon,

w hich is released at the surface is not (as at a conventional mill) a result of on

‐ surface decay of r adium over time in tailings impoundments since ISRs do not generated conventional tailings as a radon source. At ISRs, the r adon is brought t o the surface dynamically, dissolved in the lixiviant returning from under ground. Just as dynamically, that portion of the total dissolved r adon that is above the solution's saturation value is released when encountering atmospheric pressures and temperat ures.

Modern ISR uranium recovery processes are operated under “closed loop’ conditions. The circulating lixiviant goes directly from well field header houses thru the ion exchange process and is then reconstituted and returned directly to the well field as an essentially closed system. Atmospheric conditions are initially encountered during resin transfer at
the shaker screens . Accordingly, the vast majority of the “radon source term” for these
facilities is associated with small releases from the well h eads and header houses in the
well fields and from the IX

‐ resin

– elution system inter face where the process is first opened to atmospheric pressure. For facilities that have water retention ponds at the back end of the process (barren lixivian t bleeds, restoration wastes, etc), only a small percentage of the radon originally dissolved in the pregnant lixiviant initially return ing from the well fields would be expected to remain . ISRs in Texas are currently operating without these “surge ponds” and send liquid wast es directly to a permitted deep disposal well .*

* For general discussions of the radiological characteristics of ISRs, including mechanisms of radon evolution,

see: National Mining Association. Generic Environmental Report in Support of the Nuclear Regulat ory Commission’s Generic Environmental Impact Statement for In Situ Uranium Recovery Facilities, K Sweeney, NMA to L Camper, USNRC November 30, 2007 ; Brown, S. The New Generation of Uranium In Situ Recovery Facilities: Design Improvements Should Reduce Rad iological Impacts Relative to First Generation Uranium Solution Mining Plants . Proceedings of the 2008 Waste Management Symposium, Phoenix. ASME Press, New York, NY, ISBN # 978160560422 . 2008

.

F or more on mechanisms of ISR radon source terms see: Brown
, S. and Smith, R. , 1982. A Model for Determining the Radon Loss (Source) Term for a Commercial In Situ Leach Uranium Facility. In: M. Gomez (Editor), Radiation Hazards in Mining

‐ Control, Measurement, and Medical Aspect s. Soc. Min. E ng., pp. 794

— 800; Marple, M.L and Dziuk, T , Texas Department of Health

, Bureau of Radiation Control

. Radon Source Terms

at In Situ Uranium Extraction Facilities in Texas. Proceedings of the Sixth Annual Uranium Seminar, South Texas Minerals Section of AIME. Corpus Christi. September 11

‐ 14, 1982Page 8

5. What are Current Pr actices and Results in Estimating Doses to the Public from Uranium Recovery Facilities?

Calculations performed in accordance wi th existing NRC guidance are used to estimate
source terms and calculate off

‐ site dose to the public. For example, USNRC Regulato ry Guide 3.59, Section 2.6 provides methods acceptable to NRC for estimating the radon source term during ISR operations. Additionally, USNRC NUREG 1569, Appendix D, provides the MILDOS

– AREA computer code methodology acceptable to the NRC, which
includes expressions for calculating the annual Rn

‐ 222 source terms from various aspects of ISR operations which is then used by MILDOS to calculate off

‐ site public dose and demonstrate compliance with dose limits of 10 CFR 20.1301.

See e.g.: U.S. Nuclear Regulato ry Commission, NUREG

‐ 1569, Standard Review Plan for In S itu Leach Uranium Extraction License Applications , June 2003. Yuan, Y.C., J.H.C. Wang and A. Zielen. 1989. MILDOS

­ AREA: An Enhanced Version of MILDOS for Large

­ area Sources. Argonne National Laborator y (ANL) repo r t ANL/ES

‐ 161. June 1989; U.S. Nuclear Regulatory Commission (NRC), 1987 . Methods for Estimating Radioactive and Toxic Airborne Source Terms for Uranium Milling Operations . Regulatory Guide 3.59.

Regards to historical estimates of offsite rado n concentrations and public dose from ISRs as reported by its licensees , the U.S. Nuclear Regulatory Commission, in NUREG

‐ 1910, Generic Environmental Impact Statement for In

­ Situ Leach Uranium Milling Facilities ( 2009), Chapter 4.2 indicates:

• Quarterly and biannual measurements of downwind concentrations of radon at an operational ISR facility boundary from 1991 to early 2007 were below 74 Bq/m 3 [2.0 pCi/liter ] with a majority of measurements below 37 Bq/m 3 [1 pCi/liter]. For comparison, these measured v alues are well below the NRC effluent limit for radon at 10 CFR Part 20, Appendix B of 370 Bq/m 3 [10 pCi/liter ] and in fact, are probably just background values

.

