UNDERSTANDING RADIATION HEALTH EFFECTS;
A GUIDE FOR COMMUNITIES AT RISK
Prepared by Diane Quigley, Executive
Director, Childhood Cancer Research Institute, 1992
Measuring Radiation *
Scientific Notation * Types of Radiation *
How Radiation Affects
Us – Pathways Exposure * Biological Effects *
Scientists Study Effects of Radiation *
Studies - Summary * Epidemiological Findings On Child
Health And Adult Risks Of Low-Level
of particles or energy by an unstable atom on its path to becoming
stable (radioactive decay).
Radionuclide: refers to an atom that is radioactive
Curie: rate of radioactive decay
(1) curie= 37 billion emissions/second
(1) Becqueral = (1) emission/second
Chernobyl released 40 million curies
RAD: the amount of radiation absorbed by exposed material
REM: damage to human from radiation
1 RAD=1 REM in
measures of gamma and beta radiation
1 RAD=10-20 REM in measures alpha radiation
1012 (1.0 E 12)
109 (1.0 E 9)
106 (1.0 e 6)
100 (1.0 E 0)
10-3 (1.0 E -3)
10-6 (1.0 E -6)
10-9 (1.0 E -9)
10-12 (1.0 E-12)
OF IONIZING RADIATION FROM NUCLEAR REACTORS
Alpha Radiation Particles
Have a large mass and are easily slowed
down (a thin piece of paper can usually stop these particles)
Cannot penetrate human skin
Alpha-emitting material can be inhaled or
ingested into the body and the emitted alpha radiation can penetrate
cells and sensitive internal soft tissues creating serious damage.
Alpha emitters – examples: plutonium,
Have a light mass and far more
penetrating than alpha particles. Sheet of metal and heavy clothing are
required to stop these particles – depending on beta energy.
can penetrate human skin to most
Like alpha-emitting materials, beta
emitting materials are most dangerous when inhaled or ingested (skin and
eye exposure are of most concern).
Beta emitters-examples, tritium,
Form of wave energy (photons) similar to
light and radio waves but of much shorter wave length and higher
Will often pass through body
Four inches of lead or two feet of
concrete can easily stop most gamma rays
HALF-LIVES OF COMMON RADIONUCLIDES
TYPICAL PATHWAYS OF CONTAMINANTS
Direct radiation of whole body – from gamma-emitting radionuclides
passing over population (example, Cesium-137)
Inhalation of radioactive substances – from a passing cloud and from
radionuclides re-suspended after deposition on the ground (example Iodine
Direct External Radiation of whole body by gamma or beta rays emitted
from radionuclides on the ground (example Cesium 137, gamma)
Whole body Exposure: Exposure by external radiation can expose the
whole body or part of it. For gamma radiation, we assume that the whole body
(internally and externally) received the same dose.
Internal Exposure by Ingestion of radionuclides with milk, water, meat,
fruit, vegetables (example uranium, alpha)
Internal Exposures: Radionuclides inside the body irradiate mainly
their “target” organ which varies from radionuclide to radionuclide.
BIOLOGICAL EFFECTS OF RADIATION
1. Cells are killed.
2. Passes through and misses cells.
3. Cell is damaged but repairs itself.
4. Cell is damaged and reproduces a damaged cell which may result in cancer.
5. Sperm or egg is damaged and passes its mutations to offspring which may
cause stillbirths, miscarriages, birth defects, inheritable genetic damage,
and possible cancer.
RADIATION DOSES AND BIOLOGICAL EFFECTS
Acute Exposure: Expected Effects
2000 rads -
400-600 rads -
Acute radiation sickness (nausea, vomiting), bone marrow destruction,
3-5 weeks until death; (one-half of the people will die within 30 days
150-400 rads -
Acute radiation sickness, skin burns and benign tumors. Without medical
intervention, increased risk cancers, genetic effects, shorter life
50-150 rads -
Blood changes, increased risk of infection/hemorrhage, possible benign
tumors, or increased risk malignant tumors, genetic effects, shorter
25-50 rads - Blood
changes can occur, increased risk tumors, genetic effects and temporary
sterility in men
0-25 rads - Risk of
premature aging, excess tumors, genetic effects
A cell damaged by radiation may produce damaged daughter cells which can
begin the carcinogenic process (the development of tumor). Tumors tend to
become increasingly malignant through time. All organs are vulnerable to
radiation induced cancer given the right conditions of exposure.
The exact latency of radiation-induced cancers cannot be determined as it
depends on the individual and factors such as age qt exposure, sex, genetic
constitution, physiological state, smoking, and other physical and chemical
agents. Radiation can initiate a cancer or other environmental insults can
promote the cancer. Likewise, some other agent can initiate a cancer and a
radiation exposure can promote the cancer.
Leukemia, thyroid, and bone cancers have short latencies. Cancer in other
organs generally has latencies ranging from 10-25 years.
RADIONUCLIDE ORGAN DISTRIBUTION
Organs and the radioactive elements that affect them
Skin: Krypton (external exposure)
Liver: Polonium, Zinc, Cesium, Serium
Muscle: Potassium, Cesium
Spleen: Polonium, Irridium, Cesium
Kidneys: Ruthenium, Polonium, Uranium, Irridium
Bone: Radium, Strontium-Ytrium, Promethium, Barium, Throium, Phosphorous,
Uniform Distribution: Tritium, Carbon, Chromium, Sulfur, Cobalt (all forms),
Cesium, Potassium, and Zirconium
Lungs and GI Tract: Anything breathed and in insoluble form (not readily
dissolved), e.g. Zirconium, Carbide
SCIENTISTS STUDY EFFECTS OF RADIATION ON HUMAN POPULATIONS?
