Medicine and Health Sciences Commons^™

Single-Trait And Multi-Trait Genome-Wide Association Analyses Identify Novel Loci For Blood Pressure In African-Ancestry Populations, Jingjing Liang, Thu H. Le, Digna R. Velez Edwards, Bamidele O. Tayo, Kyle J. Gaulton, Jennifer A. Smith, Yingchang Lu, Richard A. Jensen, Guanjie Chen, Lisa R. Yanek, Karen Schwander, Salman M. Tajuddin, Tamar Sofer, Wonji Kim, James Kayima, Colin A. Mckenzie, Ervin Fox, Michael A. Nalls, J. Hunter Young, Yan V. Sun, Jacqueline M. Lane, Sylvia Cechova, Jie Zhou, Hua Tang, Myriam Fornage, Solomon K. Musani, Heming Wang, Juyoung Lee, Adebowale Adeyemo, Albert W. Dreisbach, Donna K. Arnett

Epidemiology and Environmental Health Faculty Publications

Hypertension is a leading cause of global disease, mortality, and disability. While individuals of African descent suffer a disproportionate burden of hypertension and its complications, they have been underrepresented in genetic studies. To identify novel susceptibility loci for blood pressure and hypertension in people of African ancestry, we performed both single and multiple-trait genome-wide association analyses. We analyzed 21 genome-wide association studies comprised of 31,968 individuals of African ancestry, and validated our results with additional 54,395 individuals from multi-ethnic studies. These analyses identified nine loci with eleven independent variants which reached genome-wide significance (P < 1.25×10⁻⁸) for either systolic and …

Discovery And Fine-Mapping Of Adiposity Loci Using High Density Imputation Of Genome-Wide Association Studies In Individuals Of African Ancestry: African Ancestry Anthropometry Genetics Consortium, Maggie C. Y. Ng, Mariaelisa Graff, Yingchang Lu, Anne E. Justice, Poorva Mudgal, Ching-Ti Liu, Kristin Young, Lisa R. Yanek, Mary F. Feitosa, Mary K. Wojczynski, Kristin Rand, Jennifer A. Brody, Brian E. Cade, Latchezar Dimitrov, Qing Duan, Xiuqing Guo, Leslie A. Lange, Michael A. Nalls, Hayrettin Okut, Salman M. Tajuddin, Bamidele O. Tayo, Sailaja Vedantam, Jonathan P. Bradfield, Guanjie Chen, Wei-Min Chen, Alessandra Chesi, Marguerite R. Irvin, Badri Padhukasahasram, Jennifer A. Smith, Wei Zheng, Donna K. Arnett

Epidemiology and Environmental Health Faculty Publications

Genome-wide association studies (GWAS) have identified > 300 loci associated with measures of adiposity including body mass index (BMI) and waist-to-hip ratio (adjusted for BMI, WHR_adjBMI), but few have been identified through screening of the African ancestry genomes. We performed large scale meta-analyses and replications in up to 52,895 individuals for BMI and up to 23,095 individuals for WHR_adjBMI from the African Ancestry Anthropometry Genetics Consortium (AAAGC) using 1000 Genomes phase 1 imputed GWAS to improve coverage of both common and low frequency variants in the low linkage disequilibrium African ancestry genomes. In the sex-combined analyses, we identified …

Outcomes After Diagnosis Of Mild Cognitive Impairment In A Large Autopsy Series, Erin L. Abner, Richard J. Kryscio, Frederick A. Schmitt, David W. Fardo, Daniela C. Moga, Eseosa T. Ighodaro, Gregory A. Jicha, Lei Yu, Hiroko H. Dodge, Chengjie Xiong, Randall L. Woltjer, Julie A. Schneider, Nigel J. Cairns, David A. Bennett, Peter T. Nelson

Epidemiology and Environmental Health Faculty Publications

OBJECTIVE: To determine clinical and neuropathological outcomes following a clinical diagnosis of mild cognitive impairment (MCI).

METHODS: Data were drawn from a large autopsy series (N = 1,337) of individuals followed longitudinally from normal or MCI status to death, derived from 4 Alzheimer Disease (AD) Centers in the United States.

