A case-comparison interview study of brain tumors and employment in occupations with presumed electric and magnetic field exposures

Results from epidemiologic studies suggest that persons working in occupations with presumed electric and magnetic field (EMF) exposures are at increased risk of brain cancer. This study utilized data from a completed, population-based, interview case-control study of central nervous system (CNS) tumors and employment in the petrochemical industry to test the hypothesis that employment in EMF-related occupations increases CNS tumor risk. A total of 375 male residents of the Texas-Louisiana Gulf Coast Area, age 20 to 79, with primary neuroglial CNS tumors diagnosed during the period 1980-84 were identified. A population-based comparison group of 450 age, race and geographically matched males was selected. Occupational histories and potential risk factor data were collected via personal interviews with study subjects or their next-of-kin.^ Adjusted odds ratios were less than 1.0 for persons ever employed in an electrical occupation (OR = 0.65; 95% CI = 0.40-1.09) or whose usual occupation was electrical (OR = 0.76; 95% CI = 0.33-1.73). Relative risk estimates did not increase significantly as time since first employment or duration of employment increased. Examination of CNS tumor risk by high (OR = 0.80), medium (OR = 0.88) and low (OR = 0.45) exposure categories for persons whose usual occupation was electrical did not indicate a dose-response pattern. In addition, the mean age of exposed cases was not significantly younger than that for unexposed cases. Analysis of risk by probability of exposure to EMFs showed non-significant elevations in the adjusted odds ratio for definite exposed workers defined by their usual occupation (OR = 1.78; 95% CI = 0.70-4.51) and ever/never employed status (OR = 1.54; 95% CI = 0.17-4.91).^ These findings suggest that employment in occupations with presumed EMF exposures does not increase CNS tumor risk as was suggested by previous investigations. The results of this study also do not support the EMF-tumor promotion hypothesis. ^

Characteristics and experiences of past participants in the Texas Peer Assistance Program for Nurses

There are nearly 200,000 licensed practicing nurses in the state of Texas, representing one-tenth of the nations' workforce. The prevalence of substance abuse among nurses is estimated to range between six and 20 percent in this professional group.^ Since March 1987, the Texas Peer Assistance Program for Nurses (TPAPN) has offered intervention, education, support and monitoring to nurses in Texas whose practice has become impaired due to substance abuse and/or mental illness. Since then approximately 44 percent of nurses who voluntarily signed participation agreements successfully completed the program; fifty-six percent have not. One determinant of completion for those nurses identified as chemically dependent is abstinence from mood altering substances. Other helping professions report higher rates of abstinence two years following treatment.^ The purpose of this study was to investigate the relationship between relapse, demographics, treatment variables, work setting, "stress" indicators and support factors for nurses who participated in TPAPN. A questionnaire was mailed to 1000 randomly selected nurses who had signed agreements since 1987 and were no longer active in the program. More than 41% of the questionnaires were returned undeliverable.^ Recipients of the questionnaire were known only to TPAPN, never to the investigator. All information was received anonymously except when the participant chose to sign the questionnaire. A cover letter explaining the study and inviting participation was enclosed. Completion and return of the questionnaire was considered consent to participate.^ Findings demonstrated a significant relationship between relapse and opiates as the drug of choice for past participants in the Texas Peer Assistance Program for Nurses. Significant associations were found among factors such as control at work, support, physical complaints, job security, self-esteem and employment in this sample. Respondents shared copious written comments about their experiences in TPAPN. These data were analyzed using qualitative methods and compared with similar studies of recovering nurses. Further research with nurses whose practice has been affected by abuse of chemical and mental illness is warranted. ^

Leukemia and occupational exposure to electromagnetic fields: An incident case-control study

The existence of an association between leukemia and electromagnetic fields (EMF) is still controversial. The results of epidemiologic studies of leukemia in occupational groups with exposure to EMF are inconsistent. Weak associations have been seen in a few studies. EMF assessment is lacking in precision. Reported dose-response relationships have been based on qualitative levels of exposure to EMF without regard to duration of employment or EMF intensity on the jobs. Furthermore, potential confounding factors in the associations were not often well controlled. The current study is an analysis of the data collected from an incident case-control study. The primary objective was to test the hypothesis that occupational exposure to EMF is associated with leukemia, including total leukemia (TL), myelogenous leukemia (MYELOG) and acute non-lymphoid leukemia (ANLL). Potential confounding factors: occupational exposure to benzene, age, smoking, alcohol consumption, and previous medical radiation exposures were controlled in multivariate logistic regression models. Dose-response relationships were estimated by cumulative occupational exposure to EMF, taking into account duration of employment and EMF intensity on the jobs. In order to overcome weaknesses of most previous studies, special efforts were made to improve the precision of EMF assessment. Two definitions of EMF were used and result discrepancies using the two definitions were observed. These difference raised a question as to whether the workers at jobs with low EMF exposure should be considered as non-exposed in future studies. In addition, the current study suggested use of lifetime cumulative EMF exposure estimates to determine dose-response relationship. The analyses of the current study suggest an association between ANLL and employment at selected jobs with high EMF exposure. The existence of an association between three types of leukemia and broader categories of occupational EMF exposure, is still undetermined. If an association does exist between occupational EMF exposure and leukemia, the results of the current study suggest that EMF might only be a potential factor in the promotion of leukemia, but not its initiation. ^

