Lung cancer incidence in Canadian petroleum workers.

OBJECTIVES: This study's purpose was to conduct a more in-depth analysis of the potential association between lung cancer, occupational exposures and smoking using data on cohort members from a Canadian petroleum company and refined statistical analyses. METHODS: Information on various exposures including asbestos and petroleum coke dust, as well as job type and operating segment were collected via manual and computerised company records. We performed life-table analyses, Poisson regression and restricted cubic splines to model exposure-response patterns while controlling for smoking status and age. Model diagnostics included the assessment of dispersion and offset parameters. RESULTS: These analyses show that lung cancer risk is strongly related to age and smoking, and to a lesser extent to province of last residence. When controlling for these covariates, there is suggestive evidence that maintenance work may also be related to lung cancer risk. Some analyses also indicate that asbestos exposure may be associated with lung cancer risk, although a clear exposure-response trend is not seen. Other exposures, including petroleum coke dust, were not strongly related to lung cancer risk, particularly when expressed as a continuous measure. CONCLUSIONS: These data suggest that maintenance work may be associated with lung cancer incidence, although exposures to the single agents studied did not emerge as strong predictors of lung cancer incidence. Maintenance work may be a surrogate for general exposures to several agents (eg, polycyclic aromatic hydrocarbons, metals, welding fumes, radiation, etc), although these results may be affected by residual confounding due to smoking or other socio-demographic factors.

Overtime work and stress response in a group of Japanese workers.

BACKGROUND: Working long overtime hours is considered a cause of mental health problems among workers but such a relationship has yet to be empirically confirmed. AIM: To clarify the influence of overtime work on response to stress and to assess the role of other stress-related factors on this relationship. METHODS: The study was conducted among 24 685 employees of a company in Japan. Stress response, job stressors and social supports were assessed by the Brief Job Stress Questionnaire. Participants were divided into five categories of overtime (0-19, 20-39, 40-59, >or=60 h of overtime per month and exempted employees). RESULTS: The nonadjusted odds ratios for stress response for 40-59 and >or=60 overtime hours per month in reference to 0-19 overtime hours were 1.11 [95% confidence interval (CI) 1.03-1.19] and 1.62 (95% CI 1.50-1.76), respectively. After adjustment for self-assessed amount of work, mental workload and sleeping time, the association between overtime work and stress response disappeared. CONCLUSIONS: This large cross-sectional study shows that overtime work appears to influence stress response indirectly through other stress factors such as self-assessed amount of work, mental workload and sleeping time.

Reproducibility of nasal lavage in the context of the inhalation challenge investigation of occupational rhinitis.

BACKGROUND: The nasal lavage (NAL) method is increasingly used to assess changes in upper airways inflammation in the investigation of occupational rhinitis (OR). A good reproducibility of the method is fundamental to accurately assess changes in markers of inflammation in nasal secretions before and after inhalation challenges. The main objective of this study was to assess the short-term reproducibility of cells and cellular markers of inflammation in NAL in the setting of specific inhalation challenge (SIC) investigating OR. An ancillary objective was to assess the reproducibility of NAL in the context of two different SIC methodologies. METHODS: Twenty-five subjects attended the laboratory for 2 separate days of NAL performed within the same week. On the first visit subjects underwent NAL before a SIC sham session and on the second visit before a SIC with the active agent. These prechallenge NAL measurements obtained on both days were used to analyze the reproducibility of the NAL method. RESULTS: The reproducibility for cell differential counts was satisfactory for neutrophils (intraclass correlation coefficient [ICC] = 0.68), for eosinophils (ICC = 0.95), for macrophages (ICC = 0.77), and for epithelial cells (ICC = 0.73). The reproducibility of total cell counting was poor (ICC = 0.12). The reproducibility of ECP concentrations was satisfactory (ICC = 0.67). Eosinophil counts were reproducible in the context of two different challenge methodologies. CONCLUSION: The NAL method was shown to be sufficiently reproducible to be considered useful for the monitoring of upper airways inflammation during the investigation of OR by SIC.

Risk of childhood leukemia associated with parental smoking and alcohol consumption prior to conception and during pregnancy: the cross-Canada childhood leukemia study.

