Cancer incidence in UK electricity generation and transmission workers, 1973-2015.

BACKGROUND: Long-term health outcomes in cohorts of workers from the electricity supply industry have been studied. AIMS: The aim of the study was to examine updated cancer incidence findings among a cohort of UK electricity generation and transmission workers. METHODS: Cancer morbidity experienced by 81 616 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-2015. All employees had worked for at least 6 months with some employment between 1973 and 1982. Standardized registration ratios (SRRs) were calculated based on national rates. RESULTS: Overall cancer morbidity was slightly below expectation in males. Significant excesses were found in male workers for mesothelioma (observed [Obs] 763, SRR 326), skin cancer (non-melanoma) (Obs 5616, SRR 106), and prostate cancer (Obs 4298, SRR 106), and in female workers for cancer of the small intestine (Obs 13, SRR 220), nasal cancer (Obs 11, SRR 407), and breast cancer (Obs 758, SRR 110). More detailed analyses showed important contrasts, particularly for mesothelioma, lung cancer, skin cancer, prostate cancer and breast cancer. CONCLUSIONS: A clear occupational excess of mesothelioma was not matched by a corresponding excess of asbestos-induced lung cancer. Confident interpretation of the excesses of cancers of the nasal cavities and small intestine is not possible, although occupational exposures received in this industry may well not be involved. An excess of skin cancer in transmission workers may be associated with outdoor working.

Childhood cancer research in Oxford I: the Oxford Survey of Childhood Cancers.

BACKGROUND: Significant research on the epidemiology and natural history of childhood cancer took place in the Universities of Oxford and Birmingham over sixty years. This is the first of three papers recording this work and describes the Oxford Survey of Childhood Cancers (OSCC), the largest case-control survey of childhood cancer ever undertaken. METHODS: The OSCC studied deaths in Britain from 1953 to 1981. Parents were interviewed and medical records from ante-natal clinics and treatment centres were followed up and abstracted. The survey left Oxford in 1975 and was run subsequently from Birmingham. The data are now being documented and archived to make them available for future study. RESULTS: Many papers have resulted from this survey, most notably those relating to the association first reported therein between childhood cancer and ante-natal X-raying. This paper is a historical review of the OSCC. CONCLUSIONS: In spite of many analyses of the study, this historic data set has continuing value because of the large number of examples of some very rare tumours and the detailed clinical and family history data that are available; and also because of the possibility of carrying out new analyses to investigate emerging research issues.

Cancer incidence in cohorts of workers in the rubber manufacturing industry first employed since 1975 in the UK and Sweden.

OBJECTIVES: Increased cancer risks have been reported among workers in the rubber manufacturing industry employed before the 1960s, but it is unclear for workers hired subsequently. The present study focused on cancer incidence among rubber workers first employed after 1975 in Sweden and the UK. METHODS: Two cohorts of rubber workers employed for at least 1 year were analysed. Standardised incidence ratios (SIRs), based on country-specific and period-specific incidence rates, were analysed for all cancers combined (except non-melanoma skin), bladder, lung, stomach cancer, leukaemia, non-Hodgkin's lymphoma and multiple myeloma. Exploratory analyses were conducted for other cancers with a minimum of 10 cases in both genders combined. RESULTS: 16 026 individuals (12 441 men; 3585 women) contributed to 397 975 person-years of observation, with 846 cancers observed overall (437 in the UK, 409 in Sweden). No statistically significant increased risk was observed for any site of cancer. A reduced risk was evident for all cancers combined (SIR=0.83, 95% CI (0.74 to 0.92)), lung cancer (SIR=0.74, 95% CI (0.59 to 0.93)), non-Hodgkin's lymphoma (SIR=0.67, 95% CI (0.45 to 1.00)) and prostate cancer (SIR=0.77, 95% CI (0.64 to 0.92)). For stomach cancer and multiple myeloma, SIRs were 0.93 (95% CI (0.61 to 1.43)) and 0.92 (95% CI 0.44 to 1.91), respectively. No increased risk of bladder cancer was observed (SIR=0.88, 95% CI (0.61 to 1.28)). CONCLUSIONS: No significantly increased risk of cancer incidence was observed in the combined cohort of rubber workers first employed since 1975. Continued surveillance of the present cohorts is required to confirm absence of long-term risk and confirmatory findings from other cohorts would be important.