Epidemiology is the science of
how disease occurs and is distributed within a population. Epidemiology
presumes that diseases are not random. Epidemiology studies examine links
between environmental exposures, risk factors and diseases. The major way to
study human effects of ionizing radiation comes from epidemiology studies.
EVIDENCE TO DATE –
RADIATION HEALTH STUDIES
A-Bomb Survivor Study
The Japanese A-Bomb Survivor Study is an ongoing cohort study following over
survivors from 1950 to the present. It has been the “bible” for the
community in understanding radiation effects. Also, historically, it has
become the source of
controversy over interpreting low-dose effects of radiation.
Effects of High Doses (100 rem
Leukemia in adults –10 to
20 years latency
Cancer of breast, thyroid,
lungs, lymphoma, multiple myeloma, stomach, esophagus, urinary tract,
salivary, brain—up to 15 years latency.
For Low Doses (20 rem and
Major Weaknesses in This Study
ASSUMED EFFECTS AT LOW DOSES
Insufficient data has been
available to base he risks of low doses from observed
Risks at low doses are
assumed from the experiences of survivors at high doses
This is basically a study
of high dose effects delivered in one blast and not of low
doses received over a period of years or decades.
HEALTHY SURVIVOR EFFECT
The A-Bomb Survivor Study
was begun in 1950, five years after the bombing; many of
the sick, weak, young children and elderly died off from the devastating
consequences of the bomb
The survivors were
actually a selected healthy survivor population; radiation
standards for the world were based on this abnormal population
DIRECT STUDIES OF LOW DOSE
Pre-natal X-Ray Findings (Case Control)
Stewart (1956) and McMahon (1964 replicated Stewart findings) found
that one pre-natal x-ray
doubled risk of childhood cancer. These studies represented irrefutable
finding of cancer
risk related to low dose radiation.
Uranium Mining/Radon (Cohort, 1971 to present)
Colorado Plateau (Lundin, 1971) – found excess lung cancers exposures were
[note 1 WLM= 100 picocuries per liter of air per month measured in mines]
U.S. Miners (Archer) – excess respiratory cancers (120 WLM)
Canadian Miners (Muller, 1983) –excess lung cancers (53 -130 WLM)
Navaho Male Miners (Gottlieb, 1979) excess lung cancers (59-2,125 WLM)
Other Health Effects Observed:
Miners—Tuberculosis, non-malignant respiratory leukemia, kidney cancer,
cancers (1,250 pCi)
Counties near mines—Adverse reproductive outcomes, decline in secondary sex
Indoor radon – International excess of myeloid leukemia, kidney cancer,
Studies of Radioactive Fallout
Marshall Islanders (Hamilton, T., 1984-91) – excess thyroid disease,
adverse reproductive outcomes
Nevada Test Site, Southwest Utah (Stevens et al., 1983-90) – excess
lymphatic leukemia found
in children downwind test site; repeated case-control studies kept detecting
an effect; doses
were only 290 millirem to 3 rem; the legal settlement established cause and
Atomic Veterans, ecologic data—Smokey Test (1983) found leukemia excesses;
(1983) found leukemia and multiple myeloma.
Nuclear Worker Studies
Mancuso, Stewart and Kneale (Hanford, 1977, 1981)—age related effects with
excess of certain
cancers (e.g. melanoma, pancreas, and lung cancer)
Wing (ORNL, 1992) –excess leukemia
Kendall (UK, 1992)—excess cancer of thyroid, leukemia, melanoma
Kneale, Stewart (1993) – age-related effects, uniform excess of all cancers
Comments on Evaluating Nuclear Worker Studies:
Studies that compare
nuclear workers to U.S. white males use inappropriate
comparisons since the “healthy worker effect’ will dilute the small
effects of small doses of
Studies with more than 25
years follow-up are required to truly begin detecting the
cancer effects of radiation
It is extremely important
to control for social class and to allow for exposure age
effects when estimating the cancer risks of nuclear workers
Cancer SMR’s (Standard
Mortality Rate) equal to or greater than 100 for nuclear
workers may be indicative of a cancer risk since the SMR for all causes
of death for nuclear
workers is well below 100
Positive findings should
not be dismissed because they disagree with the A-Bomb data
Dept. of Energy worker
studies have serious problems in keeping track of the factors
that have influenced the recording of doses in different facilities or
at the same facility
at different points in time
Nuclear workers' children have increased cancer risk
19:00 19 June 02
Exclusive from New Scientist
Working at the Sellafield nuclear plant in Cumbria may have been
harmful after all. Children of men who had been exposed to radiation
while working at the plant have twice the normal risk of leukemia
and lymphoma, according to a major new study sponsored by the
LASTING THREAT: children of radiation workers are a t risk
(Photo: P Marlow/Magnum)
Arguments have been raging for 12 years over whether radiation from
Sellafield is to blame for a local cluster of childhood cancers. The
suggestion that there was a link between the doses of radiation
received by fathers and the incidence of leukemia among their
children was first made in 1990 by the late Martin Gardner, an
epidemiologist from the University of Southampton.
his hypothesis has since been heavily criticized. Many experts have
argued that large numbers of people moving in and out of the area,
which is thought to spread infections that might increase the risk
of cancer, can explain all the extra leukemia cases seen around
Now, in the biggest and most comprehensive study to date, scientists
from the University of Newcastle have refocused the debate. "Gardner
may have been right," says Heather Dickinson from the university's
North of England Children's Cancer Research Unit. She and her
colleague Louise Parker compared the fates of 9859 children fathered
by men exposed to radiation at Sellafield with those of 256,851
children born to other fathers in Cumbria between 1950 and 1991.
