http://occmed.oxfordjournals.org/cgi/reprint/52/6/333

The Institute of Occupational Health at the University of Birmingham in the United Kingdom investigated the mortality data of 28,630 oil refinery workers and 16,480 petroleum distribution workers.  All of the study subjects were male employees who were first employed between 1946 and1974 and who worked for at least one year at one of eight UK oil refineries or from one of 476 UK petroleum distribution centers.  The study objective was to summarize available mortality data and to determine whether any part of the mortality experience of the cohort might be related to occupational exposure.  In that event, further analyses might be needed.

Results:

Mortality from the selected population were compared to the national mortality rates and showed some surprising results.  The standardized mortality ratios (SMRs) regarding some cancers were significantly elevated in oil refinery workers.  SMR ratings above 100 are considered significant.

• Mesothelioma: 38 workers had mesothelioma but only 15 were expected to, based on the national average, SMR=254 (over twice the national trend)
• Cancer of the gall bladder: 24 observed, national average 14, SMR=172
• Melanoma: 36 observed, 22.2 expected, SMR=162

Significantly elevated SMRs for cancer were not found in petroleum distribution workers.  However, two findings suggest the presence of an occupational cancer hazard.  Oil refinery workers had an excess of mesothelioma, and petroleum distribution workers had an excess of leukemia.  Both excesses occurred in long-term follow-ups for workers who were employed more than 30 years ago.  Tables can be viewed in the full journal entry, at the link above.

Mesothelioma occurred more often with operators, laborers, and engineers. It is known that asbestos was used in refineries in earlier decades, and at least some of the excess mortality from mesothelioma is likely to have been caused by exposure to this asbestos. At face value, the findings by job type suggest that asbestos exposure in oil refineries may have been a plant-wide problem rather than concentrated in one or two jobs.

In conclusion, the findings of this analysis should be welcome news for UK oil refinery and petroleum distribution workers. Their overall mortality is well below the national average. The only findings that suggested the presence of an occupational cancer hazard were the excess of mesothelioma in oil refinery employees and the excess of leukemia mortality in petroleum distribution workers, both excesses occurring in long-term follow-up for workers first exposed >30 years ago.

Materials and Methods:

The study gathered identifying particulars (name and date of birth), work history information (oil refinery or petroleum distribution center, dates of commencing and leaving employment, job title in 1975 or last job if left employment before 1975), and follow-up information (date of death, underlying cause of death and contributory causes of death) for 28,630 oil refinery workers and 16,480 petroleum distribution workers. All subjects were employed for a minimum of 12 months with some employment after 1 January 1951.  Six of the oil refineries were in England and Wales, while the remaining two were located in Scotland. A total of 403 of the petroleum distribution centers were in England and Wales, while the remaining 73 centers were located in Scotland.

The National Health Service Central Register of the Office for National Statistics and the General Register Office for Scotland provided vital status information on the closing date of the survey, December 31, 1998. For those refinery workers who had died (n = 9627), a copy of the death certificate was supplied with the underlying cause of death and other causes of death coded to the contemporaneous revision of the International Classification of Diseases (ICD); the recorded cause of death was untraced for only 84 deaths (0.9%). A total of 1659 refinery workers (5.8%) had emigrated and 254 refinery workers were untraceable (0.9%). A total of 6269 deceased were identified in the petroleum distribution workers; the recorded cause of death was untraced for only 60 deaths (1.0%).  A total of 306 distribution workers (1.9%) had emigrated and 367 distribution workers were untraceable (2.2%). 

*** POSTED FEBRUARY 23, 2007 ***