Cancer mortality in cohorts of workers in the European rubber manufacturing industry first employed since 1975.

BACKGROUND: Increased cancer risk has been reported among workers in the rubber manufacturing industry employed before the 1960s. It is unclear whether risk remains increased among workers hired subsequently. The present study focused on risk of cancer mortality for rubber workers first employed since 1975 in 64 factories. PATIENTS AND METHODS: Anonymized data from cohorts of rubber workers employed for at least 1 year from Germany, Italy, Poland, Sweden, and the UK were pooled. Standardized mortality ratios (SMRs), based on country-specific death rates, were reported for bladder and lung cancer (primary outcomes of interest), for other selected cancer sites, and for cancer sites with a minimum of 10 deaths in men or women. Analyses stratified by type of industry, period, and duration of employment were carried out. RESULTS: A total of 38 457 individuals (29 768 men; 8689 women) contributed to 949 370 person-years. No increased risk of bladder cancer was observed [SMR = 0.80, 95% confidence interval (CI) 0.46; 1.38]. The risk of lung cancer death was reduced (SMR = 0.81, 95% CI 0.70; 0.94). No statistically significant increased risk was observed for any other cause of death. A reduced risk was evident for total cancer mortality (SMR = 0.81, 95% CI 0.76; 0.87). Risks were lower for workers in the tyre industry compared with workers in the general rubber goods sector. Analysis by employment duration showed a negative trend with SMRs decreasing with increasing duration of employment. In an analysis of secondary end points, when stratified by type of industry and period of first employment, excess risks of myeloma and gastric cancer were observed each due, essentially, to results from one centre. CONCLUSION: No consistent increased risk of cancer death was observed among rubber workers first employed since 1975, no overall analysis of the pooled cohort produced significantly increased risk. Continued surveillance of the present cohorts is required to confirm the absence of long-term risk.

Neurodegenerative disease and magnetic field exposure in UK electricity supply workers.

BACKGROUND: Previous research has suggested a possible link between neurodegenerative disease and exposure to extremely low-frequency electric and magnetic fields. AIMS: To investigate whether risks of Alzheimer's, motor neurone or Parkinson's disease are related to occupational exposure to magnetic fields. METHODS: The mortality experienced by a cohort of 73051 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-2010. All employees were hired in the period 1952-82, were employed for at least 6 months and had some employment after 1 January 1973. Detailed calculations had been performed by others to enable an assessment to be made of exposures to magnetic fields. Poisson regression was used to calculate relative risks (rate ratios) of developing any of the three diseases under investigation for categories of lifetime, distant (lagged) and recent (lugged) exposure. RESULTS: No statistically significant trends were shown for risks of any of these diseases to increase with estimates of lifetime, recent or distant exposure to magnetic fields. CONCLUSIONS: There is no convincing evidence that UK electricity generation and transmission workers have suffered elevated risks from neurodegenerative diseases as a consequence of exposure to magnetic fields.

Magnetic fields and leukaemia risks in UK electricity supply workers.

AIMS: To investigate whether leukaemia risks are related to occupational exposure to low-frequency magnetic fields. METHODS: Leukaemia risks experienced by 73 051 employees of the former Central Electricity Generating Board of England and Wales were investigated for the period 1973-2010. All employees were hired in the period 1952-82 and were employed for at least 6 months with some employment in the period 1973-82. Detailed calculations had been performed by others to enable an assessment to be made of exposures to magnetic fields. Poisson regression was used to calculate relative risks (rate ratios) of developing leukaemia or leukaemia subtypes for categories of lifetime, distant (lagged) and recent (lugged) exposure. RESULTS: Findings for all leukaemias combined were unexceptional; risks were close to unity for all exposure categories and there was no suggestion of risks increasing with cumulative (or recent or distant) magnetic field exposures. There were no statistically significant dose-response effects shown for acute myeloid leukaemia, chronic myeloid leukaemia or chronic lymphocytic leukaemia. There was a significant positive trend for acute lymphocytic leukaemia (ALL), but this was based, in the main, on unusually low risks in the lowest exposure category. CONCLUSIONS: This study found no convincing evidence to support the hypothesis that exposure to magnetic fields is a risk factor for leukaemia, and the findings are consistent with the hypotheses that both distant and recent magnetic field exposures are not causally related to the generality of leukaemia. The limited positive findings for ALL may well be chance findings.