Throughout the whole of Cumbria, they found that the incidence of
leukemia and non-Hodgkin's lymphoma was twice as high among the
Sellafield children. The incidence was 15 times as great in
Seascale, a small village next to the nuclear plant. Crucially, they
also discovered that the risk to children rose in line with the
radiation dose received by their fathers.
Because a lot of people have moved in and out of Seascale, the
researchers found that population mixing did account for most of the
extra risk in that village. But for Sellafield children throughout
the county, mixing couldn't explain the two-fold increase in risk.
There is growing evidence from human and animal studies that
radiation damage can be passed from one generation to the next. But
Dickinson and Parker point out that the risks are small: only 13
children of Sellafield workers contracted leukemia over the 41
years. And because workers now receive much lower doses than in the
past, there are unlikely to be implications for the current
research was part-funded by the Westlakes Research Institute, which
is sponsored by British Nuclear Fuels (BNFL), the state-owned
company that runs Sellafield. "This study is very reassuring for our
workforce and confirms that the excess risk of leukemia and
non-Hodgkin's lymphoma, particularly in Seascale, can be largely
attributed to population mixing," says BNFL's health director Paul
local anti-nuclear campaigners see it differently. "BNFL has tried
to discredit Gardner's hypothesis for years," says Janine
Allis-Smith from Cumbrians Opposed to a Radioactive Environment.
"This study vindicates him and it is irresponsible of BNFL to ignore
More at: International Journal of Cancer (vol 99, p 437)
Sellafield (Gardner, 1990)—found relationship between paternal occupational
dose before conception and a cancer risk to that offspring; case control
(OSCC, Sorahan 1993, and Roman et al. 1993 produced similar findings)
Hanford (Sever, 1988)—excess rates of certain birth defects detected around
counties near Hanford and among children whose parents worked at Hanford;
findings were downplayed because they disagreed with A-Bomb data
Mass. Dept. Public Health (Morris, 1990)—first positive finding of excess
leukemias in populations living closest to the nuclear plant during years of
high emissions; rigorous case-control study
NCI Study (Jablon, 1991)—employed an ecological study design; compared
cancer rates in counties with nuclear plants to control counties without
nuclear plants; county data not considered adequate for assessing exposures
of the population (e.g. a large portion of the county was unexposed which
weakened the findings); death certificate data quite frequently was
Three Mile Island (Hatch, 1990) – sample of a study with low statistical
power; such studies may find raised risks but not enough to each statistical
significance; TMI lost half of exposed population within 5-mile radius as
Findings from Natural Background Studies
Studies of populations
living in areas of high natural background radiation show
genetic risks ( increases in chromosomal aberrations or Down’s syndrome
(see Barcinski 1975;
Gopel 1971; Kochupillan 1976)
Cancer risks from higher
level of natural background radiation are less conclusive;
some studies indicate a strong correlation between increased levels and
high rates of cancer
while others show no effect (see Hatch 1990, Knox 1988)
Some studies have shown a
beneficial effect from high levels of natural background
radiation; yet they are generally flawed.
HEALTH AND ADULT RISKS OF LOW-LEVEL
A. FINDINGS AROUND MAJOR NUCLEAR FACILITIES -
OF FALLOUT FROM NUCLEAR WEAPONS TESTS
OF NATURAL BACKGROUND RADIATION
OF URANIUM MINERS AND MEDICAL IRRADIATION
OF NUCLEAR WORKERS
Childhood Cancer Research Institute
P.O. Box 309
Worcester, MA 01602
Revised: March 1998
AROUND MAJOR NUCLEAR FACILITIES - COMMUNITY STUDIES
Study Type: Case-Control
1. Roman, E., et al. Case-control study
of leukemia and non-Hodgkin's lymphoma among children aged 0-4 years living
in West Berkshire and North Hampshire health districts. BMJ 1993
Study Type: Case-Control
Results - Five (9%) of the 54 cases and 14 (4%) of the 324 controls had
fathers or mothers, or both, who had been employed by the nuclear industry
(relative risk 2-2, 95% confidence interval 0-6 to 6-9). Three fathers of
cases and two fathers of controls (and no mothers of either) had been
monitored for external radiation before their child was conceived (relative
risk 9-0, 95% confidence interval 1-0 to 108-8). No father (of a case or
control) had accumulated a recorded dose of more than 5 mSv before his child
was conceived, and no father had been monitored at any time in the four
years before his child was conceived. A dose-response relation was not
evident among fathers who had been monitored.
The findings of this study suggest that the children of fathers who had been
monitored for exposure to external penetrating ionizing radiation in the
nuclear industry may be at increased risk of developing leukemia before
their fifth birthday. The findings are based on small numbers and could be
due to chance. If the relationship is real, the mechanisms are far from
clear, except that the effect is unlikely to be due to external radiation;
the possibility that it could be due to internal contamination by
radioactive substances or some other exposure at work should be pursued. The
above average rates of leukemia in the study area cannot be accounted for by
2. Sellafield Plant, Cumbria, England
a. Gardner et al. Results of case-control study of leukemia and lymphoma
among young people near Sellafield nuclear plant in West Cumbria. BMJ Vol.
300, 17 February 1990.
