Abstract/Details

Cancer mortality and incidence in an aerospace worker cohort: The extended Rocketdyne Study


2004 2004

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Abstract (summary)

We examined the occurrence of cancer deaths between 1950 and 2001 in a cohort of aerospace workers exposed to hydrazine rocket fuels and in addition, we investigated cancer incidence for the period of 1988–2000. Effect estimates were derived from Cox models using time-dependent exposure measures for hydrazine, trichloroethylene (TCE), polycyclic aromatic hydrocarbons (PAHs), mineral oils, and benzene. We found that high exposures to hydrazine rocket fuel increased colon and rectum cancer incidence, lung cancer mortality and possibly pancreatic cancer mortality; high TCE exposure increased bladder cancer incidence and possibly brain cancer mortality and kidney cancer incidence; high exposure to mineral oils increased esophagus and stomach cancer mortality, lung cancer mortality, non-Hodgkin's lymphoma (NHL) and leukemia incidence, and incidence of skin melanoma. Exposure lags of 10 and 20 years changed effect estimates only minimally and sensitivity analyses conducted for cancer incidence did not suggest major biases due to missing cases.

We examined job category effects on cancer mortality via several statistical models including the conventional Cox model and two hierarchical modeling approaches: a hierarchical multinomial logit model and a hierarchical discrete time competing risk model. The latter two models resulted in more stable estimates than the conventional one-stage Cox model as expected, but the results were quite sensitive to the specification of the second-stage variance. The hierarchical discrete time competing risk model that incorporates both the time to event and time-dependent exposure information seems to result in more reasonable parameter estimates and thus its use is recommended for the analysis of cohort data with multiple outcomes and multiple exposures.

Indexing (details)


Subject
Public health;
Occupational safety;
Oncology;
Biostatistics;
Cancer;
Mortality;
Aerospace industry
Classification
0573: Public health
0354: Occupational safety
0992: Oncology
0308: Biostatistics
Identifier / keyword
Health and environmental sciences; Biological sciences; Aerospace worker; Cancer; PAHs; Rocketdyne Study
Title
Cancer mortality and incidence in an aerospace worker cohort: The extended Rocketdyne Study
Author
Zhao, Yingxu
Number of pages
105
Publication year
2004
Degree date
2004
School code
0031
Source
DAI-B 66/03, Dissertation Abstracts International
Place of publication
Ann Arbor
Country of publication
United States
ISBN
9780542051937, 0542051931
Advisor
Ritz, Beate
University/institution
University of California, Los Angeles
University location
United States -- California
Degree
Ph.D.
Source type
Dissertations & Theses
Language
English
Document type
Dissertation/Thesis
Dissertation/thesis number
3169147
ProQuest document ID
305207224
Copyright
Database copyright ProQuest LLC; ProQuest does not claim copyright in the individual underlying works.
Document URL
http://search.proquest.com/docview/305207224
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