• Argonne National Laboratory’s MILDOS

‐ AREA computer code (Argonne National Laboratory, 1989

– see above ) is typically used to calculate radiation doses to individuals and populations from releases occurring at operating uranium recovery facilities. The code is capable of modeling airborne radiological effluent releases applicable to both conventional mills and ISR facilities ( including radon gas from well fields and processing facilities and yellowcake particulates from thermal drying operations)

• All reported doses have been well within the 10 CFR Part 20 annual radiation dose limit for the public of 1 mSv [100 mrem/yr] inc luding dose from radon and its progeny and within the EPA fuel cycle annual limit (40 CFR 190) of 0.25 mSv [25 mrem], which does not include dose due to radon and its progeny.Page 9

6

. What is known about the potential health effects to populations living in t he vicinity of uranium mines and mills?

Uranium is a heavy metal and acts similarly to other heavy metals in the body (like molybdenum, lead, mercury ) . Accordingly, for natural uranium, national and international human exposure standards are based on the possible chemical toxicity of uranium (e.g., effect on kidney

— nephrotoxicity), not on radiation and possible “cancer effects” (radiotoxicity). However, there has never been a death or permanent injury to a human from uranium poisoning *

.

* See e.g.: (1) U. S. Nuclear Regulatory Commission. Standards for Protection Against Radiation ; 10 CFR 20, Appendix B. , Table 1. 1992. (2) International Commission on Radiological Protection. Limits for Intakes of Radionuclides by Workers . ICRP Publication 30, 1979.  (3) US Dept. of Health and Human Services, Public Health Service, Agency for Toxic Substances and Disease Registry. Toxicological Profile for Uranium. 1999. (4) Acute Chemical Toxicity of Uranium. Kathryn, RL and Burkin, RK. Health Physics, 94(2), pp 170

‐ 179,
F ebruary 2008)

Regarding ionizing radiation in general, the health effects are well understood. No health effects have been observed in human populations at the exposure levels within the range and variability of natural background exposures in the US. A n official position of the National Health Physics Society is that below 5,000

– 10,000 millirem  (which includes the range of both occupational and environmental exposures), risks of health effects are either
to small to be observed or non

‐ existent (see Radiation Risks in Perspective @hps.org/hpspublications/positionstatements). International and national authorities that establish exposure standards for workers and the public rely on the work of scientific committees of the highest professional standing for their evaluations of the scientific information on the health effects of ionizing radiation. These scientific committees include
the United Nations Scientific Committee on the Effects of Ionizing Radiation (UNSCEAR);
the International Commission on Rad iological Protection (ICRP); the National Academy of Science’s Biological Effects of Ionizing Radiation (BEIR) Committee, the National Council on Radiation Protection and Measurements (NCRP) and others.

But what about the specific concerns regarding healt h effects to populations living close to uranium recovery facilities? Despite much confusion and misunderstanding, possible
health effects in populations living near uranium mines and mills have been well studied.
No additional effects have been observed w hen compared to the health status of other similar populations not living nearby. A few sources providing the scientific evidence that supports this conclusion include:

• US Department of Health and Human Services, Public Health Services, Agency for
Toxic S ubstance and Disease Registry, Toxicological Profile for Uranium , 1999. Chapter 1: Public Health Statement for Uranium, Section 1.5: How Can Uranium Effect My Health?

– “ No human cancer of any type has ever been seen as a result of exposure to natural or depleted uranium” ( Available at:Page 10

http://www.atsdr.cdc.gov/toxprofiles/tp150.html )

• Cancer and Noncancer Mortality in Populations Living Near Uranium and Vanadium Mining and Milling Operations in Montrose County, Colorado, 1950

­ 2000 . Boice, JD, Mumma, MT et al. International Epidemiolog y Institute, Rockville, MD and Vanderbilt University, Vanderbilt

‐ Ingram Cancer Center, Nashville, TN. Journal of Radiation Research, 167:711

‐ 726; 2007: “ The ab sence of elevated mortality rates of cancer in Montrose County over a period of 51 years suggests that the historical milling and mining operations did not adversely affect the health of Montrose County residents”

• Cancer Mortality in a Texas County with P rior Uranium Mining and Milling Activities,
1950

– 2001. Boice, JD, Mumma, M et al. International Epidemiolog y Institute, Rockville, MD and Vanderbilt University, Vanderbilt

‐ Ingram Cancer Center, Nashville, TN Journal of Radiological Protection, 23:247

– 2 62; 2003

– “No unusual patterns of cancer mortality could be seen in Karnes County over a period of 50 years suggesting that the uranium mining and milling operations had not increased cancer rates among residents”.

