Long-term mortality study of oil refinery workers. I. Mortality of hourly and salaried workers

Climate change risk perception in global: Correlation with petroleum and liver disease: A meta-analysis

BACKGROUND

Liver diseases have been bound to environmental factors, inclusive of air pollution. The exposure of workers to petrochemicals counts as a possible cause of Liver diseases, whereas results are inconsistent with the previous studies. In this study, a meta-analysis is conducted to assess the pooled risk.

METHODS AND FINDING

A systematic search was performed by related researchers. Correlations are analyzed among petroleum and liver cirrhosis mortality, fatty liver, alanine amino transferase (abbreviated as ALT), aspartate amino transferase (abbreviated as AST). Pooled risk ratios (RR) with 95% confidence interval (CI) and effect size(ES) with 95% confidence interval are calculated. Sensitivity analysis and publication bias are also tested. Data are analyzed from 5 studies involving 296 participants. Results are incorporated through adopting a random effects meta-analysis. Working in a petrochemical plant shall not increase the death risk posed by cirrhosis (RR = 0.44, 95% CI [0.36; 0.54]). Yet the incidence of fatty liver increases (RR = 1.22, 95% CI [1.21; 1.23]). Abnormal incidence of ALT and AST also increases.

CONCLUSIONS

Occupational exposure plays an important role in causing ALT abnormalities and fatty liver among oil workers, but not a risk factor of cirrhosis, AST abnormalities and liver cancer.

Occupational risk factors for low grade and high grade glioma: results from an international case control study of adult brain tumours

The majority of suspected occupational risk factors for adult brain tumours have yet to be confirmed as etiologically relevant. Within an international case-control study on brain tumours, lifelong occupational histories and information on exposures to specific substances were obtained by direct interviews to further investigate occupational risk factors for glioma. This is one of the largest studies of brain tumours in adults, including 1,178 cases and 1987 population controls from 8 collaborating study centres matched for age, gender and centre. All occupational information, was aggregated into 16 occupational categories. In a pooled analysis, odds ratios (OR), adjusted for education, were estimated separately for men and women and for high-grade glioma (HGG) and low-grade glioma (LGG), focusing especially on 6 categories defined a priori: agricultural, chemical, construction, metal, electrical/electronic and transport. For men, an elevated OR of glioma associated with the category "metal" (OR = 1.24, 95% CI 0.96-1.62) was seen, which appeared to be largely accounted for by LGG (OR = 1.59, 95% CI 1.00-2.52). For the other 5 occupational categories, no elevated risks for glioma were observed. For women the only noteworthy observation for the 6 a priori categories was an inverse association with the "agriculture" category (OR = 0.60, 95% CI 0.36-0.99). Apart from the 6 major categories, women working in food production or food processing (category "food") showed an increased OR of 1.95 (95% CI 1.04-3.68). None of the 20 substance groups was positively associated with glioma risk. Although some other point estimates were elevated, they lacked statistical significance. The results do not provide evidence of a strong association between occupational exposures and glioma development.

Cancer incidence among refinery and petrochemical employees in Louisiana, 1983–1999

PURPOSE

The purpose of this study is to determine the incidence of cancer among employees at two petrochemical facilities in south Louisiana, and to compare their cancer rates to those of the general population of south Louisiana.

METHODS

Records on 4639 active and former employees and retirees from the two plants were linked to the Louisiana Tumor Registry (LTR) database by LTR staff to ascertain incident cases of cancer. Standardized incidence ratios (SIRs) were then calculated using the south Louisiana population as the comparison and adjusted for age, race, and time period.

RESULTS

There was a significant 16% deficit of overall cancer cases for males in this cohort (SIR=0.84; 95% CI, 0.74-0.95). The only significantly elevated SIR in males was for cancer of the bone and joint (SIR=6.89; 95% CI, 1.42-20.1). This result was based on three non-fatal cases of bone cancer with different histologies, occurring in different parts of the body. These cases worked in different units of one plant. Significant deficits were seen for lung cancer, non-Hodgkin's lymphoma, and cancer of the oral cavity and pharynx. Cancer incidence among 719 female employees was non-significantly increased (SIR=1.24; 95% CI, 0.81-1.82). Breast cancer accounts for the excess (SIR=1.46; 95% CI, 0.73-2.61). Seventy percent of the breast cancer cases worked in an office setting.

CONCLUSIONS

This study found little evidence of any association between cancer incidence and employment at these two petrochemical facilities. The increased incidence of bone cancer is unlikely to be due to occupational exposures. The non-significant excess of breast cancer may be due to early detection or other important unmeasured confounders, such as certain reproductive factors.

