ML20134C806
| ML20134C806 | |
| Person / Time | |
|---|---|
| Issue date: | 11/29/1994 |
| From: | NRC OFFICE OF PUBLIC AFFAIRS (OPA) |
| To: | |
| Shared Package | |
| ML20134B716 | List: |
| References | |
| ACRS-GENERAL, NACNUCLE, S-94-28, NUDOCS 9610080364 | |
| Download: ML20134C806 (31) | |
Text
._-
/,.....,7s.
UNITED STATES t
(
> 1 NUCLEAR REGULATORY COMMISSION
\\'
//
Office of Public Affairs Washington, D.C. 20555 No. S-28-94 Tel. 301-415-8200 Remarks by Dr. E. Gail de Planque Commissioner, U.S. Nuclear Regulatory Commission before the NRC Workshop on Site Characterization for Decommissioning Rockville, Maryland November 29,1994 In Search of... Background it is a pleasure to be here this morning at the NRC Workshop on Site Characterization for Decommissioning. I'm so pleased to see so many in attendance because I think that the issue of decommissioning is one of the most significant issues on the Commission's plate, one that will have long lasting and far reaching impacts.
I Intmduction As you know, the NRC is undergoing a lengthy process aimed at formulating radiological criteria for the decommissioning of NRC-licensed facilities. During that process, extensive discussions have focused on four possible approaches to this task: (1) establishing an annual risk or dose limit for an individual; (2) establishing an annual risk or dose goal; (3) requiring use of the best available technology; or (4) requiring return of the site to background radioactivity.
While many ccmmenters preferred a risk-based or dose-based standard, many others favored the
" return-to-%immd" approach.
The proposed rule attempts to accommodate both groups by establishing a dose limit for release of the site of 15 millirem per year Total Effective Dose Equivalent (TEDE) for residual radioactivity distinguishable from background with further reductions As Iow As Reasonably Achievable, or ALARA.
First, an aside. To make life easier, I will usually use the quantity total effective dose equivalent expressed in units of mrem. But for brevity's sake, I will ese the term " dose" when speakmg of total effective dose equivalent.
i 1
9610080364 960326 PDR ACRS CENERAL PDR
J The objective expressed in the proposed rule is to cleanup up to dose levels that are indistinguishable from background. Return to background!
Sounds good, doesn't it? On the surface, this seems like a relatively easy, common-sense approach: for example, survey a nearby spot unaffected by a nuclear facility, use that radiation level as a baseline, clean up the contaminated site to that level, and... voila! The site is decommissioned, the method indisputable, the job completed.
But, as we all know, the devil is in the details. And in this case, the devil could produce a series of torments for those involved in returning a site to bact: ground.
I'd like to discuss some of the details with you this moming, particularly the details that are relevant to determining what background is and how it is measured. But I'd also like to place this discussion of the details within the broader context of a regulatory decision-making proce Risk-Based Decision-Making The decision making process I'm referring to is " risk-based" decision-making, a process gaining popularity both in the Clinton Administration and in Congress, and widely advocated the most recent Supreme Court member, Justice Stephen Breyer. I.et me say at the outset that as far as I know this particular mode of making decisions was not followed in any rigorous way in formulating the proposed rule. Nevertheless, for reas>ns which I hope will be clear later in this talk, it may offer a useful framework for working out the details of a decommissioning program.
Risk based decision-making allows for the assumption that the resources available for GU limiting risks are not inexhaustible and seeks to ensure that the resources which are available to society as a whole will be pat to the best overall use considering risk, cost and benefit. It can be divided into three basic components as illustrated by the following Sydney Harris cartoons:
(1) risk assessment, (2) selection of an acceptable level of risk, and (3) risk management.
In the context of decommissioning, risk assessment is an evaluation of the hazard associated with residual radioactivity remaining at a site released for unrestricted or restricted use. Selection of an acceptable risk level involves weighing the benefits of lowering risk to a certain level against the costs and may involve comparing the risk at issue with other similar risks confronting society. Risk management consists of a regulatory process designed to keep the risk below the level found to be acceptable.
Risk Assessasent As the NRC begins to formulate a regulatory program to manage the risk associated with sites cleaned up to levels of radiation contamination that are indistinguishable from background, it might be useful to revisit Step 1 of the risk-based decision-making process: risk assessment.
Perhaps this can most easily be done by reviewing the levels of radiation to which humans are typically exposed and the health consequences of those levels, t
G
Broadly speaking, the average American's annual radiation dose is anthropogenic radiation which produces the remaining 18%
sources:
9 naturally-occumng radiation which has been present since the formation o Humans are bathed in a sea of 56% of the average annual dose is from radon and its decay products.
other internal sources, mainly from inhalation and ingestion of food and w naturally occurring radio..ctive elements. The remainder is from external so from cosmic rays and about 7.5% from terrestrial gamma ray sources su potassium, and thorium, that are present naturally in soil and rocks.
Just to complete the picture, let's look at the anthropogenic sources. Abou average annual dose comes from medical x-rays, about 4% from nuclear medicine 3% from consumer products such as smoke detectors. 'Ihe small remainder weapons testing, and occupational exposures at various nuclear facilities.
The proposed rule defines " background radiation
- as:
radiation from cosmic sources; naturally occurring radioactive material, i (except as a decay product of source or special nuclear material); and global it exists in the environment from the testing of nuclear explosive device nuclear accidents like Chernobyl which contribute to background radiation and i
under the control of the licensee.
l Although naturally-occurring radiation and fallout from atmospheric weapon O
the Chernobyl accident are present everywhere, each of these components of w V
as background, and the corresponding dose delivered, is by no means constant.
Background
levels fluctuate significantly due to various physical phenomena that differ fro and change with time at any given place. For example, over the long-term, cosmic ra varies by about 10% over the 11 year solar cycle.
Seasonal cycles produce changes in soil moisture, rainfall, snow cover, and evapotranspiration that cause variations in the do terrestrial gamma radiation, fallout and radon. Many sporadic geophysical phenomena v eruptions or earthquakes for example, can also introduce radioactivity into the environme Temporal variations can also occur over the short term. Rain, for example, will was out radon and other radionuclides from the air causing an immediate rapid increase in dose th typically decreases exponentially after the rain stops. Doses from radon typically exh diurnal cycle due to local climate conditions.
Radiation varies spatially. The dose from cosmic radiation is a function of both latitude and altitude. The population of the city of Denver, at an altitude of a mile receives an annual cosmic ray dose that is a factor of 2 higher than the U.S. average. Terrestrial gamma radiatio including fallout, varies from place to place because of differing amounts of uranium, pot and thorium in the earth's surface material and can easily differ by a factor of 10 across the Granite, for example, contains higher than average uranium concentrations and country.
I fV
i monazite sands can have particularly high concentrations of thorium. Furthermore, humans sometimes alter soil content with fertilizer which contains varying amounts of potassium-40.
Spatial variations occur locally as well; the well-known Reading Prong in New Jersey provides an interesting regional example.
The average annual dose from gamma radiation is approximately 50 mrem but if one resides closer to the rock formations along the prong, the annual dose can be much greater. About sixty miles away at the New Jersey shore, the gamma radiation dose levels fall to less than 10% of the average measured over the Prong.
Even in the immediate environment of a typical facility site (this happens to be Shoreham, Long Island), significant fluctuations occur (Figure 1). For this site with an annual average terrestrial gamma dose of about 35 mrem, when measured simultaneously, levels varied by more than 50% over a distance of only a mile within the site boundary, and the areas within a 4-or 5-mile radius of the site exhibited variations with even greater extremes.
This site in rural New Jersey, used as a background monitoring station, is only 50' by 200' (Figure 2). And even within such a small area, simultaneously measured terrestnal gamma radiation dose levels, which average about 125 mrem per year, differ by as much as 30% from spot to spot. That translates into differences of close to 40 mrem per year.
Other local variations occur due to the types of houses and buildings in which people live and work. Persons living in a wood frame house usually receive lower doses than persons living in an all brick house because, even though brick is a better shield of outdoor radiation, it has higher concentrations of naturally occuning radioactivity than wood. Persons working in granite and marble buildings may receive higher doses due to the radioactivity in the stone. Even moving from a rural to an urban setting may increase an individual's annual dose, due to the 8
level of radioactivity present in concrete. The dose from cosmic rays can be measurably higher W
on the top floor of a high rise than on the ground floor. Measurements in a 12 story building in Manhattan indicated a cosmic ray dose on the ground floor one third that on the 12th floor, due principally to the shielding effect provided by many stories of concrete from the building in question as well as adjacent structures. In addition, a person's annual dose from radon can vary dramatically, by a factor of 10 or more, depending upon where they are and the adequacy of ventilation.