Study Type: Case Control
Investigators discovered strong associations between paternal occupational
exposures and subsequent childhood cancers in the village of Seascale,
England, close to the site of the British nuclear reprocessing plant, known
as Sellafield. Gardner's finding suggests that father receiving as little as
1 - 5 rem exposure to radiation, (less than six months before conception may
be passing on a mutation to their offspring that increases the offspring’s'
subsequent risk of cancer. The village, Seascale, had 12 times as many
childhood cancers as expected. A dose-response relationship was observed,
the association being strongest in the highest paternal dose group. Gardner
demonstrated in a case/control study that a high proportion of these cancers
were linked to father's occupation at the Sellafield plant. (Exposures; 1 -
5 rem or more)
Study Type: Ecologic - b, c, d.
b. Gardner (1987) Brit. Med. J. 295 - Study shows leukemia excess for SMR's
(standard mortality rates) of children born in Seascale.
c. Gardner (1987) Brit. Med. J. 295 - Study showed no excess disease for
children who moved to Seascale after birth.
d. Craft, et al. (1984, Lancet, ii) - Leukemia excess for SIR (Standard
Incidence Rates) for census wards around and distant from Sellafield.
3. Dounreay Studies
Heasman, et al. "Childhood Leukemia in Northern Scotland" (1986). Letter to
Study Type: Ecologic
SIRS for areas up to 300 km away from Dounreay plant found five cases of
leukemia in children when .5 were expected in children of same age from
1979-84, within a 12.5 km area near the plant.
Urquhart, JD, et al. Case-control study of leukemia and non-Hodgkin's
lymphoma in children in Caithness near the Dounreay nuclear installation.
BMJ 1991, 302:687-92.
Study Type: Case-Control
Urquhart concluded that the raised incidence of childhood leukemia and
non-Hodgkin's lymphoma around Dounreay could not be explained by paternal
occupational radiation exposure.
Opposing Evidence to Dounreay and Sellafield link to Childhood Leukemias.
Study Type: Ecologic
Kinlen, L., 1988 - Evidence for an infective cause of childhood leukemia,
comparison of a Scottish new town with nuclear reprocessing sites in
Britain. Lancet: i: 1323-26. Study attempts to demonstrate that an influx of
new workers with concommitment increase in viral infections has caused
childhood leukemia excesses.
4. Other British Studies
Study Type: Ecologic for a through d.
a. Ewings, PD, et al. (1988) BMJ: 299 Incidence of Leukemia in Young People
in Vicinity of Hinkley Point Nuclear Power Station - found increased
incidence of leukemia and lymphoma.
b. Roman, et al. 1987. Childhood leukemia in West Berkshire and Basingstoke
and North Hampshire District Health Authorities in relation to nuclear
establishments in the vicinity - Brit. Med. Journal 294: 597-602. Roman
described a cluster of 29 cases of leukemia (14.4 expected) in children,
aged 0-4 year living within ten km or more of nuclear facilities in Southern
c. Gillis and Hole 0 1986. Childhood Leukemia in the West of Scotland -
Lancet: 2, 525 - Comparing SIRs for West Scotland to all of Scotland. 31
cases observed to 24.3 expected for children aged 0-14 living in regions
adjacent to four nuclear facilities in Western Scotland.
d. Forman, et al. Cancer near Nuclear Installations. Nature, Vol. 329, 8
October 1987 (Commentary).
This detailed study of cancer near nuclear installations in the United
Kingdom analyzed childhood and adult cancers in local authority areas that
had one third of its population living with a 6-10 mile proximity to a
nuclear installation. The age group of 0-24 years had excess cases of
lymphoid leukemia and brain tumors. Particularly high excesses were noted
around Sellafield and two nuclear installations in Scotland (Dounreay and
Opposing Evidence - Cook-Mazaffari, et al. Cancer Near Potential Sites of
Nuclear Installations - November 1989, Lancet, p. 1145.
Study Type: Ecologic
Excess mortality due to leukemia and Hodgkin's disease in young people who
lived near potential reactor sites was similar to that in young people near
existing sites with exception of Sellafield, possible Dounreay sites.
5. Sorahan, T., Ph.D., and Roberts, Penelope, Ph.D.
Childhood Cancer and Paternal Exposure to Ionizing Radiation: Preliminary
Findings from the Oxford
Survey of Childhood Cancers. Am. Jrnl. Indust. Med. 23:343-354 (1993)
Paternal occupational data already collected as pat of the Oxford Survey of
Childhood Cancers have been reviewed. Information on occupations during or
before the relevant pregnancy was sought for 15,279 children dying from
cancer in England, Wales, and Scotland in the period 1953-81, and for an
equal number of matched controls. Estimates were made for paternal exposure
to human-made external ionizing radiation in the six months before
conception of the survey child - as judged from job histories and dates of
birth. Assessments were also made for potential exposure to unsealed sources
of radionuclides. Of the eight fathers placed in the highest dose group (˛
10 mSv, external radiation), four were cases and four were controls. For the
second dose group (5-9 mSv), the corresponding numbers were eight and four,
and for the lowest exposed group (1-4 mSv), they were 55 and 42. There were
27 case fathers with potential exposure to radionuclides and only 10 control
fathers. The independent effects of the two radiation variables were
assessed by means of multiple logistic regressions. Relative risks for
estimated doses of external radiation were close to unity, but for
radionuclide exposure the relative risk was 2.87 (95% CI = 1.15-7.13). These
preliminary findings suggest that paternal exposure to radionuclides is a
more likely risk factor for childhood cancer than exposure to external
6. U. S. Studies
a. Hanford Nuclear Complex, Washington State
A Case-Control Study of Congenital Malformations and Occupational Exposure
to Low-Level Ionizing Radiation. Lowell E. Sever, et al. American Journal of
Epidemiology, Vol. 127, No. 2, 1988.
