Working environment and myeloproliferative neoplasm: A population-based case-control study following a cluster investigation.

BACKGROUND: Occupational exposures, including those to polycyclic aromatic hydrocarbons (PAH), are suspected risk factors for myeloproliferative neoplasms (MPN). METHODS: We investigated occupational exposures and MPN risk (54 cases and 472 controls) in a population-based case-control study in three rural Pennsylvania counties. Occupational histories, coded to SIC/SOC 1980, were linked to a previously created PAH job-exposure matrix. Odds ratios for industry (17 categories), occupation (26 categories), and PAH exposure were adjusted using logistic regression. RESULTS: No industries or occupations were strongly or consistently associated with increased MPN risk. Analysis of employment duration found that being employed for 5 or more years in transportation, communications, and other public utilities was associated with MPN risk. There was no indication of an association with cumulative PAH exposure. CONCLUSIONS: These few associations did not appear to have a common exposure. This exploratory study does not support the hypothesis that occupational exposure, including PAH, are strong risk factors for MPNs.

Self-reported symptoms associated with the use of printer and photocopier machines: Results from the nano-Control, International Foundation survey.

OBJECTIVES: To document adverse health effects among office, copy and print shop workers using the nano-Control International Organization Survey. METHODS: Self-reported information on 16 health outcomes and three surrogate exposure variables were collected from 1998 individuals between 1999-2010. Logistic regression models, adjusted for age, gender, and smoking status, assessed the association between printer exposure and health symptoms. RESULTS: Among the participants, 61.9 % were office workers, 5.5% technicians and 23.3% held other professions. Technicians had a higher risk for cancer compared to office workers (OR = 2.5, p-value <0.01). Visible toner dust exposure was associated with chronic fatigue (OR = 9.6, <0.01), bronchial hyperresponsiveness (OR = 5.1, <0.01), cardiovascular diseases (OR = 3.6, <0.01), asthma, allergies, and other diseases (OR range 1.4 -3.2, <0.01). CONCLUSIONS: The increased chronic and acute health risks among these workers warrant further investigations of causal associations.

Gestational age at birth and risk of autism spectrum disorders in Alberta, Canada.

OBJECTIVE: To examine the association between autism spectrum disorders (ASD) and each completed week of gestation using a graphical method of presenting results at all possible categorizations of gestational age (GA). STUDY DESIGN: The risk of ASD in a total of 218110 singleton live births with complete data from Alberta, Canada between 1998 and 2004 was examined through linkage to health insurance records. The relative risk of developing ASD according to the 21 dichotomizations of shorter gestation (GA ≤ 23 weeks vs >23 weeks to ≤ 43 weeks vs >43 weeks, in 1-week increments) was calculated using log-binomial regression and adjusted for fetal sex, socioeconomic status, and birth year. RESULTS: We observed a gradual increased risk of ASD with shorter gestation. Cutoffs only between 29 and 40 weeks clearly denoted an elevated risk of developing ASD compared with longer gestation, and the risk increased with earlier GA cutoff. The results were not affected by sex or measures of fetal growth. CONCLUSION: Our data confirm the role of shortened gestation in ASD risk. We warn against the use of prespecified or a data-driven GA cutoff, however; instead, we recommend systematically examining all plausible cutoffs for GA to avoid overstating the homogeneity of risk in children on either side of a given cutoff, as well as to increase the comparability of studies.

Dichotomization: 2 x 2 (x2 x 2 x 2...) categories: infinite possibilities.

BACKGROUND: Consumers of epidemiology may prefer to have one measure of risk arising from analysis of a 2-by-2 table. However, reporting a single measure of association, such as one odds ratio (OR) and 95% confidence interval, from a continuous exposure variable that was dichotomized withholds much potentially useful information. Results of this type of analysis are often reported for one such dichotomization, as if no other cutoffs were investigated or even possible. METHODS: This analysis demonstrates the effect of using different theory and data driven cutoffs on the relationship between body mass index and high cholesterol using National Health and Nutrition Examination Survey data. The recommended analytic approach, presentation of a graph of ORs for a range of cutoffs, is the focus of most of the results and discussion. RESULTS: These cutoff variations resulted in ORs between 1.1 and 1.9. This allows investigators to select a result that either strongly supports or provides negligible support for an association; a choice that is invisible to readers. The OR curve presents readers with more information about the exposure disease relationship than a single OR and 95% confidence interval. CONCLUSION: As well as offering results for additional cutoffs that may be of interest to readers, the OR curve provides an indication of whether the study focuses on a reasonable representation of the data or outlier results. It offers more information about trends in the association as the cutoff changes and the implications of random fluctuations than a single OR and 95% confidence interval.

