Validity of exposure in one job as a surrogate for exposure in a cohort study

Low Dose Radiation and Solid Tumors Mortality Risk

BACKGROUND

US nuclear capable shipyard workers have increased potential for occupational radiation exposure.

OBJECTIVE

The aim of the study is to examine solid tumor mortality risks at low doses.

METHOD

437,937 workers working from 1957 to 2004 at eight US shipyards were studied.

RESULTS

Radiation workers with a median life-time dose at 0.82 mSv had a significantly lower solid tumor mortality risk (relative risk [RR]: 0.96, 95% confidence interval [CI]: 0.94-0.98) than nonradiation workers. Among 153,930 radiation workers, the RRs of solid tumors increased with increasing dose categories without statistical significance. The dose category >0-<25 mSv had significantly lower RR (0.95, 95% CI: 0.91-0.99) versus 0 dose and the excess relative risk was 0.05/100 mSv (95% CI: 0.01-0.08).

CONCLUSIONS

Solid tumor risk might increase with radiation dose, but not linearly at low doses. Actual mortality risk may be dependent on dose received.

Peak Inhalation Exposure Metrics Used in Occupational Epidemiologic and Exposure Studies

Peak exposures are of concern because they can potentially overwhelm normal defense mechanisms and induce adverse health effects. Metrics of peak exposure have been used in epidemiologic and exposure studies, but consensus is lacking on its definition. The relevant characteristics of peak exposure are dependent upon exposure patterns, biokinetics of exposure, and disease mechanisms. The objective of this review was to summarize the use of peak metrics in epidemiologic and exposure studies. A comprehensive search of Medline, Embase, Web of Science, and NIOSHTIC-2 databases was conducted using keywords related to peak exposures. The retrieved references were reviewed and selected for indexing if they included a peak metric and met additional criteria. Information on health outcomes and peak exposure metrics was extracted from each reference. A total of 1,215 epidemiologic or exposure references were identified, of which 182 were indexed and summarized. For the 72 epidemiologic studies, the health outcomes most frequently evaluated were: chronic respiratory effects, cancer and acute respiratory symptoms. Exposures were frequently assessed using task-based and full-shift time-integrated methods, qualitative methods, and real-time instruments. Peak exposure summary metrics included the presence or absence of a peak event, highest exposure intensity and frequency greater than a target. Peak metrics in the 110 exposure studies most frequently included highest exposure intensity, average short-duration intensity, and graphical presentation of the real-time data (plots). This review provides a framework for considering biologically relevant peak exposure metrics for epidemiologic and exposure studies to help inform risk assessment and exposure mitigation.

Concordance between current job and usual job in occupational and industry groupings: assessment of the 2010 national health interview survey

OBJECTIVE

To determine whether current job is a reasonable surrogate for usual job.

METHODS

Data from the 2010 National Health Interview Survey were utilized to determine concordance between current and usual jobs for workers employed within the past year. Concordance was quantitated by kappa values for both simple and detailed industry and occupational groups. Good agreement is considered to be present when kappa values exceed 60.

RESULTS

Overall kappa values ± standard errors were 74.5 ± 0.5 for simple industry, 72.4 ± 0.5 for detailed industry, 76.3 ± 0.4 for simple occupation, 73.7 ± 0.5 for detailed occupation, and 80.4 ± 0.6 for very broad occupational class. Sixty-five of 73 detailed industry groups and 78 of 81 detailed occupation groups evaluated had good agreement between current and usual jobs.

CONCLUSIONS

Current job can often serve as a reliable surrogate for usual job in epidemiologic studies.

Comparison of first, last, and longest-held jobs as surrogates for all jobs in estimating cumulative exposure in cross-sectional studies of work-related asthma

BACKGROUND

Previous occupational studies have used exposure in most recent job as a surrogate for all jobs or "total work history" exposure. This method may not be valid for diseases in which disability brought on by one job may influence later work history, such as asthma. We investigated different surrogates for total work history for the outcome of asthma symptoms.

