No Excess Mortality Risk Found in Counties with Nuclear Facilities 

 A National Cancer Institute (NCI) survey published in the Journal of the American 

Medical Association, March 20, 1991, showed no general increased risk of death from cancer for 

people living in 107 U.S. counties containing or closely adjacent to 62 nuclear facilities. The 

facilities in the survey had all begun operation before 1982. Included were 52 commercial 

nuclear power plants, nine Department of Energy research and weapons plants, and one 

commercial fuel reprocessing plant. The survey examined deaths from 16 types of cancer, 

including leukemia. In the counties with nuclear facilities, cancer death rates before and after the 

startup of the facilities were compared with cancer rates in 292 similar counties without nuclear 

facilities (control counties). 

 The NCI survey showed that, in comparison with the control counties, some of the study 

counties had higher rates of certain cancers and some had lower rates, either before or after the 

facilities came into service. None of the differences that were observed could be linked with the 

presence of nuclear facilities. "From the data at hand, there was no convincing evidence of any 

increased risk of death from any of the cancers we surveyed due to living near nuclear facilities," 

said John Boice, Sc.D., who was chief of NCI's Radiation Epidemiology Branch at the time of 

the survey.

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 He cautioned, however, that the counties may be too large to detect risks present only in 

limited areas around the plants. "No study can prove the absence of an effect," said Dr. Boice, 

"but if any excess cancer risk due to radiation pollution is present in counties with nuclear 

facilities, the risk is too small to be detected by the methods used." 

 The survey, conducted by Seymour Jabon, Zdenek Hrubec, Sc.D., B.J. Stone, Ph.D., and 

Dr. Boice, was begun in 1987 for scientific purposes in response to American public health 

concerns, and after a British survey of cancer mortality in areas around nuclear installations in 

the United Kingdom showed an excess of childhood leukemia deaths near some facilities.1 No 

increases in total cancer mortality were found in the British study, and other smaller surveys of 

cancer deaths around nuclear facilities in the United States and the United Kingdom have yielded 

conflicting results. 

 The NCI scientists studied more than 900,000 cancer deaths in the study counties using 

county mortality records collected from 1950 to 1984. The researchers evaluated changes in 

mortality rates for 16 types of cancer in these counties from 1950 until each facility began 

operation and from the start of operation until 1984. For four facilities in two states (Iowa and 

Connecticut), cancer incidence data were also available. Data on cancer incidence in these 

counties resembled the county's mortality data patterns. 

 For each of the 107 study counties, three counties that had populations similar in income, 

education, and other socioeconomic factors, but did not have or were not near nuclear facilities, 

were chosen for comparison. The study and control counties were within the same geographic 

region and usually within the same state. Over 1.8 million cancer deaths were studied in the 

control counties. 

 

1 “Cancer Near Nuclear Installations,” David Forman, Paula Cook-Mozaffari, Sarah Darby, et al. Nature, October 8, 

1987. 

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 The numbers of cancer deaths in the study counties and in the control counties were 

analyzed and compared to determine the relative risk (RR) of dying of cancer for persons living 

near a nuclear facility. A relative risk of 1.00 means that the risk of dying of cancer was the 

same in the study and control counties; any number below 1.00 indicates that the overall risk was 

lower in the study county than in the control county; and any number greater than 1.00 indicates 

a higher risk in the study county. For example, an RR of 1.04 would indicate that there was a 

4 percent higher risk of cancer death in the study county. Conversely, an RR of 0.93 would 

indicate a 7 percent lower risk in the study county. 

 For childhood leukemia in children from birth through age 9 years, the overall RR 

comparing study and control counties before the startup of the nuclear facilities was 1.08; after 

startup the RR was 1.03. These data indicate that the risk of childhood leukemia in the study 

counties was slightly greater before startup of the nuclear facilities than after. The risk of dying 

of childhood cancers other than leukemia increased slightly from an RR of 0.94 before the plants 

began operation to an RR of 0.99 after the plants began operating. 

 For leukemia at all ages, the RRs were 1.02 before startup and 0.98 after startup. For other 

cancer at all ages, the RRs were essentially the same: 1.00 before startup and 1.01 after startup. 

These results provide no evidence that the presence of nuclear facilities influenced cancer death 

rates in the study counties. 