Magnetic fields and brain tumour risks in UK electricity supply workers.

AIMS: To investigate whether brain tumour risks are related to occupational exposure to low-frequency magnetic fields. METHODS: Brain tumour risks experienced by 73 051 employees of the former Central Electricity Generating Board of England and Wales were investigated for the period 1973-2010. All employees were hired in the period 1952-82 and were employed for at least 6 months with some employment in the period 1973-82. Detailed calculations had been performed by others to enable an assessment to be made of exposures to magnetic fields. Poisson regression was used to calculate relative risks (rate ratios) of developing a brain tumour (or glioma or meningioma) for categories of lifetime, distant (lagged) and recent (lugged) exposure. RESULTS: Findings for glioma and for the generality of all brain tumours were unexceptional; risks were close to (or below) unity for all exposure categories and there was no suggestion of risks increasing with cumulative (or recent or distant) magnetic field exposures. There were no statistically significant dose-response effects shown for meningioma, but there was some evidence of elevated risks in the three highest exposure categories for exposures received >10 years ago. CONCLUSIONS: This study found no evidence to support the hypothesis that exposure to magnetic fields is a risk factor for gliomas, and the findings are consistent with the hypotheses that both distant and recent magnetic field exposures are not causally related to gliomas. The limited positive findings for meningioma may be chance findings; national comparisons argue against a causal interpretation.

Cancer incidence in UK electricity generation and transmission workers, 1973-2008.

BACKGROUND: The effects of magnetic field exposure on cancer risks remains unclear. AIMS: To examine cancer incidence among a cohort of UK electricity generation and transmission workers. METHODS: Cancer morbidity experienced by a cohort of 81 842 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-2008. All employees had worked for at least 6 months with some employment between 1973 and 1982. Standardized registration ratios (SRRs) were calculated on the basis of national rates. RESULTS: Overall cancer morbidity was slightly below expectation in males and females. Significant excesses were found in male workers for mesothelioma (Observed [Obs] 504, SRR 331), skin cancer (non-melanoma) (Obs 3187, SRR 107) and prostate cancer (Obs 2684, SRR 107) and in female workers for cancer of the small intestine (Obs 10, SRR 306) and nasal cancer (Obs 9, SRR 474). Brain cancers were close to expectation in males and below expectation in females. Leukaemia incidence (all types) was slightly below expectation in males and females. More detailed analyses showed import ant contrasts for mesothelioma and leukaemia. CONCLUSIONS: The clear occupational excess of mesothelioma was not matched by a corresponding excess of lung cancer, and the level of asbestos-induced lung cancer in this industry must be low. Leukaemia risks declined with period from hire; confident interpretation of this finding is not possible. The excesses of cancers of the nasal cavities and small intestine are probably not occupational, though the excess of skin cancer may be due to outdoor work.

Cancer risks in chemical production workers exposed to 2-mercaptobenzothiazole.

OBJECTIVES: To investigate cancer risks in chemical production workers exposed to 2-mercaptobenzothiazole (MBT). METHODS: The mortality (1955-2005) and cancer morbidity experience (1971-2005) of a cohort of 363 male production workers exposed to MBT while employed at a chemical factory in north Wales were investigated. Two analytical approaches were used, indirect standardisation and Poisson regression. RESULTS: Based on national mortality rates, significant excess mortality was found for cancers of the large intestine (observed; Obs 8, standardised mortality ratio (SMR) 232, 95% CI 100 to 457) and bladder (Obs 8, SMR 374, 95% CI 162 to 737). Non-significant excesses were shown for lung cancer (Obs 27, SMR 138, 95% CI 91 to 201) and multiple myeloma (Obs 3, SMR 440, 95% CI 91 to 1287). Based on national cancer incidence rates, significant excess morbidity was found for cancer of the bladder (Obs 12, standardised registration ratio (SRR) 253, 95% CI 131 to 441) and multiple myeloma (Obs 4, SRR 465, 95% CI 127 to 1191). Non-significant excesses were shown for cancers of the large intestine (Obs 9, SRR 181, 95% CI 83 to 344) and lung (Obs 26, SRR 152, 95% CI 99 to 223). In analyses that included follow-up information on an additional 1797 plant employees not exposed to MBT, Poisson regression showed significant positive trends both for risks of cancer of the large intestine and for risks of multiple myeloma in relation to estimated cumulative exposure to MBT. CONCLUSIONS: MBT may be a human carcinogen; confident evaluation awaits findings from other studies.