Non-Hodgkin's lymphomas and organic solvents

Organic solvents have been suggested as a possible risk factor for non-Hodgkin's lymphomas (NHL). We studied 109 NHL incident cases and 276 controls with other cancers (1990/1996) in the city of Salvador, Brazil. Occupational exposure to organic solvents was evaluated through standardized questionnaires and defined by industrial hygienists, taking into account individuals' lifetime history. An association between occupational exposure to organic solvents and NHL was observed, OR = 1.67 (95% CI, 0.97 to 2.87), especially among individuals less than 64 years, OR = 1.91 (95% CI, 0.99 to 3.67), and among those who used domestic insecticides, OR = 2.24 (95% CI, 1.01 to 3.97). Odds ratios were similar for nodal and diffuse NHL. These results suggest that organic solvents may contribute to the causation of NHL, especially among young individuals, and that synergism may play a role in the process of lymphomagenesis.

Epidemiology of organic solvents and connective tissue disease

Case reports suggest that solvents are associated with various connective tissue diseases (systemic sclerosis, scleroderma, undifferentiated connective tissue disease, systemic lupus erythematosis, and rheumatoid arthritis), particularly systemic sclerosis. A small number of epidemiological studies have shown statistically significant but weak associations between solvent exposure, systemic sclerosis, and undifferentiated connective tissue disease. However, the interpretation of these positive findings is tempered by a lack of replication, an inability to specify which solvents convey risk, and an absence of increasing risk with increasing exposure. Existing studies, on aggregate, do not show conclusively that solvents (either as a group of chemicals or individual chemicals) are causally associated with any connective tissue disease. Further investigations should be carried out to replicate the positive existing findings and to specify the solvents and circumstances of exposure that carry risk.

Hodgkin's disease, work, and the environment. A review

Hodgkin's disease (HD), a lymphoma with an annual incidence in the United States of approximately 7500 cases, primarily affects the lymph nodes, spleen, and liver. The point of this article is to critically review the literature regarding the purported relationships between HD, certain occupations, and exposure to chemical agents. Attention will also be focused on recent advances in molecular genetics in the etiology of this ailment. A MEDLINE search was conducted to assess case-control and mortality evaluations that investigated links between HD and certain occupations and exposure to designated hazards. A review of citations in the Silver Platter Occupational and Environmental Medicine CD-ROM database was also conducted to ensure that all pertinent reports were obtained. Of the industries evaluated, woodworking showed the most consistent link between an increased risk of HD (relative risk, 1.8 to 7.2), but not all studies conducted showed positive associations. Although certain chemicals (ie, chlorophenols, pesticides) were reported as risks, no chemical was consistently and unambiguously linked with HD. Recent investigative work, however, points to a major etiological role for the Epstein-Barr virus (EBV), genetic fragments of which have been noted in Reed-Sternberg cells, the classic malignant cells of HD. The occupation most consistently associated with HD appears to be woodworking, although no specific chemical has been consistently linked with this lymphoma. The most persuasive evidence regarding the cause of HD arises from recent studies, including epidemiological, clinical, and genetic studies, that point to a major role by the EBV.

Non-Hodgkin's lymphoma risk derived from exposure to organic solvents: a review of epidemiologic studies

The rate of non-Hodgkin's lymphomas (NHL) has increased around the world during the last decades. Apart from the role of the human immunodeficiency virus (HIV) infection in the development of NHL, exposure to chemical agents like phenoxyacetic pesticides, hair dyes, metal fumes and organic solvents are suspected to be involved. The present review evaluates the results of studies that directly or indirectly searched for an association between solvent exposure and NHL. The selected studies comprised those published from 1979 to 1997, designed to investigate risk factors for NHL, whether specifically looking for solvent exposure or for general risks in which solvent exposure could be included. In 25 of the 45 reviewed studies (55.5%), fifty-four statistically significant associations between NHL and solvent exposure related occupations or industries were reported. Statistical significance was more frequently shown in studies where solvent exposure was more accurately defined. In eighteen of such studies, 13 (72.2%) defined or suggested organic solvents as possible risk factors for NHL.

Benzene--a review of the literature from a health effects perspective

A literature review of the impact on human health of exposure to benzene was conducted. Special emphasis in this report is given to the health effects reported in excess of national norms by participants in the Benzene Subregistry of the National Exposure Registry--people having documented exposure to benzene through the use of benzene-contaminated water for domestic purposes. The health effects reported in excess (p < or = .01) by some or all of the sex and age groups studied were diabetes, kidney disease, respiratory allergies, skin rashes, and urinary tract disorders; anemia was also increased for females, but not significantly so.

Multiple myeloma and benzene exposure in a multinational cohort of more than 250,000 petroleum workers