To further complicate matters, these temporal and spatial variations can be interdependent. For example, determining the average annual dose received from terrestrial gamma radiation cannot be done simply by measuring differences in soil concentration, since it is also affected by weather conditions. Moreover, usage must be considered and can result in what is often referred to as technologically enhanced natural background radiation. Finally, the actual dose to panicular humans is heavily dependent upon the specific external and internal pathways of exposure.
Obviously then, there is no single number that represents the annual dose to U.S. citizens from background. But for perspective, it is useful to know that the average annual background dose for the U.S. population is about 300 mrem with about 200 mrem from radon, about 40 4
mrem from other internal sources, about 25 mrem from cosmic rays and about 25 mrem fro tenestnal samma rays. The average annual dose from fallout is less than 1 mrem.
However, because of the many factors that cause both spatial and temporal vanations, the a U.S. dose from background can easily range from 100 mrem for people who live in well-ventilated wooden houses on sandy soil at sea level to about 1000 mrem for people living i Denver area, a factor of 10 (Figure 3).
At the Shoreham site, annual doses from terrestrial gamma radiation differed with location alone by as much as 25 miem per year. At the small New Jersey site, the equivalent spot to spot difference was as high as 40 mrem per year. It in the context of these variations that the selection of 15 mrem over background as the mera*2ble annual dose for residual radiation from a decommissioned site must b additional perspective, consider that we rarely choose our residenas or domestic habits based on exposure to background radiation, yet the choice to live in a brick rather than a wood-frame house can increase one's annual dose by 45 or 50 mrem. A gas stove can deliver about 15 mrem per year to the lungs due to naturally occurring radioactive elements in the gas and a single flight across the U.S. yields about 4 mrem. A Denver resident can receive double the cosmic ray dose, triple the terrestrial dose, quadruple the radon dose, and a higher intake of radionuclides in drinking water compared to persons living in a coastal region-and if the house is not well ventilated the total dose could be still higher!
Selection of an AcceptaMe Level of Jtisk To place the risk from exposure to background radiation in context, let's look at some general risks to the population. About 33% of the general population in the United States die of heart disease and about 23% die of cancer. Non-cancerous lung disease (7.7%), strokes (6.7%) and accidents (4.3%) also figure strongly as major causes of death (Figure 4).
Comparing these causes of death, all of which carry a risk of greater than 1%, with the elective or accidental risks faced by selected groups or by the general population illustrates the complexity of adding societal choice to risk-based decision making in terms of selection of an acceptable level of risk (Figure 5). Smoking one pack of cigarettes daily will result in death from a related cause for about 28% of smokers and a motorcyclist has about an 11% lifetime chance of dying in a motorcycle accident. By comparison, the average American's risk of dying in an air accident is several orders of magnitude lower, about 0.02%.
As I said earlier, the annual dose from natural background in the U.S. ranges from 100 to 1,000 mrem with an average of about 300 mrem. When relating these annual doses to risk, the risk umamant models developed by the Intemational Commission of Radiological Protection (or ICRP) are usually applied. The ICRP performs risk assessments for both determmistic and stochastic effects of exposure to radiation based on research reports of radiation effects on tissues and animals, as well as on human epidemiology studies and modeling. For the purposes of radiation protection, the ICRP arsumes a linear non-threshold dose-effect model and basically extrapolates to estimate the probability of harm resulting from low doses and dose ra:es where there is little, if any, human health effects data.
0
Using ICRP's method of risk assessment, the average annual 300 mrem dose from background produces a lifetime risk of fatal cancer of slightly less than 1 in 100, or approximately 0.82%. The corresponding lifetime fatal cancer risk for 100 and 1000 mrem are approximately 0.27% and 2.7%, respectively (Figure 6).
So how would an additional increment of 15 mrem change the public's risk from natural background? 1. coked at in isolation,15 mrem per year over a 70 year lifetime would result in a risk of about 0.04% yet another decade lower on this log scale. When added to the risks associated with low, average, and high annual doses from background it is barely distinguishable (Figure 7). Indeed 15 mrem represents 5% of the average annual dose and is lost within the range of background which spans a factor of 10.
It is perhaps useful to note that for members of the public, the NCRP recommends an annual limit of 100 mrem for continuous exposure and an annual limit of 500 mrem for infrequent exposures due to all anthropogenic sources and recommends that ALARA be practiced below that. They further recommend that where there are multiple sources, no single source or set of sources under one control should result in an individual being exposed to more than 25 mrem annually.
What does one conclude from all of this? The limit of 15 mrem, including 4 mrem from drinking water which in itself is material for a lengthy lecture which I won't attempt to address here, carries a risk that is a small increment over the risk from background itself. Given that the risk is small and masked by the variation in the risk over the range of background doses, one must ask what all this should imply for the third or final component of risk-based decision-making, risk management.
Risk Management The major questions for risk management are: (1) What is it that will be measured or used to represent " background" at a particular decommissioning site? (2) What will be measured to determine compliance with the 15 mrem limit? and (3) What margins of error or what uncertainties will be considered acceptable in determining comp 0ance?
The difficulties involved in answering these questions become apparent when a site's decommissioning efforts are broken down into a series of steps and the complications that can exist with each step are examined. The overall process consists of, first, an analysis of the activities that have been performed at the site to be decommissioned; second, an assessment or survey to establish what represents background and a survey of the site to determine the degree of cleanup required; third, cleanup; fourth, a resurvey of the site; and, finally, release of the decontaminated site.
Each of these activities can be further broken down into sub-steps. For example, the person performing an analysis of the activity at the site must ask a series of questions: (1) Did the licensed activities involve single or multiple radionuclides? (2) With respect to each 6
I radionuchde, does it also exist in background or is it only produced as a result of lice activities at the site? (3) For each radionuclide, are there single or multiple pa result in exposure to humans?
Surveying also has multiple sub-steps. Survey methods and the required number of surveys of each type must be determined to establish the background level or levels.
The corresponding number of site surveys that will be==
y to establish the level of residual radioactivity on site with reasonable confidence must be determined and the backg and initial site surveys e.=: men be performed.
l The Mte is now ready for cleanup. Based on the analysis and survey results, the appropnate methods must be chosen and cleanup performed with periodic re-surveying to determme the level of progress until the release criteria are met and the site is ready for rele Let's consider a few examples of how this process actually works. First, consider a simple example in which the residual radioactivity involves a single, non-naturally oc nuclide. For simplicity's sake, postulate that the radionuclide has only one pathway ofexp This will result in a single set of surveys, presurnably a single method of decontamination, an a straightforward path toward releasing the site.
For a second example, let's consider a slightly more complicated scenano, involving multiple naturally occurring nuclides, at least one of which is known to result in human expo via several pathways. 'Ihis analysis is still relatively simple, but the surveys will be somewhat more complex. In this situation background will have to be established in a unner that accounts for variability, and that will differentiate quantitatively bere.
. backgrour:c, radiation and that produced by site activities. The clean-up may also be somewhat more complex due to the multiple nuclides and pathways of exposure.
The third scenario, unfortunately, may be the most realistic picture for most licensees, including reactor facilities.
In this case, the analysis may involve a whole spectrum of radionuclides, some, but not all, of which occur in background. It may also involve a variety of interrelated pathways of human exposure. As a result, establishing background becomes much more complicated, even for a site with a detailed pre-operational survey. Multiple elements of spatial and temporal variation will complicate this scenario further, requiring a higher number of surveys and sometimes multiple methods to achieve the necessary degree of confidence.
'Ihe decontamination of such a site, of course, will be ccirwiingly more difficult, invetymg multiple clean-up methods and, quite possibly, repeated attempts, with re-surveys perfassned as necessary until the criterion of 15 mrem above background has been met and the site is medy for unrestricted release.
How does this affect cost, certainly an element in risk based decision-making? Survey costs alone, not even considering cleanup costs, will vary based on the complexity of the situation considering the number of surveys taken and the quality of those surveys in terms of the degree of confidence required, or level of uncertainty considered acceptable.