OBJECTIVE: As part of a larger case-control study, the authors evaluated risk of childhood leukemia relative to parental self-reported smoking and alcohol consumption. METHODS: Children 0-14 years of age diagnosed with leukemia between 1990 and 1994 were ascertained through population-based sources at the time of diagnosis. For each participating case, an age, gender, and area-matched control was randomly selected from provincial government health insurance rolls. Risk factor information was obtained through personal interviews with each child's parents. Conditional logistic regression models were used to examine risk of leukemia associated with parental smoking and drinking. RESULTS: Maternal alcohol consumption prior to conception (OR = 1.37, 95% CI, 0.99-1.90) and during pregnancy (OR = 1.39, 95% CI, 1.01-1.93) was associated with an excess risk of childhood leukemia, with a positive dose-response trend for increasing weekly consumption (p < 0.05). Similar results were observed for children diagnosed with acute lymphoblastic leukemia (ALL). Odds ratios for maternal cigarette smoking before and during pregnancy were consistently elevated above one, but not statistically significant. No relationship was observed with paternal drinking or smoking in the perinatal period. CONCLUSIONS: Our study suggests that maternal alcohol drinking before or during pregnancy may contribute to an increased risk of childhood leukemia.

Risk of childhood leukemia associated with vaccination, infection, and medication use in childhood: the Cross-Canada Childhood Leukemia Study.

Current hypotheses consonant with the peak in leukemia incidence in early childhood point to an infectious etiology. The authors examined the effect of postnatal exposures predicted to affect early immune functioning, including childhood vaccinations, illness, medication use, and breastfeeding patterns. Children 0-15 years of age diagnosed with leukemia from 1990 to 1994 and resident within principal cities across Canada were eligible for inclusion. Through pediatric oncology centers and population-based cancer registries, 399 cases were ascertained at the time of diagnosis. For each participating case, an age-, gender-, and area-matched control was randomly selected from government health insurance rolls. Risk factor information was obtained through personal interviews with each child's parents or guardians. Conditional logistic regression was used to calculate odds ratios, with adjustment for potential confounders. Use of immunosuppressant medication by the index child led to a deficit of risk (odds ratio = 0.37, 95% confidence interval: 0.16, 0.84), while vitamin intake was positively associated with leukemia (odds ratio = 1.66, 95% confidence interval: 1.18, 2.33). Breastfeeding for more than 6 months was also protective (p < 0.05). Results persisted for cases diagnosed with acute lymphoblastic leukemia and for children diagnosed at 1-5 years of age. These findings suggest a role for early immunologic challenge in the expression of childhood leukemia.

Effort-reward imbalance and social support are associated with chronic fatigue among medical residents in Japan.

The purpose of this study was to determine the associations of effort-reward imbalance and social support with chronic fatigue among medical residents in Japan. A total of 104 men and 42 women at 14 teaching hospitals participated in this study. Chronic fatigue was measured by the checklist individual strength questionnaire. Effort, reward and overcommitment were determined by the effort-reward questionnaire developed by Siegrist. Social support was determined by a visual analog scale. Sleeping hours for the last 30 days were estimated based on the number of overnight shifts worked, the average number of sleeping hours, and the number of hours of napping during overnight work. Multiple regression analysis was used to examine the multivariate relationship between these variables and chronic fatigue. In both men and women, effort-reward imbalance was positively associated, and higher social support was negatively associated with chronic fatigue. In men, higher overcommitment was positively associated with chronic fatigue. In women, longer sleeping hours was negatively associated with chronic fatigue and an interaction between sleeping hours and social support was found. The adjusted variance in fatigue explained by the exposure variables was 34% in men and 51% in women. The result of this study suggested that it is desirable to take these factors into consideration in the management of chronic fatigue among medical residents.

Associations of excessive sleepiness on duty with sleeping hours and number of days of overnight work among medical residents in Japan.

Despite long-standing concerns regarding the effects of working hours on the performance and health of medical residents, and the patients' safety, prior studies have not shown an association of excessive sleepiness with the number of sleeping hours and days of overnight work among medical residents. In August 2005, a questionnaire was mailed to 227 eligible participants at 16 teaching hospitals. The total number of sleeping hours in the last 30 d was estimated from the average number of sleeping hours during regular days and during days with overnight work, and the number of days of overnight work. Multiple logistic regression analysis was used to adjust for potentially associated variables. A total of 149 men and 47 women participated in this study. The participation rate was 86.3%. Among the participants, 55 (28.1%) suffered from excessive sleepiness. Excessive sleepiness was associated with sleeping for less than 150 h in the last 30 d (corrected odds ratio [cOR]=1.57; 95% confidence interval [CI], 1.02-2.16). The number of days of overnight work in the last 30 d showed no association with excessive sleepiness. Excessive sleepiness was also associated with smoking (cOR, 1.65; 95%CI, 1.01-2.32). Medical residents who slept for less than 150 h in the last 30 d and smoked had a significantly higher risk of excessive sleepiness on duty.