RESULTS: Mean follow‐up was 7.9 years. Of the 874 individuals ever diagnosed with MCI, final clinical diagnoses were varied: 39.2% died with an MCI diagnosis, 46.8% with a dementia diagnosis, and 13.9% with a diagnosis of intact cognition. The latter group had pathological features resembling those with a final clinical …

Cpt1a Methylation Is Associated With Plasma Adiponectin, S. Aslibekyan, A. N. Do, H. Xu, S. Li, M. R. Irvin, D Zhi, H. K. Tiwari, D. M. Absher, A. R. Shuldiner, T. Zhang, W. Chen, K. Tanner, C. Hong, B. D. Mitchell, G. Berenson, Donna K. Arnett

Epidemiology and Environmental Health Faculty Publications

Background and Aims—Adiponectin, an adipose-secreted protein that has been linked to insulin sensitivity, plasma lipids, and inflammatory patterns, is an established biomarker for metabolic health. Despite clinical relevance and high heritability, the determinants of plasma adiponectin levels remain poorly understood.

Methods and Results—We conducted the first epigenome-wide cross-sectional study of adiponectin levels using methylation data on 368,051 cytosine-phosphate-guanine (CpG) sites in CD4+ T-cells from the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN, n= 991). We fit linear mixed models, adjusting for age, sex, study site, T-cell purity, and family. We have identified a positive association (regression …

Association Of Body Mass Index With Dna Methylation And Gene Expression In Blood Cells And Relations To Cardiometabolic Disease: A Mendelian Randomization Approach, Michael M. Mendelson, Riccardo E. Marioni, Roby Joehanes, Chunyu Liu, Åsa K. Hedman, Stella Aslibekyan, Ellen W. Demerath, Weihua Guan, Degui Zhi, Chen Yao, Tianxiao Huan, Christine Willinger, Brian Chen, Paul Courchesne, Michael Multhaup, Marguerite R. Irvin, Ariella Cohain, Eric E. Schadt, Megan L. Grove, Jan Bressler, Kari North, Johan Sundström, Stefan Gustafsson, Sonia Shah, Allan F. Mcrae, Sarah E. Harris, Jude Gibson, Paul Redmond, Janie Corley, Lee Murphy, Donna K. Arnett

Epidemiology and Environmental Health Faculty Publications

Background

The link between DNA methylation, obesity, and adiposity-related diseases in the general population remains uncertain.

Methods and Findings

We conducted an association study of body mass index (BMI) and differential methylation for over 400,000 CpGs assayed by microarray in whole-blood-derived DNA from 3,743 participants in the Framingham Heart Study and the Lothian Birth Cohorts, with independent replication in three external cohorts of 4,055 participants. We examined variations in whole blood gene expression and conducted Mendelian randomization analyses to investigate the functional and clinical relevance of the findings. We identified novel and previously reported BMI-related differential methylation at 83 CpGs …

Dna Methylation Signatures Of Chronic Low-Grade Inflammation Are Associated With Complex Diseases, Symen Ligthart, Carola Marzi, Stella Aslibekyan, Michael M. Mendelson, Karen N. Conneely, Toshiko Tanaka, Elena Colicino, Lindsay L. Waite, Roby Joehanes, Weihua Guan, Jennifer A. Brody, Cathy Elks, Riccardo Marioni, Min A. Jhun, Golareh Agha, Jan Bressler, Cavin K. Ward-Caviness, Brian H. Chen, Tianxiao Huan, Kelly Bakulski, Elias L. Salfati, Whi-Empc Investigators, Giovanni Fiorito, Charge Epigenetics Of Coronary Heart Disease, Simone Wahl, Katharina Schramm, Jin Sha, Dena G. Hernandez, Allan C. Just, Jennifer A. Smith, Donna K. Arnett

Epidemiology and Environmental Health Faculty Publications

Background: Chronic low-grade inflammation reflects a subclinical immune response implicated in the pathogenesis of complex diseases. Identifying genetic loci where DNA methylation is associated with chronic low-grade inflammation may reveal novel pathways or therapeutic targets for inflammation.