METHODS

In a cross-sectional study, we quantitatively compared three exposure surrogates (last job, first job, and longest-held job) with the total cumulative work exposure (all jobs) in a cohort of 1778 aluminium industry workers. The chemical exposures we compared were total fluoride dust, inspirable dust, and sulfur dioxide with the respiratory symptoms of wheeze, chest tightness, and rhinitis.

RESULTS

When extrapolated over time, all surrogates quantitatively overestimated the gold standard "all jobs" for all three exposures investigated. For the symptom of wheeze, last job was found to be the worst surrogate for all jobs for the three exposure types investigated. Prevalence ratios for fluoride exposure and the symptom of occupational wheeze were last job 1.07 (95% confidence interval, 0.92-1.26), longest job 1.10 (0.94-1.30), first job 1.14 (0.97-1.35), and all jobs 1.27 (1.05-1.53).

CONCLUSIONS

Although last job has been found to be a satisfactory surrogate for all jobs in cancer studies, we do not recommend the use of this metric in studies of chronic diseases where development of disability may occur with early exposure. We found that both first job and longest job held were better metrics in studies where the adverse health effect may influence the job history of subject.

Longest Held Job in U.S. Occupational Groups: The National Health Interview Survey

OBJECTIVE

We sought to assess the validity of using current or most recent occupation as surrogate for longest-held job (and its exposures).

METHODS

The National Health Interview Survey (NHIS) is an annual, probability, cross-sectional U.S. population survey. The 1986 and 1988 NHIS occupational supplements provided information for more than 49,000 workers. Using Cohen's Kappa, concordance was assessed by occupational group and several subgroups.

RESULTS

Statistically significant results were observed for all occupational groups. More than 70% of 13 broad occupations had a Kappa of 50.0 or greater, with variable concordance by subpopulation. Among 206 occupational groups, there was more variability: Kappa ranged from 92.7 (dentists) to 9.2 (farm managers).

CONCLUSIONS

Moderate-to-high levels of agreement was observed in this large, representative sample of US workers. Therefore, current occupation can be used as a surrogate for longest-held job for many occupational subgroups.

Occupational Exposures and Salivary Gland Cancer Mortality Among African American and White Workers in the United States

We conducted a large death certificate-based case-control study to assess occupational risks for salivary gland cancer. African American (168 cases, 672 controls) and white (2237 cases, 8748 controls) cases from 24 states (1984-1989) were matched to controls by age, sex, race, and region. Race- and sex-stratified multiple logistic regression models calculated adjusted odds ratios. The proportion of young cases (<50 years) was greatest among African Americans (20.8% vs. 8.8%). Higher socioeconomic status, ionizing radiation, formaldehyde, solvents, outdoor work, and animal contact were associated with elevated risk among white men. Physical activity reduced mortality risks among men, although significantly only among whites. Odds ratios for formaldehyde, solvents, benzene, and animal contact were 2.0 or greater among African American women, although not statistically significant. These findings suggest occupational and demographic factors needing further investigation.

Formaldehyde and cancer morbidity among male employees in Denmark

Formaldehyde, a genotoxic and potent animal carcinogen, is widespread in the working environment as well as in private homes. The risk for cancer morbidity in Denmark during 1970-84 was estimated from standardized proportionate incidence ratios (SPIR) among men whose longest employment had been held since 1964, at least 10 years before diagnosis, in 265 companies in which exposure to formaldehyde was identified. The results do not support the hypothesis that formaldehyde is associated with lung cancer (SPIR = 1.0, 410 cases). Significantly elevated risks were found for cancers of the colon (SPIR = 1.2, 166 cases), kidney (SPIR = 1.3, 60 cases), and sino-nasal cavities (SPIR = 2.3, 13 cases). For sino-nasal cancer, a relative risk of 3.0 (95 percent confidence interval = 1.4-5.7) was found among blue-collar workers with no probable exposure to wood dust, the major confounder. This study provides further evidence that occupational exposure to formaldehyde increases the risk for sino-nasal cancer.