7
i 2
major decommismaning effort (Figure 8).' Assessing t
a multi-nuclide site could require a complete pathway analysis, including measure i
external gamma dose; air, soil and vegetation samples; and samples of surfa water, and precipitation. Obviously, to attempt to sample and measure every cubic me relevant environment would be both impractical and prohibitively expensive.
strategy must be developed combining radiation survey readings over large areas with se sampling and analysis at representative locations, using the results of past measure as appropriate.
Even with an efficient sampling strategy, however, the cost of performing surveys to establish background can escalate sharply depending on the degree of uncertain *y th acceptable, which will directly influence both the survey methods employed and the number of surveys taken. In general, measuring smaller doses means increasmg costs as more sophistic techniques are employed.
1 Similarly the costs of site surveys and decontamination increase based on the backg criteria employed and the level of sensitivity and confidence desired. For some radion the detection limits of standard laboratory instruments can be reached, causing the surv to rise dramatically as sophisticated research techniques become ry. For naturally i
occurring radionuclides or those present in residual levels from weapons fallout, it may be virtually impossible to distinguish the contribution of site activities given the spanal and tem variations in background discussed earlier.
Just as an example, consider the cost of measuring cesium-137 in soil (Figure 9).2h At dose increments of about 30 mrem per year or higher, the cost is about $50 per sample. The W
cost roughly quadruples when trying to measure at levels of 10 mrem per year or less-based on the need for more sensitive laboratory methods--and increases dramatically again, to about $500 per sample, when measuring at a level of 0.3 mrem per year, which requires sophisticated research techniques. Because cesium-137 is present in residual radioactivity from weapons fallout, the typical levels and degree of variability make the cost of measuring this radionuclide at dose increments of 0.1 mrem per year more or less indeterminate.
What all this reveals is that every assessment of dose due to either natural or anthropogenic radiation will entail some degree of uncertainty Whether that uncertainty stems from spanal or ^_.gvud variations, the limitations of the measurement technique, or the ability of the analyst to interpret data, it is still uncertainty, and it can never be entirely eliminated.
Now let's review how the compliance process might work. First, background (x,) must be
'NUREG 1496. Vol 2. "Genenc Environmental Impact statement in support of Rulemaking on radiologwal Arteru for Decommissionmg of NRC-1.icensed Nuclear Facuities,* Appendaces, p. A 44. August,1994.
'NUREG-1496. Vol 2. "Genene Environmental Impact Statement in Sapport of Rulemaking on radiological Artena for Decommissioning of NRC Licensed Nuclear Facditics," Appendices, p A-53. August.1994 8
1 determined. But, unless it is zero, this is clearly not well-defmed and carries an uncertain (a.). To deemmine if cleanup is sufficient, the site must be surveyed to determine what remains (xi) which may or may not include natural background as discussed earlier. This, too, of course, cames an uncertamty (ai). Compliance requires that what remains after cleanup not contribute more than 15 mrem above background.
In addition, the proposed rule requires that further reductions be made As Low As Reasonably Achievable. Defining ALARA, in this framework, might be much more problematic than when working with higher, more readily measurable doses. Can ALARA he assigned a cost-per dose-increment value, as is done for occupational exposures? Is it simply a matter of vague principle? And how will it take into consideration other risks, such as those associated with the decommissioning activities themselves? These are the questions of the risk management phase of risk-based decision-making.
Now let us return to the framework of risk-based decision-making which is pmmised on balancing risk, cost, and benefit. To implement the 15 mrem criterion, as well as ALARA, in this context, one needs to ask at least two fundamental questions:
- 1) How should both background and residual radioactivity be defined or measured in practical terms, and what degree of uncertainty will be considered acceptable? Recall from the examp%s of our earlier discussion that if one takes into account spatial or temporal variations of background, not to mention measurement uncertainties, the sigma may easily be of the same order as, or even multiples of, the 15 mrem criterion.
- 2) The second question follows naturally from the first: given that the risk associated with a 15 mrem residual dose adds very little to the risk of exposure to background.
i and indeed is buried in the noise of the natural variations of that background, then how much money and effort should be spent not only to clean up to this level, but to assure compliance?
Conclusion These are among the questions that we, as regulators, licensees, and members of the public must consider as we proceed toward final decommissioning rulemaking. And remember, I've only touched the surface. For example, we haven't even discussed the proposed 4 mrem criterion for the water pathway and the associated risk management scheme necessary to assure compliance. These are challenges of risk based decision-making as we all go in search of background.
In this endeavor, I would urge that we be ever mindful of our goal as captured in the NRC's mission, that is, "to help assure that the use of nuclear materials is carried out in such a way that public health and safety, the common defense and security and environment are protected," and that we be mindful of the principles of good regulation, namely, independence.
9 yr
,w rv
citizens of our nation and fulfill our responsib protect the welcome the challenge, daunting as it may seem, and I look forward I, for one, participation of all parties as we proceed toward what I ho contributions and final rulemaking.
ns e 9
I 10
G O
O RELATIVE TERRESTRIAL GAMMA RADIATION LEVELS (MAY 1974)
]
SITE F
1.2 1-09 STREAM 0.7 9
a 1.0 s,
g' - s.
1.0 1.2 i
K j
G 1.0 j
1.2 D
0.6 l
/
H
SITE BOUNDARY
- =.5 MILES M
1.3 1.1 l
/
=
i
_ __ F
i I'
i l
RELATIVE TERRESTRIAL GAMMA RADIATION LEVELS (SEPTEMBER 1974) l t
200' 0.91 0.99 1.05 1.07 1.13 E
-r i
0 92 0.98 1.01 1.18 50' o
0.89 0.92 0.94 i
~
BUILDINGS / STRUCTURES FIGURE 2
~
G O
O RANGE OF-ANNUAL RADIATION DOSE:
NATURAL SOURCES (MREM) i c
i p 1000 i
i 900
-u n
n.A 800 700 600 3
500 ia 400 l
3
~v AVERAGE: 300 i
4'- %
300
, p} (;-
w A
200 FNJ 100 l
o M
,1co e 3 c
L i
LIFETIME MORTALITY RISKS 9
1l PERCENT OF GENERAL POPULATION) 100 %
HEART DISEASE (33.5%)
CANCER (23.5%)
LUNG DISEASE 10%
g (NON-CANCER) (7.7%)
- STROKE (6.7%)
ACCIDENTS (4.3%)
h DIABETES (2.2%)
SUICIDE (1.4%)
+_ LIVER CIRRHOSIS 1%
(1.2%)
HIV INFECTION (1.2%)
HOMICIDE (1.2%)
0.1%
g 0.01 %
d i
f O
LIFETIME MORTALITY RISKS (PERCENT;I (SELECTED (GENERAL POPULATIONS)
POPULATIONS) 100 %
CIGARETTE SMOKERS (1 PACK PER DA (27.5%
MOTORCYCLE RIDERS (11%)
10%
0 MOTOR VEHICLE 1%
ACCIDENTS (1.3%)
DROWNING (0.12%)
PUBLIC AIR
' TRAVEL g
~
(0.021%)
0.01 %
FIGURE f
1 LIFETIME MORTALITY RISKS i; PERCENT?
g i
i i
I l
i 100 %
i HEART DISEASE c
(33.5%)
i CANCER (23.5%)
i 10%
i
~
1000 mrem / YEAR l
HIGH BACKGROUND (2.75%)
300 mrom/ YEAR MOTOR VEHICLE AVERAGE 1%
ACCIDENTS (1.3%)
BACKGROUND
=
(0.82%)
100 mrom/ YEAR LOW BACKGROUND (0.27%)
DROWNING (0.12%)
0.1%
PUBLIC AIR TRAVEL 0.01 %
(0.021a/o) gy FIGURE 6 JL
j 1
)
lg LIFETIME MORTALITY RISKS (PERCENT) 1 100 %
10%
1000 mrom/ YEAR 1015 mrom/ YEAR HIGH BACKGROUND HIGH BACKGROUND (2.75%)
(2.79%)
300 mrom/ YEAR 315 mrom/ YEAR AVERAGE AVERAGE BACKGROUND 1%
BACKGROUND (0.82%)
(0.86%)
100 mrom/ YEAR 5
115 mrem / YEAR LOW BACKGROUND LOW BACKGROUND j
(0.27%)
(0.31%)
~
0.1%
s O.01 %
FIGURE 7
/7
ESTIMATED COSTS OF RADIATION MEASUREMENTS COST PER METHOD SAMPLE ALPHA SPECTROMETRY
$300-1000 BETA ANALYSIS
$50-750 4
EXTERNAL GAMMA EXPOSURE SURVEY
$50 EXTERNAL GAMMA TLD MEASUREMENT
$20 GAMMA SPECTROMETRY
$100-300 RADON MEASUREMENT
$10-20 SOIL SAMPLE COLLECTION
$100-200 SOIL SAMPLE PROCESSING
$100-400 THERMAL IONIZATION MASS SPECTROMETRY
$1000 FIGURE 8
}
t G
O ESTIMATED COST PER MEASUREMENT I
OF CESIUM-137 IN SOIL 0.03 0.1 j
0.3 l
E
<t 1
i m>m co -
3 l
OE 10 l
30 i
60 i
100 i
i.
i O
50 100 150 200 250 300 350 400 450 500 COST PER MEASUREMENT ($)
FIGUH t:
'8 i
3 I f
-(
~
]
0/
e w
w res l
N E W S L ',E T T E R w..