Results: We performed a meta-analysis of epigenome-wide association studies (EWAS) of serum C-reactive protein (CRP), which is a sensitive marker of low-grade inflammation, in a large European population (n = 8863) and trans-ethnic replication in African Americans (n = 4111). We found differential methylation at 218 CpG sites to be associated with CRP (P < 1.15 × 10^–7) in the discovery panel …

A Dna Methylation Biomarker Of Alcohol Consumption, C. Liu, R. E. Marioni, Å. K. Hedman, L. Pfeiffer, P. -C. Tsai, L. M. Reynolds, A. C. Just, Q. Duan, C. G. Boer, T. Tanaka, C. E. Elks, S. Aslibekyan, J. A. Brody, B. Kühnel, C. Herder, L. M. Almli, D. Zhi, Y. Wang, T. Huan, C. Yao, M. M. Mendelson, R. Joehanes, L. Liang, S. -A. Love, W. Guan, S. Shah, A. F. Mcrae, A. Kretschmer, H. Prokisch, K. Strauch, Donna K. Arnett

Epidemiology and Environmental Health Faculty Publications

The lack of reliable measures of alcohol intake is a major obstacle to the diagnosis and treatment of alcohol-related diseases. Epigenetic modifications such as DNA methylation may provide novel biomarkers of alcohol use. To examine this possibility, we performed an epigenome-wide association study of methylation of cytosine-phosphate-guanine dinucleotide (CpG) sites in relation to alcohol intake in 13 population-based cohorts (n_total=13 317; 54% women; mean age across cohorts 42–76 years) using whole blood (9643 European and 2423 African ancestries) or monocyte-derived DNA (588 European, 263 African and 400 Hispanic ancestry) samples. We performed meta-analysis and variable selection in …

Accuracy Of Name And Age Data Provided About Network Members In A Social Network Study Of People Who Use Drugs: Implications For Constructing Sociometric Networks, April M. Young, Abby E. Rudolph, Amanda E. Su, Lee King, Susan Jent, Jennifer R. Havens

Epidemiology and Environmental Health Faculty Publications

Purpose—Network analysis has become increasingly popular in epidemiologic research, but the accuracy of data key to constructing risk networks is largely unknown. Using network data from people who use drugs (PWUD), the study examined how accurately PWUD reported their network members’ (i.e., alters’) names and ages.

Methods—Data were collected from 2008 to 2010 from 503 PWUD residing in rural Appalachia. Network ties (n=897) involved recent (past 6 months) sex, drug co-usage, and/or social support. Participants provided alters’ names, ages, and relationship-level characteristics; these data were cross-referenced to that of other participants to identify participant-participant relationships and to determine …

Epigenetics Of Lipid Phenotypes, Sergi Sayols-Baixeras, Marguerite R. Irvin, Donna K. Arnett, Roberto Elosua, Stella W. Aslibekyan

Epidemiology and Environmental Health Faculty Publications

Dyslipidemia is a well-established risk factor for cardiovascular disease, the main cause of death worldwide. Blood lipid profiles are patterned by both genetic and environmental factors. In recent years, epigenetics has emerged as a paradigm that unifies these influences. In this review, we have summarized the latest evidence implicating epigenetic mechanisms—DNA methylation, histone modification, and regulation by RNAs—in lipid homeostasis. Key findings have emerged in a number of novel epigenetic loci located in biologically plausible genes (eg, CPT1A, ABCG1, SREBF1, and others), as well as microRNA-33a/b. Evidence from animal and cell culture models suggests a complex interplay …

Association Of Dna Methylation At Cpt1a Locus With Metabolic Syndrome In The Genetics Of Lipid Lowering Drugs And Diet Network (Goldn) Study, Mithun Das, Jin Sha, Bertha Hidalgo, Stella Aslibekyan, Anh N. Do, Degui Zhi, Dianjianyi Sun, Tao Zhang, Shengxu Li, Wei Chen, Sathanur R. Srinivasan, Hemant K. Tiwari, Devin Absher, Jose M. Ordovas, Gerald S. Berenson, Donna K. Arnett, Marguerite R. Irvin

Epidemiology and Environmental Health Faculty Publications

In this study, we conducted an epigenome-wide association study of metabolic syndrome (MetS) among 846 participants of European descent in the Genetics of Lipid Lowering Drugs and Diet Network (GOLDN). DNA was isolated from CD4+ T cells and methylation at ~470,000 cytosine-phosphate-guanine dinucleotide (CpG) pairs was assayed using the Illumina Infinium HumanMethylation450 BeadChip. We modeled the percentage methylation at individual CpGs as a function of MetS using linear mixed models. A Bonferroni-corrected P-value of 1.1 x 10⁻⁷ was considered significant. Methylation at two CpG sites in CPT1A on chromosome 11 was significantly associated with MetS (P for cg00574958 = …