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Questions and Answers

National Cancer Institute (NCI) Survey 

Cancer Mortality in Populations Living Near Nuclear Facilities

1. Which nuclear facilities were included in the survey?

Only major nuclear facilities that are or once were in operation and went into service 

before 1982 were included in the survey. All 52 commercial nuclear power facilities in the 

United States that started before 1982 were included. A facility may include more than 

one reactor. 

In addition to the commercial nuclear power facilities, nine U.S. Department of Energy 

(DOE) nuclear installations and one commercial fuel reprocessing plant were included. 

These facilities do not generate electrical power for commercial use. 

Facilities such as small research reactors at universities were not included. See the 

Appendix for a complete list of facilities. 

2. Why were the DOE facilities included?

In the British study that helped to prompt this survey, an excess of childhood leukemias 

was found mainly around nuclear installations that were involved in the enrichment, 

fabrication, and reprocessing of nuclear fuel or research and development of nuclear 

weapons. The DOE facilities included in the study are similar to these British facilities. 

Also, some DOE installations have been operating since 1943, which is longer than any 

commercial nuclear power plant in the United States. The first commercial nuclear power 

plant began operation in 1957. 

The DOE facilities were evaluated both as part of the total group of nuclear facilities and 

separately. 

3. Which counties were included in the survey?

All counties with a major nuclear facility that is or once was in operation and went into 

service before 1982 were included in the survey as study counties. Other adjacent counties 

that contain one-fifth of the land that lies within a 10-mile radius of these facilities were 

also included as study counties. In total, 107 counties were identified as study counties. 

See the Appendix for a complete list. 

For each study county, three control counties within the same geographic region that do 

not have or are not near nuclear facilities were identified for comparison. Control counties 

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were chosen that were the most similar to study counties based on population size and 

socioeconomic characteristics such as race and income. 

4. What were the 16 types of cancer surveyed?

The following 16 types of cancer were surveyed: leukemia; all cancers other than 

leukemia (as a group); Hodgkin lymphoma; lymphomas other than Hodgkin lymphoma; 

multiple myeloma; cancers of the digestive organs (as a group and separately), including 

cancer of the stomach, colon and rectum, and liver; cancer of the trachea, bronchus, and 

lung; female breast cancer; thyroid cancer; cancer of the bone and joints; bladder cancer; 

brain and other central nervous system cancer; and other benign or unspecified tumors. 

5. Why was childhood leukemia a special focus of the analysis?

The excess risk identified in the British study pertained to leukemia deaths among persons 

under the age of 25. Leukemia is one of the major cancers induced by high doses of 

radiation and may occur as soon as 2 years after exposure. Other cancers associated with 

high-dose radiation may not develop until 10 years after exposure. 

Studies have also suggested that children are more sensitive to the cancer-producing 

effects of radiation than adults. Children may spend more time in and around the home 

than parents, whose jobs may take them to other areas. They are also more likely to come 

in close contact with the soil, upon which radioactive releases may have been deposited 

following discharges from the facilities. 

6. Why were cancer deaths (mortality) compared instead of the number of cancer cases 

that occurred (incidence)?

Although data on cancer incidence (the number of newly diagnosed cases in a given period 

of time) could provide a more complete evaluation of the possible impact of living near 

nuclear facilities, cancer incidence data for the entire Nation do not exist. The reporting of 

county mortality data by state provides nationwide data that can show important 

geographic and time-related patterns of cancer. In past NCI studies, mortality data have 

proven useful in developing clues about the causes of cancer and in targeting areas for 

future research. 

Cancer incidence data were available in two states (Iowa and Connecticut) for four 

facilities. The cancer registries that provided this information were among those that 

participate in the NCI Surveillance, Epidemiology, and End Results Program and are 

of high quality. Survey results using cancer incidence data resembled results using cancer 

mortality data. 

7. Did any individual county or plant have an excess risk of cancer death?

Overall, the risks for childhood leukemia, adult leukemia, and all cancers were about the 

same in the counties with nuclear installations as in the control counties. The areas around 

some facilities appeared to have higher risks of leukemia while others had lower risks. 

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Generally, however, the differences are not large and are consistent with the random 

variations seen when making many comparisons based on geographic data. 

