Asbestos fibre dimensions and lung cancer mortality among workers exposed to chrysotile

ObjectivesTo estimate exposures to asbestos fibres of specific sizes among asbestos textile manufacturing workers exposed to chrysotile using data from transmission electron microscopy (TEM) and to evaluate the extent to which the risk of lung cancer varies with fibre length and diameter.Methods3803 workers employed for at least 1 day between 1 January 1950 and 31 December 1973 in any of three plants in North Carolina, USA that produced asbestos textile products and followed for vital status through 31 December 2003 were included. Historical exposures to asbestos fibres were estimated from work histories and 3578 industrial hygiene measurements taken in 1935–1986. Exposure–response relationships for lung cancer were examined within the cohort using Poisson regression.ResultsIndicators of fibre length and diameter obtained by TEM were positively and significantly associated with increasing risk of lung cancer. Exposures to longer and thinner fibres tended to be most strongly associated with lung cancer, and models for these fibres fit the data best. Simultaneously modelling indicators of cumulative mean fibre length and diameter yielded a positive coefficient for fibre length and a negative coefficient for fibre diameter.ConclusionsThe results support the hypothesis that the risk of lung cancer among workers exposed to chrysotile asbestos increases with exposure to longer fibres. More research is needed to improve the characterisation of exposures by fibre size and number and to analyse the associated risks in a variety of industries and populations

Lung Cancer Risk Associated with Regulated and Unregulated Chrysotile Asbestos Fibers

BACKGROUND: Regulation of asbestos fibers in the workplace is partly determined by which fibers can be visually counted. However, a majority of fibers are too short and thin to count this way and are, consequently, not subject to regulation. METHODS: We estimate lung cancer risk associated with asbestos fibers of varying length and width. We apply an order-constrained prior both to leverage external information from toxicological studies of asbestos health effects. This prior assumes that risk from asbestos fibers increases with increasing length and decreases with increasing width. RESULTS: When we apply a shared mean for the effect of all asbestos fiber exposure groups, the rate ratios for each fiber group per unit exposure appear mostly equal. Rate ratio estimates for fibers of diameter 40 μm in the thinnest fiber group are similar in magnitude to estimates of risk associated with long fibers in the regulated fraction of airborne asbestos fibers. Rate ratio estimates for longer fibers are larger than those for shorter fibers, but thicker and thinner fibers do not differ as the toxicologically derived prior had expected. CONCLUSION: Credible intervals for fiber size-specific risk estimates overlap; thus, we cannot conclude that there are substantial differences in effect by fiber size. Nonetheless, our results suggest that some unregulated asbestos fibers may be associated with increased incidence of lung cancer

Exploration of Work and Health Disparities among Black Women Employed in Poultry Processing in the Rural South

We describe an ongoing collaboration that developed as academic investigators responded to a specific request from community members to document health effects on black women of employment in poultry-processing plants in rural North Carolina. Primary outcomes of interest are upper extremity musculoskeletal disorders and function as well as quality of life. Because of concerns of community women and the history of poor labor relations, we decided to conduct this longitudinal study in a manner that did not require involvement of the employer. To provide more detailed insights into the effects of this type of employment, the epidemiologic analyses are supplemented by ethnographic interviews. The resulting approach requires community collaboration. Community-based staff, as paid members of the research team, manage the local project office, recruit and retain participants, conduct interviews, coordinate physical assessments, and participate in outreach. Other community members assisted in the design of the data collection tools and the recruitment of longitudinal study participants and took part in the ethnographic component of the study. This presentation provides an example of one model through which academic researchers and community members can work together productively under challenging circumstances. Notable accomplishments include the recruitment and retention of a cohort of low-income rural black women, often considered hard to reach in research studies. This community-based project includes a number of elements associated with community-based participatory research

In-home evaluation of efficacy and titration of a mandibular advancement device for obstructive sleep apnea

There is increasing evidence that mandibular advancement devices (MADs) can be an effective treatment for some patients with obstructive sleep apnea, a highly prevalent chronic disease. In this study, the objectives were to objectively assess the effectiveness of MAD therapy using a limited channel recorder, and to develop a model for identifying patients who may be appropriate for MAD therapy as the initial treatment option. Thirty patients were prospectively recruited and studied at two independent dentist offices and the participants’ homes. Subjects wore the ARES Unicorder for two nights before insertion of the MAD, and again when the dentist determined that the patient had reached the titration endpoint. Self-reported measures of depression, sleepiness, and quality of life were obtained pre- and posttreatment. The reviewer was blinded to the study status while the physiological signals were being visually inspected. Significant reductions in the apnea/hypopnea index (AHI), hypoxemia measures, and snoring level were observed posttreatment. Twenty-seven of the 30 (90%) patients had a posttreatment AHI (using a 4% desaturation for hypopneas) below a clinical cut-off of 10. All but one patient (97%) exhibited at least a 50% decrease in AHI or had a posttreatment AHI ≤ 10. Significant differences in body mass index, weight, and neck circumference in patients with posttreatment AHIs above and below a clinical cut-off of five were identified. The linear regression used to predict the posttreatment AHI using pretreatment data resulted in an R2 of 0.68. The model correctly predicted two patients who were unable to obtain a posttreatment AHI of 10 or less. This study was designed to demonstrate two models of collaboration between a dental sleep medicine specialist and a sleep medicine physician in the monitoring of a patient treated with a MAD. The outcome data suggest that the limited channel recording system can be used as an alternative to laboratory polysomnography to reduce the cost of MAD treatment, and to improve the quality and consistency of posttreatment patient care

IARC Monographs: 40 Years of Evaluating Carcinogenic Hazards to Humans

Background: Recently, the International Agency for Research on Cancer (IARC) Programme for the Evaluation of Carcinogenic Risks to Humans has been criticized for several of its evaluations, and also for the approach used to perform these evaluations. Some critics have claimed that failures of IARC Working Groups to recognize study weaknesses and biases of Working Group members have led to inappropriate classification of a number of agents as carcinogenic to humans. Objectives: The authors of this Commentary are scientists from various disciplines relevant to the identification and hazard evaluation of human carcinogens. We examined criticisms of the IARC classification process to determine the validity of these concerns. Here, we present the results of that examination, review the history of IARC evaluations, and describe how the IARC evaluations are performed. Discussion: We concluded that these recent criticisms are unconvincing. The procedures employed by IARC to assemble Working Groups of scientists from the various disciplines and the techniques followed to review the literature and perform hazard assessment of various agents provide a balanced evaluation and an appropriate indication of the weight of the evidence. Some disagreement by individual scientists to some evaluations is not evidence of process failure. The review process has been modified over time and will undoubtedly be altered in the future to improve the process. Any process can in theory be improved, and we would support continued review and improvement of the IARC processes. This does not mean, however, that the current procedures are flawed. Conclusions: The IARC Monographs have made, and continue to make, major contributions to the scientific underpinning for societal actions to improve the public’s health

IARC Monographs: 40 Years of Evaluating Carcinogenic Hazards to Humans

Background: Recently, the International Agency for Research on Cancer (IARC) Programme for the Evaluation of Carcinogenic Risks to Humans has been criticized for several of its evaluations, and also for the approach used to perform these evaluations. Some critics have claimed that failures of IARC Working Groups to recognize study weaknesses and biases of Working Group members have led to inappropriate classification of a number of agents as carcinogenic to humans