Epidemiology of hyperhidrosis in 2 population-based health care databases.

BACKGROUND: Population-based and clinical case reports of hyperhidrosis (HH) provide prevalence estimates that vary widely across reported studies because of differences in case ascertainment. OBJECTIVE: In this study, we specify diagnostic, symptom, and prescription codes for HH to estimate incidence and prevalence for the United Kingdom and the United States. METHODS: Data from UK and US health care databases were analyzed to ascertain HH cases and estimate incidence and prevalence from health care records during calendar years 2011 through 2013. RESULTS: On the basis of 2013 data for the United States and United Kingdom, between 1.0% and 1.6% of these populations have health care records indicating diagnosis or treatment of HH. Women accounted for approximately 60% of incident and prevalent cases in both databases. LIMITATIONS: Because the case ascertainment methods rely on available data for those seeking health care, we may have underestimated the number of HH cases in both countries. CONCLUSIONS: The findings represent a plausible estimate for incidence and prevalence of HH among persons seeking medical care for excessive sweating. Improved practices for identifying HH in clinical settings may increase the sensitivity and specificity of future studies and improve characterization and quantification of the population burden of this significant disease.

Bayesian Approach to "Healthy Worker Hire Effect" in Standardized Mortality Ratio Analysis.

OBJECTIVES: In this study, we address the healthy worker hire effect that arises when people with greater than average health are recruited to work in industrial jobs. METHODS: Epidemiologists have used both general and working population reference rates to gauge influence of healthy worker hire effect on the standardized mortality ratio. We propose a Bayesian procedure that uses information derived from general and working population reference rates to calculate standardized mortality ratio. RESULTS: The procedure is illustrated in the context of heart disease and lung cancer mortality analyses of a cohort of workers from a fluoropolymer production facility. CONCLUSIONS: Application of our method should allow for fuller discussions of the healthy worker effect when one of its components, the healthy worker hire effect, is evaluated quantitatively. Our method can be utilized to improve risk estimates for a cohort with occupational exposure.

Evaluating uncertainty to strengthen epidemiologic data for use in human health risk assessments.

BACKGROUND: There is a recognized need to improve the application of epidemiologic data in human health risk assessment especially for understanding and characterizing risks from environmental and occupational exposures. Although there is uncertainty associated with the results of most epidemiologic studies, techniques exist to characterize uncertainty that can be applied to improve weight-of-evidence evaluations and risk characterization efforts. METHODS: This report derives from a Health and Environmental Sciences Institute (HESI) workshop held in Research Triangle Park, North Carolina, to discuss the utility of using epidemiologic data in risk assessments, including the use of advanced analytic methods to address sources of uncertainty. Epidemiologists, toxicologists, and risk assessors from academia, government, and industry convened to discuss uncertainty, exposure assessment, and application of analytic methods to address these challenges. SYNTHESIS: Several recommendations emerged to help improve the utility of epidemiologic data in risk assessment. For example, improved characterization of uncertainty is needed to allow risk assessors to quantitatively assess potential sources of bias. Data are needed to facilitate this quantitative analysis, and interdisciplinary approaches will help ensure that sufficient information is collected for a thorough uncertainty evaluation. Advanced analytic methods and tools such as directed acyclic graphs (DAGs) and Bayesian statistical techniques can provide important insights and support interpretation of epidemiologic data. CONCLUSIONS: The discussions and recommendations from this workshop demonstrate that there are practical steps that the scientific community can adopt to strengthen epidemiologic data for decision making.

Cancer risk among tetrafluoroethylene synthesis and polymerization workers.

Tetrafluoroethylene (TFE), a compound used for the production of fluorinated polymers including polytetrafluoroethylene, increases the incidence of liver and kidney cancers and leukemia in rats and mice. This is the first time the cancer risk in humans has been explored comprehensively in a cohort mortality study (1950-2008) that included all polytetrafluoroethylene production sites in Europe and North America at the time it was initiated. A job-exposure matrix (1950-2002) was developed for TFE and ammonium perfluoro-octanoate, a chemical used in the polymerization process. National reference rates were used to calculate standardized mortality ratios (SMRs) and 95% confidence intervals. Among 4,773 workers ever exposed to TFE, we found a lower rate of death from most causes, as well as increased risks for cancer of the liver (SMR = 1.27; 95% confidence interval: 0.55, 2.51; 8 deaths) and kidney (SMR = 1.44; 95% confidence interval: 0.69, 2.65; 10 deaths) and for leukemia (SMR = 1.48; 95% confidence interval: 0.77, 2.59; 12 deaths). A nonsignificant upward trend (P = 0.24) by cumulative exposure to TFE was observed for liver cancer. TFE and ammonium perfluoro-octanoate exposures were highly correlated, and therefore their separate effects could not be disentangled. This pattern of findings narrows the range of uncertainty on potential TFE carcinogenicity but cannot conclusively confirm or refute the hypothesis that TFE is carcinogenic to humans.