• Cancer Incidence and Mortality in Popul ations Living Near Uranium Milling and Mining Operations in Grants, New Mexico, 1950

– 2004

. Boice, JD, Mumma, M et al. International Epidemiolog y Institute, Rockville, MD and Vanderbilt University,
Vanderbilt

‐ Ingram Cancer Center, Nashville, TN. Journal of Radiation Research

, 174,
624

– 636. 2010

– “ With the exception of male lung cancer ( in former underground
miners ) , this study provides no clear or consistent evidence that the operation of uranium mills and mines adversely affected cancer incidence or mortality of county
residents”.

7. But what about the known health impacts (e.g., lung cancer) to many uranium miners who worked underground in the 1950s and 1960s?

These miners worked in conditions that by today’s standards we would consider unaccepta ble. They were exposed to very high levels of radon progeny (which are decay products of uranium) in poorly ventilated underground mines. Many of these miners also had severe smoking habits, which enhanced the ability of the radon daughters to deliver
radi ation dose to the lung. Follow up of 68,000 former miners over many years indicated
the occurrence of about 2700 lung cancers in this population; much higher than the expected incidence . This is an incidence rate of about 4%. As a point of comparison, the baseline incident rate of lung cancer in non

‐ smoker , Caucasian males today is about 0.4 % ( Dr. John Boice, International Epidemiology Institute, Vanderbilt University

– personal
communication )

These conditions existed before we had Federal Agencies (Occup ational Safety and HealthPage 11

Administration

‐ OSHA, Mine Safety and Health Administration

‐ MSHA, US Nuclear Regulatory Commission

‐ NRC) and laws to better protect workers throughout American industry (construction, manufacturing, farming, mining, etc). Base d on the best scientific information available, we consider as safe the occupational exposure standards we have today as enforced by these agencies. The level of exposure of some of these early uranium
miners was 100

– 1000 times higher than our current Fe deral standards.

As just one of many possible historical comparisons regards to working conditions in American industry decades ago, it is of note that almost 100 men died from construction and related accidents in the building of the Hoover Dam in the 19 20s, long before Federal regulations were in place to protect workers. These circumstances would of course also be unacceptable today

Conclusions:

(1) The existing public radiation exposure criteria for uranium mills and in situ recovery
facilities in 40 CFR Parts 61, 190 and 192 are adequately protective since they represent small fractions of the natural radiation background variation across the US. Our lifestyles, where we choose to live, what we eat and drink, has a much larger impact on our radiation exposure than exposure at these very low regulatory limits

. (2) Regarding ionizing radiation in general, the health effects are well understood. No health effects have been observed in human populations at the exposure levels within the range and variabili ty of natural background exposures in the US

. (3) Radon emission rates ( flux) from water impoundments (evaporation ponds) at licensed conventional mills and ISRs are not expected to be significantly different than that from typical background radon emissi on associated with land surfaces almost anywhere due to the very poor diffusion of radon through water.

(4) Historical environmental measurements made in the vicinity of uranium recovery facilities and public dose assessment performed and reported to the U SNRC indicate radon concentrations at site boundary locations and doses to the public are consistently well
below Federal limits.

(5) The possibility of health effects in populations living near uranium mines and mills over 50 years have been well studied by national scientific bodies of the highest professional standing

. No additional effects have been observed when compared to the health status of other similar populations not living nearby.

(6) However, given that 40 CFR 192 was released in 1983, changes and updates have been made in the basic dosimetry models and science we use today to estimate radiological
doses and risks. Accordi ngly, EPA should consider reassessing exposure terminology and
criteria (e.g., as used in 40 CFR 190) to be consis tent with current nation al and international methods and models, e.g., (1) International Commission on RadiologicalPage 12

Protection, 2008. “Publication 103 Recommendations of the ICRP, Annals of the ICRP.”
2008 and (2) National Research Council, 2006. “Health Risks for Exposure to Low Levels of Ionizing Radiation; BEIR VII, Phase II. ”