Study Type: Case-Control
In a case-control study, the authors investigated the association of
parental occupational exposure to low-level external whole-body penetrating
ionizing radiation and risk of congenital malformations in their offspring.
Cases and controls were ascertained from births in two counties in
southeastern Washington State, where the Hanford Site has been a major
employer. A unique feature of this study was the linking of authoritative
individual measurement of external whole-body penetrating ionizing radiation
exposure of employees at the Hanford Site, using personal dosimeters, and
the disease outcome, congenital malformations. The study population included
672 malformation cases and 977 matched controls from births occurring from
1957 through 1980. Twelve specific malformation types were analyzed for
evidence of association with employment of the parents at Hanford and with
occupational exposures to ionizing radiation. Two defects, congenital
dislocation of the hip and tracheoesophageal fistula, showed statistically
significant associations with employment of the parents at Hanford, but not
with parental radiation exposure. Neural tube defects shoed a significant
association with parental preconception exposure, on the basis of a small
number of cases. Eleven other defects, including Down syndrome, for which an
association with radiation was considered most likely, showed no evidence of
such an association. When all malformations were analyzed as a group, there
was no evidence of an association with employment of the parents at Hanford,
but the relation of parental exposures to radiation before conception was in
the positive direction. Given the observed positive correlations are likely
to represent false positive findings. In view of strong contradictory
evidence, based on no demonstrated effects in genetic studies of atomic bomb
survivors in Hiroshima and Nagasaki, it is unlikely that these correlations
result form a case and effect association with parental radiation exposure.
The Prevalence at Birth of Congenital Malformations in Communities near the
Hanford Site. Lowell E. Sever, et al. American Journal of Epidemiology, Vol.
127, No. 2; 1988.
Study Type: Ecologic
The authors examined the prevalence of congenital malformations among births
in Benton and Franklin counties, in southeastern Washington State, from 1968
through 1980. Hospital and vital records were used to identify 454
malformation cases among 23,319 births, this yielded a malformation rate of
19.6 per 1,000 births, a rate similar to those reported in other studies.
The rates of specific malformations ascertained during the first year of
life were compared wit combined rates from the states of Washington, Oregon,
and Idaho from the Birth Defects Monitoring Program. Among defects that
would be expected to be comparably neural tube defects was observed (1.72
per 1,000 births vs. 0.99 per 1,000). Rates of cleft lip were significantly
lower in Benton and Franklin counties than in the Birth Defects Monitoring
Program (0.59 per 1,000 vs. 1.17 per 1,000). For congenital heart defects,
pylotic stenosis and Down syndrome, which are often not diagnosed in the
newborn period, Birth Defects Monitoring Program data, did not offer
appropriate comparisons. The rates of these defects did not appear to be
elevated in relation to rates found in other relevant populations. When
rates of neural tube defects were compared with those in populations other
than the Birth Defects Monitoring Program, the Benton and Franklin county
rates were still considered to be elevated. The increased bicounty rate
cannot be explained by employment of the parents at Hanford or by the impact
of plant emissions on the local population.
b. Pilgrim Plant, Plymouth, MA.
Study Type: Case-Control
Morris M. Knorr R. The Southeastern Massachusetts Health Study 1978-1986 -
Report of the Massachusetts Department of Public Health, October 1990. This
case-control study found an association between radiation released form the
plant and leukemia incidence among cases diagnosed before 1984. A
dose-response relationship was observed in that the relative risk of
leukemia increased (four-fold) as potential for exposure to plant emissions
also increased. The study was later published in Archives in Environmental
Health 51(4) 1996.
See also: Clapp R, Cobb S, Chan C, Walker, B.
"Leukemia Near Massachusetts Nuclear Power Plant". Letter, Lancet, Dec. 5,
Study Type: Ecologic - a through d.
a. Jablon, et al. 1980 - Cancer in Populations Living Near Nuclear
Facilities. JAMA 1991; 265:1403-08.
A mortality survey was conducted in populations living near nuclear
facilities in the United States. All facilities began service before 1982.
Over 900,000 cancer deaths occurred from 1950 through 1984 in 107 counties
with or near nuclear installations. Each study county was matched for
comparison to three "control counties" in the same region. There were 1.8
million cancer deaths in the 292 control counties during the 35 years
studied. Deaths due to leukemia or other cancers were not more frequent in
the study counties than in the control counties. For childhood leukemia
mortality, the relative risk comparing the study counties with their
controls before plant start-up was 1.08, while after start-up it was 1.03.
For leukemia mortality at all ages, the relative risks were 1.02 before
start-up and 0.98 after. For counties in two states, cancer incidence data
were also available. For one facility, the standardized registration ratio
for childhood leukemia was increased significantly after start-up. However,
the increase also antedated the operation of this facility. The study is
limited by the correlation approach and the large size of the geographic
areas (counties) used.
b. Crump, KS et al, 1987 - Cancer incidence patterns in the Denver
metropolitan area in relation to Rocky Flats Plant, Am. J. of Epidem.,
This study showed no variation in cancer incidence rates in the vicinity of
c. Hatch et al - 1990 - Cancer Near the Three Mile Island Nuclear Plant:
Radiation Emissions. Amer. J. of Epid., vol. 132, #3.
