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UNDERSTANDING RADIATION HEALTH EFFECTS; 
A GUIDE FOR COMMUNITIES AT RISK 
Excerpts 
Prepared by Diane Quigley, Executive Director, Childhood Cancer Research Institute, 1992

CONTENTS:
Measuring Radiation *  Scientific Notation * Types of Radiation * Half-Lives * How Radiation Affects Us – Pathways Exposure * Biological Effects *
How Scientists Study Effects of Radiation * Radiation Health Studies - Summary * Epidemiological Findings On Child Health And Adult Risks Of Low-Level Radiation

MEASURING RADIATION

Radioactivity: emission 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
 

SCIENTIFIC NOTATION
 

TYPES 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, uranium

Beta Radiation Particles

• 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 sensitive layer.

• 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, strontium-90.

Gamma Radiation

• Form of wave energy (photons) similar to light and radio waves but of much shorter wave length and higher frequency

• 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
 

HOW RADIATION AFFECTS US
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 131, beta)

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 - Immediate death

• 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 (LD-30)

• 150-400 rads - Acute radiation sickness, skin burns and benign tumors. Without medical intervention, increased risk cancers, genetic effects, shorter life span.

• 50-150 rads  - Blood changes, increased risk of infection/hemorrhage, possible benign tumors, or increased risk malignant tumors, genetic effects, shorter life span.

• 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

Long-Term 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.

Latency:
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

Thyroid: Iodine
Skin: Krypton (external exposure)
Liver: Polonium, Zinc, Cesium, Serium
Ovaries: Zinc
Prostate: Zinc
Muscle: Potassium, Cesium
Spleen: Polonium, Irridium, Cesium
Kidneys: Ruthenium, Polonium, Uranium, Irridium
Bone: Radium, Strontium-Ytrium, Promethium, Barium, Throium, Phosphorous, Calcium, Plutonium 
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

HOW DO 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 200,000 
survivors from 1950 to the present. It has been the “bible” for the mainstream scientific 
community in understanding radiation effects. Also, historically, it has become the source of 
controversy over interpreting low-dose effects of radiation.

Major Findings: 

Effects of High Doses (100 rem or more)

• 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 below)

• Linear extrapolation from high to low doses assumes acceptable health risks at low 
  doses.

Major Weaknesses in This Study

ASSUMED EFFECTS AT LOW DOSES

• Insufficient data has been available to base he risks of low doses from observed 
  cases

• 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 lifestyle 
  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 EFFECTS

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 (120-3720 WLM) 
[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, melanoma, childhood 
cancers (1,250 pCi)
Counties near mines—Adverse reproductive outcomes, decline in secondary sex ratio
Indoor radon – International excess of myeloid leukemia, kidney cancer, melanoma, certain 
childhood cancers

Studies of Radioactive Fallout
Marshall Islanders (Hamilton, T., 1984-91) – excess thyroid disease, chromosomal aberrations, 
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 effect precedent

Atomic Veterans, ecologic data—Smokey Test (1983) found leukemia excesses; British tests 
(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 
  radiation

• 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

Community Studies

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 incomplete

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 they 
moved away.

Natural Background Radiation Studies

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.

EPIDEMIOLOGICAL FINDINGS  
ON CHILD HEALTH AND ADULT RISKS OF LOW-LEVEL RADIATION

Contents:

A. FINDINGS AROUND MAJOR NUCLEAR FACILITIES - COMMUNITY STUDIES

B. STUDIES OF FALLOUT FROM NUCLEAR WEAPONS TESTS

C. STUDIES OF NATURAL BACKGROUND RADIATION

D. STUDIES OF URANIUM MINERS AND MEDICAL IRRADIATION

E. STUDIES OF NUCLEAR WORKERS

Prepared by
Childhood Cancer Research Institute
P.O. Box 309
Worcester, MA 01602

Contact:
CCRI Office
Tel. (508)-751-4634

Revised: March 1998 


A. FINDINGS 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 #306:614-21.

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 these findings.

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 Lancet, 1.266.

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 England.

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 Hunterston).

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 (² 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 radiation.


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, 1987. (Ecologie)

Negative Findings

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., #126.

This study showed no variation in cancer incidence rates in the vicinity of the plant.

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.

studies index

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

Findings
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, 1990.

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).

See also:

Lyon, J. and Schumack, 1984 - Radioactive Fallout and Cancer (letter) JAMA 252 (14):1854-5.

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.

See also:

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 expected).

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 (RES) neoplasms.

See also:

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 Myelomas.

studies index

C. STUDIES OF NATURAL BACKGROUND RADIATION

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.

studies index

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.

See Also:

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.

See Also:

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.

studies index

E. STUDIES OF NUCLEAR WORKERS


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, Berkeley, CA

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.

Findings:

• 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 particular site.

• 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 general population.

• 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 that range.

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.

See also:
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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