Linda D. Dell

Medical insurance claims associated with international business travel

OBJECTIVES: Preliminary investigations of whether 10,884 staff and consultants of the World Bank experience disease due to work related travel. Medical insurance claims filed by 4738 travellers during 1993 were compared with claims of non-travellers. METHODS: Specific diagnoses obtained from claims were analysed overall (one or more v no missions) and by frequency of international mission (1, 2-3, or > or = 4). Standardised rate of claims ratios (SSRs) for each diagnostic category were obtained by dividing the age adjusted rate of claims for travellers by the age adjusted rate of claims for non-travellers, and were calculated for men and women travellers separately. RESULTS: Overall, rates of insurance claims were 80% higher for men and 18% higher for women travellers than their non-travelling counterparts. Several associations with frequency of travel were found. SRRs for infectious disease were 1.28, 1.54, and 1.97 among men who had completed one, two or three, and four or more missions, and 1.16, 1.28, and 1.61, respectively, among women. The greatest excess related to travel was found for psychological disorders. For men SRRs were 2.11, 3.13, and 3.06 and for women, SRRs were 1.47, 1.96, and 2.59. CONCLUSIONS: International business travel may pose health risks beyond exposure to infectious diseases. Because travellers file medical claims at a greater rate than non-travellers, and for many categories of disease, the rate of claims increases with frequency of travel. The reasons for higher rates of claims among travellers are not well understood. Additional research on psychosocial factors, health practices, time zones crossed, and temporal relation between travel and onset of disease is planned.

Lung cancer mortality in the german chromate industry, 1958 to 1998

Objectives: We conducted a mortality study of two German chromate production facilities and evaluated possible dose-response relationships between hexavalent chromium exposure and lung cancer. Methods: Mortality was followed-up through 1998 and limited to those employed since each plant converted to a no-lime production process. More than 12,000 urinalysis results of chromium levels were available, as was smoking information. Results: All-cause mortality indicated a healthy worker effect (standardized mortality ratio [SMR] = 0.80, 95% confidence interval [CI] = 0.67–0.96); however, lung cancers appeared to be increased (SMR = 1.48, 95% CI = 0.93–2.25). No clear dose-response was found in stratified analyses by duration of employment and time since hire. On the basis of urinary chromium data, lung cancer risk was elevated only in the highest exposure group (SMR = 2.09, 95% CI = 1.08–3.65). Conclusions: These data suggest a possible threshold effect of occupational hexavalent chromium exposure on lung cancer.

A cohort mortality study of employees in the U.S. carbon black industry.

Objectives: The objectives of this study are to evaluate historical mortality patterns, especially due to cancers, among employees of the U.S. carbon black industry and to address the methodological shortcomings of previous U.S. mortality studies. Methods: We followed mortality of 5011 workers employed 1 year or more since the 1930s at 18 carbon black facilities through December 31, 2003. Age-, race-, sex-, and calendar year-adjusted standardized mortality ratios (SMRs) were calculated using state-specific mortality rates. Results: Follow up was 96% complete. All-cause (SMR = 0.74, 95% confidence interval [CI] = 0.70–0.78) and all-cancer mortality (SMR = 0.83, 95% CI = 0.74–0.92) showed significant deficits. No excess was observed from lung (SMR = 0.97, 95% CI = 0.82–1.15) or bladder (SMR = 0.93, 95% CI = 0.47–1.87) cancers or from nonmalignant respiratory diseases (SMR = 0.99, 95% CI = 0.83–1.18). No trends were seen with duration of employment or time since hire for any cause of death. Conclusion: Employment in carbon black production in the United States seems not to be associated with increased mortality overall, cancer overall and, in particular, lung cancer. Further research, however, incorporating a detailed exposure assessment is needed to determine whether exposure to carbon black at high levels may be associated with an increased risk of cancer.