Retailers' knowledge of tobacco harm reduction following the introduction of a new brand of smokeless tobacco.

BACKGROUND: Tobacco retailers are potential public health partners for tobacco harm reduction (THR). THR is the substitution of highly reduced-risk nicotine products, such as smokeless tobacco (ST) or pharmaceutical nicotine, for cigarettes. The introduction of a Swedish-style ST product, du Maurier snus (dMS) (Imperial Tobacco Canada Limited), which was marketed as a THR product, provided a unique opportunity to assess retailers' knowledge. This study examined retailers' knowledge of THR and compliance with recommendations regarding tobacco sales to young adults. METHODS: Male researchers, who may have looked younger than 18 years old, visited 60 stores in Edmonton that sold dMS. The researchers asked the retailers questions about dMS and its health risks relative to those from other tobacco products. They also attempted to purchase dMS to ascertain whether retailers would ask for identification to verify that they were at least 18 years old. RESULTS: Overall, the retailers were only moderately knowledgeable about THR and the differences between dMS and other tobacco products. About half of the retailers correctly indicated that snus is safer than cigarettes; half of whom knew it is safer because it is smoke-free. Fifty percent incorrectly believed that snus causes oral cancer. Less than fifty percent indicated that dMS differs from chewing tobacco because it is in pouches and is used without spitting or chewing (making it more promising for THR). Most (90%) of the retailers asked the researchers for identification when selling dMS. CONCLUSION: Tobacco retailers are potentially important sources of information about THR, particularly since there are restrictions on the promotion of all tobacco products (regardless of the actual health risks) in Canada. This study found that many retailers in Edmonton do not know the relative health risks of different tobacco products and are therefore unable to pass on accurate information to smokers.

Smokeless tobacco: the epidemiology and politics of harm.

The health burden from tobacco smoking results almost entirely from inhalation of the components of smoke, although this is not widely known. The primary benefit of smoking is nicotine delivery, but nicotine can be obtained without combustion. Thus there is potential for tobacco harm reduction (THR), the substitution of lower-risk nicotine products for smoking. Epidemiological evidence suggests that smokeless tobacco causes about one one-hundredth the health risk of smoking. Despite the practice of harm reduction being widely accepted in public health, however, THR has faced fierce opposition from antitobacco activists. These activists have effectively misled the public about what aspect of smoking cigarettes causes the harm, convincing them that nicotine and tobacco themselves are harmful, ignoring the smoke. In the interests of promoting public health and rescuing science from politics, experts on inhalation hazards and health could play an important role in educating the public and policy makers about THR.

Survey of smokers' reasons for not switching to safer sources of nicotine and their willingness to do so in the future.

Despite the well-known risks of smoking, policy, social pressure, and accessible cessation programs, tens of millions of North American adults continue smoking rather than quitting or switching to less harmful non-combustion nicotine products. We surveyed people smoking in public in Edmonton, Canada (n = 242, year = 2007) to investigate smokers' reasons for resisting switching to low-risk nicotine sources. 43% had used low-risk products (mostly pharmaceutical nicotine). 75% indicated willingness to consider switching to low-risk products. Smokers cited similar reasons for not switching to smokeless tobacco and pharmaceutical nicotine, largely based on misinformation. Accurate risk information may lead many to try low-risk nicotine products.

The effect of name-based reporting and partner notification on HIV testing in New York State.

OBJECTIVES: We examined the effect of New York's HIV Reporting and Partner Notification law on HIV testing levels and on the HIV testing decisions of high-risk individuals. METHODS: In-person interviews were administered to 761 high-risk individuals to assess their knowledge, attitudes, and behaviors regarding HIV testing and reporting. Trends in HIV testing were also assessed in publicly funded HIV counseling and testing programs, Medicaid, and New York's Maternal Pediatric Newborn Prevention and Care Program. RESULTS: High-risk individuals had limited awareness of the reporting and notification law, and few cited concern about named reporting as a reason for avoiding or delaying HIV testing. HIV testing levels, posttest counseling rates, and anonymous-to-confidential conversion rates among those who tested HIV positive were not affected by the law. Medicaid-related HIV testing rates also remained stable. HIV testing during pregnancy continued to trend upward following implementation of the law. Findings held true within demographic and risk-related subgroups. CONCLUSIONS: HIV reporting has permitted improved monitoring of New York's HIV/AIDS epidemic. This benefit has not been offset by decreases in HIV testing behavior, including willingness to test among those at high risk of acquiring HIV.