THE NATURAL AND ORTHOGONAL INTERACTION (NOIA) MODELS FOR QUANTITATIVE TRAITS (QTs) AND COMPLEX DISEASES

My dissertation focuses on developing methods for gene-gene/environment interactions and imprinting effect detections for human complex diseases and quantitative traits. It includes three sections: (1) generalizing the Natural and Orthogonal interaction (NOIA) model for the coding technique originally developed for gene-gene (GxG) interaction and also to reduced models; (2) developing a novel statistical approach that allows for modeling gene-environment (GxE) interactions influencing disease risk, and (3) developing a statistical approach for modeling genetic variants displaying parent-of-origin effects (POEs), such as imprinting. In the past decade, genetic researchers have identified a large number of causal variants for human genetic diseases and traits by single-locus analysis, and interaction has now become a hot topic in the effort to search for the complex network between multiple genes or environmental exposures contributing to the outcome. Epistasis, also known as gene-gene interaction is the departure from additive genetic effects from several genes to a trait, which means that the same alleles of one gene could display different genetic effects under different genetic backgrounds. In this study, we propose to implement the NOIA model for association studies along with interaction for human complex traits and diseases. We compare the performance of the new statistical models we developed and the usual functional model by both simulation study and real data analysis. Both simulation and real data analysis revealed higher power of the NOIA GxG interaction model for detecting both main genetic effects and interaction effects. Through application on a melanoma dataset, we confirmed the previously identified significant regions for melanoma risk at 15q13.1, 16q24.3 and 9p21.3. We also identified potential interactions with these significant regions that contribute to melanoma risk. Based on the NOIA model, we developed a novel statistical approach that allows us to model effects from a genetic factor and binary environmental exposure that are jointly influencing disease risk. Both simulation and real data analyses revealed higher power of the NOIA model for detecting both main genetic effects and interaction effects for both quantitative and binary traits. We also found that estimates of the parameters from logistic regression for binary traits are no longer statistically uncorrelated under the alternative model when there is an association. Applying our novel approach to a lung cancer dataset, we confirmed four SNPs in 5p15 and 15q25 region to be significantly associated with lung cancer risk in Caucasians population: rs2736100, rs402710, rs16969968 and rs8034191. We also validated that rs16969968 and rs8034191 in 15q25 region are significantly interacting with smoking in Caucasian population. Our approach identified the potential interactions of SNP rs2256543 in 6p21 with smoking on contributing to lung cancer risk. Genetic imprinting is the most well-known cause for parent-of-origin effect (POE) whereby a gene is differentially expressed depending on the parental origin of the same alleles. Genetic imprinting affects several human disorders, including diabetes, breast cancer, alcoholism, and obesity. This phenomenon has been shown to be important for normal embryonic development in mammals. Traditional association approaches ignore this important genetic phenomenon. In this study, we propose a NOIA framework for a single locus association study that estimates both main allelic effects and POEs. We develop statistical (Stat-POE) and functional (Func-POE) models, and demonstrate conditions for orthogonality of the Stat-POE model. We conducted simulations for both quantitative and qualitative traits to evaluate the performance of the statistical and functional models with different levels of POEs. Our results showed that the newly proposed Stat-POE model, which ensures orthogonality of variance components if Hardy-Weinberg Equilibrium (HWE) or equal minor and major allele frequencies is satisfied, had greater power for detecting the main allelic additive effect than a Func-POE model, which codes according to allelic substitutions, for both quantitative and qualitative traits. The power for detecting the POE was the same for the Stat-POE and Func-POE models under HWE for quantitative traits.

Social integration, health behaviors and health status among Mexican-American women in the *southwestern United States

Using the Hispanic Health and Nutrition Examination Survey (HHANES), this research examined several health behaviors and the health status of Mexican American women. This study focused on determining the relative impact of social contextual factors: age, socioeconomic status, quality of life indicators, and urban/rural residence on (a) health behaviors (smoking, obesity and alcohol use) and (b) health status (physician's assessment of health status, subject's assessment of health status and blood pressure levels). In addition, social integration was analyzed. The social integration indicators relate to an individual's degree of integration within his/her social group: marital status, level of acculturation (a continuum of traditional Mexican ways to dominant U.S. cultural ways), status congruency, and employment status. Lastly, the social contextual factors and social integration indicators were examined to identify those factors that contribute most to understanding health behaviors and health status among Mexican American women.^ The study found that the social contextual factors and social integration indicators proved to be important concepts in understanding the health behaviors. Social integration, however, did not predict health status except in the case of the subject's assessment of health status. Age and obesity were the strongest predictors of blood pressure. The social contextual factors and obesity were significant predictors of the physician's assessment of health status while acculturation, education, alcohol use and obesity were significant predictors of the subject's assessment of health status. ^