Will Hiv Vaccination Reshape Hiv Risk Behavior Networks? A Social Network Analysis Of Drug Users' Anticipated Risk Compensation, April M. Young, Daniel S. Halgin, Ralph J. Diclemente, Claire E. Sterk, Jennifer R. Havens

Epidemiology and Environmental Health Faculty Publications

Background

An HIV vaccine could substantially impact the epidemic. However, risk compensation (RC), or post-vaccination increase in risk behavior, could present a major challenge. The methodology used in previous studies of risk compensation has been almost exclusively individual-level in focus, and has not explored how increased risk behavior could affect the connectivity of risk networks. This study examined the impact of anticipated HIV vaccine-related RC on the structure of high-risk drug users' sexual and injection risk network.

Methods

A sample of 433 rural drug users in the US provided data on their risk relationships (i.e., those involving recent unprotected sex …

Hiv Vaccine Acceptability Among High-Risk Drug Users In Appalachia: A Cross-Sectional Study, April M. Young, Ralph J. Diclemente, Daniel S. Halgin, Claire E. Sterk, Jennifer R. Havens

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: A vaccine could substantially impact the HIV epidemic, but inadequate uptake is a serious concern. Unfortunately, people who use drugs, particularly those residing in rural communities, have been underrepresented in previous research on HIV vaccine acceptability. This study examined HIV vaccine acceptability among high-risk drug users in a rural community in the United States.

METHODS: Interviewer-administered questionnaires included questions about risk behavior and attitudes toward HIV vaccination from 433 HIV-negative drug users (76% with history of injection) enrolled in a cohort study in Central Appalachia. HIV vaccine acceptability was measured on a 4-point Likert scale. Generalized linear mixed models …

Type And Dose Of Radiotherapy Used For Initial Treatment Of Non-Metastatic Prostate Cancer, Dian Wang, Alex Ho, Ann S. Hamilton, Xiao-Cheng Wu, Mary Lo, Steven Fleming, Michael Goodman, Trevor Thompson, Jean Owen

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: We sought to describe patterns of initial radiotherapy among non-metastatic prostate cancer (PC) patients by recurrence risk groups.

METHODS: Medical records were abstracted for a sample of 9017 PC cases diagnosed in 2004 as a part of the Center for Disease Control and Prevention's Prostate and Breast Patterns of Care Study in seven states. Non-metastatic PC cases are categorized as low-risk (LR), intermediate-risk (IR) or high-risk (HR) groups based on pretreatment PSA, tumor stage, and Gleason score per 2002 NCCN guidelines. Univariate and multivariate analyses were employed to determine factors associated with the type and dose of radiotherapy by …

Human Papillomavirus Genotype Prevalence In Invasive Penile Cancers From A Registry-Based United States Population, Brenda Y. Hernandez, Marc T. Goodman, Elizabeth R. Unger, Martin Steinau, Amy Powers, Charles F. Lynch, Wendy Cozen, Maria Sibug Saber, Edward S. Peters, Edward J. Wilkinson, Glenn Copeland, Claudia Hopenhayn, Youjie Huang, Meg Watson, Sean F. Altekruse, Christopher Lyu, Mona Saraiya, The Hpv Typing Of Cancer Workgroup

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: Human papillomavirus (HPV) is estimated to play an etiologic role in 40-50% of penile cancers worldwide. Estimates of HPV prevalence in U.S. penile cancer cases are limited.

METHODS: HPV DNA was evaluated in tumor tissue from 79 invasive penile cancer patients diagnosed in 1998-2005 within the catchment areas of seven U.S. cancer registries. HPV was genotyped using PCR-based Linear Array and INNO-LiPA assays and compared by demographic, clinical, and pathologic characteristics and survival. Histological classification was also obtained by independent pathology review.