3,
State of Research and Perspective
....s.....
.r.se fCL-on Radiation Hormesis in Tanan e
-, e m J
I" I
Commerves Maussas SADAO HATTORI unrer w an Vaar Amulas Ceanet Rnerarch lasermar offincme ?>anr indantry (OtEM) r sm j
Juan ameni assa u 104 OermerAr. Chapade&is. Te6ps5 Japes
(
r s n,
<s
)
,a a..were mD ABSTRACT
,"*'",'[ y[
In 19H2. Prof. Thomas D. Luckey of the Unhersuv of blissoun published a p. pen in l
i
- o. r
.er.,=
the journal of Health Phmes desenbang radianon hormess. Radiation horn:esas j
hanyer.nemnn research in Japan has been based on the rauonale that if Lockey's claim were to be.
f j uncount nm en D true, radiasmn mannerment in Japan has heen extremek erroneous.
% r '..w m o After reuiles mere obcamed from sanous expersraents on the health effects of low l
,,,,,-.m..
Anes of radiationi suppin ung the Imrmems hspotheus. a Ror.rrd Robin collaboraene uma F,ta.s. ND inung pontram = as lin Gu'd on ahuut mentv research plans wuh more than ten
~
ssns j
j,,,,, g,
unnerunes in Japan. Thew actnsues are categorued as follomv A. Effects of tree j
w*
radicals pnnlim.ed bi lom dose radiauon 8. Shalecular beological responses to low dov l
D['",$,I,0 radiatum C. Radiatuni efTetts on the neurotransmission s6mem D. Samidaus e effeca ot pn t.rin,n m o lom dose radsataan un the unmune misem E. Epidemanlogical studnes
..w a.m % Mart. Ph n INTRODI JTION w1n l
In the ressew arucle *Phwological Senents from Low I.eseis of Ionizing Radiauon' ir l
Health Phmes iDecember 19811. Luches assened the exissence of *radiauon j
l'.*,",' 1*
hormens'. This reudted m the first Internanomal Spnpomusn on Radanoon Hormesis "D
oma so s mD at Oakland in Cahfornia. August 1985. Subsequently, interesang surveys and l
Q*
expenmenu on the eKects of low dose radaanon on mamunals injapan have expanded
,m m o --i yr on the body of knoededge which in genetal have supponed Laackey's claim that *1ow l
8 '*a"e* S'emi. 4.D-dose redinoon is susnuluing and essential for life'* The i"- i'= arucle wdl desenbe an. - n--e s 1
m, sg.,, ma venous radsanon hormeza research Andings and the current *Round Robin Radiauon l
8 5 *=
Honnemis* resenneh pengram inJapan which represens a collaborzove P Y,,,*,,,"i,,,,,,
et,, N =nonal endi avor involving CRIEPI and vanous research orga.iizations t.a== h==m. rka including vanous univerwues.
. nee i
D==w t. s=====. rk.a TOPICS OF RADIA*!10N HORASSIS RESEARCH I
O*4Wre. f.'
j auctra 't,an Thesism Ph D IMM'rt r4A4.see Seiristeers "C
The follow up data of people who recened radannon from the Anoauc Bomb shom us On.m il alunass Ph D i
n, v.
c.
an interestirig feature especialk in the low dose range. Figs. I and 2 show that about e j
cGv is the opumum done for the suppression ofleuke.nia through the survo of the
- op,.
people of Hiroshima and Nagasaki exposed to the radsanon of die Asomic bomb The i
exposed groups are showing nonger lives through the compenson of the death rate et ja each age between exposed group and nen exposed group (Fig. 3).
- * = -** '*
J ru..n.wiin rAE telte MbeSWE l
J Jo
-~~}
Tiw Bone)(aelE ret ofMassa Spa ' Professor Ementus of Osaka Unwraiv Dr. Nondo and Dr. Tanooka, fonner C.hasrman ofJapan Radiation Research Society, j tot to conducied snausocal compensons of cancer of the people of Misasa j[ villages (i.e. high radon lesels in 73 dnnkmg water), adpacent wilages $g [ and alljapan. The result was S meaningful as shown m Fig 4 E$ Ain*=t C" - : Tm *iC="= 100 r rate of leukemia N h n "'"E g g deaths am o. r.meme noem sac = and = Y Suj*[CQ supprew the reappearance of cancer j ;y in the hospital ofTohoku Un=rmev, oc.g 10 h For example, he apphed 10 cGy twice weeWy for several weeks successfully Organ Absocbed Dose (cGy) aganastliver cancer and lyutphase tumors. He is successfully applying whole body or half bodylowlevel Figure i Dose response relanon o(leukemia deaths among A4omb marmors-dose combined with local high dose irradaanon to treat non-hodgkin's lpnphoma. The low surmal rate of 36% m panents 3-with ac. t W. ivesphoma after ave years of the therapy ampseued we' 90% survival rase with a low riose treaanent schema. Some analyncal results -Q dennonstrase an increase of the raco of the helper T { cells to s ppressor T cells. k Suppammes e/Lang Camer Hiroshima Isini of ca:EFI and Hosoi of Tohoku t;niv. eaamined 2 ~ the suppresson of nietascans by counting long 7s colosses of mice (Fig. 5). Isini also measured the l 3 acavason of rat splenocytes, as shown in Fu. 6 by low es dose rashamon espoem 'E cra a, -mm j Humaoka 13IEF measured the v i== *IC'll r
- s mentr, anes and -; 4 dismusase aconsbes. Fig. 7 U
Nagasaki h das h some of his esperiments. I ~ g andnese Adapenase Ikushasa of spos. Unie. esammed de r%w. 3 response as shoum hi Fig. 8. Chinoue hasasect V 79 i Caus were incubased with SH-Thymedane for 16 hrs l (one cell cycle) and irradiated with a dose of 1 Gy of 6oco gammaan $4 Gy/ min). The cens== axed 0 0 10 30 50 and==r'd for da 8=='=a fr*t**ac7 'hh' nucronuctem 6 hrs aner irrd=- Misoooo of Organ Abeorbed Dose (cGy) cartrie em op.mumirrama dose ro, radioMag==- as shown in Fig. 9.