Case reports have suggested an association between benzene exposure and multiple myeloma. Because petroleum workers are exposed to benzene or benzene-containing liquids, studies of these workers provide an opportunity for investigating the relationship between benzene and multiple myeloma. A large number of cohort studies of petroleum workers have been conducted. However, few of them have reported results of multiple myeloma separately. One reason is that multiple myeloma is usually grouped with other lymphopoietic cancers in the analysis. Another reason is that multiple myeloma is relatively rare, and few individual studies are large enough to provide reliable risk estimates. To determine the risk of multiple myeloma in petroleum (refinery, distribution, production, and pipeline) workers, we have identified 22 cohort mortality studies of petroleum workers in the United States, the United Kingdom, Canada, and Australia. Authors of these studies were contacted, and data on the number of observed deaths and age-specific person-years of observation were requested. Data from individual studies were combined in a pooled analysis (meta-analysis). In addition to the pooled analyses, results for individual cohorts, most of which have never been reported before, are also presented. The combined multinational cohort consisted of more than 250,000 petroleum workers, and the observation period covered an interval of 55 years from 1937 to 1991. A total of 205 deaths from multiple myeloma were observed, compared to 220.93 expected, a total derived from respective national mortality rates. The corresponding standardized mortality ratio (SMR) was 0.93 and the 95% confidence interval (95% CI) was 0.81-1.07. Additional analyses were performed by type of facility and industrial process. Stratum-specific SMRs (95% CIs) were 0.92 (0.77-1.09) for refinery workers and 0.93 (0.69-1.23) for distribution workers. When individual cohorts were stratified by length of observation, no pattern was detected. The pooled analysis indicates that petroleum workers are not at an increased risk of multiple myeloma as a result of their exposure to benzene, benzene-containing liquids, or other petroleum products in their work environment. This conclusion is supported by cohort studies of workers in other industries who were exposed to benzene as well as by population-based case-control studies of multiple myeloma and occupational exposures.

A 50-year mortality follow-up of a large cohort of oil refinery workers in Texas

To investigate further the possible role of occupational exposures on mortality, an update of a large Texas petroleum refinery cohort was undertaken. Between 1937 and 1987, 6799 deaths were identified among 17,844 employees. Relative to the general population of Texas, the overall standardized mortality ratio (SMR) showed a statistically significant deficit, as did nine other cause-of-death categories. Statistically significant mortality excesses were found for bone cancer (SMR = 207.8: 95% confidence interval [CI], 110.6 to 355.3), acute lymphocytic leukemia (ALL) (SMR = 259.6; 95% CI, 112.1 to 511.5), and benign/unspecified neoplasms (SMR = 194.9; 95% CI, 129.5 to 281.7). However, none of these diseases demonstrated an exposure-response relationship with length of employment. Subcohort mortality analyses by sex and race groups, length of employment, interval since hire, period of hire, and pay status were also performed. Overall, the update findings do not indicate that any excess mortality occurred as a result of employment at the refinery.

Excess cancer mortality among children and adolescents in residential districts polluted by petrochemical manufacturing plants in Taiwan

We have collected data on the cancer deaths of children and adolescents 0-19 yr old living in a residential area near 3 large petroleum and petrochemical complexes in and near Kaohsiung city (petrochemical industrial districts, PIDs) in the period of 1971-1990 and compared these with the cancer deaths of children and adolescents 0-19 yr old among the entire population of Taiwan (national reference) and among the residents of 26 administrative districts, comprising all of Kaohsiung city and Kaohsiung county (local reference), except for 8 sparsely populated, rural districts. Having scrutinized all cancer death certificates, we have identified various statistically significant excess deaths, as compared with the national and local reference, due to cancers at all sites. Cancer of the bone, brain, and bladder in boys and girls 0-9 yr and 10-19 yr of age in the 1981-1990 decade that followed the establishment of petrochemical production in the PIDs was studied. However, excess cancer deaths seemed to have clustered in the 10-19 yr age group, who had been potentially exposed to the petrochemical pollutants for the longest period of time from the youngest age. Almost all bone, brain, and bladder cancer deaths registered were within 3 km of the 3 complexes. Bone and brain cancers in particular occurred in girls in the PIDs more frequently than in boys, even though these are believed to occur more in males than females elsewhere.

Cancer mortality in workers employed at a transformer manufacturing plant

This study examined mortality to December 31, 1989 in a cohort of 2,222 males employed between 1947 and 1975 at a transformer manufacturing plant in Canada, where there had been extensive use of transformer fluid, some containing polychlorinated biphenyls (PCBs). A combined cohort list of 2,222 names was independently obtained from plant management and union officials. Mortality of 1,939 workers with known birthdates was ascertained by record linkage with the Canadian Mortality Data-base. Standardized mortality ratios (SMRs) for different criteria for acceptance of the death certificate link and for cohort membership (based on work history) ranged from .71-1.05. There was no significant increase in overall cancer deaths. The only significant site-specific increased mortality was pancreatic cancer (11 deaths), with SMRs ranging from 2.92-7.64 and higher mortality risk in those who entered the cohort prior to 1960. All but one of these deaths had a latency period of at least 10 years, and greatest SMRs were found in departments with the greatest exposure to transformer fluid. Several previous studies have found excess pancreatic cancers in association with oil exposures and electrical equipment manufacturing. The need to further investigate pancreatic cancer in transformer manufacturing and related exposures is evident.