RESULTS: HPV DNA was present in 50 of 79 (63%) of invasive penile cancer cases. Sixteen viral …

Population Cancer Risks Associated With Coal Mining: A Systematic Review, Wiley D. Jenkins, W. Jay Christian, Georgia Mueller, K. Thomas Robbins

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: Coal is produced across 25 states and provides 42% of US energy. With production expected to increase 7.6% by 2035, proximate populations remain at risk of exposure to carcinogenic coal products such as silica dust and organic compounds. It is unclear if population exposure is associated with increased risk, or even which cancers have been studied in this regard.

METHODS: We performed a systematic review of English-language manuscripts published since 1980 to determine if coal mining exposure was associated with increased cancer risk (incidence and mortality).

RESULTS: Of 34 studies identified, 27 studied coal mining as an occupational exposure …

Significant Sequelae After Bacterial Meningitis In Niger: A Cohort Study, Jean-François Jusot, Zilahatou Tohon, Abdoul Aziz Yazi, Jean-Marc Collard

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: Beside high mortality, acute bacterial meningitis may lead to a high frequency of neuropsychological sequelae. The Sahelian countries belonging to the meningitis belt experience approximately 50% of the meningitis cases occurring in the world. Studies in Africa have shown that N. meningitidis could cause hearing loss in up to 30% of the cases, exceeding sometimes measles. The situation is similar in Niger which experiences yearly meningitis epidemics and where rehabilitation wards are rare and hearing aids remain unaffordable. The aim of this study was to estimate the frequency of neuropsychological sequelae after acute bacterial meningitis in four of the …

Task-Based Noise Exposures For Farmers Involved In Grain Production, Michael J. Humann, Wayne T. Sanderson, Kelley J. Donham, Kevin M. Kelly

Epidemiology and Environmental Health Faculty Publications

Few studies have been done examining noise exposures associated with agricultural tasks. This study was conducted to address that research gap by calculating the noise exposures for tasks and equipment associated with grain production and assessing the variability in those exposures. An additional aim of this study was to identify tasks and equipment that could be targeted for intervention strategies as a means toward reducing the total noise exposures of farmers and farm workers. Through the use of personal noise dosimetry and direct observation, over 30,000 one-minute noise exposure measurements and corresponding task and equipment data were collected on 18 …

Cattle-Related Injuries And Farm Management Practices On Kentucky Beef Cattle Farms, Steven R. Browning, Susan C. Westneat, Wayne T. Sanderson, Deborah B. Reed

Epidemiology and Environmental Health Faculty Publications

While working on farms with livestock increases the risk of injury among farm workers in comparison to other commodity farms, few studies have examined the role offarm management practices in association with the risk of cattle-related injury. We examined the farm management practices of Kentucky beef cattle farms in association with self-reported rates of cattle-related injuries among workers. We conducted a mail survey of a random sample of 2,500 members of the Kentucky Cattlemen's Association. Results from 1,149 farm operators who were currently raising beef cattle and provided complete survey response are reported. During the busy season, the principal operator …

Does Place Of Residence Affect Risk Of Suicide? A Spatial Epidemiologic Investigation In Kentucky From 1999 To 2008, Daniel M. Saman, Sabrina Walsh, Anna Borówko, Agricola Odoi

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: Approximately 32,000 people take their own lives every year in the United States. In Kentucky, suicide mortality rates have been steadily increasing since 1999. Few studies in the United States have assessed spatial clustering of suicides. The purpose of this study was to identify high-risk clusters of suicide at the county level in Kentucky and assess the characteristics of those suicide cases within the clusters.

METHODS: A spatial epidemiological study was undertaken using suicide data for the period January 1, 1999 to December 31, 2008, obtained from the Kentucky Office of Vital Statistics. Descriptive analyses using Pearson's chi-square test …

A Spatial Cluster Analysis Of Tractor Overturns In Kentucky From 1960 To 2002, Daniel M. Saman, Henry P. Cole, Agricola Odoi, Melvin L. Myers, Daniel I. Carey, Susan C. Westneat

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: Agricultural tractor overturns without rollover protective structures are the leading cause of farm fatalities in the United States. To our knowledge, no studies have incorporated the spatial scan statistic in identifying high-risk areas for tractor overturns. The aim of this study was to determine whether tractor overturns cluster in certain parts of Kentucky and identify factors associated with tractor overturns.

