Cancer Incidence in the Community Surrounding
the Rocketdyne Facility in Southern California (Santa Susana)
Final Report
<-- LA Rocketdyne Nuclear Meltdown
Download: Community Cancer Incidence Report
Cancer Incidence in the Community Surrounding
the Rocketdyne Facility in Southern California
Final Report
to
Eastern Research Group
Lexington, MA 02421-3136
Subcontract No. CDC-10039/2
Prime Contactor:
Agency for Toxic Substances and Disease Registry (ATSDR)
Centers for Disease Control and Prevention (CDC)
Contract No. CDC 200-2000-10039
Hal Morgenstern, Ph.D.
Principal Investigator
Jennifer Beebe-Dimmer, M.P.H., Ph.D.
Co-Investigator
Sunkyung Yu, M.S.
Research Associate
University of Michigan School of Public Health
Department of Epidemiology
109 Observatory Street
Ann Arbor, MI 48109-2029
(734) 764-5435
March 2007
Conclusion: Despite the methodologic limitations of this study, the findings suggest
there may be elevated incidence rates of certain cancers near SSFL that have been linked in
previous studies with hazardous substances used at Rocketdyne, some of which have been
observed or projected to exist offsite. There is no direct evidence from this investigation,
however, that these observed associations reflect the effects of environmental exposures
originating at SSFL. Given these provocative findings and unanswered questions, it is tempting
to recommend further analyses or future studies to address the health concerns of the community.
Unfortunately, it is not clear at this time whether such additional analyses or studies will be
sufficient to determine whether operations and activities at Rocketdyne affected, or will affect,
the risk of cancer in the surrounding neighborhoods.
Summary
Background: An epidemiologic study of cancer incidence in the residential population
surrounding the Santa Susana Field Laboratory (SSFL) was initiated in response to community
concerns about the use of radioactive and toxic substances at this Rocketdyne facility and its
possible effects on the health of those residents. The focus on cancer was motivated by previous
findings from the UCLA Study of Rocketdyne Workers (1993-1999) in which occupational
exposures to ionizing radiation among nuclear workers and exposures to chemicals used at the
rocket-engine test stands were linked to excess rates of dying from several types of cancer
between 1950 and 1994.
Methods: The investigators of this study explored the rates at which newly diagnosed
cases of cancer occurred in Ventura and Los Angeles Counties between 1988 and 2002 in
relation to distance from SSFL. The two-county region was divided into three exposure areas
(less than 2 miles, 2-5 miles, and greater than 5 miles from SSFL), and the study period was
divided into two follow-up periods (1988-1995 and 1996-2002). Data on more than 600,000
cancers and census block-group data for the residential population in the two-county region were
obtained from the California Cancer Registry. Using these data, incidence rates of cancer were
estimated for each exposure area, by category of age, gender, and race/ethnicity (non-Hispanic
white, Hispanic, and other non-Hispanic).
Because exposure to radiation and chemicals used at SSFL may affect the risk of several
types of cancers, analyses focused on the association between distance from SSFL and 12 adult
cancer outcomes�three general groupings and 9 specific types of cancer. The general groupings
were total cancers (excluding non-melanoma skin cancer), �radiosensitive� cancers believed to
be affected by ionizing radiation (lung, female breast, thyroid, bone, and leukemias), and
�chemosensitive� cancers believed to be affected by the types of chemicals used at SSFL (lung,
bladder, liver, kidneys, and bone marrow). The specific cancer outcomes were melanoma,
cancers of the colon and rectum, cancers of blood and lymph tissue (including leukemias,
lymphomas, and multiple myeloma), lung cancer, female breast cancer, bladder cancer, prostate
cancer, thyroid cancer, and cancers of the upper aerodigestive tract (oral and nasal cavities,
pharynx, larynx, and esophagus). Total cancers for children under 15 years were analyzed
separately.
For each cancer outcome, the incidence rates for residents living less than 2 miles and 2-5
miles from SSFL were compared with the incidence rate for residents living more than 5 miles
from SSFL. These comparisons were expressed as ratios of incidence rates, i.e., �incidence rate
ratios.� If environmental hazards originating at SSFL migrated offsite and if community
residents were exposed to those hazards, the expected incidence rate of cancer would likely be
most elevated in the area closest to SSFL, i.e., the expected incidence rate ratio would be greater
than 1 for persons living within 2 miles of SSFL. Estimated incidence rate ratios were corrected
statistically (�standardized�) for differences between exposure areas in the distribution of age,
gender, and race/ethnicity; i.e., the main results presented in this report, comparing the exposure
areas, were not biased (distorted) by the effects of these three demographic variables on cancer
risk.
Results: Associations between distance from SSFL and cancer incidence differed by
type of cancer outcome. Standardized incidence rate ratios were close to 1, indicating little or no
association, for total cancers and radiosensitive cancers among adults; but the incidence rate of
chemosensitive cancers was slightly elevated during both follow-up periods in the population
living within 2 miles of SSFL. Results for the 9 specific cancers revealed some elevated
incidence rates between 1988 and 1995 among persons living within 2 miles of SSFL.
Specifically, the standardized incidence rate ratio was greater than 1.6 for cancers of blood and
lymph tissue, bladder, thyroid, and upper aerodigestive tract. Between 1996 and 2002, the rate
ratio among persons living within 2 miles of SSFL was greater than 1.6 for thyroid cancer.
There were too few childhood cancers to yield informative results.
Discussion: The strongest and most consistent association observed in this study was for
thyroid cancer, which was associated with distance from SSFL in both follow-up periods. This
finding may have public-health significance because perchlorate, a component of rocket fuel
used in large quantities at SSFL, is known to disrupt thyroid function, it has been shown to
induce thyroid tumors in laboratory animals, and there is evidence from two other investigations
that perchlorate migrated offside to contaminate the groundwater in areas surrounding SSFL. In
addition, findings from one of those other studies suggest that the 1959 partial meltdown of a
nuclear reactor at SSFL could have released appreciable amounts of radioactive cesium and
iodine, which might have increased the incidence of thyroid cancer in the population surrounding
SSFL. Furthermore, our results for cancers of the bladder, blood and lymph tissue, and upper
aerodigestive tract are consistent with associations observed in the UCLA Worker Study between
mortality from these cancers and occupational exposures to radiation and chemicals.
It is important to recognize that associations observed between distance from SSFL and
the incidence of specific cancers are based on small numbers of cases in the region closest to
SSFL. Thus, these associations are estimated imprecisely and may represent chance findings. In
addition, observed associations may have been biased by certain methodologic limitations�use
of distance from SSFL as a crude proxy measure for environmental exposures, mobility of the
residential population before and during the follow-up period, and lack of information on other
cancer risk factors, such as cigarette smoking and socioeconomic status, that might distort the
observed associations.
Download: Community Cancer Incidence Report
<-- LA Rocketdyne Nuclear Meltdown
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