UC Irvine

The association between asbestos exposure and lung cancer, as well as between asbestos exposure and mesothelioma, had long since been established, while the relationship between asbestos exposure and other types of malignancies remains unclear. Aside from asbestos, numerous other potential exposures are present in the shipyard. Several occupations are exposed to substances such as welding fumes. The purpose of this dissertation is to examine the association between occupational agents in the Long Beach Naval shipyard and the health outcomes experienced by the workers employed in the shipyard. The study will assess the relationship between asbestos exposure and colorectal cancer by asbestos exposures levels, as well as, the incidence and mortality rates of lung cancer in relation to the exposure to welding fumes.

The leading causes of deaths and the incidence of cancers was evaluated in 13,924 shipyard workers employed in the Long Beach Naval shipyard employed between 1978 and 1985. Mortality data (1978-2013) was ascertained through the California Deaths Statistical Master files. The incidence of cancer (1988-2011) was ascertained through the California cancer registry. Workers were classified into low, intermediate, and high asbestos exposure groups. Workers were also separated into exposed versus non-exposed to examine the effects of welding fumes exposure. Age-specific standardized mortality ratio and age-specific standardized incidence ratio for cancer were calculated using the general population of the state of California as the standard population. The Kaplan-Meier method was used to determine the time until occurrence of disease for colorectal cancer and lung cancer among workers exposed to asbestos and workers exposed to welding fumes.

The leading causes of deaths in the Long Beach Naval shipyard included diseases of the circulatory and neoplasms. There was excess mortality and incidence of cancer in the study cohort including excess mesothelioma, lung, and colorectal cancer. Excess incidence of mesothelioma were observed in all three asbestos exposure groups. The study found no statistical difference in the time to disease occurrence between exposure groups for colorectal and lung cancer outcomes. This study showed that employment in the Long Beach Naval shipyard increased workers’ risk to a wide variety of cancers including asbestos-related malignancies.