Steven R. Browning

Arsenic exposure from drinking water and birth weight

Background: Arsenic exposures from drinking water increase the risk of various cancers and noncancer health endpoints. Limited evidence suggests that arsenic may have adverse human reproductive effects. We investigated the association between drinking water arsenic exposure and fetal growth, as manifest in birth weight. Methods: We conducted a prospective cohort study in two Chilean cities with contrasting drinking water arsenic levels: Antofagasta (40 &mgr;g/L) and Valparaíso (<1 &mgr;g/L). Study subjects completed in-depth interviews and provided urine samples for exposure analysis. We obtained pregnancy and birth information from medical records. The birth weight analysis was restricted to liveborn, singleton infants born between December 1998 and February 2000. Results: The final study group consisted of 424 infants from Antofagasta and 420 from Valparaíso. After controlling for confounders, results of the multivariable analysis indicated that Antofagasta infants had lower mean birth weight (–57 g; 95% confidence interval = –123 to 9). Conclusion: This study suggests that moderate arsenic exposures from drinking water (<50 &mgr;g/L) during pregnancy are associated with reduction in birth weight, similar in magnitude to that resulting from other environmental exposures such as environmental tobacco smoke and benzene.

Cancer mortality among electric utility workers exposed to polychlorinated biphenyls.

OBJECTIVES: To assess whether excess mortality from cancer, malignant melanoma of the skin, and cancers of the brain and liver in particular, is associated with long term occupational exposure to polychlorinated biphenyls (PCBs). METHODS: An epidemiological study of mortality was conducted among 138,905 men employed for at least six months between 1950 and 1986 at five electrical power companies in the United States. Exposures were assessed by panels composed of workers, hygienists, and managers at each company, who considered tasks performed by workers in 28 job categories and estimated weekly exposures in hours for each job. Poisson regression was used to examine mortality in relation to exposure to electrical insulating fluids containing PCBs, controlling for demographic and occupational factors. RESULTS: Neither all cause nor total cancer mortality was related to cumulative exposure to PCB insulating fluids. Mortality from malignant melanoma increased with exposure; rate ratios (RRs) relative to unexposed men for melanoma were 1.23 (95% confidence interval (95% CI) 0.56 to 2.52), 1.71 (0.68 to 4.28) and 1.93 (0.52 to 7.14) for men with < 2000, > 2000-10,000, and > 10,000 hours of cumulative exposure to PCB insulating fluids, respectively, without consideration of latency. Lagging exposure by 20 years yielded RRs of 1.29 (0.76 to 2.18), 2.56 (1.09 to 5.97), and 4.81 (1.49 to 15.50) for the same exposure levels. Mortality from brain cancer was modestly increased among men with < 2000 hours (RR 1.61, 95% CI 0.86 to 3.01) and > 2000-10,000 hours exposure (RR 1.79, 95% CI 0.81 to 3.95), but there were no deaths from brain cancer among the most highly exposed men. A lag of five years yielded slightly increased RRs. Mortality from liver cancer was not associated with exposure to PCB insulating fluids. CONCLUSIONS: This study was larger and provided more detailed information on exposure than past investigations of workers exposed to PCBs. The results suggest that PCBs cause cancer, with malignant melanoma being of particular concern in this industry.

Agricultural injuries among older Kentucky farmers : The Farm Family Health and Hazard Surveillance Study

This population-based study reports the cumulative incidence of agricultural injuries during a 1-year period in a sample of 998 farmers aged 55 years and older living in Kentucky. A total of 98 farm-related injuries were reported among 88 older farmers for a crude injury rate of 9.03 injured farmers per 100 farmers (95% confidence interval (CI) = 7.03-11.03) over a 1-year period. The leading external causes of farm injury were falls (24.9%), machinery (22.5%), wood-cutting (14.6%), and animal-related events (14.3%). Farmers working on farms with beef cattle (alone) (odds ratio = 1.90; 95% CI = 1.02-3.55) or farms with beef cattle and tobacco (odds ratio = 2.15; 95% CI = 1.00-4.59) had a statistically significant increased risk for a farm-related injury. Farmers reporting a prior injury that limited their ability to farm were at increased risk for a farm-related injury. Approaches to using farm injury surveillance data for injury control programs in the state are discussed.

A Database Analysis of Potentially Inappropriate Drug Use in an Elderly Medicaid Population

We conducted a cross‐sectional retrospective review of 1996 Kentucky Medicaid Pharmacy claims data to examine the prevalence of potentially inappropriate drug use in 64,832 Medicaid recipients aged 65 years and older who received a prescription. Twenty‐seven percent of patients received at least one potentially inappropriate agent. Prevalence was higher for nursing home residents (33%) than for community dwellers (24%). Amitriptyline (7.6%), propoxyphene (6.5%), doxepin (4.0%), and indomethacin (2.3%) were the most prescribed potentially inappropriate agents. Education programs and interventions aimed at optimizing the prescribing and dispensing of the most appropriate drugs are needed.