The county surrounding the Millstone Power Plant located in New London, Connecticut, 

had a significant excess of cases of leukemia in children under 10 years of age (shown in 

incidence statistics) in comparison to its control counties. The RR was 3.04 after startup 

of the facility. Upon review, the excess risk shown using incidence data arose partly from 

comparison with significantly low cancer rates in the control counties rather than from a 

high rate in the study county. 

No other excesses of childhood leukemia were found that could be linked to any of the 

nuclear facilities. Further, three facilities—San Onofre in Orange County and San Diego 

County, California; Quad Cities in Rock Island County and Whiteside County, Illinois; 

and Vermont Yankee in Windham County, Vermont—were marked by significant deficits 

in the RR for leukemia death at ages 10 to 19 years. The RRs were 0.75, 0.24, and 0.09, 

respectively. 

8. Is it possible that "chance" could explain some of the high or low relative risks 

observed in the survey?

Due to the large scope of the study and the many comparisons made, it could be expected 

that a number of "statistically significant" increased or decreased RRs would be observed 

due to chance alone. Further, significant variations in rates might also result from 

underlying differences in other cancer risk factors that have nothing to do with the 

presence of nuclear facilities. The prevalence of important risk factors, such as cigarette 

smoking and diet, might be the cause of many of the observed differences in cancer rates 

between study and control counties. As expected, comparisons of cancer rates in study 

and control counties showed substantial variation, but there was no general tendency for 

cancer rates to be higher after nuclear facilities began operating than before operation 

began. 

9. Did the counties with DOE facilities, individually or as a group, have an increased 

risk of cancer for the surrounding counties?

The findings for the DOE facilities were similar to those for the electricity-generating 

plants. There was no overall suggestion of cancer excesses that could be attributed to 

the presence of the DOE nuclear facilities. The lone commercial fuel reprocessing plant 

was included in the overall evaluation of DOE facilities. 

For these counties, the RRs for childhood leukemia (ages birth to 9 years) were 1.45 

before the facilities began operation and 1.06 after opening. For all other childhood 

cancers, the RRs were 1.06 and 0.95 before and after operation began, respectively. For 

leukemia at all ages, the RRs were 1.07 before startup and 0.96 after startup. For other 

cancer at all ages, the RRs were essentially the same, 1.06 before startup and 1.04 after 

startup. 

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10. Why was the study based on the county as the geographic unit?

The data for a study based on counties were readily available for the entire United States. 

The NCI and the U.S. Environmental Protection Agency have prepared detailed data on 

cancer mortality by county since 1950. Population data, which are needed to calculate 

cancer rates, are also available by county. Thus, the county was the smallest geographic 

unit for which nationwide data could be quickly evaluated. 

11. Have similar county-based studies been valuable in the past?

Yes, surveys using methods that analyze county mortality patterns have been used 

effectively several times by NCI. Based on findings from NCI "cancer maps" constructed 

from county mortality statistics, a clustering of lung cancer deaths was seen among 

residents of counties along the southern Atlantic coast. Across the United States, counties 

with shipyard industries were found to have elevated rates of lung cancer deaths, 

particularly in men. Subsequent indepth studies of the high-risk areas linked the excess 

lung cancer deaths to asbestos and cigarette smoke exposure in shipyards, especially 

during World War II. 

In another study, mortality rates from lung cancer were found to be elevated among men 

and women living in counties with smelters and refineries that emitted arsenic. A previous 

NCI study had shown arsenic to cause lung cancer in smelter workers who were heavily 

exposed to the substance. Further analytical study of counties with smelters showed an 

elevated risk of lung cancer associated with residential exposure to arsenic released by 

smelters into the local environment. 

The county mortality surveys are often considered a first step toward directing future 

research efforts. These surveys also have their limitations. The county may be too large to 

detect risks present only in limited areas, death certificates are sometimes not accurate 

regarding the actual cause of death, and exposures to individuals are unknown.

12. Would a study based on smaller geographic units be feasible?

Mortality and population data are not available on a national basis for areas smaller than 

counties. The data required for studies of small areas, such as cities or neighborhoods, are 

collected at the state or local level when they are available. 

Using the existing county mortality data, the survey took 3 years to complete. A national 

survey using data for areas smaller than counties would take much longer. 