Screening persons newly diagnosed with HIV/AIDS for risk of intimate partner violence: early progress in changing practice.

Interventions to prevent intimate partner violence (IPV), including among those at risk for or living with HIV/AIDS, are needed. In 2001, screening persons who test positive for HIV for risk of IPV was required in New York State, launching the first large-scale program to screen for IPV risk in conjunction with HIV counseling and testing (HCT). Written surveys of counselors, physicians, and agency supervisors explored attitudes, practices, knowledge, and training needs surrounding screening for risk of IPV during HCT. Most HCT providers were aware of screening requirements, but practice varied. Counselors were more likely to screen than were physicians and asked more screening questions. Despite guidelines, screening was generally not standardized and sporadic. IPV screening in conjunction with HCT is possible. Building capacity and commitment of local HCT providers through provision of training and by fostering partnerships with public health partner services staff can help overcome identified barriers to preventing IPV in a high-risk population.

Hepatitis C management by addiction medicine physicians: results from a national survey.

Drug users are disproportionately affected by hepatitis C virus (HCV), yet they face barriers to health care that place them at risk for levels of HCV-related care that are lower than those of nondrug users. Substance abuse treatment physicians may treat more HCV-infected persons than other generalist physicians, yet little is known about how such physicians facilitate HCV-related care. We conducted a nationwide survey of American Society of Addiction Medicine physicians (n = 320) to determine substance abuse physicians' HCV-related management practices and to describe factors associated with these practices. We found that substance abuse treatment physicians promote several elements of HCV-related care, including screening for HCV antibodies, recommending vaccinations against hepatitis A and B, and referring patients to subspecialists for HCV treatment. Substance abuse physicians who also provide primary medical or HIV-related care were most likely to facilitate HCV-related care. A significant minority of physicians were either providing HCV antiviral treatment or willing to provide HCV antiviral treatment.

A Simulation Study of Categorizing Continuous Exposure Variables Measured with Error in Autism Research: Small Changes with Large Effects.

Variation in the odds ratio (OR) resulting from selection of cutoffs for categorizing continuous variables is rarely discussed. We present results for the effect of varying cutoffs used to categorize a mismeasured exposure in a simulated population in the context of autism spectrum disorders research. Simulated cohorts were created with three distinct exposure-outcome curves and three measurement error variances for the exposure. ORs were calculated using logistic regression for 61 cutoffs (mean ± 3 standard deviations) used to dichotomize the observed exposure. ORs were calculated for five categories with a wide range for the cutoffs. For each scenario and cutoff, the OR, sensitivity, and specificity were calculated. The three exposure-outcome relationships had distinctly shaped OR (versus cutoff) curves, but increasing measurement error obscured the shape. At extreme cutoffs, there was non-monotonic oscillation in the ORs that cannot be attributed to "small numbers." Exposure misclassification following categorization of the mismeasured exposure was differential, as predicted by theory. Sensitivity was higher among cases and specificity among controls. Cutoffs chosen for categorizing continuous variables can have profound effects on study results. When measurement error is not too great, the shape of the OR curve may provide insight into the true shape of the exposure-disease relationship.

Pooling Bio-Specimens in the Presence of Measurement Error and Non-Linearity in Dose-Response: Simulation Study in the Context of a Birth Cohort Investigating Risk Factors for Autism Spectrum Disorders.