Mortality from Alzheimer's, motor neuron and Parkinson's disease in relation to magnetic field exposure: findings from the study of UK electricity generation and transmission workers, 1973-2004.

BACKGROUND: There are a number of reports linking magnetic field exposure to increased risks of Alzheimer's disease and motor neuron disease. METHODS: The mortality experienced by a cohort of 83 997 employees of the former Central Electricity Generating Board of England and Wales was investigated for the period 1973-2004. All employees were employed for at least six months with some employment in the period 1973-82. Computerised work histories were available for 79 972 study subjects for the period 1971-93. Information on job and facility (location) were used to estimate exposures to magnetic fields. Two analytical approaches were used to evaluate risks, indirect standardisation (n = 83 997) and Poisson regression (n = 79 972). RESULTS: Based on serial mortality rates for England and Wales, deaths from Alzheimer's disease and motor neuron disease were unexceptional. There was an excess of deaths from Parkinson's disease of borderline significance. No statistically significant trends were shown for risks of any of these diseases to increase with lifetime cumulative exposure to magnetic fields (RR per 10 µT-y: Alzheimer's disease 1.10 (95% CI 0.90 to 1.33); motor neuron disease 1.06 (95% CI 0.86 to 1.32); Parkinson's disease 0.88 (95% CI 0.74 to 1.05)) CONCLUSIONS: There is no convincing evidence that UK electricity generation and transmission workers have suffered increased risks from neurodegenerative diseases as a consequence of exposure to magnetic fields.

Cancer risks in a historical UK cohort of benzene exposed workers.

AIMS: To examine mortality from different causes and cancer incidence among a cohort of benzene workers in England and Wales. METHODS: A cohort of 5514 workers who had been occupationally exposed to benzene in 1966/67 or earlier was assembled by the former Factory Inspectorate and the Medical Research Council from details provided by 233 employers in England and Wales. The cohort was followed up for mortality (1968-2002) and cancer registrations (1971-2001). National mortality rates and cancer registration (incidence) rates were used to calculate standardised mortality ratios and standardised registration ratios. RESULTS: Mortality was close to expectation for all causes and significantly increased for cancer of the lip, cancer of the lung and bronchus, secondary and unspecified cancers, acute non-lymphocytic leukaemia (ANLL), and all neoplasms. Significant deficits were shown for three non-malignant categories (mental disorders, diseases of the digestive system, accidents). SMRs for other leukaemia, lymphomas, and multiple myeloma were close to or below expectation. There was some evidence of under-ascertainment of cancer registrations, although significantly increased SRRs were shown for lung cancer and cancer of the pleura (mesothelioma). CONCLUSIONS: Many study subjects would have been exposed to carcinogens other than benzene (for example, asbestos, rubber industry fumes, foundry fumes, polycyclic aromatic hydrocarbons), and the excesses of lung cancer and mesothelioma are likely to reflect exposures to these other carcinogens. The carcinogenic effects of benzene exposure on the lymphohaematopoietic system were limited to ANLL.

Mortality of workers at a nickel carbonyl refinery, 1958-2000.

BACKGROUND: Excess risks of respiratory cancer have been shown in some groups of nickel exposed workers. It is clear, however, that not all forms of nickel exposure are implicated in these excess risks. AIM: To determine whether occupational exposures received in a modern nickel carbonyl refinery lead to increased risks of cancer, in particular nasal cancer and lung cancer. METHODS: The mortality experienced by a cohort of 812 workers employed at a nickel refinery was investigated. Study subjects were all male workforce employees first employed in the period 1953-92 who had at least five years' employment with the company. Observed numbers of cause specific deaths were compared with expectations based on national mortality rates; SMRs were also calculated by period from commencing employment, year of commencing employment, and type of work. RESULTS: Overall, standardised mortality ratios (SMRs) were close to 100 for all causes (Obs 191, SMR 96, 95% CI 83 to 111), all neoplasms (Obs 63, SMR 104, 95% CI 80 to 133), non-malignant diseases of the respiratory system (Obs 18, SMR 97, 95% CI 57 to 153), and diseases of the circulatory system (Obs 85, SMR 94, 95% CI 75 to 116). There were no significantly increased SMRs for any site of cancer. There was a non-significant excess for lung cancer (Obs 28, Exp 20.17, SMR 139, 95% CI 92 to 201), and in subgroup analyses a significantly increased SMR of 231 (Obs 9) was found for those 142 workers with at least five years' employment in the feed handling and nickel extraction departments. In the total cohort there was a single death from nasal cancer (Exp 0.10). CONCLUSIONS: The non-significant excess of lung cancer deaths may well be a chance finding, but in light of previous studies some role for nickel exposures cannot be excluded.