- 2. sass efiferummu Figure 2 ThreshokHike dose -
esumnaed from Yonesawirof Unnersity of Osaka prefecture h _ relation curve o(leukemia death; co,,,,rmed two phases of radso.honococ responses tn usmg a pnasng dose and survvval after a subiethal BEU.E A- +- 2 3.I
i dose adnunastratsoa. He Sound that a low (i e. priming) dose (i.e. bormene dose) enhanced resiseance ao subiethat 30 40 50 60 70 60 a.radieuon gun two months but not i rwo weeb tater. (Fig.10). Opposte resuhs were observed when the pnmary dose was substanually greater (Fig.101. } 10.000 ~ maase.taen s/ Human Cres g j Watanabe of Nagaraki Univ. compared .\\lale / iIV 099 I the growth rate of human embryonic g p I cells which had been exposed to a high j acute dose or to periodic multiple doses. ( f j Cells wtuch received 7.5 cGy/ week 3 showed an hormetic response. Fig.1I S g 1.000 1.000- , hows one of his +.a.tal resula 3 i Aa Egre en Ar New,,esasmasing Sysers Mlvachi ofTohoku Univ. discovered an ,C g interesting beharnor of mice when he 100l Female initiated the firm work of his hormens E 2 researth in CRIE.Pt. The 5 - 10 cGy 7 ,100 whole body X rav irratiation to the ICR j i g j mke which inevitably fight caused a .5 l drasoc change of the behanor after l j l seven dan. Fig.12 shows one of has tesu resulu Stoderauon of offensne g" g behavior was observed with the isolated-30 40 50 60 70 80 rendent wrsus isolated 4ntruder paradigm. Significant differences AEC (p<0.01) between control and irradaated groups are represented by Figure J Higher death rate after 55 years old (doned isne) ->u,~. de to the people who were not esposed to A. Bomb Imng in Nagasaki. Lower the astertsk-death rate after 55 scars sad Oohd line) corresponos to A. Bomb sur. m ers. Dr. Mori. former principal researcher of NanonalInstitute of Radiological Sciences, is derectmg epedenuologkal foGow up stadbes on thorotrast podene Male Female inJapan. He hasinJessed no M % caer sionwss w caer sawnse lung effects are cheerved Snowing a 10 year exposure to 2 Orsea an internal alphmy source. Respenst s{$33 Profeuor Onishi of Nara Medical ea 4 ,g g College discovered a marked increase of g 'I stress protem production by p53 genes.
- o.,
Doses of 10 to 25 cGy were effectree. Fig. 13 shows his W atal remnits. or C l=per18aa af Leer peer Sessary irredasaen u,,,, con. ^'<a Prof. Nomura confirined the importance oo , ~ ~ of meady low done itradlados for gene W Mc, m si. i. ivna repaartog activities, giving evidence that steady low dose adrttirtistradoc is j esmitial for obiaming beneficial health c5ects. Figure 4 compenson of mandardmed mortahey ratio. Misesa/concel aret e.r t w, LA. tens 2 2.
~ THE ROUND ROttN TY.5TS PROGRAM i Soaliminoind Ratum Tess Program (1993 1996) on arilamon Hannens bang camed ominJapan is as folkswr $g NM W #"P""'" p 100 4 = d m a or G.? 80 tareas i.e d by w =c 2 P<M5 h { gg 60 gm' 10 T"a *8'"a sn=P* an wwkung on ae 3 ,,m._ - -c,a,,, i, doc,4 37 P}jyh h (um)w v 40 52 " < " ~ ' T W u d"e d 10 ._ '--. = ihrough dw 3M E
- 4 *(
Cf7 ausenenesmos dahe immune sraem hp,m3 m 20 g$p br mR mmg AsR mice.nw od-r is yjpg. Z /syyrt 8%$ 7 i&R loohng a die,,. '=- d chesucal 0 cartmogen (Fe#TA) induced nuns 1,,Gy to,,,,,,,,n,,,,n e,i,m,ced sod l_cGy + < 7- ~ - -3 .,,,,,7, wa. L,ontrols a 3 OK432 ip raisk namartner
- 1. AniMaukemogenesis Test (5.
Sakamoso. Facuky d Medicme. Figure 5 inhrbiewwi of spontaneous metastanea in lung he whoic harty Lrs,i"*- Tohoku l'as.orney) dution wwh 15 cGv and combmed treatmem. t la cG was erradored 20doveaAeri., -roon wuh munne squamous cell cacmoman.
- 2. sod and Pasatne suppresson d FeWTA induced Tumor (E.
Utsam. Insonnes d Medical l Scunce.Ceaser dAdiak Diseases. Kurashaki) A d dghgBSeem E Two dlSerumagroups are lookag u the PombWerdWRinchsced increme 5 200 e p<ie " ishas hrerkhoumarrania m. rosahkdepresne esseisatumon. s_ E $ 130 12 8"'EmE Paum dahe hummm srammand/ormamamary, or gu somy usehotum se esmed ming 11! o8 4 4 sAu (assamance Asosieresed Meuse) {------------- ,,,,,,,, % m 100 - - - - - - - - - - - - - - - ,g g 3 1 Ikis4Eamushst 9 bg 50 .c 2 Dom on the Asins Pmeus (Y. 4 7 okumura,recuhr dm. NagasakiUnhuuhr) 0 .m
- 2. La=*ose Radiados and Eaavr 0.1 1
10 100 1000 Meehensa nagubdos (A. Mari. ""F " " " "'6 " 0*"r"=* Dose of Whole Body Exposure (cfry) Uni rde 8eManishakdassem one snur is knoW=5 # 088 Pambuin rism, e raeci.t = d it oie nod, xor - on con & of LDRinduced incrummein longevity I mduced ^1._ ~ rispense of rat splenocws. The splenocyte - d human,,. "" - usag dw dma were ehemsned hem rati at 4 hrs ener x esy irr-m-.-i muu. w 4 y
m l LDR. ineettew and ineracesular egnal transrtie en is i105 Waianshe \\l FEers af msn.,,i,ir,adiannn.oh inn a, "f ***' ' '" ;' C' AA. cal eransformanon anr1 esasnswd u' n dtis M. I Title & Raamarcher gromth abihti of human embrso cells m nitro, int l nadiar n.nl ino2. Vol ri2. Nn a
- 1. DNA Damage Repair Slechanisms (T. ILuthem.i.
- ili \\fifune \\l.. Konet, %. Tananka 11 es al. Cancer \\fonakn Research Reactor Center Ktoso l'niserun i
'"'" 'n a Sria area 4 Wasa. lapans woh a hwh r3< tan
- 2. Cellular Resp and Signal Transfer (M.
hacksmund.1 Jpn Canm nes. Im as Wat.mahc Departmen' of l' hat m.nt. Nag.itaks ' I U I'I"' ' %"8'"'"'*"*" '" *"E'"*"d'" "'I I"hf'f 3'"* I.* *CW "1 of ru.nico.rseen hi i rt.. mh..le 'wwh Urradueunt. NIPPO.N.WI A ItADIOLOGICA 50. i101.1990 C*.05tNG 11: Yamaoka li, lacrea. cit sod actmnce amt Decrea.,,t Formauon of free elestrans and fre i.utwah in uimzmg L' lad Frr"'"ic lesci m rat nesans mduced hi io ume r radiauon creates many complex chemnal exuons hanan. Free Rattral B oican Ar Medirme 1941. I1. i folloised he agmAcant hoological responses This article i desenbes imporunt research directsons that wdl pronde (14) Vanesawa M., Takeda A. Masonoh j. Acquired radeoresseiance after low dose X4rradianon m mice J unportant mechansac underssandings of hour cens and gagganion g igger. 31 (ISS). organsams adapt to ennronenental sumu8.i such as low done * (15) Rondo S., HEALTH EFFECTS OF LOW 42 VEL radsanon RADIATION. Ibnki l'aer. Press and Medical Phmes I ACINOWLEDGDONT Pubinhingynconens im A prehmmarv senson of the aruele was presented at the l Intemational Simpomum on teologwal Ef.ects of Lom Leul Esponeres. Octoher i21 A. lo41 Changchun. Chma. I appreciate the macere adsise and directions gnen far T al l the Radianon Hormems research artnmes 4,h
- e..: ur. no r 1 &
,,,,n, Those L'micesin persons who are sigma re.pciiful achine f
- *
- n'..am.m and dirernan to the research are Dr 1.oc kes t \\lismons Dr i.
