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Morbidity patterns among employees at a petroleum refinery
S P Tsai1, C M Dowd, S R Cowles
1Shell Oil Company, Corporate Medical Department, Houston, TX 77252-2463.
Journal of Occupational Medicine. : Official Publication of the Industrial Medical Association
|October 1, 1991
Summary
Petroleum refinery workers experienced similar overall illness rates compared to other manufacturing employees. However, staff reported more musculoskeletal disorders and injuries, while production workers had higher rates of skin conditions.
Area of Science:
- Occupational Health
- Epidemiology
- Industrial Hygiene
Background:
- Assessing worker health in industrial settings is crucial for identifying potential occupational hazards.
- Prospective cohort studies provide valuable insights into disease patterns within specific workforces.
Purpose of the Study:
- To evaluate the morbidity experience of male employees at a petroleum refinery.
- To identify any elevated disease prevalence compared to a relevant internal comparison group.
Main Methods:
- A prospective cohort of 2132 male petroleum refinery employees was studied from 1981-1988.
- Morbidity data included illness-absence episodes exceeding 5 days.
- Standardized morbidity ratios (SMRs) were calculated using Shell Oil Company manufacturing employees as the internal comparison group, mitigating healthy worker effect bias.
Main Results:
- Overall morbidity was comparable between refinery workers and the comparison group (2,311 observed vs. 2,318 expected events).
- Statistically significant increases in musculoskeletal disorders (SMR=136) and injuries (SMR=125) were observed in staff employees.
- Production employees showed a higher prevalence of skin and subcutaneous tissue disorders (SMR=138), though none were linked to chemical or solvent exposure.
- A slight, non-significant elevation in lymphatic and hematopoietic neoplasms was noted in production employees (3 cases vs. 2.4 expected), with no leukemia cases.
Conclusions:
- While overall morbidity was similar, specific occupational groups within the petroleum refinery exhibited increased risks for certain conditions.
- Musculoskeletal disorders, injuries, and skin conditions represent areas for potential targeted health surveillance in this workforce.
- The study design effectively controlled for the healthy worker effect, strengthening the validity of the findings.