Parental cigarette smoking and childhood risks of hepatoblastoma: OSCC data.

Reported cigarette smoking habits for the parents of 43 UK children who died with hepatoblastoma (1953-55 deaths, 1971-81 deaths) have been compared with corresponding information for the parents of 5777 healthy control children by means of unconditional logistic regression. Hepatoblastoma risks were doubled if both parents smoked relative to neither parent smoking (RR 2.28, 95% CI 1.02-5.09).

Mortality of workers at a plant manufacturing nickel alloys, 1958-2000.

BACKGROUND: Excess risks of respiratory cancer have been demonstrated in some groups of nickel-exposed workers. It is clear, however, that not all forms of nickel exposure are implicated in these excess risks. Aim To determine whether occupational exposures received in the manufacture of nickel alloys lead to increased risks of cancer, in particular nasal cancer and lung cancer. METHODS: The mortality experienced by a cohort of 1999 workers employed at a plant manufacturing nickel alloys has been investigated. Study subjects were all those male workforce employees first employed in the period 1953-1992 who had at least 5 years employment with the company. Observed numbers of cause-specific deaths were compared with expectations based on national mortality rates. Standardized mortality ratios (SMRs) were calculated by period from commencing employment and by operating area of first job. In addition, rate ratios derived from Poisson regression and based on an internal standard were calculated by levels of duration of employment. RESULTS: SMRs were significantly below 100 for all causes (observed 557, expected 704.3, SMR 79), all neoplasms (observed 169, expected 209.4, SMR 81) non-malignant diseases of the respiratory system (observed 50, expected 73.0, SMR 69) and diseases of the circulatory system (observed 261, expected 335.5, SMR 78). Significantly elevated SMRs were not shown for any cause of death and mortality was below expectation for stomach cancer (observed 8, expected 16.0, SMR 50), lung cancer (observed 64, expected 73.6, SMR 87) and bladder cancer (observed 3, expected 8.0, SMR 38). There were no deaths from nasal cancer (expected 0.33). More detailed findings were unexceptional. CONCLUSIONS: The analyses did not suggest the presence of an occupational cancer hazard in the mortality experience of the cohort.

Lung cancer mortality in UK nickel-cadmium battery workers, 1947-2000.

AIMS: To investigate mortality from lung cancer in nickel-cadmium battery workers in relation to cumulative exposure to cadmium hydroxide. METHODS: The mortality of a cohort of 926 male workers from a factory engaged in the manufacture of nickel-cadmium batteries in the West Midlands of England was investigated for the period 1947-2000. All subjects were first employed at the plant in the period 1947-75 and employed for a minimum period of 12 months. Work histories were available for the period 1947-86; the factory closed down in 1992. Two analytical approaches were used, indirect standardisation and Poisson regression. RESULTS: Based on serial mortality rates for the general population of England and Wales, significantly increased mortality was shown for cancers of the pharynx (observed (Obs) 4, expected (Exp) 0.7, standardised mortality ratio (SMR) 559, p<0.05), non-malignant diseases of the respiratory system (Obs 61, Exp 43.0, SMR 142, p<0.05), and non-malignant diseases of the genitourinary system (Obs 10, Exp 4.1, SMR 243, p<0.05). Non-significantly increased SMRs were shown for lung cancer (Obs 45, Exp 40.7, SMR 111) and cancer of the prostate (Obs 9, Exp 7.5, SMR 116). Estimated cumulative cadmium exposures were not related to risks of lung cancer or risks of chronic obstructive pulmonary diseases, even when exposure histories were lagged first by 10, then by 20 years. CONCLUSIONS: The study findings do not support the hypotheses that cadmium compounds are human lung carcinogens.

Cancer in the offspring of radiation workers: an investigation of employment timing and a reanalysis using updated dose information.