Incomplete follow-up in the National Cancer Institute's formaldehyde worker study and the impact on subsequent reanalyses and causal evaluations.

Three of us (G.M., A.Y., and P.M.) performed reanalyses of the National Cancer Institute cohort study on nasopharyngeal cancer (NPC) risk among formaldehyde exposed workers (Hauptmann et al., 2004). Both reanalyses (Marsh and Youk, 2005; Marsh et al., 2007) were published in this journal. However, the mortality follow-up performed by the NCI working group reported in two publications by Hauptmann et al. (2003, 2004) was later stated to be incomplete (Beane Freeman et al., 2009a,b). This incomplete follow-up may impact the validity of the results of our reanalyses. At this time, corrected estimates for solid cancer mortality risks including NPC as reported in Hauptmann et al. (2004) have not been provided as an erratum by the authors or reported anywhere else to our knowledge. We would like to inform readers about these issues and ask for a prompt corrigendum of the 2004 publication by the NCI working group since this study has played such a prominent role in causal evaluations.

Mortality among workers exposed to acrylonitrile in fiber production: an update.

OBJECTIVE: The investigation updates the mortality experience through 2002 for a cohort of workers exposed to acrylonitrile (AN). METHODS: Standardized mortality ratios (SMR) were estimated based on two reference populations: the US population and a regional employee population. Exposure-response analyses were conducted using Cox regression models for cumulative and mean intensity exposure measures. RESULTS: In the cohort of 2548 workers, 839 deaths have occurred with 91 deaths due to respiratory system cancer. Most standardized mortality ratio estimates are at or near no-effects levels. Hazard ratio (HR) estimates indicate no increased mortality risk for respiratory system cancer (adjusted HR = 0.96, 95% confidence interval: 0.74, 1.25). CONCLUSIONS: In summary, no mortality outcome of a priori interest, principally respiratory system cancer, is associated with increased AN exposure among fiber production workers over five decades of follow-up.

Retrospective cohort mortality study of workers in a polymer production plant including a reference population of regional workers.

PURPOSE: Based on previous reports of increased serum lipid levels in workers at a U.S. polymer manufacturing facility, the study objective was to investigate ischemic heart disease (IHD) mortality as well as a broad range of mortality causes for an occupational cohort at the facility. METHODS: The cohort comprised 6,027 men and women who had worked at the facility between 1948 and 2002; these years delimit the mortality follow-up period. Standardized mortality ratios (SMR) were estimated to compare observed numbers of deaths to expected numbers derived from mortality rates for 3 reference populations: the U.S. population, the West Virginia state population, and an 8-state regional employee population from the same company. RESULTS: Most SMR estimates based on U.S. and state populations were below 100. Comparison to the employee population also resulted in many SMR estimates at or near a no-effect level. Relative to the regional worker population, a nonsignificant elevation for IHD mortality was observed (SMR = 109, 95% confidence interval [CI]: 96, 124). Mortality associated with diabetes was significantly increased compared to the regional worker population (SMR = 197, 95% CI: 123, 298). A corresponding increase in the SMR for IHD and diabetes mortality was not detected for comparisons with the two general populations. CONCLUSIONS: The results reported herein show little evidence of increased cause-specific mortality risks for workers at the plant. This study demonstrates the utility of comparing occupational cohorts with a similar worker reference population in order to reduce bias associated with the healthy worker effect.

Asbestos exposures to truck drivers during World Trade Center cleanup operations.

This article presents results of asbestos air sampling conducted to assess the exposure to truck drivers working at the World Trade Center site. Sampling consisted of a combination of area and personal monitoring of 49 truck drivers and included optical and electron microscopic analyses. Three sampling periods were conducted: October 1-7, 2001, October 17-26, 2001, and April 13-23, 2002. Area sample locations were selected to estimate airborne concentrations around the perimeter of the site, on top of the pile, and in the pit. Air samples were collected using a 50-mm conductive cowl and a 25-mm mixed cellulose ester filter at flow rates ranging from 0.5-2 L/min. Samples were analyzed using a combination of phase contrast microscopy (PCM) NIOSH method 7400, transmission electron microscopy (TEM) NIOSH method 7402, and the direct method specified under the Asbestos Hazardous Emergency Response Act. Sample times and flow rates were adjusted to prevent overloading while maximizing sample volume. Personal sampling results suggest that asbestos fiber exposures to truck drivers at the site were low. Exposures based on TEM results generally ranged from less than detectable to 0.1 structures per cubic centimeter (s/cm(3)). TEM-based results further indicate that the majority of asbestos fibers were chrysotile and less than 5 microm in length. PCM-based estimates were generally higher than the TEM results. This is likely due to the counting of nonasbestos fibers. This conclusion is supported by the NIOSH 7402 TEM results, which did not detect asbestos fibers longer than 5 micro m. Area sample results were generally less than the personal results (except for the sample collected on top of the rubble pile) and decreased over the course of the cleanup. Our results show low airborne asbestos concentrations and a predominance of short fibers. Given these low concentrations, evidence of short fibers, and the short duration of the exposure (less than 10 months to complete the cleanup), it is likely that truck drivers working at the site are not at an increased risk for asbestos-related disease.