13. Were the study design and results reviewed?

In addition to internal review, the design of the study was evaluated by an expert team of 

scientists from outside the U.S. Government who also reviewed the entire intramural 

research program of the Radiation Epidemiology Branch in the Division of Cancer 

Etiology (DCE), NCI. 

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Because of the importance of clarifying any potential health hazards associated with living 

near nuclear facilities, a special advisory group was also established to help evaluate the 

study results. The advisory group consisted of selected members of DCE's Board of 

Scientific Counselors as well as other scientists from outside the U.S. Government with 

expertise in radiation epidemiology. 

14. What levels of radiation might be expected from the normal operation of most of the 

nuclear facilities studied?

Reported radioactive releases from monitored emissions of nuclear facilities in the United 

States show very low radiation exposure to the surrounding populations. Maximum 

individual radiation doses from these plants are reported to be less than 5 millirem 

annually, or less than 5 percent of what is received annually from natural background 

sources of radiation, such as cosmic rays and radon. Levels this low are believed to be too 

small to result in detectable harm. However, there have been high releases of radioactive 

emissions from some facilities, such as the Hanford facility (Benton, Franklin, and Grant 

Counties, Washington). 

It is important to distinguish between a major release of radioactivity from a reactor 

accident, such as the accident at Chernobyl in the former Soviet Union, and the small 

amounts of radiation that are likely to be emitted by nuclear facilities under normal 

operation. 

15. Will there be more research on the possible hazards of living near nuclear facilities?

The NCI county mortality survey is only the initial step in evaluating the possible hazards 

of living near nuclear facilities. The study provides background information that will 

complement that from other studies being conducted or planned by the Centers for Disease 

Control and Prevention, various state health departments, and other groups. Information 

gained from this survey and other ongoing projects will guide future research efforts. 

In its consensus statement, the ad hoc advisory committee that reviewed and evaluated this 

study has also recommended areas for further research. 

The complete three-volume report titled Cancer in Populations Living Near Nuclear Facilities

can be ordered from the Superintendent of Documents, U.S. Government Printing Office, 

Washington, DC 20402-9325. The GPO stock number is 017-042-00276-1. 

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Appendix 

Facilities and Counties Included in the Study

State County Study Facility Year of Startup

Alabama Houston 

Lawrence 

Limestone 

Farley 

Browns Ferry 

Browns Ferry 

1977 

1973 

1973 

Arkansas Pope Arkansas 1974 

California Amador 

Humboldt 

Orange 

Sacramento 

San Diego 

San Joaquin 

Rancho Seco 

Humboldt Bay 

San Onofre 

Rancho Seco 

San Onofre 

Rancho Seco 

1974 

1963 

1967 

1974 

1967 

1974 

Colorado Boulder 

Jefferson 

Larimer 

Weld 

Fort St. Vrain 

*Rocky Flats 

*Rocky Flats 

Fort St. Vrain 

Fort St. Vrain 

1976 

1953 

1953 

1976 

1976 

Connecticut Middlesex 

New London 

Haddam Neck 

Millstone 

1967 

1970 

Delaware New Castle Salem 1976 

Florida Citrus 

Dade 

St. Lucie 

Crystal River 

Turkey Point 

St. Lucie 

1977 

1972 

1976 

Georgia Appling 

Burke 

Early 

Toombs 

Hatch 

*Savannah River 

Farley 

Hatch 

1974 

1950 

1977 

1974 

Idaho Bingham 

Butte 

Jefferson 

*Idaho National 

 Engineering Lab. 

*Idaho National 

 Engineering Lab. 

*Idaho National 

 Engineering Lab. 

1949 

1949 

1949 

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Illinois Grundy 

Lake 

Rock Island 

Whiteside 

Will 

Dresden 

Zion 

Quad Cities 

Quad Cities 

Dresden 

1960 

1972 

1972 

1972 

1960 

Iowa Benton 

Harrison 

Linn 

Duane Arnold 

Fort Calhoun 

Duan Arnold 

1974 

1973 

1974 

Kentucky Ballard 

McCracken 

*Paducah Gas. Diff. 

*Paducah Gas. Diff. 