We sought to determine the potential effects of pooling on power, false positive rate (FPR), and bias of the estimated associations between hypothetical environmental exposures and dichotomous autism spectrum disorders (ASD) status. Simulated birth cohorts in which ASD outcome was assumed to have been ascertained with uncertainty were created. We investigated the impact on the power of the analysis (using logistic regression) to detect true associations with exposure (X1) and the FPR for a non-causal correlate of exposure (X2, r = 0.7) for a dichotomized ASD measure when the pool size, sample size, degree of measurement error variance in exposure, strength of the true association, and shape of the exposure-response curve varied. We found that there was minimal change (bias) in the measures of association for the main effect (X1). There is some loss of power but there is less chance of detecting a false positive result for pooled compared to individual level models. The number of pools had more effect on the power and FPR than the overall sample size. This study supports the use of pooling to reduce laboratory costs while maintaining statistical efficiency in scenarios similar to the simulated prospective risk-enriched ASD cohort.

The role of genotypes that modify the toxicity of chemical mutagens in the risk for myeloproliferative neoplasms.

BACKGROUND: The etiology of myeloproliferative neoplasms (MPN) (polycythemia vera; essential thrombocythemia; primary myelofibrosis) is unknown, however they are associated with a somatic mutation--JAK2 V617F--suggesting a potential role for environmental mutagens. METHODS: We conducted a population-based case-control study in three rural Pennsylvania counties of persons born 1921-1968 and residing in the area between 2000-2008. Twenty seven MPN cases and 292 controls were recruited through random digit dialing. Subjects were genotyped and odds ratios estimated for a select set of polymorphisms in environmentally sensitive genes that might implicate specific environmental mutagens if found to be associated with a disease. RESULTS: The presence of NAT2 slow acetylator genotype, and CYP1A2, GSTA1, and GSTM3 variants were associated with an average 3-5 fold increased risk. CONCLUSIONS: Exposures, such as to aromatic compounds, whose toxicity is modified by genotypes associated with outcome in our analysis may play a role in the environmental etiology of MPNs.

Quantifying the potential impact of measurement error in an investigation of autism spectrum disorder (ASD).

The Early Autism Risk Longitudinal Investigation (EARLI), an ongoing study of a risk-enriched pregnancy cohort, examines genetic and environmental risk factors for autism spectrum disorders (ASDs). We simulated the potential effects of both measurement error (ME) in exposures and misclassification of ASD-related phenotype (assessed as Autism Observation Scale for Infants (AOSI) scores) on measures of association generated under this study design. We investigated the impact on the power to detect true associations with exposure and the false positive rate (FPR) for a non-causal correlate of exposure (X2, r=0.7) for continuous AOSI score (linear model) versus dichotomised AOSI (logistic regression) when the sample size (n), degree of ME in exposure, and strength of the expected (true) OR (eOR)) between exposure and AOSI varied. Exposure was a continuous variable in all linear models and dichotomised at one SD above the mean in logistic models. Simulations reveal complex patterns and suggest that: (1) There was attenuation of associations that increased with eOR and ME; (2) The FPR was considerable under many scenarios; and (3) The FPR has a complex dependence on the eOR, ME and model choice, but was greater for logistic models. The findings will stimulate work examining cost-effective strategies to reduce the impact of ME in realistic sample sizes and affirm the importance for EARLI of investment in biological samples that help precisely quantify a wide range of environmental exposures.

Respirable crystalline silica exposure-response evaluation of silicosis morbidity and lung cancer mortality in the German porcelain industry cohort.

OBJECTIVE: To quantify silicosis and lung cancer risks among porcelain workers occupationally exposed to respirable crystalline silica. METHODS: We reread historical radiographs to identify silicosis and estimated exposure on the basis of detailed work history and about 8000 industrial hygiene measurements. Cox proportional hazards models estimated risks by cumulative and average exposure. RESULTS: Adjusted silicosis hazards ratios were 5.3 (95% confidence interval [CI], 1.6 to 17.3); 7.3 (95% CI, 2.6 to 20.8); and 6.8 (95% CI, 3.0 to 15.3) for cumulative exposures >4 to 5; >5 to 6; and >6 mg/m-years, and 3.3 (95% CI, 0.8 to 14.7), 13.6 (95% CI, 4.2 to 44.4) and 23.2 (95% CI, 8.2 to 65.8) for average exposures >0.1 to 0.15; >0.15 to 0.2 and >0.2 mg/m, respectively. Exposure was not associated with any cause of death including lung cancer. CONCLUSIONS: Respirable crystalline silica exposure more than 4 mg/m-years (cumulative) or more than 0.15 mg/m (average) were strongly associated with silicosis, but unrelated to lung cancer risks.