The role of drug use in welfare to work: Evidence from Houston, Texas

The purpose of this study is to examine the prevalence of drug abuse among welfare recipients in Houston, TX and compare the work activities and employment barriers of drug abusers in order to better understand the potential effects of welfare reform for this population. Four hypotheses were tested comparing the work activities and employment barriers of drug abusers to others on welfare and the relative importance of drug abuse and employment barriers in predicting work activity. ^ This cross-sectional study examined the characteristics and work activities of 447 welfare recipients (81 drug abusers and 366 non-abusers) who were surveyed between October 1998 and April 1999 in Houston, TX. Subjects were introduced and recruited to participate in the study through a flyer, door to door visits, and peer driven recruitment/referral. ^ About 18% were found to be drug abusers, which is consistent with the national average (10–33%) among welfare recipients. Compared to others on welfare, drug abusers were less involved in work activities, and had more employment barriers. Employment barriers were found to be more predictive of welfare to work activities than drug abuse. The results suggest that alleviating employment barriers should be stressed in programs aimed at welfare recipients with drug abuse problems. ^

Funding the utilization of community health workers in Texas

Community health workers (CHWs) are volunteers or paid members of communities that perform outreach, patient assistance, health education, and assist in navigation of healthcare system amongst other duties. The utilization of CHWs in hospital and community setting provides health benefits to their communities while reducing cost to the overall healthcare system. ^ The general population of Texas lacks adequate access to primary care. An important indicator of such a crisis is excessive usage of emergency department services in Texas, especially by the large minority population within the state. Also, unmanaged chronic diseases have been shown to be correlated with the excessive usage of emergency services. According to a recent survey of 25 Houston metropolitan area hospitals, almost 54% of the ER visits could have been resolved in primary care settings. A Galveston based study also indicated that the ER usage was higher amongst African-Americans and Latinos. Meanwhile, 28.5% of the total ER visits were made by Latinos from the surrounding areas (Begley et al., 2007). There is substantial evidence present which indicates enormous cost-savings that CHWs have produced in Texas and nationwide through reduction in unnecessary ER visits along with better management of chronic diseases (Fedder et al, 2003). ^ This paper provides an analysis regarding the need and importance for sustainable and stable sources of funding for Community health workers (CHWs) in Texas utilizing Kingdon's model of Agenda Setting as framework. The policy analysis is also aimed at reporting on the policy process and actions taken by Children at Risk to address this critical issue. Children at Risk, a Houston based advocacy organization, has created a legislative proposal that calls on the Texas Health and Human Commission to apply for a Medicaid §§1115 waiver to provide sustainable sources of funding for CHWs, Rep. John Zerwas sponsored HB 2244 bill and it was filed on March 3, 2011. The bill would affect the use of CHWs in Texas in two ways: 1) through the establishment and operation of a program designed to train and educate CHWs 2) by creating a statewide training and certification advisory committee. The advisory committee is required in the bill to submit recommendations for providing sustainable funding and employment for CHWs. The HB 2244 failed to move out of the House Public Health committee. However, HB2244 was amended into HB 2610 introduced by Representative Guillen. The House Bill 2610 is geared towards establishing a community-based navigator program in order to assist individuals applying for public assistance through the Internet. The House Bill 2610 was signed by the Governor and will be effective September 1, 2011.^

Baseline quality of life as a predictor of exercise intervention adherence among endometrial cancer survivors

Background: The objective of this analysis is to test whether baseline quality of life (QOL) measurements, body mass index (BMI) and prior exercise behavior are significantly associated with (1) telephone counseling adherence, and (2) activity at the final assessment, in a physical activity promoting intervention among endometrial cancer survivors.^ Methods: One hundred endometrial cancer survivors not currently meeting physical activity guidelines completed baseline QOL and anthropometric assessments to measure general physical and mental health [Medical Outcomes Survey (SF-36)], sleep patterns and sleep quality [Pittsburgh Sleep Quality Index (PSQI)], perceived stress [Perceived Stress Scale (PSS)], cancer-specific concerns of long-term survivors [Quality of Life in Adult Cancer Survivors (QLACS)], and psychological distress [Brief Symptom Inventory-18 (BSI-18)]. Survivors were counseled by telephone during the 6-month intervention and their completion rate determined their adherence. The primary variables of interest included age, baseline BMI, baseline activity level, time since diagnosis, education, treatment received, and the SF-36 physical and mental component scores.^ Results: Final activity was most closely linked with baseline activity (p<.001) and less invasive surgery, being leaner and older, and experiencing less pain and more vitality. Telephone counseling was also predicted well by baseline activity, working less and having better overall cancer-related functioning.^ Conclusion: Above and beyond the QOL measures, baseline activity was the strongest predictor of both final activity and telephone counseling adherence. While education, surgery treatment type and bodily pain were important predictors for final exercise and employment status and cancer-related quality of life were important predictors for telephone counseling adherence, considering adaptive exercise interventions that focus heavily on engaging inactive participants may be a way to produce better exercise-related outcomes in the endometrial cancer survivor population.^