State of the science on the carcinogenicity of gasoline with particular reference to cohort mortality study results

As a result of the content of benzene in various streams of refinery products, including gasoline, it is not surprising that over the years studies and case reports have linked gasoline exposure to lymphopoietic cancers (LPC), particularly leukemia and multiple myeloma (MM). Of three recently conducted studies of gasoline-exposed workers, one shows strong associations with leukemia and MM, a second suggests some association with leukemia and did not analyze data for MM, and the third study is not possible to evaluate because of a major problem with study design. Other diseases of particular interest in relation to gasoline exposure are kidney cancer, malignant melanoma, and heart disease. One study suggests an association with kidney cancer, but the second study did not. There appears to be no association between employment in refineries or gasoline exposure and heart disease. However, evaluation of risk of kidney cancer and heart disease is somewhat difficult because investigators did not control for cigarette smoking, even though it is related to these diseases. This is of particular concern when studying gasoline-exposed workers, who because of the explosive nature of gasoline probably smoke less than the general population used for comparison of mortality. Some studies of refinery workers and gasoline-exposed workers in particular show an excess risk of death from malignant melanoma. Whether this latter association is the result of benzene/gasoline exposure, sunlight exposure, or a combination of the two cannot be determined with the data currently available.(ABSTRACT TRUNCATED AT 250 WORDS)

Kidney cancer and hydrocarbon exposures among petroleum refinery workers

To evaluate the hypothesis of increased kidney cancer risk after exposure to hydrocarbons, especially those present in gasoline, we conducted a case-control study in a cohort of approximately 100,000 male refinery workers from five petroleum companies. A review of 18,323 death certificates identified 102 kidney cancer cases, to each of whom four controls were matched by refinery location and decade of birth. Work histories, containing an average of 15.7 job assignments per subject, were found for 98% of the cases and 94% of the controls. To each job, industrial hygienists assigned semiquantitative ratings for the intensity and frequency of exposures to three hydrocarbon categories: nonaromatic liquid gasoline distillates, aromatic hydrocarbons, and the more volatile hydrocarbons. Ratings of "present" or "absent" were assigned for seven additional exposures: higher boiling hydrocarbons, polynuclear aromatic hydrocarbons, asbestos, chlorinated solvents, ionizing radiation, and lead. Each exposure had either no association or a weak association with kidney cancer. For the hydrocarbon category of principal a priori interest, the nonaromatic liquid gasoline distillates, the estimated relative risk (RR) for any exposure above refinery background was 1.0 (95% confidence interval [CI] 0.5-1.9). Analyses of cumulative exposures and of exposures in varying time periods before kidney cancer occurrence also produced null or near-null results. In an analysis of the longest job held by each subject (average duration 9.2 years or 40% of the refinery work history), three groups appeared to be at increased risk: laborers (RR = 1.9, 95% CI 1.0-3.9); workers in receipt, storage, and movements (RR = 2.5, 95% CI 0.9-6.6); and unit cleaners (RR = 2.3, 95% CI 0.5-9.9).

Further follow up of mortality in a United Kingdom oil refinery cohort

The results of an extension of follow up (1976 to 1989) of a cohort of workers employed for at least one year between 1 January 1950 and 31 December 1975 at eight oil refineries in Britain are reported. Over 99% of the workers were successfully traced to determine their vital status at 31 December 1989. The mortality observed was compared with that expected from the death rates of all the male population of England and Wales and Scotland. The mortality from all causes of death for the total study population was lower than that of the comparison population, and reduced mortality was also found for many of the major non-malignant causes of death. Raised mortality patterns were found for diseases of the arteries, in particular aortic aneurysm, and accidental fire and explosion, for the total study population, and across several refineries and other subgroups. Mortality from all neoplasms was lower than expected overall, largely due to a deficit of deaths from malignant neoplasm of the lung. Raised mortality from all neoplasms was found for labourers and in particular for malignant neoplasms of the oesophagus, stomach, and lung, although the mortality was also high for all men in this social class in the national population. Regional variations may have accounted for some of the high mortality. There were other raised mortality patterns in malignant neoplasms of the intestine, rectum, larynx, and prostate but these tended to be isolated and not consistent across refineries and other subgroups. As in the earlier follow up there was raised mortality from melanoma in several job groups.

Cancer risks related to electricity production

The International Agency for Research on Cancer has previously evaluated the cancer risks associated with fossil fuel-based industrial processes such as coal gastification and coke production, substances and mixtures such as coal tars, coal tar pitch and mineral oils, and a number of substances emitted from fossil-fuelled plants such as benzo[a]pyrene and other polycyclic aromatic hydrocarbons, arsenic, beryllium, cadmium, chromium, nickel, lead and formaldehyde. Based on these evaluations and other evidence from the literature, the carcinogenic risks to the general population and occupational groups from the fossil fuel cycle, the nuclear fuel cycle and renewable cycles are reviewed. Cancer risks from waste disposal, accidents and misuses, and electricity distribution are also considered. No cycle appears to be totally free from cancer risk, but the quantification of the effects of such exposures (in particular of those involving potential exposure to large amounts of carcinogens, such as coal, oil and nuclear) requires the application of methods which are subject to considerable margins of error. Uncertainties due to inadequate data and unconfirmed assumptions are discussed. Cancer risks related to the operation of renewable energy sources are negligible, although there may be some risks from construction of such installations. The elements of knowledge at our disposal do not encourage any attempt toward a quantitative comparative risk assessment. However, even in the absence of an accurate quantification of risk, qualitative indication of carcinogenic hazards should lead to preventive measures.