Assessing truck driver exposure at the World Trade Center disaster site: personal and area monitoring for particulate matter and volatile organic compounds during October 2001 and April 2002.

The destruction of the World Trade Center (WTC) in New York City on September 11, 2001, created a 16-acre debris field composed of pulverized and burning material significantly impacting air quality. Site cleanup began almost immediately. Cleanup workers were potentially exposed to airborne contaminants, including particulate matter, volatile organic compounds, and asbestos, at elevated concentrations. This article presents the results of the exposure assessment of one important group of WTC workers, truck drivers, as well as area monitoring that was conducted directly on site during October 2001 and April 2002. In cooperation with a local labor union, 54 drivers (October) and 15 drivers (April) were recruited on site to wear two monitors during their 12-hour work shifts. In addition, drivers were administered a questionnaire asking for information ranging from "first day at the site" to respirator use. Area monitoring was conducted at four perimeter locations during October and three perimeter locations during April. During both months, monitoring was also conducted at one location in the middle of the rubble. Contaminants monitored for included total dust (TD), PM10, PM2.5, and volatile organic compounds. Particle samples were analyzed for mass, as well as elemental and organic carbon content. During October, the median personal exposure to TD was 346 microg/m3. The maximum area concentration, 1742 microg/m3, was found in middle of the debris. The maximum TD concentration found at the perimeter was 392 microg/m3 implying a strong concentration gradient from the middle of debris outward. PM2.5/PM10 ratios ranged from 23% to 100% suggesting significant fire activity during some of the sampled shifts. During April, the median personal exposure to TD was 144 microg/m3, and the highest area concentration, 195 microg/m3, was found at the perimeter. During both months, volatile organic compounds concentrations were low.

Impact of the 2002 Canadian forest fires on particulate matter air quality in Baltimore city.

With increasing evidence of adverse health effects associated with particulate matter (PM), the exposure impact of natural sources, such as forest fires, has substantial public health relevance. In addition to the threat to nearby communities, pollutants released from forest fires can travel thousands of kilometers to heavily populated urban areas. There was a dramatic increase in forest fire activity in the province of Quebec, Canada, during July 2002. The transport of PM released from these forest fires was examined using a combination of a moderate-resolution imaging spectroradiometer satellite image, back-trajectories using a hybrid single-particle Lagrangian integrated trajectory, and local light detection and ranging measurements. Time- and size-resolved PM was evaluated at three ambient and four indoor measurement sites using a combination of direct reading instruments (laser, time-of-flight aerosol spectrometer, nephelometer, and an oscillating microbalance). The transport and monitoring results consistently identified a forest fire related PM episode in Baltimore that occurred the first weekend of July 2002 and resulted in as much as a 30-fold increase in ambientfine PM. On the basis of tapered element oscillating microbalance measurements, the 24 h PM25 concentration reached 86 microg/m3 on July 7, 2002, exceeding the 24 h national ambient air quality standard. The episode was primarily comprised of particles less than 2.5 microm in aerodynamic diameter, highlighting the preferential transport of the fraction of PM that is of greatest health concern. Penetration of the ambient episode indoors was efficient (median indoor-to-outdoor ratio 0.91) such that the high ambient levels were similarly experienced indoors. These results are significant in demonstrating the impact of a natural source thousands of kilometers away on ambient levels of and potential exposures to air pollution within an urban center. This research highlights the significance of transboundary air pollution and the need for studies that assess the public health impacts associated with such sources and transport processes.

Racial and ethnic disparities in the purchase of nongroup health insurance: the roles of community and family-level factors.

OBJECTIVE: To evaluate the influence of community- and family-level factors on racial/ethnic disparities in the uptake of nongroup (individual) health insurance. DATA SOURCES: Responses to the 1996-1997 Community Tracking Study Household Survey plus community-level descriptors from several sources including census data, the Area Resource File, and community and migrant health center Medicare cost reports. STUDY DESIGN: Logistic regression was used to compare families in which at least one person had nongroup health insurance to families without nongroup insurance in which at least one person was uninsured. Sequential models were constructed examining family- and community-level factors. RESULTS: Twenty-three percent of families with otherwise-uninsured persons purchased nongroup insurance, ranging from 11% to 41% among the 60 communities sampled. Disadvantaged minority group members, especially Spanish-speaking Hispanics, had half or less the odds of whites of purchasing nongroup insurance. Education had a weaker association with purchasing nongroup insurance among minority group members than among whites. Community-level factors had minimal effect on disparities in uptake, although greater housing segregation was associated with lower uptake among blacks. CONCLUSIONS: Minority group members are much less likely to purchase nongroup insurance than whites. Family income and community factors do not explain this gap. Programs aimed at stimulating voluntary insurance purchase will continue to underenroll disadvantaged minorities if nonfinancial barriers to acquiring insurance coverage, including the interplay between race/ethnicity and education, are not better understood and addressed.