1950 

1950 

Maine Lincoln 

Sagadahoc 

Maine Yankee 

Maine Yankee 

1972 

1972 

Maryland Calvert Calvert Cliffs 1974 

Massachusetts Berkshire 

Franklin 

Plymouth 

Yankee Rowe 

Vermont Yankee 

Yankee Rowe 

Pilgrim 

1960 

1972 

1960 

1972 

Michigan Berrien 

Charlevoix 

Emmet 

Monroe 

Vanburen 

Cook 

Big Rock Point 

Big Rock Point 

Fermi 

Palisades 

1975 

1962 

1962 

1963 

1971 

Minnesota Goodhue 

Sherburne 

Wright 

Prairie Island 

Monticello 

Monticello 

1973 

1971 

1971 

Missouri Atchinson Cooper Station 1974 

Nebraska Gage 

Lancaster 

Nemaha 

Richardson 

Washington 

Hallam 

Hallam 

Cooper Station 

Cooper Station 

Fort Calhoun 

1962 

1962 

1974 

1974 

1973 

New Hampshire Chesire Vermont Yankee 1972 

New Jersey Ocean 

Salem 

Oyster Creek 

Salem 

1969 

1976 

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New York Cattaraugus 

Oswego 

Rockland 

Wayne 

Westchester 

**Nuclear Fuel 

 Services 

Nine Mile Point/ 

Fitzpatrick 

Indian Point 

Ginna 

Indian Point 

1966 

1969 

1962 

1969 

1962 

North Carolina Brunswick 

Gaston 

Lincoln 

Mecklenburg 

Brunswick 

McGuire 

McGuire 

McGuire 

1975 

1981 

1981 

1981 

Ohio Butler 

Hamilton 

Montgomery 

Ottawa 

Pike 

Warren 

*Fernald 

*Mound 

*Fernald 

*Mound 

Davis Besse 

*Portsmouth Gaseous 

Diffusion 

*Mound 

1951 

1947 

1951 

1947 

1977 

1952 

1947 

Oregon Columbia Trojan 1975 

Pennsylvania Beaver 

Dauphin 

Lancaster 

York 

Shippingport/Beaver 

 Valley 

Three Mile Island 

Peach Bottom 

Three Mile Island 

Peach Bottom 

Three Mile Island 

1957 

1974 

1974 

1974 

1974 

1974 

South Carolina Aiken 

Barnwell 

Chesterfield 

Darlington 

Oconee 

Pickens 

*Savannah River 

*Savannah River 

Robinson 

Robinson 

Oconee 

Oconee 

1950 

1950 

1970 

1970 

1973 

1973 

South Dakota Lincoln 

Minnehaha 

Pathfinder 

Pathfinder 

1964 

1964 

Tennessee Anderson 

Hamilton 

Roane 

*Oak Ridge 

Sequoyah 

*Oak Ridge 

1943 

1980 

1943 

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Virginia Caroline 

Hanover 

Isle of Wight 

Louisa 

Surry 

North Anna 

North Anna 

Surry 

North Anna 

Surry 

1978 

1978 

1972 

1978 

1972 

Vermont Windham Vermont Yankee 1972 

Washington Benton 

Cowlitz 

Franklin 

Grant 

*Hanford 

Trojan 

*Hanford 

*Hanford 

1943 

1975 

1943 

1943 

Wisconsin Kenosha 

Kewaunee 

Manitowoc 

Pierce 

Vernon 

Zion 

Kewaunee 

Point Beach 

Kewaunee 

Point Beach 

Prairie Island 

La Crosse (Genoa) 

1972 

1973 

1970 

1973 

1970 

1973 

1967 

West Virginia Hancock Shippingport/Beaver 

 Valley 

1957 

*Department of Energy facility 

**Commercial fuel reprocessing plant 

# # # 

Related NCI materials and Web pages: 

• National Cancer Institute Fact Sheet, I–131 and Radioactive Fallout: Questions and 

Answers (http://www.cancer.gov/cancertopics/factsheet/I131qa)

• Radioactive I–131 from Fallout Web Page (http://www.cancer.gov/i131) 

For more help, contact: 

NCI’s Cancer Information Service 

Telephone (toll-free): 1–800–4–CANCER (1–800–422–6237) 

TTY (toll-free): 1–800–332–8615

LiveHelp® online chat: https://cissecure.nci.nih.gov/livehelp/welcome.asp

This fact sheet was reviewed on 5/20/96 

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