A retrospective cohort mortality study of blending and packaging workers of Mobil Corporation

This retrospective cohort mortality study examined 2,467 workers in lubrication products blending and packaging (B&P) operations at two refineries of Mobil Corporation between January 1, 1945 and December 31, 1978. Ninety-seven percent were male. Compared with U.S. males, there were significantly fewer deaths observed among males due to all causes, external causes, and diseases of the circulatory, respiratory, digestive, and genitourinary systems. Deaths observed from all cancer were fewer than expected, although not statistically significant. No statistically significant excess cause-specific mortality occurred at B&P facilities combined or separately. Nonsignificant increases in mortality were observed for cancers of the stomach, large intestine, prostate, the category of "other lymphatic tissue" cancer, and leukemia and aleukemia. Analyses demonstrated a statistically significant pattern of increasing SMR with employment duration for "other lymphatic tissue" cancer. Within the highest cumulative duration of employment category, the excess was confined to workers after 30 or more years since first employment. Although the interpretation of cancer mortality patterns is limited due to small numbers of deaths, the absence of associations with specific B&P departments is evidence against a causal interpretation.

Mortality patterns among petroleum refinery and chemical plant workers

A historical cohort study was conducted to evaluate the mortality experience of 6,831 employees of the Shell Oil Company, Deer Park, Texas, petroleum refinery and chemical plant with emphasis on cancer mortality. Subjects were all workers with potential plant exposure who were employed for at least 3 months during 1948-72. Vital status was determined as of 12/31/83 for 98% of the cohort and death certificates were obtained for 95.4% of 1,180 observed deaths. The statistical analyses excluded 159 female study members. For all causes of death combined, all cancers combined, and for most of the nonmalignant disease categories examined, there were deficits in mortality among refinery workers, chemical plant workers, and workers with experience in both areas. These deficits were generally most pronounced for chemical plant workers. An analysis of specific cancer sites revealed patterns of increased risk suggestive of a possible relationship between occupational exposures in the refinery and lympho-reticulosarcoma. Patterns of increased risk were also observed among chemical plant workers for a category of lymphopoietic tissue cancers, including multiple myeloma, myelofibrosis, polycythemia vera, and certain non-Hodgkin's lymphomas. Some very limited evidence of a possible workplace association was also found among refinery workers for leukemia and cancers of the central nervous system and biliary passages/liver. No evidence was found of an increased risk for cancer of the respiratory system or stomach or for malignant melanoma. A work history review of all suspect cancer excesses failed to identify any common work areas, job assignments, or exposure potentials, although the lack of detailed data on specific chemical exposures precluded accurate assessments of exposure-response.

Astrocytoma risk related to job exposure to electric and magnetic fields

To investigate the association between occupational exposure to low-frequency electric and magnetic (EM) fields and risk of brain tumors, a study was performed in Los Angeles County on 272 male adults with primary intracranial gliomas or meningiomas and 272 neighborhood controls. Complete occupational histories were collected. Risk associated with employment for more than 10 years in jobs that are presumed to entail exposure to EM fields was computed for various histological groupings. A nonsignificantly elevated risk of 1.7 was found for gliomas (all types pooled: 95% confidence interval 0.7-4.4), and a nonsignificantly reduced risk of 0.3 (95% confidence interval 0.03-3.2) was found for meningiomas. For astrocytomas, which form a subtype of the gliomas, a significantly elevated risk of 10.3 (95% confidence interval 1.3-80.8) was found; a significant upward trend (P = .01) of tumor incidence with increasing length of employment was observed. Most astrocytoma patients who worked in occupations involving exposure to EM fields were electricians or electrical engineers.

Are non-whites at greater risk for occupational cancer?

All occupational cancer epidemiology articles that reported data on non-whites from four major journals were identified for the years 1984-1987. In addition to these 14 papers, four more papers were identified from computer searches, and another 13 were found by following up references from the original 14. Within these 31 papers, there were 36 analyzable cohorts (subgroups by job and sex). Five cohorts had elevated all-cancer mortality ratios in non-whites without an increase in whites. Sixteen cohorts showed elevated ratios in both racial groups, with 11 of the 16 having a higher non-white cancer mortality ratio than white cancer mortality ratio. For the 25 studies in which at least one racial group's cancer ratio was elevated, the non-white ratio exceeded the white ratio in 17 (68%). The overall paucity of articles on non-white cancer mortality, as well as the apparent trend toward increased occupational cancer mortality in non-whites, is discussed.

