The relationship between low-level benzene exposure and leukemia in Canadian petroleum distribution workers.

This study was conducted to evaluate the relationship between leukemia occurrence and long-term, low-level benzene exposures in petroleum distribution workers. Fourteen cases were identified among a previously studied cohort [Schnatter et al., Environ Health Perspect 101 (Suppl 6):85-89 (1993)]. Four controls per case were selected from the same cohort, controlling for birth year and time at risk. Industrial hygienists estimated workplace exposures for benzene, without knowledge of case-control status. Average benzene concentrations ranged from 0.01 to 6.2 ppm. Company medical records were used to abstract information on other potential confounders such as cigarette smoking. Odds ratios were calculated for several exposure metrics. Conditional logistic regression modeling was used to control for potential confounders. The risk of leukemia was not associated with increasing cumulative exposure to benzene for these exposure levels. Duration of benzene exposure was more closely associated with leukemia risk than other exposure metrics, although results were not statistically significant. A family history of cancer and cigarette smoking were the two strongest risk factors for leukemia, with cumulative benzene exposure showing no additional risk when considered in the same models. This study is consistent with other data in that it was unable to demonstrate a relationship between leukemia and long-term, low-level benzene exposures. The power of the study was limited. Thus, further study on benzene exposures in this concentration range are warranted.

Influence of parental and biological factors on the male birth fraction in the United States: an analysis of birth certificate data from 1964 through 1988.

OBJECTIVE: To determine the role of parental and biological factors on the U.S. male birth fraction from 1964 through 1988. DESIGN: Logistic regression on annual U.S. male births by race group. SETTING: Population-based data. PATIENT(S): Live births in the United States 1964 through 1988. INTERVENTION(S): None. MAIN OUTCOME MEASURE(S): Annual U.S. male birth fraction by parental and biological factors. RESULT(S): During the study period, the annual U. S. male birth fraction showed changes based on race group, parental age, and low birth weight. The overall influence of parental age on the U.S. male birth fraction is strong and is stronger in nonwhites than in whites. The U.S. male birth fraction is also strongly influenced by the percentage of low birth weight infants in nonwhites, but not in whites. The male birth fraction declines with increasing age of either parent and with an increase in the percentage of low birth weight infants. CONCLUSION(S): The relative magnitude of influences on the U.S. male birth fraction depend on the race group, which may be a reflection of the range of observed data rather than biological differences. The developed models have reasonable predictive power and are an appropriate first step in understanding the factors influencing the male birth fraction. These types of parental and biological variables should be included in models before examining other exogenous and population level variables.

Mortality experience of a young petrochemical industry cohort. 1979-1992 follow-up study of US-based employees.

This retrospective study examines the mortality patterns of a relatively young cohort of 81,746 former and current petrochemical company employees. Standardized mortality ratios (SMR) for 1979 through 1992 are generally from about unity to well below unity for major causes and numerous specific causes of death studied by gender/race/job subgroups. Findings of note include a SMR (based on incidence rates) of 1.94 (95% confidence interval [CI], 1.04 to 3.33) for mesothelioma, and a SMR of 1.81 (95% CI, 0.90 to 3.24) for chronic lymphocytic leukemia, both among males hired before 1960. All male semiskilled operatives have a 1.6-fold increase (95% CI, 1.07 to 2.29) in motor vehicle accident deaths, with declining rates since the mid-1980s. The overall SMR for acquired immunodeficiency syndrome (AIDS) is at unity (69 deaths), with excesses in technician and office worker subgroups. Four decedents with lymphoma (code 202.8 in 9th revision ICD) had AIDS as a secondary cause of death, suggesting the need to examine secondary causes when studying lymphopoietic conditions. This routine surveillance activity provides leads regarding the presence or absence of excess mortality risk.

A framework for addressing health issues in or near a manufacturing facility.

Clustering of health events in or around industrial facilities sometimes leads to worker and community concerns that plant management or local health professionals must address. We provide an eight-step process to deal with these concerns systematically. We emphasize the use of good scientific practices with managerial oversight for effective worker and community communication. This process is directed to plant management and the local health professional and emphasizes the practical aspects of the investigation.

Characteristics of participants and nonparticipants in worksite health promotion.

PURPOSE: To identify demographic characteristics associated with worksite health promotion participation and to determine whether employees with high-risk health-related behaviors, as measured by a health risk appraisal, were participating in programs designed to address these behaviors. DESIGN: Descriptive. SETTING: A petrochemical research and development company where employees were offered a health risk appraisal questionnaire, a series of on-site wellness programs, and an on-site fitness center. SUBJECTS: All employees (n = 2290) working continuously from May 1, 1990, through February 28, 1992. MEASURES: Demographic and behavioral risk characteristics of participants and nonparticipants. RESULTS: Participation was 37% (health risk appraisal), 64% (all wellness programs), and 10% (fitness center), with women participating at higher rates than men in all programs. Most programs attracted 10% to 40% of the employees at risk for the particular behavior addressed by the program, although lower penetration (7% to 9%) was observed for the on-site fitness center and blood pressure education programs. With the exception of wellness programs for weight, smoking, and blood pressure, employees at lower behavioral risk tended to be more likely to participate than employees at high risk. CONCLUSIONS: Efforts to increase participation by all company employees, especially among those with high-risk behaviors, would benefit all health promotion programs, particularly the on-site fitness center.