Kondo (Osakat. Dr Susamara iKuw.o. Dr sakam.wo r (Tnhokul. Dr stakmortan i L Cl.U. De t $ka<t.: i ToLuil. Di 2 '* h. "
- Sasaki tLoto). Dr. Yamada (l'uhol lit isot==lera i Inkia 5.
i Sciencel. Dr. Watanshe (NatasakO. Dr. Tennnka (Nananal f 4; Cancer Inst. L and Dr. Aoisma (Shiga Medwall. J 3 I RDERENCES 2* g il) Lucket T.D Phwoolngical Senefire frnm Leiels of 1.- Inmimg Radianoa 14caith Pho loa 2. 41. 4 0 g (2) Lucker T.D., Hormems wuh lonmns ILwhatwie, LRC Press. Soca Raton F1,19eo Passage number (3) Laachev T.D.. Radianon Hormems. CRC Press. loca Figure il The growth rese at each passage in humast entbev. Raton. FL.1991, a"'r hbmhiasts (HE7) irradiesed with a dose at (4) Loren L. Geologwal EKects of Estemal Camma gamme.rsys (SL ' of C.187 l passage O(Al and muluple doses of 7.5 Radianon. Pars 1. (IIRRLL R.E ed),"a Maccesw35. sw net.1964. , yg (5) Stewart A.M., Duluped gNaces of Mioenb l Radiation: A asseen of assem Monality Ram ] and Ridt se nur Saemr samors. artt.J. I 1'O-d I o Epid. ar Comm. Hamlei 198E. 5 '~ g j TJ 100-Guangdong. Chin.J. Radiot. Med.1985. Proc. 5 'E g-I, a c,,,,,e (6) Uu 5.Z A Ramudy of huusiune Functions of the inhabitants in a High Sackground Area in i g. \\ a a' i 15 cGy' Defense Mechanums 1991. Rooto, Japan. 2 40-( \\g$. [ / (7) Proceedings of the Intemanonal Conference i 60-1 on Low Dome irrednesson and Seological E /,y (8) Mori T., Thorotrast Lase Effect. Current f 'O Encyclopedia of ressmeegy, vol lo.1990. - Expowre -5 b"5 l0 l5 2O 25 (9) T., Cairrevet thejaponese follow. i up sudy of the Thorotrast patients and its ' Days after irradiation i I relationshape to the sistwical anahms of the j anatoper senes. Entnah Insutute of Radiology F"egure 12 Erect of loendose X.rses on aggresanon desplayed by I 1989 Lmadon isolated rusadent vs esoissed intruder. + 4 Vol 3. Ne I. July I9N
f f 50 O control k 40 E 25 cGy,12h 2 g 30 - o I E go. 1 I m Ti 10 I 0 '- "" ' %l%l'% el*%{%g,%k %e i neure n v cumui.wi..n. r i.u,n,.in.......,.in. i., u.. Spontaneous DNA Damage and Its Significance for the " Negligible Dose" Controversy in Radiation Protection I, Daniel Billen MedseelSarner Dis uien Ook Rike Assanned l'anwutna i One of the crucial problesns in radiation protection is account for 50 06% o(measured ' ndiada= damage in r the reality of the negligible dose or dr munimiu crw* cept cess (5,6). High tET radiaalen, on the other hand, (14). This usue of a 'precace aero'and its resolution is penouces unsepse DNA damage ( 7) prinner9y by direct I s central to our __M; of the contamersy con-effect s (5) which is less likely to be property repaared (7). I cerning the endseeses e(a " safe
- dose in radiological taneous or intname==aalaenda= o(cellular I
health. Howeser. Ier very low loels of esmronmental DNA is ubiquitous ist nature and libety to be a major mutagens and ca. - _:inchading low dows oflow-LET radiations (less than I cGv or i rad), spontaneous cause of background mutatsons (8), cancer (9), and other diseases (10). he docuamentation of this intrinsic I or endogenous DNA damage may haw an increasing impact on the biological consequences of the induced DNA decay has increased at a rapid pace in recent years cellular response. It is this issue that n addreswd in this and has not gone unnoeced by conteenpoetry j communication. radiotnologists. Setlow (11) and maore recendy Saul and The followmg docussion is intentionally limited to a Ames (12) summansed the Endaags of f W1 and cornpanoon oflo*IET radiauon ance its effects are due Karts.rorri (IS) and others (14) which suggest that Pnmanly to indirect damage in cellular DNA brought approximately 10.000 measurable DNA mod 6 cation about by OH radicals. Indirect efeca o(low.t.ET ewnts occu/per hour in each siamunahan ce!! due to radiacon under aerobic conditions are reported to 'ntnnne causes. I s ar.uz s.,,,- y
. - - -. - - - ~ -. - bases of the Asomac Bomb Surshurs Healin Sursev Talg & Ranmarcher 3[ 4
- 1. Anatyas as Das eheming the _ r,2, increann,
.; __ j'. y wf. 4 r EKect ofI.meOose udag Data Saw of A-8nmb ~5 A Survners Henkh Surwy in Nagssaki (Y. Okumurs. jj
- ,h j'c Fai.ulev t,f Medicme. Naganski Unnciun-)
s-I -y I ur cia i Studnes en binhanosuu underkonglwueer E$rts l $. j ?" Activesien of Semic Bielegical Functions i$ ~ There are four d:Kerent groups here: Oae is looking 15 j f at orfanic radicals with long half tiws produced hv 0 W LDR. and their beological/ molecular eNecu. The 30; g% other is looking at the saimunaute esecu of J g. fractionated LDR on the proliferation of cultured j g 20-k' i cous. Using humaan : "., _ - M ntwohlasts, total U1 n sis.es p. Passges, transformadon freiuency, mutanon j{ frapsency and other aiseremons of cells are p-f W-SOD esamined in this study. 'nne third group is looking at 0 seem< ell acth3 tion through apopions induced by 30 LDR. The efeca of protracted arradanoon with low y dose rates are esamined in intessinal crypu of mice. g,, . u w.m ow ' Unng LacZ gene introduced transgenx Mutamouse. J r somacc cell mutauon induced by LDR is hemg j 2 01 J N h". d,.o r,4 by another group. Mutation frevivency and .g m% spectrum in the macodused LacZ. gene are examined 1P after acute and/or chronx LDR. I i g Inig & Ranmarcher 50 .00 ".;:0
- 1. Identincanon of the Initial Radicals induced hv Dose of X-ray (cGy]
Low Dose (T. Minaaki Facular of Engmeerms. Nagoya Univerutv) I'Eure 7 Does and adent changes in lipid peron-1 de( ) les=L SOO artmey and membrane flu-
- 2. Examinancin of the inhabitory Efects of Low-Dose idley (w/s resio) of ren's brain cones he X rar erra.
l diation. on Cell Agmg and iu Mechanism (M. Watanabe. u m.mn n n. e e n is nenei 4 Department of Pharmacy. Nagasaki Uniwrmtv) sm.p.i==, w/s -am.=ma ar m =is e e6 sr l 3 Stem <eu Acuvauon by 1.ow Dose through OM7.T Apoptoms laduenon (R. Ijiri Radioisotope Center. Pw" C.'.',,."f",,''""""'" "".' ",T,', "'d""'" Tokyo Unnerney)
- 4. Speci6 canon of the 'Eas==ar Ceu Mutation induced by ImmOcer using Musannouse (T. Ono.
F=eutsy of mame=a Tohobs Unhermey) j Assivustom etInstWedmassese-g9 There are ese h gsoups in this sandy. Two j[ groups are looking as the acquered radlorensiance in t.R mice. When the radloremmance appears after .E 3 fMh _ _# [ 4 { conditionmg irradnamon. how kmg it lasts and the 2E emh- ~ relation to the recovery of W,----; : tissues are jj e======ad in . " -d rnice. Relationship S3 between seremors, anchubag LDR. rnd defense (10cG) i mechanisms is also esasuned in the inice pretreated 2g [ with seressful miseuli, asch as diet resencion. i.p. dE.10-8 10-8 10-' 108 101 1. injection of heavy metals, skinescamon and LDR. Acevanan of defense awck====== is also looked at in ?H-THYMIDINE CONC.(kBq/mD I retanon io the atanulaeon c !seeuxeu proliferauon through apopeosis by LDR..A '- _ of the rigure a An op 6 nnidase range ot to newt armum for the I 77 Ahrmansmar Cell Death ;;,, M to essan< ells in micromsetet ladisessen of +-d t'**e resPoa'e5 Val J, No. l.fudy J998
l thymus and other hensaaoponene tissues are emanuned m this study. 1 ame im.c: u Depresson of agresave behavior observed -e, b a
- "" i"***"d "ho**d Parnan, on f
100 the head paroon with low door X<ers ~3.# suggests the organians can perceive the LDR i g%"" through the cemral nervous sneem (CNS). g- }u One group en lookang at the e6ects of LDR on hem 1 i3,,,,,,,,,,iem. as wea as behavior. 80 because the defense mechansens are closelv connected w6th CNS hancoon Radicals ^
- 3 y _M by LDRare deensened by a de.omacados sysism widch includes a group
.c 60 of easynes, asch as cuenteer.500 and 3 7' peroiddase. An 1,7 -cM that 5 cGy(59) LDR can induce emprendon of genes and a d 888 Produce utsed a ?? %M arief 8 B 40 deto"*"'a= of radicais is aho esammed in toeGy160: retaden to aceveson of smoteeminr/ biocheadcal defense mechamans. M
- secn+n
- 1. Acquired Radlovenstance in Lowoose j
20 - m Irradiased Mice (M. Yonesswa. Basearch
- 0;:
222,N' Center of 8% Osaka Presecture Unherway)
- 2. Acqmred Redsoremmaare and the OI 5
10 15 20 25 N Acavand Desense Mechanismas G. I Days after irradtauen Maumbera. raculty of Medicae. Tokyo University) 3, ,g.Aiarisedc Cet Death p1gure e surv6 el redos of ne a irradased wah low desse 2 monehe Insfore the ascond'/y a.=aasi with 775 i,G, of X.rsa
- 7, - -"-(Seissuindon of Seen Cell Protiserstion through LowOose Induced Two types of acquir sd radiocesistance after small Apopensis) (T.1hamada. School of Meecame.Toho Uniesneer) doses of X-rays in Mice
- 4. Action of Lan>Oose to the Central Nervous System and Am6eiress EHects of Radieresistance.