Incident cancers among area residents for the period 1975-1985 (n = 3,483)
were identified by a review of the records at all local and regional
hospitals; preaccident and post-accident trends in cancer rates were
examined. For accident emissions, the authors failed to find definite
effects of exposure on the cancer types and population subgroups thought to
be most susceptible to radiation. No associations were seen for leukemia in
adults or for childhood cancers as a group. For leukemia in children the
odds ratio was raised, but cases were few (n = 4), and the estimate was
highly variable. Moreover, rates of childhood leukemia in the Three Mile
Island area are low compared with national and regional rates. For exposure
to routine emissions, the odds ratios were raised for childhood cancers as a
whole and for childhood leukemia, but confidence intervals were wide and
included 1.0. For leukemia in adults, there was a negative trend. Trends for
two types of cancer ran counter to expectation. Non-Hodgkin's lymphoma
showed raised risks relative to both accident and routine emissions; lung
cancer (adjusted only indirectly for smoking) showed raised risk sensitive
to accident emissions, routine emissions, and background gamma radiation.
Overall, the pattern of results does not provide convincing evidence that
radiation releases from the Three Mile Island nuclear facility influenced
cancer risk during the limited period of follow-up.
d. Enstrom, et al. 1983 - Cancer mortality patterns around San Onofre
nuclear power plant (1960 - 78). Am. J. Pub. Health 73 (1). Death rates
compared pre and post plant operation: Childhood leukemia rate compared at
various distances - no significant excesses found.
7. Canadian Studies
Study Type: Ecologic - a. and b.
a. Clarke, GA, et al (1989) - Childhood Leukemia around Nuclear Facilities.
(Atomic Energy Control Board) - they reported no increase in leukemia in
children 0-5 years of age who lived near any of several facilities.
b. Johnson, K. 1991 - Tritium Releases from the Pickering Nuclear Generating
Station and Birth Defects and Infant Mortality in Nearby Communities 1971-88
- Atomic Energy Control Board.
A general look at the rates of stillbirth, infant death and fatal birth
defects year by year and summarized over 1971-1988 showed that in comparison
to the rates for the entire province, the rates of stillbirth and infant
death were not high in any of the studied communities. In fact, the rates
were generally lower than the provincial average. No cause of death was
significantly elevated in any municipality, and the rates of death
attributed to birth defects were all similar to Ontario as a whole.
A comparison of the occurrence of three major groups of birth defects with
measured releases of airborne and waterborne tritium from the power station,
and with tritium concentrations in air showed that no associations at all
were found with waterborne tritium releases. The only association between
release levels and the three birth defect groups was between central nervous
system (CNS) defects in the Pickering municipality and the highest airborne
tritium releases as measured at the station stack. However, there was no
corroboration of this finding using the ground monitoring data, and the
report points out that the overall rate of CNS defects in the 1973-1988
periods was 20 percent lower for Pickering than for Ontario as a whole.
An assessment of 22 birth defect categories for the communities closest to
the power plant, Ajax and Pickering was conducted, checking tritium release
levels against anything found with a higher than expected rate.
Of the 22 birth defect categories, only one, Down Syndrome, was found to
have a significantly elevated rate in Pickering, with a lesser elevation in
Ajax. However, there was no consistent pattern between these rates and the
tritium releases or ground monitoring data. The report noted that Pickering
was one of two geographic areas in Ontario where the Down Syndrome rates was
significantly high, statistically speaking, the other being a county far
from any nuclear power plants.
B. STUDIES OF
FALLOUT FROM NUCLEAR WEAPONS TESTS
1. Kerber, R. et al. A Cohort Study of Thyroid Disease in Relation to
Fallout from Nuclear Weapons Testing. JAMA Vol. 270, No. 17, Nov. 1993
Study Type: Cohort
Investigators reported that doses to the thyroid ranged from 0 to 460 rem
and averaged 17 rem in Utah for a cohort of 4818 schoolchildren . These
doses were significantly associated with thyroid cancers,
2. Stevens, et al. Leukemia in Utah and Radioactive Fallout from the
Nevada Test Site. A Case-Control Study. JAMA, Vol. 264, No. 5, August 1,
Study Type: Case Control
A study published in JAMA in August 1990 showed an excess risk of acute
lymphatic leukemia for those individuals who were younger than 20 years of
age when exposed to fallout from nuclear testing at the Nevada Test Site
between 1951-55. Estimated doses to the population ranged between 2.9 mGy to
30 mGy (290 mr - 3 rems).
Lyon, J. and Schumack, 1984 - Radioactive Fallout and Cancer (letter) JAMA
Lyon J., 1979 - Childhood Leukemia Associated with Fallout in New England,
Journal of Medicine, #300.
Machado S. et al - Cancer Mortality and Radioactive Fallout in Southwest
Utah, Am. J. Epid. #125.
3. Thomas E. Hamilton, MD, PhD. The Health Effects of Radioactive
Fallout on Marshall Islanders: Health Policy Issues of Nuclear Weapons
Production. PSRQ; 1991; 1:15-23.
Study Type: Cohort
The most prevalent long-term health effect in the Marshallese population has
been the development of benign and malignant thyroid neoplasms.
Approximately 30% of adults on Rangelap (and over 60% of children exposed
when younger than 10 years of age) developed thyroid nodules, a small
proportion of which were thyroid carcinoma.
Long-term health effects other than thyroid neoplasia have included
hypothyroidism, growth retardation in several individuals, and most probably
two deaths, one each from acute myelogenous leukemia and gastric carcinoma,
among the 86 Rangelapese persons who were highly exposed. In addition,
chromosomal aberrations in this group were increased relative to comparison
groups 10 years after exposure to fallout radiation.
Thomas E. Hamilton, MD, PhD; Gerald van Belle, PhD; James P. LoGerfo, MD,
MPH. Thyroid Neoplasia in Marshall Islanders Exposed to Nuclear Fallout.
JAMA Aug. 7, 1987 - Vol. 258, No. 5.