Lymphohaematopoietic malignancies and quantitative estimates of exposure to benzene in Canadian petroleum distribution workers.

OBJECTIVE: To evaluate the relation between mortality from lymphohaematopoietic cancer and long term, low level exposures to benzene among male petroleum distribution workers. METHODS: This nested case control study identified all fatal cases of lymphohaematopoietic cancer among a previously studied cohort. Of the 29 cases, 14 had leukaemia, seven multiple myeloma, and eight non-Hodgkin's lymphoma. A four to one matching ratio was used to select a stratified sample of controls from the same cohort, controlling for year of birth and time at risk. Industrial hygienists estimated workplace exposures for benzene and total hydrocarbons, without knowledge of case or control status, for combinations of job, location, and era represented in all work histories. Average daily benzene concentrations ranged from 0.01 to 6.2 parts per million (ppm) for all jobs. Company medical records were used to abstract information on other potential confounders such as cigarette smoking, although the data were incomplete. Odds ratios (ORs) were calculated with conditional logistic regression techniques for several exposure variables. RESULTS: Risks of leukaemia, non-Hodgkin's lymphoma, and multiple myeloma were not associated with increasing cumulative exposure to benzene or total hydrocarbons. For leukaemia, the logistic regression model predicted an OR of 1.002 (P < 0.77) for each ppm-y of exposure to benzene. Duration of exposure to benzene was more closely associated with risk of leukaemia than other exposure variables. It was not possible to completely control for other risk factors, although there was suggestive evidence that smoking and a family history of cancer may have played a part in the risk of leukaemia. CONCLUSION: This study did not show a relation between lymphohaematopoietic cancer and long term, low level exposures to benzene. The power of the study to detect low-such as twofold-risks was limited. Thus, further study on exposures to benzene in this concentration range are warranted.

Oral and pharyngeal cancer and occupation: a case-control study.

We studied the relation between occupation and oral and pharyngeal cancer with a population-based case-control study conducted in four areas of the United States. The study group included 1,114 incident male and female cases and 1,268 frequency-matched controls. After adjustment for age, race, smoking, alcohol, and study location, an analysis of lifetime occupational histories revealed a small number of noteworthy associations. Risk was increased among male carpet installers (23 cases, 4 controls), with an adjusted odds ratio of 7.7 [95% confidence interval (CI) = 2.4-24.9], and tended to rise with longer duration of employment. A decreased risk was found among male and female textile mill workers (odds ratio 0.48, 95% CI = 0.27-0.88). Previously reported increases in oral cancer risks among printing workers, electrical and electronics workers, and workers other than carpet installers who were possibly exposed to formaldehyde were not found in this study. For several employment groups, including male machinists, primary metal industry workers, petroleum industry workers, painters, furniture and fixture industry workers, woodworking machine operators, and workers with inferred exposure to fossil fuel combustion, odds ratios were approximately 2.0 for cancers of pharyngeal sites.

Incidence of lymphohaematopoietic malignancies in a petrochemical industry cohort: 1983-94 follow up.

OBJECTIVES: In response to a previous finding of increased mortality from lymphohaematopoietic (LH) malignancies, this study examines incidence of LH malignancy in a petrochemical industry cohort. Emphasis is on chronic lymphocytic leukaemia (CLL) and on comparisons by period of first employment. METHOD: The study cohort consists of 8942 employees who were active in the period 1970-92 and alive on 31 December 1982. Record linkage with the Louisiana tumour registry (LTR) provided information on cancer for cases occurring between 1983 and 1994. Standardised incidence ratios (SIR), with the south Louisiana population as a comparison, were computed for all cancers, all LH malignancies and specific LH subtypes. Analyses were conducted for sex and race categories, and by period of first employment, job type, duration of employment, and latency. RESULTS: 672 Cases of cancer were identified, including 59 LH malignancies. Women (n=1169) had an overall cancer SIR below unity and four LH malignancies versus 2.28 expected. Among the 7773 men, those first employed before 1950 had no overall cancer excess, a significant 1.4-fold increase in overall LH malignancies (43 observed versus 30.78 expected), and four CLL cases versus 3.27 expected. Findings for men first employed after 1950 are based on fewer cases, but there was no indication of excesses of overall cancer or LH malignancy. Numbers were too small in the group first employed after 1950 for meaningful analysis of LH malignancy subtypes such as CLL (one case). CONCLUSION: These findings do not suggest a continuing excess of CLL but do suggest a small increase in incidence of overall LH malignancy for workers first employed before 1950. This may reflect associations with earlier workplace conditions, although work related patterns are mixed. Interpretation is limited by the diverse group of diseases within LH malignancies, and the lack of control for non-work factors other than sex, age, race, and period of diagnosis. This study has a major advantage of more complete and reliable cancer ascertainment compared with the mortality investigation, and shows the feasibility and benefits of using cancer registry incidence data in an occupational cohort study.