Process chemicals in the oil and gas industry: potential occupational hazards

Numerous chemicals are used in various processes of the oil and gas industry: drilling, cementing, completion, stimulation, and production. The number and the complexity of composition of process chemicals has increased greatly over the last three decades. The occupational hazards of exposure to these agents has received little attention. We reviewed the various processes in the industry, the type of chemicals used in each process, and some of their characteristics. We placed emphasis on those for which significant toxicity has been established or is suspected, and those for which there is incomplete information on their chemistry and health hazards. This report is intended to form a basis for a more complete survey of the process chemicals, and to draw attention to the possibilities for toxic exposure resulting from use of these agents in the oil and gas industry. The ultimate objective is to promote the safe use of these agents in the industry.

Mortality study of cancer risk among oil refinery workers

The mortality experience of 1595 male workers employed in one of the largest Italian refineries in the period from 1949-1982 was examined. From the comparison with national and local death rates, increases in mortality owing to lung and kidney cancers, brain tumors, and leukemias emerged. No definite trends according to duration of exposure and years since first exposure were apparent. The increases regarding cancer of the lung, kidney and brain appeared to be associated with the early period of operations. Analysis by exposure category suggested an association of the increased mortality from leukemias with working in production (observed = 2; expected = 0.61). Kidney cancer mortality was elevated among maintenance workers (obs. = 2; exp. = 0.18). Small numbers prevented firmer conclusions. Workers in the moving department had a significantly increased mortality from all cancers (obs. = 22; exp. = 11.7), and lung cancer (obs. = 11; exp. = 3.6). Confounding by smoking could be excluded as sufficient explanation of the three-fold increase in lung cancer deaths. It was in moving that highest airborne levels of polynuclear aromatic hydrocarbons had been discovered in an independent environmental investigation.

Primary liver cancer death and occupation in Texas

A death certificate case-control study of primary liver cancer and occupation was conducted to determine if the high risk of liver cancer in Mexican-Americans can be explained by farmworker exposures to pesticides. The association of liver cancer with the petroleum and chemical industry and with other potentially high-risk occupations was also examined. For the years 1969 to 1980, 1,742 deaths from primary liver cancer were identified for Texas males. Controls were randomly selected from other causes of deaths among males excluding all neoplasms, liver and gallbladder diseases, infectious hepatitis, and alcoholism, and were frequency matched to cases by age, race, ethnicity, and year of death. Risk for farmworkers based on age, race, and ethnicity-adjusted odds ratios (ORs) was not excessive (OR = 1.4, 95% confidence limits [C.L.] 0.8-2.2) but was larger than the risk for farmers (OR = 1.0, 95% C.L. 0.8-1.2). Excess risk in the petroleum and chemical manufacturing industries was confined to oil refinery workers (OR = 2.0, 95% C.L. 1.1-3.5). Other occupations with twofold risk or greater were plumbers and pipefitters (OR = 2.0, 95% C.L. 1.0-3.8), butchers and meat cutters (OR = 2.6, 95% C.L. 1.1-6.6), textile workers (OR = 3.1, 95% C.L. 1.2-7.8), cooks (OR = 2.2, 95% C.L. 1.1-4.5), and longshoremen (OR = 2.2, 95% C.L. 0.6-7.4).

Critical review of cancer epidemiology in petroleum industry employees, with a quantitative meta-analysis by cancer site

A critical review of close to 100 published and unpublished but otherwise available epidemiologic reports of petroleum industry employees from the United States, United Kingdom, Canada, Europe, Australia, and Japan was conducted. Analyses by duration of employment and latency are discussed, and summary standardized mortality ratios (SMRs) or meta-SMRs are developed for selected cancer sites. Findings indicate that the industry experienced a significantly lower cancer mortality than the general population for all cancer sites combined, digestive system, stomach, and lung. For the industry as a whole, SMRs similar to the general population were observed for skin, brain, pancreatic, prostatic, and kidney cancers. However, some data indicate that certain small groups within the industry might have elevated prostatic and kidney cancer risk. This review supports the conclusion that some refinery employees, particularly those employed before the 1940s, may have been at increased risk of leukemia. There is some indication that cancer of other lymphatic tissue may also be elevated. Unresolved issues affecting these conclusions are discussed, and specific directions for future research are offered.

Chemical exposures and central nervous system cancers: a case-control study among workers at two nuclear facilities

In a nested case-control study of workers employed between 1943 and 1977 at two nuclear facilities, we evaluated the possible association of primary CNS cancers with occupational exposure to chemicals. Seventy-two white male and 17 white female workers who, according to the information on death certificates, died of primary CNS cancers were identified as cases. For each case, four controls were matched on race, sex, facility at which initially employed (cohort), year of birth, and year of hire. Each job title/department combination was subjectively evaluated for potential exposure to each of 26 chemicals or chemical groups. Statistically significant associations were not found between CNS cancer deaths and any of the 26 chemicals. An increased risk of CNS cancer occurrence was observed among subjects employed for more than 20 yr (OR = 7.0, 95% CI = 1.2,41.1, cases = 9).

