Updated epidemiological study of workers at two California petroleum refineries, 1950-95

Area of Science:

• Occupational Health
• Epidemiology
• Environmental Health

Background:

• Occupational exposures in petroleum refineries may pose health risks.
• Previous studies have investigated worker mortality, necessitating updated analyses.

Purpose of the Study:

• To evaluate the mortality risk associated with employment at two California petroleum refineries.
• To update a cohort study assessing occupational exposures and long-term health outcomes.

Main Methods:

• A cohort study of 18,512 employees with 456,425 person-years of observation (1950-1995).
• Standardized mortality ratios (SMRs) and 95% confidence intervals (95% CIs) compared to the general California population.
• Specific analyses for lymphatic/hematopoietic cancers and asbestos-related diseases.

Main Results:

• Overall and total cancer mortality were significantly lower than expected.
• No significant increases in leukemia, non-Hodgkin's lymphoma, or asbestos-related diseases (lung cancer, mesothelioma).
• A marginally significant excess of multiple myeloma was observed, confined to pre-1949 employees, with no duration-response trend.

Conclusions:

• This second update provides further reassurance of no increased mortality risk for workers at these refineries.
• Employment at these petroleum refineries is not associated with elevated mortality.
• Findings suggest occupational exposures at these sites do not lead to increased cancer or other disease risks.