Low-level hexavalent chromium exposure and rate of mortality among US chromate production employees

Objectives: Although numerous studies have reported an elevated lung cancer risk among chromium chemical production employees, few studies have focused on employees hired after major process changes and enhanced industrial hygiene controls were implemented. Methods: This study examines the mortality experience of two postchange cohorts of chromate production employees constituting the current US chromium chemical industry. Results: Mortality among chromium chemical workers generally was lower than expected on the basis of national and state-specific referent populations. Lung cancer mortality was 16% lower than expected, with only three lung cancer deaths (3.59 expected). Conclusion: The absence of an elevated lung cancer risk may be a favorable reflection of the postchange environment. However, longer follow-up allowing an appropriate latency for the entire cohort will be needed to confirm this conclusion.

Vinyl chloride and liver and brain cancer at a polymer production plant in Louisville, Kentucky.

Studies of overlapping cohorts in the United States have shown an excess mortality from brain cancer in vinyl chloride (VC)-exposed workers. One plant located in Louisville, Kentucky, is included in many of these studies. We separated this plant from the large US cohort and re-analyzed the mortality experience. Louisville experienced significantly elevated liver (standardized mortality analyses [SMR] = 400) and brain cancer (SMR = 229) mortality. Liver cancer mortality remained significantly elevated (SMR = 344) in the remaining cohort; however, brain cancer mortality was markedly reduced (SMR = 112) when Louisville was removed. In contrast with liver cancer, a preliminary review of work assignments did not suggest that the brain cancer excess was related to VC exposure. The Louisville brain cancer cluster has had a significant impact on the reported literature. Although unrelated to VC, the cause of this cluster remains uncertain.

Formaldehyde Exposure and Mortality Risks From Acute Myeloid Leukemia and Other Lymphohematopoietic Malignancies in the US National Cancer Institute Cohort Study of Workers in Formaldehyde Industries

Objectives: To evaluate associations between cumulative and peak formaldehyde exposure and mortality from acute myeloid leukemia (AML) and other lymphohematopoietic malignancies. Methods: Cox proportional hazards analyses. Results: Acute myeloid leukemia was unrelated to cumulative exposure. Hodgkin lymphoma relative risk estimates in the highest exposure categories of cumulative and peak exposures were, respectively, 3.76 (Ptrend = 0.05) and 5.13 (Ptrend = 0.003). There were suggestive associations with peak exposure observed for chronic myeloid leukemia, albeit based on very small numbers. No other lymphohematopoietic malignancy was associated with either chronic or peak exposure. Conclusions: Insofar as there is no prior epidemiologic evidence supporting associations between formaldehyde and either Hodgkin leukemia or chronic myeloid leukemia, any causal interpretations of the observed risk patterns are at most tentative. Findings from this re-analysis do not support the hypothesis that formaldehyde is a cause of AML.

State-of-the-science assessment of non-asbestos amphibole exposure: Is there a cancer risk?

The distinction between amphibole asbestos fibers and non-asbestos amphibole particles has important implications for assessing potential cancer risks associated with exposure to amphibole asbestos or amphibole-containing products. Exposure to amphibole asbestos fibers can pose a cancer risk due to its ability to reside for long periods of time in the deep lung (i.e., biopersistence). In contrast, non-asbestos amphibole particles are usually cleared rapidly from the lung and do not pose similar respiratory risks even at high doses. Most regulatory and public health agencies, as well as scientific bodies, agree that non-asbestos amphiboles possess reduced biological (e.g., carcinogenic) activity. Although non-asbestos amphibole minerals have been excluded historically from Federal regulations, non-asbestos structures may be counted as asbestos fibers on the basis of dimensional criteria specified in analytical protocols. Given the potential to mischaracterize a non-asbestos structure as a “true” asbestos fiber, our objective was to assess whether exposure to non-asbestos amphiboles that may meet the dimensional criteria for counting as a fiber pose a cancer risk similar to amphibole asbestos. We reviewed analytical methods as well as the mineralogical, epidemiological, and toxicological literature for non-asbestos amphiboles. No evidence of demonstrable cancer effects from exposure to non-asbestos amphiboles that may be counted as fibers, under certain assessment protocols, was found. Data gaps (industrial hygiene data for amphibole-exposed cohorts), inconsistencies (analytical laboratory methods/protocols used to count fibers), and sources of potential bias from misclassification of exposure were identified.