Primms De s of ) X-rays '.:Gy) 2 weeks taserval 2 months mterval of Weecine,Toho Unheruler)
- 5. Seress Prossin and the Empmenom of No E
Genes retaand to Actise Ouygues (M.
- 3 5-10 No N'
leous.Facuter of Meechas. Osaka Oty l M 20 No No (15 months) UM) 30-50 Aashusles of DesmageReessery N ' No Ad8P 'e f*8Poness se cuAndon sagest thati d e lacrease m 30-day survival rate are subtethat cats haue intrinInc thesmase spuisses agentet X-triadtanon circummaaness thes sught ausse irreversible damage.Dere are amo grongs One group is f tookhag at the methodos of games==="d M DNAmpair.kt des mulyindsud gene ga:sandexpresdomofgunareinsed e Figure 10 Pmrredemoe wish 5-10 cGy resuhed in the radiommance.DNA@ are=====e==8 udag cialmared OiO 2 neonths laser. The aeganised redseressuaance was also observed wtnen the sdee were esposed to 30-50 cGy. In thes ceEL % e adsis group is knoking at crButer Freuveemmen steh the teammuseuse doses of 15 20 cGv dad changes ts the adspese roupomme induced be case, the raserensener appeared 2 use6+ sser,
== mam i , r mor-==-- - arr u.w.,n 17
The current radados thertture wtll be interpreted ta most cellular DNA at arr, one time. From the data ~ show that -100 (or fewer) measurable DNA sherations summarized in Table Iit is not unreasonable to suegest occur per cent: gray oflow LET radiation per that. at a mmimum. the spontaneous DNA damage is of mamm.*lian cell. Therefore everv Aewr human a..d other 3 the order of 610 x 10 events / cell /h and to use it X mammalian. ells undergo at least 50100 umes as mu' 103 DNA damage evenu/ cell /h as a reasonable awrage spontaneous or natural DNA damage as sapuid result int the pu of discussion This allowg a calculati<m from exposure to I cCv ofionizmg radianon Since of I O x 10 Spontaneous cellular DN A damagmat background radiation is usualh less than 100400 mrem ev*nu/ cell /da. or 7 x 10 per year in mammals 7 (12 mSv),'v. it can he concluded, as discussed hv Muller meluding humans (Table II). The lifetime load 3f and Mott-Smith (15), tha: spontaneous DNA damage is sprmtaneous DNA damage events per cellis ' ben -5 s due primarily to causes other than background 10 il an awrage life span of 75 years is allowed for 9 radiation, humans. "laertes6c" Or "fp n _" DNA Desmage DNA Desmage ladeced ByIrradiadon DNA is not as structurcDe stable as once thought. On Sewral recent renews summarize the types and the costrary, there appears to be a natural background quantities of aheramon of DNA in cells caused by of chemscal and physical lemons introduced into exposure to low IET radsanon (1618). The reader cellular DNA by thermal as well as oxidathe insult. In should refer to these for references to the ongmal addidon. in the course of evolution man, ceils have works from which the renews were drawn evohrd biochemic mechanisms for repasr or b9 ass of The estimate of about 100 DNA evenu/ceU/cGv used i these lessons. in this discussion is based on information contained in Some of the more common natural
- DNA changes the renews by Watt (16. 20) and assurnes the molecular include depunnauon. depmmedmauon. deammaunti, ucight of the mammahan genomic DNA to be 6 X 1012 smgteatrand breaks (558s), double strand becaks Da. i emstitutmg ahnsit l'1 of the cell weight.
IDSBs1 hate modsficanon, and protem DNA ttonlinks Watd (Table !! (16)) lisu the amount of energy These are c.used be thermodmamic decar processes as ileposited in uinous DNA consutuents/ cell /G3. From well as reactne molecules formed hv metahnlic this table a total of 13.3 DNA esents/cGv is calculated. processes leading to free radicah such as OH. His enimate of damaged DNA sites /ceH/cGv is 10100. I peromsdes. and rescuve oxvgen species. chose the 1004esson esumate to make as reasonable a Shapiro (14) has recently discussed and summanred consernthe comparison with spontaneous DNA tne frequency at which varmus kinds of spontaneous damage as poemble (Table H). This nur~ her of damaged n DNA damage occur. Spontaneous DNA damage estnu mies would include both direct and indirect DNA per cell per hour are shown in Table I and were damage esumated from the data presented by Shapero (Table S-- vs WW M Was And 11(14)] $ sehr Q f 5 w For ungk arr.adzd DNA of mammahan cells at least. 3 Wallace has recently renewed the nature of the DNA 8x10 damage eveses occur /ceu/hr, whereas for 5 lesions caused by acwve osunaing specses produced doublegeranded DNA there were -6 x10 damage both naturany and by lowtET radiamon (17). Oxxhung I events per hour GuMe I). While the raso of angle-rarticals and especiaDy OH radicals resulting frons either stranded DNA to doublegeranded DNA vanes with cause produce sunRar types of DNA lessons (1719). The phase of the cell cycle,it is reasonable to assume that enrymes invoked in their repaar are similar whether the double stranded DNA is the usual configurauen for DNA damage is produced spontaneously or by ~ Table ! Esemated Spontaneous DNA Degradauon Events (Cell.'h)a Reacuon Singiegtrand DNA Doublegtrand DNA i Depunnauon 4000 IM i Depyrimidination 200 50 t Deammation of cytosine 4000 15 Chain break resustmg from depurinadon IN Direct chaan break 48 a Calculated from Shapiro (14)
r=* mon. Howewr. rwhaami is known to induce an hgauon step. error prone repair system iss hectenal cells and perhaps A survey of the literau:re on the doubling dose for in mammalian cells as we# (!!. 22), mutagenesis in eukanotes exposed to tow LET DN/ vlycemiases and endrmucleases are imuhed in radiat <m indicates a range of 4 to $00 cGv and f. the repair of h.i < <tamage. Other nucleases am uti mogenem a range of 100 to 400 cGv. Ilung the 3 available for sugar damwe repair (17). Recngmtion of hahpark value of approximately 100 DNA the damage site by the appropnate enmnes is esents/ cell /ct,v. thes would represent a range of 400 to dependent not im the mitiating event but on the 40.u00 mduced DNA damage events per doubling donc rhemical nature of the end procluct. These end Osmg 100 cGv as the appmx mate douhhng dose. a products appear to be similar whether induced hv toul of I x itsi DNA damage ewnts would he required natural causes or radiation (17). It would seem to nduce mutauons in numbers equal to that obseited reasonable to conclude that, due to common oudazmg in nature. This is approximately the number of DNA 3 3 radicals, many of the qualitauve changes m DNA are ewnts (M 0 x 10 ) produced spontaneously in each quite similar for radiacoranduced or spontaneous DNA cell /h (Table !!), damage. The Ne@ Dose Ca. 7 i The quantity and distribudon of each class ofImon The conipanson ofloinLET radiatiorsaduced DNA l may, howewr. difTer signincantly. As indicated earlier damage with that which occurs spontaneously indicates ! there weuld appear to be relatively more DNA esrand (Table 11) that a retadvely large number of DNA breaks than other lesions resulting Imm spontaneous damage ewnts can occur spontaneounty dunng the causes as compared to radiation insult. A good poruou g;g og,gg g g g of these may result from depunnanon (Table 1) with Dose protraction over a penod of weeks or months producuon of 3' OH iernuni ( clean end*7 as part of ,o,,ld lead to an increasmg rauo of spontaneous DNA i the repast process.