Study Type: Cohort - 3., 4., 5.
4. Caldwell G., et al, 1983 - Mortality and Cancer Frequency Among
Military Nuclear Test (Smoky) Participants, 1957-79. JAMA: 250 (5): 620-624.
Found a significant increase in Leukemia mortality (10 observed, 4
5. Caldwell, 1984, JAMA #252 - four cases of polycythemia observed,
.2 expected in participants of Smoky Test.
6. EG Knox, T Sorahan, A Stewart. Cancer Following Nuclear Weapons
Tests. Letter to the Editor, The Lancet, April 9, 1983.
The South Pacific tests - whose local base was Christmas Island - overlapped
in time with other weapons tests. Thus, there were twelve tests in Western
and South Australia between 1952 and 1957, and nine South Pacific tests
between May, 1957, and November, 1958. The follow-up of the South Pacific
population is far from complete but already there is evidence of an
abnormally high incidence of Leukemia and other reticulo- endothelial system
Robinette C.D., et al. 1985 - Studies of Participants in Nuclear Tests,
Wash. DC National Research Council - Confirms Smoky findings for leukemias.
Darby, et al, 1988 - Br. Med. J., #296 - Excess Leukemias and Multiple
C. STUDIES OF NATURAL
Study Type: Ecolog, c - 1 - 4.
1. Hatch et al. Background Gamma Radiation and Childhood Cancers
Within Ten Miles of a US Nuclear Plant. International Journal of
Epidemiology, Vol. 19, No. 3, 1990.
Investigators found a positive correlation between background gamma
radiation and childhood cancers in census tracts within ten miles of the
Three Mile Island Nuclear Facility. For childhood cancers, as a whole,
incidence rates relate significantly to background radiation; the
association is strongest in children ages 10-14 years. Their data indicate a
50% increase in risk of cancer for children under 15 with ever 0.1 mgy (10
millirem) increase in estimated annual background gamma ray dose rate.
2. Knox, Stewart, Gilman and Kneale. Background Radiation and
Childhood Cancers. J. Radiol. Prot. 1988, Vol. 8, No. 1 9-18.
These investigators matched outdoor levels of terrestrial gamma radiation
with local childhood cancer rates for every 10 KM square in Great Britain. A
statistically significant positive correlation was found between exposures
to background radiation levels and rates of childhood cancer mortality. The
finding suggests that radiation might be a primary cause in the majority of
all childhood cancers. Increases in overall fetal radiation exposures, from
whatever cause, would then be expected to result in a near proportional
increase in the subsequent cancer rate. Average absorbed fetal dose is .22
mGy (20 millrems).
3. Barcinski, MA, et al - 1975. Cytogenic investigation in a
Brazilian population living in an area of high natural radioactivity. A. J.
Human Genet, 27:802-806.
200 villagers exposed to excess gamma and alpha radiation from monazite
sands (thorium) - 640 milirems/year compared with a control group from a
similar village - exposed group showed increase in chromosomal aberrations.
4. Gopal A, et al - 1971. High background radiation effects on
selected population on Kerala coast - India. Proceedings from 4th
International Conference on Peaceful Uses of Atomic Energy and Kochupittan
N, et al. Nature 262. Population receives annual exposures of 380 millirems
(thorium in sands). Both studies show increased numbers of chromosome
aberrations and Down Syndrome.
See also: Tao, Z. et al, 1986 - J. Radiat. Res. 27.
D. STUDIES OF
URANIUM MINERS AND MEDICAL IRRADIATION
Archer, Victor E. and Wagoner, Joseph K. Lung Cancer Among Uranium
Miners in the United States. Health Physics, Pergamon Press 1973. Vol. 25
(Oct.), pp. 351-371.
Study Type: Cohort
Excess respiratory cancer has been demonstrated among all groups of uranium
miners who have had more than 120 Working Level Months of radon daughter
exposure. Lung cancer incidence rose with increasing exposure. Factors which
might distort the exposure-response relationship were reviewed. Exposure to
other agents such as cigarettes probably contributed to the excess, but
these factors should not be considered in setting permissible levels.
Respiratory cancers are continuing to appear at a high rate among the Study
Group even though radon daughter levels have been markedly reduced and most
of the Study Group has stopped mining.
Wagoner, Joseph K; Archer, Victor E; Carroll, Benjamin E; Holaday, Duncan
A; Lawrence, Pope A. Cancer Mortality Patterns Among U.S. Uranium Miners
and Miller, 1950 through 1962. Journal of the National Cancer Institute,
Vol. 32, No. 4, April 1964.
E. G. Knox, A.M. Stewart, G. W. Kneale, E. A. Gilman. Prenatal
Irradiation and Childhood Cancer. Journal of The Society for Radiological
Protection, Volume 7, No. 4 (1987).
Study Type: Case-Control
Estimates of the relative risk of childhood cancer, following irradiation
during fetal life, are reported. They are based upon extended case-control
investigations of childhood cancer deaths in England, Wales an Scotland
between 1953 and 1979 comprising 14,759 geographically-matched and
birth-date-matched case/control pairs.
There was no evidence among cases or controls of any systematic reduction in
the frequency of pregnancy x-rays between 1950 and 1979. During this period
of time, about 7 percent of all childhood cancers, and 8 percent of those
with onset between the ages of 4 and 7 years, were caused by x-ray
examinations. The dose-response relationship was one death per 990 obstetric
x-ray examinations; or 2,000 deaths per 104 man-Gy.
MacMahon, Brian. Prenatal X-Ray Exposure and Childhood Cancer.
Journal of the National Cancer Institute, 28:1173-1191, 1962.