Does occupational exposure to formaldehyde cause hematotoxicity and leukemia-specific chromosome changes in cultured myeloid progenitor cells?

Abstract Several cross-sectional studies of a single population of workers exposed to formaldehyde at one of two factories using or producing formaldehyde–melamine resins in China have concluded that formaldehyde exposure induces damage to hematopoietic cells that originate in the bone marrow. Moreover, the investigators interpret observed differences between groups as evidence that formaldehyde induces myeloid leukemias, although the mechanisms for inducing these diseases are not obvious and recently published scientific findings do not support causation. Our objective was to evaluate hematological parameters and aneuploidy in relation to quantitative exposure measures of formaldehyde. We obtained the study data for the original study (Zhang et al. 2010) and performed linear regression analyses. Results showed that differences in white blood cell, granulocyte, platelet, and red blood cell counts are not exposure dependent. Among formaldehyde-exposed workers, no association was observed between individual average formaldehyde exposure estimates and frequency of aneuploidy, suggested by the original study authors to be indicators of myeloid leukemia risk.

Cause-specific mortality among Kelly Air Force Base civilian employees, 1981-2001.

In response to concerns about occupational and environmental exposures, and a perceived cluster of amyotrophic lateral sclerosis (ALS) in the community, the mortality experience among 31,811 civilian employees who worked for at least 1 year between 1981 and 2000 at Kelly Air Force Base, Texas was ascertained. A total of 3264 deaths occurred through October 31, 2001. Overall, significant deficits in mortality were observed for all causes of death and all cancers combined. An excess of breast cancer [standardized mortality ratio (SMR) = 216; 95% confidence interval (CI) = 128–341] among blue-collar women was identified, and remained elevated after adjusting for race and ethnicity [rate ratio (RR) = 2.83; 95% CI = 1.50–5.34]. Mortality from motor neuron disease, which includes ALS deaths, was not increased overall (SMR = 0.98; 95% CI = 0.52–1.68), and was lower among blue-collar employees and higher among white-collar employees than expected, based on small numbers. Overall, mortality patterns indicated a healthy worker population and no large increased mortality associated with employment at Kelly Air Force Base.

Cohort Study of Carbon Black Exposure and Risk of Malignant and Nonmalignant Respiratory Disease Mortality in the US Carbon Black Industry.

Objective: To evaluate lung cancer and respiratory disease mortality associations with cumulative inhalable carbon black exposure among 6634 US carbon black workers. Methods: This analysis was performed using standardized mortality ratio (SMRs) and Cox regression analyses. Results: Lung cancer mortality was decreased overall (SMR = 0.77; 95% confidence interval [CI], 0.67 to 0.89) but less so among hourly male workers (SMR = 0.87; 95% CI, 0.71 to 1.05). No exposure–response association was observed with time-dependent cumulative inhalable carbon black: hazard ratio [HR] = 1.0 (95% CI, 0.6 to 1.6) for 20 to less than 50 mg/m3·yr); HR = 1.3 (95% CI, 0.8 to 2.1) for 50 to less than 100 mg/m3·yr; and HR = 1.4 (95% CI, 0.9 to 2.1) for 100 mg/m3·yr or more compared with referent (<20 mg/m3·yr). No consistent associations were observed between cumulative inhalable carbon black exposure and respiratory disease mortality. Conclusion: Quantitative carbon black exposure estimates were not related to lung cancer or nonmalignant respiratory disease mortality.