Reproducibility of acoustic rhinometry in the investigation of occupational rhinitis.

BACKGROUND: To diagnose occupational rhinitis, it is mandatory to conduct an objective assessment of changes in nasal patency during specific inhalation challenge (SIC). The reproducibility of acoustic rhinometry measurements in the setting of occupational challenges has never been examined. This study assessed the reproducibility of acoustic rhinometry during SIC investigation of occupational rhinitis. METHODS: Twenty-four subjects underwent acoustic rhinometry measurements during SIC investigation of occupational rhinitis. Subjects attended 3-6 days of SIC within a week by means of a realistic or closed-circuit apparatus methodology RESULTS: All of the within-day intraclass correlation coefficients (ICCs) for nasal volume (2-5 cm) and minimum cross-sectional area (MCA) based on a different number of measurements (2-7) were above 0.85; all of the coefficients of variation (CVs)for the same parameters were low (below 10%). The between-day CVs based on different numbers of SIC sessions ranged from 8.0 to 8.8% and from 6.8 to 8.8%for nasal volume and MCA, respectively. The between-day ICCs ranged from 0.80 to 0.88 and from 0.83 to 0.94 for nasal volume and MCA, respectively. CONCLUSION: Acoustic rhinometry showed good within- and between-day reproducibility and can be recommended for the objective monitoring of nasal patency during SIC investigating occupational rhinitis.

Application of the stratum-specific likelihood ratio (SSLR) analysis to results of a depressive symptoms screening survey among Japanese workers.

BACKGROUND: The stratum-specific likelihood ratio (SSLR) has been widely used as a convenient method to interpret the results of screening surveys. In the present paper, an SSLR analysis is applied to the results of a survey that used the Center for Epidemiologic Studies Depression Scale (CES-D) to identify depressive symptoms in a group of Japanese workers in an attempt to determine score categories that have predictive clinical values in a screening context. METHODS: The self-reported CES-D and the Mini International Neuropsychiatric Interview (MINI) were administered to 2,219 workers (84.2% men; age 21-68 years) during a periodical medical examination. The SSLR was calculated to determine strata with optimal discrimination for major depressive disorder (MDD). RESULTS: For MDD, the SSLR was 0.06 (95%CI: 0.02-0.18) for the CES-D score range 0-16, 1.90 (0.78-4.62) for the score range 17-19, and 12.4 (10.2-15.1) for the score above 20. CONCLUSIONS: The SSLR shown in this study proposes score categories that guide clinicians in selecting the workers most at risks of having MDD among Japanese workers.

Validity of the Center for Epidemiologic Studies Depression Scale as a screening instrument of major depressive disorder among Japanese workers.

BACKGROUND: The Center for Epidemiologic Studies Depression Scale (CES-D) is used at workplaces to screen depressive disorders. The aim of this study was to examine the validity of the CES-D for depression in a workplace. METHODS: The CES-D was administered to 2,219 workers (84.2% men; age 21-68 years) at a manufacturing company in Japan. Concomitantly all workers had an interview with the Mini International Neuropsychiatric Interview (MINI) as a gold standard for diagnosing major depressive disorder (MDD). The validity was evaluated by a receiver operating characteristic (ROC) curve. RESULTS: The area under the ROC curve of the CES-D was 0.96 [95% Confidence Interval (CI): 0.94-0.99]. The optimal cut-off score of MDD was 19 for screening. CONCLUSIONS: The validity of CES-D is confirmed and it is a valid instrument for detecting MDD in working populations in Japan.

Categorizing nasal septal perforations of occupational origin as cases of corrosive rhinitis.

BACKGROUND: In clinical practice a perforation of the nasal septum secondary to an occupational exposure to corrosive chemicals is not considered a sequel of rhinitis. METHODS: Relevant articles published in the last 26 years were searched and retrieved from PubMed. RESULTS: Patients with nasal septal perforations of occupational origin show a history of rhinitis with a gradual installation of symptoms and damage of the nasal mucosa progressing to ulceration and ultimately to perforation of the nasal septum. CONCLUSION: Patients with nasal septal perforations of occupational origin exhibit the clinical and histopathological features of rhinitis whereby they should be categorized as rhinitics. This rhinitis should be considered as a type of irritant-induced occupational rhinitis and classified as corrosive rhinitis.