Occupational hydrocarbon exposure and renal histopathology

A blinded, retrospective study of histological sections from ten hydrocarbon-exposed and twenty unexposed nephrectomized renal cell carcinoma cases was conducted to evaluate the histopathologic features present in the apparently normal kidney parenchyma removed with the tumor. Tissue sections from each of the thirty cases were independently reviewed by three consulting pathologists and scored using well defined criteria. Occupational hydrocarbon exposure indices were developed by a team of industrial hygienists and applied to the detailed occupational history of each exposed case. A positive correlation was observed between age and the total renal pathology score (rs = .40, p less than .03). No correlation was found between indices of occupational hydrocarbon exposure and renal pathology scores among exposed cases. No significant differences in renal pathology scores were noted when exposed cases were matched to unexposed cases by age, sex, and race. These results are limited by the inclusion of only cases with historical hydrocarbon exposures. It is recommended that a follow-up study be conducted, utilizing sensitive quantitative methods, to define what, if any, cytopathologic renal effects occur in conjunction with current occupational exposures to hydrocarbons.

An industry wide mortality study of chemical workers occupationally exposed to benzene. I. General results

The cohort (7676) of this historical prospective study consisted of a group of male chemical workers from seven plants who had been occupationally exposed (continuously or intermittently) to benzene for at least six months and a comparison group of male chemical workers from the same plants who had been employed for at least six months during the same period but were never occupationally exposed to benzene. The observed mortality of the cohort, by cause, was compared with the expected based on the US mortality rates, standardised for age, race, sex, and calendar time. Standardised mortality ratios (SMRs) from all lymphatic and haematopoietic (lymphopoietic) cancer combined, leukaemia, non-Hodgkin's lymphoma (lymphosarcoma, reticulosarcoma, and other lymphoma), and non-Hodgkin's lymphopoietic cancer (non-Hodgkin's lymphoma and leukaemia) for the exposed group were slightly, but not significantly, raised above the national norm. These SMRs were considerably higher than those in the comparison group. When the group with no occupational exposure was used for direct comparison, the continuously exposed group experienced a relative risk from lymphopoietic cancer of 3.20 (p less than 0.05). Furthermore, the Mantel-Haenszel chi-square showed that the association between continuous exposure to benzene and leukaemia was statistically significant (p less than 0.05).

Texaco mortality study: III. A cohort study of producing and pipeline workers

While there have been numerous epidemiology studies of refinery workers, no studies have been done on producing and pipeline workers. This is a retrospective follow-up study of all persons who were employed for at least 6 months at a Texaco producing or pipeline location and who worked at some time during the period 1946-1980. Of the 11,098 white men in the cohort, 8,964 were alive, 1,886 were known to be dead, and the vital status of the remaining 248 as of December 31, 1980 was unknown. The standardized mortality ratio (SMR) of 63 for all causes was significantly low, on the basis of 2,976 expected deaths. Statistically significant deficits also were seen for all major causes of death. Mortality patterns were also examined for the major job categories in these departments. Similar patterns of mortality were seen, although there was a significant excess of thyroid cancer in those employed as pumper-gaugers. However, it was based on only four cases.

Health experience of workers in the petroleum manufacturing and distribution industry: a review of the literature

A review of 120 papers on the health effects on workers in the petroleum manufacturing and distribution industry revealed inconsistent results. This may be due in part to the variable quality of the epidemiological studies. There is, however, the consistent finding of a deficit for "all causes mortality" and for "all cancers mortality," thus implying that a widespread serious health effect of gasoline exposure seems remote. For specific health effects, the possibility exists that occupational etiological factors may play a part in the pathogenesis of brain cancer and renal disease. The evidence for a link between occupational and other health effects is weak. Further work of better quality is necessary to investigate those diseases in which there remains a suspicion of an occupational etiology.

A survey of cancer and occupation in young and middle aged men. II. Non-respiratory cancers

In a search for clues to previously unrecognised industrial carcinogens the occupational and smoking histories of young and middle aged men with different types of cancer have been compared. The study population comprised men aged 18-54 and resident in the counties of Cleveland, Humberside, and Cheshire (including the Wirral). Within this population 2942 patients in whom cancers were first diagnosed during the period 1975-80 were identified retrospectively from hospital and cancer registration records. Lifetime occupational and smoking histories were then sought from these subjects (or if they had died by proxy from their next of kin), using a postal questionnaire. The overall response rate was 52.1%. Analysis of limited occupational data obtained from the hospital notes of 89% of the patients suggests that no serious bias arose from the incomplete response to the questionnaire. The present paper describes the findings for non-respiratory cancers. Some tumours did not occur with sufficient frequency to warrant formal statistical analysis. Nevertheless, examination of the histories of patients with these cancers showed several interesting occupational clusters. In particular, five out of 29 patients with acute myeloid leukaemia had worked in electrical trades. The more common cancers were studied by statistical techniques. A large number of possible occupational associations were examined, and some will probably have achieved conventional levels of statistical significance by chance. The results should therefore be interpreted with caution, taking into account evidence from other studies and the biological plausibility of suggested hazards. Among the more interesting findings were an excess of bladder cancer in lorry drivers (RR=1.6, CI 1.0-2.4) and in men employed in the manufacture of vegetable and animal oils and fats (RR = 4.8, CI 1.8-12.9).