METHODS: A spatial statistical analysis using Kulldorff's spatial scan statistic was performed to identify county clusters at greatest risk for tractor overturns. A regression analysis was then performed to identify factors associated with tractor overturns.

RESULTS: The spatial analysis …

Atrazine Exposure In Public Drinking Water And Preterm Birth, Jessica L. Rinsky, Claudia Hopenhayn, Vijay Golla, Steven R. Browning, Heather M. Bush

Epidemiology and Environmental Health Faculty Publications

Objectives

Approximately 13% of all births occur prior to 37 weeks gestation in the U.S. Some established risk factors exist for preterm birth, but the etiology remains largely unknown. Recent studies have suggested an association with environmental exposures. We examined the relationship between preterm birth and exposure to a commonly used herbicide, atrazine, in drinking water.

Methods

We reviewed Kentucky birth certificate data for 2004–2006 to collect duration of pregnancy and other individual-level covariates. We assessed existing data sources for atrazine levels in public drinking water for the years 2000–2008, classifying maternal county of residence into three atrazine exposure groups. …

Farmwork-Related Injury Among Farmers 50 Years Of Age And Older In Kentucky And South Carolina: A Cohort Study, 2002-2005, Jennifer L. Marcum, Steven R. Browning, Deborah B. Reed, Richard Charnigo

Epidemiology and Environmental Health Faculty Publications

Farmers in the U.S. are becoming more diverse; the average age of the farmer is increasing, as is the number of women and minority farm operators. There is limited research on injury risk factors in these special populations of farmers. It is especially important to study the risk factors for injury in these growing and at-risk groups. A longitudinal survey was conducted of farmers (n = 1,394) age 50 and older who resided in Kentucky and South Carolina. The questionnaire was administered by telephone and mail surveys four times between 2002 and 2005 to the fixed cohort of farmers, obtained …

Does Comorbidity Explain The Ethnic Inequalities In Cervical Cancer Survival In New Zealand? A Retrospective Cohort Study, Naomi Brewer, Barry Borman, Diana Sarfati, Mona Jeffreys, Steven T. Fleming, Soo Cheng, Neil Pearce

Epidemiology and Environmental Health Faculty Publications

BACKGROUND: There are large ethnic differences in cervical cancer survival in New Zealand that are only partly explained by stage at diagnosis. We investigated the association of comorbidity with cervical cancer survival, and whether comorbidity accounted for the previously observed ethnic differences in survival.

METHODS: The study involved 1,594 cervical cancer cases registered during 1994-2005. Comorbidity was measured using hospital events data and was classified using the Elixhauser instrument; effects on survival of individual comorbid conditions from the Elixhauser instrument were also assessed. Cox regression was used to estimate adjusted cervical cancer mortality hazard ratios (HRs).

RESULTS: Comorbidity during the …

Suicides Among Farmers In Three Southeastern States, 1990-1998, Steven R. Browning, Susan C. Westneat, Robert H. Mcknight

Epidemiology and Environmental Health Faculty Publications

Several studies have documented higher rates of suicide among farmers in comparison to other occupational groups, both in the U.S. and internationally. The purpose of this study is to describe the epidemiology of farmer suicides in three southeastern states (Kentucky, North Carolina, and South Carolina) during the nine-year period 1990-1998. Electronic death certificate data were obtained from the National Center for Health Statistics. Over the nine-year period, there were 590 deaths related to suicide (E-codes: 950-959) among farmers (occupation codes: 473, 474, 475, 477, and 479) in the states of Kentucky, North Carolina, and South Carolina. The results of this …

Tractor Driving Among Kentucky Farm Youth: Results From The Farm Family Health And Hazard Surveillance Project, Steven R. Browning, Susan C. Westneat, Raeanne Szeluga

Epidemiology and Environmental Health Faculty Publications

This article documents the extent of children's involvement in tractor operations among a representative sample of Kentucky children living and working on family farms. Specifically, we describe children's exposures to tractor-related work activities, profile their use of the tractor (number of days worked), and assess compliance with generally recommended safety measures, such as using tractors equipped with ROPS (rollover protective structures), avoiding riding as passengers on tractors, and operating tractors on public roadways. Data for this study were collected in 1994 and 1995 as part of the NIOSH-sponsored Farm Family Health and Hazard Surveillance Project (FFHHSP). Despite recognition in the …