An earlier case-control study found no evidence of paternal preconceptional irradiation (PPI) as a cause of childhood leukaemia and non-Hodgkin's lymphoma (LNHL). Although fathers of children with LNHL were more likely to have been radiation workers, the risk was most marked in those with doses below the level of detection. The timing of paternal employment as a radiation worker has now been examined. The previously reported elevated risk of LNHL in the children of male radiation workers was limited to those whose fathers were still radiation workers at conception or whose employment also continued until diagnosis. Children whose fathers stopped radiation work prior to their conception were found to have no excess risk of LNHL. It was not possible to distinguish between the risks associated with paternal radiation work at conception and at the time of diagnosis. A reanalysis of the original study hypothesis incorporating updated dosimetric information gave similar results to those obtained previously. In particular, the risks of LNHL did not show an association with radiation doses received by the father before conception. It seems likely that the increased risk of LNHL among the children of male radiation workers is associated with an increased exposure to some infective agent consequent on high levels of population mixing.

Breastfeeding and childhood cancer risks: OSCC data.

Matched pair analysis relating to 3376 mothers of children who died of cancer 1972-1981 and of healthy control children from the Oxford Survey of Childhood Cancers showed no evidence of protection from breastfeeding for acute lymphocytic leukaemia (OR 1.04, 95% CI 0.86-1.26), for all cancers combined (OR 1.04, 95% CI 0.93-1.15) or for other groupings. Analyses by duration of breastfeeding also failed to support the protective hypothesis.

Mortality and cancer morbidity of production workers in the UK flexible polyurethane foam industry: updated findings, 1958-98.

AIMS: To describe cause specific mortality and site specific cancer morbidity among workers employed in factories that produce polyurethane foams, and to determine if any part of the experience may be caused by occupation, in particular to investigate any association between respiratory disease (malignant and non-malignant) and exposure to diisocyanates. METHODS: The mortality (1958-98) and cancer morbidity (1971-94) experienced by a cohort of 8288 male and female employees from 11 factories in England and Wales engaged in the manufacture of flexible polyurethane foams were investigated. All employees were employed for at least six months with some period of employment in the period 1958-79. Two analytical approaches were used, indirect standardisation and Poisson regression. RESULTS: Compared with the general population of England and Wales, mortality from lung cancer in female employees was significantly increased (observed (Obs) 35, expected (Exp) 19.4, standardised mortality ratio (SMR) 181). A similar excess was not found for male employees (Obs 134, Exp 125.0, SMR 107). There were no significantly increased cause specific SMRs among the subcohort (n = 1782) with some period of isocyanate exposed employment. No significant positive trends were found between risks of lung cancer or risks of non-malignant diseases of the respiratory system and durations of "lower" or "higher" exposures to diisocyanates. CONCLUSIONS: The study has been unable to link isocyanate exposed employment either with risks of lung cancer or with risks of non-malignant diseases of the respiratory system. The increased SMR for female lung cancer is most likely caused by factors unrelated to the industry under study.

Mortality of United Kingdom oil refinery and petroleum distribution workers, 1951-1998.

The mortality experienced by cohorts of 28 630 oil refinery workers and 16 480 petroleum distribution workers has been investigated. Study subjects were all those male employees first employed in the period 1946-1974 at one of eight UK oil refineries or at one of 476 UK petroleum distribution centres; all subjects had a minimum of 12 months employment with some employment after 1 January 1951. The observed numbers of cause-specific deaths were compared with expectations based on national mortality rates. The resultant standardized mortality ratios (SMRs) were significantly below 100 for all causes, in both oil refinery workers (observed, 9341; expected, 10 649.7; SMR = 88) and petroleum distribution workers (observed, 6083; expected, 6460.3; SMR = 94). Significantly elevated SMRs were shown in oil refinery workers for cancer of the gall bladder (observed, 24; expected, 14.0; SMR = 172), cancer of the pleura (observed, 38; expected, 15.0; SMR = 254) and melanoma (observed, 36; expected, 22.2; SMR = 162). Significantly elevated SMRs were not found in petroleum distribution workers for any site of cancer. SMRs for selected causes of death were calculated by period from commencing employment, by year of hire and by job type. The only findings that suggested the presence of an occupational cancer hazard were an excess of mesothelioma in oil refinery workers and an excess of leukaemia in petroleum distribution workers, both excesses occurring in long-term follow-up for workers first employed >30 years ago.