Long-term mortality study of oil refinery workers: V. Comparison of workers hired before, during, and after World War II (1940-1945) with a discussion of the impact of study designs on cohort results

The mortality experience of a large refinery cohort (1937-1978) was examined by dividing it into three subcohorts according to hire dates: those hired before 1940, those hired during the period 1940-1945, and those hired after 1945. These three periods are approximately equivalent to before, during, and after World War II and span a total hiring period of more than 75 years. The results showed that a substantial portion of the cohort (3,330 or 27%) had been recruited during 1940-1945, and they contributed 980 or 28% of the total deaths. However, their mortality experience was quite different from the rest. A series of significant increases were seen among the external causes for accidents, suicide, and homicide. In terms of overall mortality and in contrast to the rest of the cohort, no "healthy worker effect" was seen (SMR = 1.00). They also showed increases in several types of cancer including cancers of the pancreas and prostate and leukemia. These unusual experiences cannot be explained either on the basis of their war-related deaths or on their period of employment (one-half were terminated within 1 year from date of hire), and data is insufficient to separate the role of hiring practices or their socioeconomic status. However, their life-styles were probably quite different judged from the fact that alcoholism-related deaths were increased as much as fivefold. Almost two-thirds of the total deaths occurred among 4,080 workers in the before 1940 subcohort. Further, the 5,117 workers of the after-1945 subcohort contributed only 5% of the total deaths. Thus, the results of the original refinery cohort (1937-1978) primarily reflect the experience of those employees hired before 1940. Given the same cohort method (historical prospective), cohort results vary widely according to different study designs, and this has implications for "generalizable" risk assessment or risk projections. A prospective study of new hires with 30 years of follow-up is rather inefficient because it would yield only a small number of deaths, with a strong healthy worker effect. The same is true for studies based on active workers with a short period of follow-up. Studies based on time of hire, however, provide a means for controlling time-related occupational exposures.

Occupational liver injury. Present state of knowledge and future perspective

Epidemiological studies have mapped the occurrence of hepatitis B among health personnel with the use of specific serologic markers and thereby made rational preventive precautions possible. Follow-up studies have demonstrated the effect of this prevention, and the newly developed hepatitis B vaccine has further improved the possibilities for effective prophylaxis against occupational hepatitis B. On the other hand, there is the chemically induced occupational liver damage. Only a few of the thousands of industrially used chemicals have been sufficiently investigated for hepatotoxicity and the list of suspected and confirmed hepatotoxic agents is still growing. The worrisome example of vinylchloride-induced serious liver disease among PVC-workers, revealed after 42 years of industrial use by alert clinicians, calls for intensified activities in the field of occupational hepatotoxicity. However, the clinical, biochemical, and morphological features of liver disease are often vague and unspecific. A non-invasive, convenient quantitative liver function test is needed. Circumstantial evidence and a few epidemiological studies suggest that part of the so-called cryptogenic liver diseases, such as liver cirrhosis, may be caused by occupational exposure to chemicals. This should be further studies. Animal experiments have shown that one chemical agent may potentiate the hepatotoxic effect of another chemical agent. This should be the subject of investigations in the work environment, where exposure to various chemicals is the rule rather than the exception. Alcohol consumption may also interfere with the hepatotoxicity of occupationally used chemicals.

Benzene exposure in the United States 1978-1983: an overview

Due to the interest in reducing the benzene exposure limit from 10 to 1 ppm, the benzene exposure data collected since 1977 were compiled and evaluated. Some 38,000 data points representing either time-weighted air samples or persons exposed were collected from five industries which produce and/or use benzene and two government organizations. Of the reported data, 87% represented exposure levels of 1.0 ppm or less. Petroleum and chemical operations where elevated exposure levels were reported included petrochemical and bulk loading operations. Benzol and by-product plants in the iron and steel industry showed similar elevated results.

Occupational exposure and brain tumors

Epidemiological evidence of an occupational risk of brain cancer has been reported in four industries where chemical exposures are likely, most recently in a series of prospective studies in the petrochemical industry. However, only in the case of vinyl chloride exposure has an occupational central nervous system carcinogen been identified. This report reviews the convergence of epidemiological and laboratory evidence that established the occupational carcinogenicity of vinyl chloride, and discusses in detail the current evidence for an occupational risk of brain tumors in the petrochemical industry.

"Health Watch": the Australian petroleum industry health study surveillance programme

A surveillance system, capable of linking experience in specific jobs with certain health outcomes, has been established within the Australian petroleum industry. A defined population of 11 596 employees has been assembled, after personal interviews. Events recorded are death and its cause, and diagnosis of cancer. Members of the study population are followed up after leaving the industry. By the end of 1983, 33 deaths had occurred, fewer than would be expected from the prevailing rates in the general Australian population. With progressive accumulation of follow-up data, questions of greater complexity will be addressed.