- d. image esenu to those caused by irradiauon. Bv j
%Iany of the DNA strand breaks cause<lin lent l.ET curapolation from high doses and high dose rate as j radiation are mcanable of sening as pnmer for DNA imcussed tw Ward (16. 20). I cGv delivered in I i would I pohtnerase (23). Homever endo and exontarleases (au se 40 50 times as many DNA dama6 ng evenu pee i
- xist which can restore these blocking ends to clean tell as that caused spontaneousiv dunng the same time en<ts and allow compleuon of the repast process t17).
spa (TWe II). h. I cGy deliwred ennh over I A strong correlauon exisu between DNA DSBs and r e cause @n ) less than 1 DNA j lethality in mammalian cells for low LET radiation. damaging event per cell / day. This can be compared to l While the quantity of DSBs produced be ionuing 5 -2 x 10 natural ewnu caused per cell / day. radiation is fairiv well documented, this is not true for from these numbers, it seesns reasonable to suggest spontaneous DSB production in mammalian cells. that there does exist a *neghgible* dose in the range of In spontaneous DNA decay, formation ot a DS8 is our terrestnal background annual radiation dose of-1 likely to be the result of single strand ewnts occurnng mSv (-10 DNA ewnis/ cell / year). This can be i in close proximity on each daughter strand and leading compared to the a,,,.m asely 7 x 10 DNA l 7 to cohesne ends wiuch can be repaired easily by a events / cell / year produced by spontaneous==s = Table U DNA Damage Esents pee Mammalian Cell Spontaneous DNA damage e cents Character of event Per second Per hour Per year DNA <tarnape/cG,a i Singlestrand breaks 1.4 -5 x 10' - 4. 4 x 10' 10 Double strand breakr, 0.4 I Depunnauon and/or -1.5 s 10' -81.4 x 10' base lessons 0.8 - 1.25 x 10' - 1.1 x 10' 9.5 Total evenu 2.2 -8 0 x 10' -7 x 10' -20 cGy equivalents 0.022 8 0 x 10' 7 x 10', ( l cGy = 100 evenu)b a From Ward s*t()). b Since other adianorwnduced DNA damage such as DNAprotem creenhnksi$g and base w~4.'s (18) occur.100 events /cGy a used as a 'ballpark* value for ease of coenpanson wuh spontaneous events. l WIIE Neu'shm-In
Adler and Weinherg (141 have proposed that the
- 12. Saul. R L. and Amen. 8 N. (lea 6 Background lesch of standasd deviation of the becliground irradiauon (-0 2 DNA dan age in the pnpulaten. sane I_de Sitt. 38 529-mSv) he used as an acceptable addet6onal dose due in 1
human actmues. This isould lead to -2 additional 13 lmdahl. T and Earistrom. S. (1973). Heat mduced mduced DNA damaspng events'celinear as compated depstimutanon n4 DNA. Rauchemistrv. 23 3131.W,4 7 to - 7 s 10 spor - us DNA damage esents. 14 shapien. R. t19 ell. Damage to DNA cauwd b. Considenne the maquitude of the sporitancoitsiv hidrnhin in Chr-n-.-. and am, a g induced DNA changes m each human cell,it is not vcberig and K. Kleppe.. di i Plenum. New ynrL pp t 3" unreasonable to ptedkt that 0.2 m5s ddaceed mer.i scar umuld h.ite neglichte hinlogical conscTience* l *, \\luller. li f. and Mnu.5mith. L%I. t 103h Fodence When teinporal conaderations are factored in. it that natural radicartmtv n madenuate to esplam the g,, s.g g g, becomes clear that spontaneous DNA damage ut USA.16 277 2e5 mammalian cells may he many orders of magnitude greater than that caused by low and protracted radeauen in manimalian cells: Idenones. mechanism of radiauon doses, especially in the terrestrial background formason, and repasrabehey. Prag.Nucime Acad Res. range of 12 m5v (100 200 mrem) per Sear. It is WeiJal, 35-95 125. important that further suadnes on the effects of hoth
- 17. Wallace. S.S. (1988). APendonucleases and DNA.
iontamg radiations and spontaneous events on DNA ghcondases that recognise osidnine DNA damage. decay and repair be conducted to better understand the Enuron,.stal. Mutaman.12:431 477. practical health consequences of low and protracted la limchmson. F t 1983). Chemical changes induced m doses of radiauon (2. 9. 25). DNA be somemt radiaten. Prag. Nucleic Acid Res. Mal. References Amt. 32:115134. 1. Daus. l P t 19#tel the future ne ihe 4 =ren=snioncepi I" Inenic. It i1989i. Geneur toucologs of ongen. Mal 3L Healt h Ptns. *.i t*'t. bi2 Sc3 2191,94204 2. Natumal Researrh Oneme il t(San ~.imimure em the .'O Ward. l T. ' "MT) P u.nanon chemical methods of cell Biolvpal Effeiis ut fontamit Radiatino. Ileakh Lifecu or drash. In: Precandangs of the Ath innernanpnal Coneress j E-~e eo la Lesels ud ionumn R.nh.m..n.(tEl n ad Radiauon Research tE.M Fielden.J F. Fowler.J H Nan mal 1adrun Pre **. Wadungion. L>t !!cmin. and D % nu. Eds 1. T.nint & Francis. London ) PP' 3. NCRP. t 1987). Recummendauuns un Lmuss for Euaosure to tomaine R.adianun Reguirt ut. Nanonal 21 Pohl-Ruling.j.. f'esrher. P and Hasa.O. (1983). Effect i Council nn Radhoon Proscenna and Measurements. nflow<loar acuec s.stradiscon on the frequencies of Bethesda. MD. chi h -2 abe:Tations in human penpheral '""P oc"*s sa s** Minak.Bai.110:71.s2. h 4. Roose. H.H. (1989). The threshold que= tion and the search for msmers. Radant. Bas. 119:576 373, 22 Wolf. S. (l999). Are radianon educed eWecu hormenc? h.2W75. 5. Roots. R. Chatterpec. A., Chang. P Lommel. L. and Blakeh EA (1985). Charactensanon of hvdrosvi 23 mn Sonntag. C.. Hagen.11 * * -- N;;. A.. and Shutt. r3 decal <nduced deneage aher sparse;v and denselv Frohhnde. D. (1981). Radlanon<nduced urand breaks ionmng irradiasism. las. J. Radies. BinL 47.157166 m DNA: Chemical and ensymanc analysm of end gmups and mechanouc aspect. Adr. Radies. Esel 9109142. j 6. Billen. D. (1957). Free radicalsesvengmg and the l espresnan of pensasisar lethal damage in X irradiated
- 24. Adler. H.L. and Weinta'5 A.M. (1987). An approach to repaar<lencient Eartnertas esA Radnes. Bas.. Ii1:354 360.
setting radianon standania. Hankh Pim. 52-663469 7 Rsiter. M A. Cleever.j A. and Tobias. CA 1977).
- 25. Totter.J R. I1900). L x cancer and its possible High-LET radianons mduce a large proporuun of non.
relanonship to ougen metaboism. Pre hl AM Sci USA. 77:17631767. rerommg DNA breaks Maugg. 266:G534*e3 8. Drake.J.W. Chekman. B.W., and Riplev. LS. (1983). Aclunowledgessent Updatmg the theory of mutanon! &mJga 71621430 This article was repnnted from Badaanon Research 9. Ames. 8 N., and Cross C.E. (1987). Osvlen radicals 124 242 "45 (1990) with permiseson. and human disease. Ann. Intern Med. 107.526 545
- 10. Halln ell. 8. (19R7). Osidants and human disease:
e, Some new concepts. [Ag&j 1:358 364. L 1. Sedow. R.R. (1982). DNA repair. agmg and cancer Natt Cancer inst. Monagr. 60 249-255. Vol J. No 1.Buh I994 &}}