Study Type - Case-Control
The higher frequency of prenatal x-ray in the cancer cases than in the
sample was statistically significant. After correction for birth order and
other complicating variables, it was estimated that cancer mortality
(including leukemia mortality) was about 40% higher in the x-rayed than in
the un-x-rayed members of the study population. This relationship held for
each of the three major diagnostic categories--leukemia, neoplasms of the
central nervous system, and other neoplasms.
E.A. Gilman, G.W. Kneale, E.G. Knox and A.M. Stewart. Pregnancy
X-rays and Childhood Cancers: Effects of Exposure Age and Radiation Dose. J.
Radiol. Prot. 1988, Vol. 8, No. 1, 3-8.
Alice Stewart, Josefine Webb, David Hewett. A Survey of Childhood
Malignancies. British Medical Journal, June 28, 1958, Vol. i, pp. 1495-1508.
E. STUDIES OF NUCLEAR
1. Morgenstern, H. et al., Epidemiologic Study to Determine Possible
Adverse Effects to Rocketdyne/Atomics International Workers from Exposure to
Ionizing Radiation., June 1997, Final Report to the Public Health Institute,
Study Type: Cohort
These investigators found that among 4,607 workers exposed to external
radiation at doses higher than 20 rem (200 mSv), they had an increased risk
of dying from cancers of the blood and lymph system. As dose increased,
these workers had an increased risk of dying from all cancers. For workers
monitored for internal radiation exposures, those receiving doses of 3 rem
(30 mSv) or more, there was an increased risk for cancers of the blood and
lymph system as well as mouth, throat, esophagus and stomach cancers. (Final
Report to Public Health Institute, Berkeley, CA, June 1997)
2. Kendall, G. M., et al. Mortality and Occupational Exposure to
Radiation: First Analysis of the National Registry for Radiation Workers.
RMJ 1992:304, 220-5
Study Type: Cohort
An investigation of cause-specific mortality of radiation workers with
particular reference to associations between fatal neoplasm and level of
exposure to radiation.
Sixty two percent of the workers had a lifetime dose of less than < 10 mSv
(.1 rem) and 9% had a lifetime dose greater than 100 mSv (1 rem). There are
no estimates of doses from internal emitters.
Analysis - The study's analyses include standard mortality ratios in which
death rates in registry participants are compared with the general
population of England and Wales. The second analysis is a test for trend
with dose in which steps are taken to allow for factors that might obscure a
dose-effect relationship - i.e., social class.
The SMR for thyroid cancer was
significantly raised; however, a detectable trend with external
radiation dose was not apparent or common occupational exposure at any
Leukemia and multiple myeloma showed
evidence for an increase in mortality with radiation dose and the
association was significant for leukemia and robust in subsidiary
analyses. SMR's for leukemia/multiple myeloma were lower than the
There was no evidence for an association
between prostate cancer and radiation.
The study discusses how risk estimates for low
doses of radiation to these British radiation workers compares to current
ICRP (International Commission for Radiological Protection) risk estimates.
The findings from this study reflect risks for all cancers to be 2.5 times
higher and for leukemia, to be 1.9 times higher than ICRP risk estimates.
The authors qualify these higher risk estimates by stating that the study's
90% confidence internals are large and the ICRP risk factors fall within
3. Kneale, G. W., et al. Reanalysis of Hanford Data: 1944-1986
Deaths. Am. Jrnl. Indust. Med. 23:371-389 (1993).
Study Type: Cohort/Case-Control
Reanalysis of Hanford date by a method, which is new only in the sense that
it makes new uses of standard epidemiological procedures, has produced
evidence of a cancer risk at low dose levels. By a conservative estimate,
about three percent of the pre-1987 cancer deaths of Hanford workers had
occupational exposures to external radiation as the critical (induction)
event. These radiogenic cancers were evenly distributed among five
diagnostic groups, but as a result of there being much greater sensitivity
to "cancer induction by radiation" after, rather than before, 50 years of
age, they were concentrated among the cancers which proved fatal after 70
years of age. The reanalysis provides no support for the idea that radiation
is more likely to cause leukemia than solid tumors, or the idea that there
is reduced cancer effectiveness of radiation at low dose levels (dose rate
effectiveness factor of DREF hypothesis), but the estimated proportion of
radiogenic cancers was much higher for the 175 nonfatal cancers (which had
other certified causes of death) than for the 1,732 fatal cases.
Finally, according to the latest publication of the U.S. Committee on
Biological Effects of Ionizing Radiation (BEIR V), dose rate is more
important than exposure age, and even a single exposure to 10 rem would only
increase the normal cancer risk by four percent. Nevertheless, for all
recorded exposures of Hanford workers, the estimated doubling dose was close
to 26 rem; for exposures after 58 years, it was close to 5 rem, and for
exposures after 62 years, it was less than 1 rem.
4. Wing S. et al. (1991). Mortality among Workers at Oak Ridge
National Laboratory: Evidence of Radiation Effects in Follow-up Through
1984. JAMA 265 (11):1397- 1402
Study Type: Cohort
Findings: Wing studied workers from 1943-1972 (8,318 population with 1,524
deaths) His major findings include leukemia mortality 33% higher in the all
-worker cohort and 63% higher in the “white male cohort” with median
cumulative doses of 140 millirems Data suggest a radiation effect for lung
cancer for non-monitored workers.
Wilkinson and Dreyer (Epid.1991:2) reviewed 7 studies of nuclear workers(1.4
million person years) and found an of excess leukemia to workers from
occupational exposures to very low doses of radiation (1 to 5 rem).
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