Bone Markers Predict Cardiovascular Events in Chronic Kidney Disease

Recent studies have indicated a link between bone metabolism and cardiovascular events in patients with chronic kidney disease (CKD). CKD is a major health problem worldwide. This study evaluates the role of noninvasive markers of bone metabolism in predicting cardiovascular morbidity (coronary artery disease, peripheral vascular disease, stroke) and mortality in patients with mild to severe forms of CKD. In a prospective cohort study, 627 patients with CKD were screened. To focus on bone metabolism, traditional risk factors for cardiovascular events were excluded, and 135 patients with CKD stages 1–5 were followed for 4 yr. Glomerular filtration rate was calculated by the Modification of Diet in Renal Disease formula. PTH (measured by four different assays), vitamin D 25 and 1,25, bone‐specific alkaline phosphatase (BSALP), TRACP‐5b, osteocalcin, serum collagen cross‐link molecules, RANKL, and osteoprotegerin were determined. Predictors of cardiovascular events were evaluated by multivariable logistic regression, Kaplan‐Meier survival, and Cox regression analysis. There were a total of 45 cardiovascular events (33%). Event rates were 5.6%, 29.1%, 45.2%, and 45.0% in CKD stages 1–2, 3, 4, and 5, respectively. In logistic regression, cardiovascular events were predicted only by (1) CKD stage (independent of age or sex; p < 0.001); (2) BSALP (p = 0.03); and (3) TRACP‐5b (p = 0.04). Markers of bone formation (BSALP) and resorption (TRACP‐5b) can serve as predictors of cardiovascular morbidity and mortality in CKD.

Atrazine exposure in public drinking water and preterm birth.

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. We used logistic regression to analyze the relationship between atrazine exposure and preterm birth, controlling for maternal age, race/ethnicity, education, smoking, and prenatal care. Results. An increase in the odds of preterm birth was found for women residing in the counties included in the highest atrazine exposure group compared with women residing in counties in the lowest exposure group, while controlling for covariates. Analyses using the three exposure assessment approaches produced odds ratios ranging from 1.20 (95% confidence interval [CI] 1.14, 1.27) to 1.26 (95% CI 1.19, 1.32), for the highest compared with the lowest exposure group. Conclusions. Suboptimal characterization of environmental exposure and variables of interest limited the analytical options of this study. Still, our findings suggest a positive association between atrazine and preterm birth, and illustrate the need for an improved assessment of environmental exposures to accurately address this important public health issue.

Sleep deprivation and injuries in part-time Kentucky farmers: impact of self reported sleep habits and sleep problems on injury risk.

Part-time farmers who hold off-farm jobs may be at risk for injuries because of impaired performance resulting from inadequate sleep. For this study, 1,004 part-time male Kentucky farmers completed a telephone interview for the 1994 to 1995 National Institute for Occupational Safety and Health-funded Farm Family Health and Hazard Surveillance Project. Questions were included about demographics, sleep habits, and injury occurrence. Twelve percent of the farmers reported an injury requiring medical intervention in the previous year. Farmers reported sleeping an average of 7.6 hours daily. Approximately 6.7% of the sample had three symptoms of sleep apnea. Although hours of sleep were not related to injury incidence, sleep medication use (odds ratio [OR] = 2.11, 95% confidence interval [CI] = 1.01 to 4.40) and presence of three sleep apnea symptoms (OR = 2.48, 95% CI = 1.13 to 5.41) were related to injury incidence. These data support the need for further research to examine sleep habits and promote strategies that reduce the risk for injuries caused by lack of sleep

The Hidden Work of the Farm Homemaker

Despite women’s involvement in agricultural production, the work role of women residing in farm households has not been thoroughly examined. Data collected in 1994-1995 as part of the NIOSH-sponsored Farm Family Health and Hazard Surveillance Project were used to address task issues and health status of farm women in Kentucky. In 1996, the farm woman component of the Kentucky study was replicated in five counties in west Texas, allowing an examination of farm women in two large agricultural states. The Kentucky study employed a two-stage cluster design; the Texas study was based on a systematic quota sample of farms. Both studies selected a sample of women aged 18 years and older living in farm households. A total of 992 women in Kentucky (response rate = 85%) and 665 women in Texas completed a structured 30-min telephone interview on work roles, health status, injuries, and demographics. The results indicated that although 46.4% of the Kentucky respondents and 46.3% of the Texas respondents characterized themselves as farm homemakers, they regularly engaged in farmwork. Reported tasks included work with animals, tobacco-related chores, field irrigation, farm equipment operation, and farm management. Further, women who characterized themselves as homemakers reported rates of farm injuries that were comparable with women who classified themselves in other roles such as full agricultural partners. Role definition may influence the woman’s perception of risk on the farm, preclude participation in farm safety programs, and prevent an accurate occupational medical history. This two-state descriptive study highlights the hidden work role of the farm woman—a role that remains invisible to the farm woman herself—and emphasizes the important occupational exposures that farm women encounter.

Secondhand Tobacco Smoke Exposure, Nicotine Dependence, and Smoking Cessation

OBJECTIVE To explore the association among the number of sources of secondhand tobacco smoke (SHS) exposure, nicotine dependence (ND), and smoking cessation. DESIGN A secondary analysis of cross-sectional data. Responses for the main study were obtained in 2001 from a controlled trial of the Quit and Win Tobacco Free Contest in Kentucky. SAMPLE 822 current smokers. MEASUREMENTS Demographic variables (age, gender, educational status, income, and ethnicity) the number of sources of SHS exposure, smoking frequency, length of abstinence from smoking, age of smoking initiation, smoking cessation attempts, intentions to quit smoking, and ND. RESULTS The number of sources of SHS exposure was associated with higher ND and smoking frequency, and related to low intentions and attempts to quit smoking. The number of sources of SHS exposure contributed to 11% of the variance in the final ND model, after accounting for control and potential mediating variables. CONCLUSIONS The number of sources of SHS exposure may be an important factor influencing ND and intentions and attempts to quit smoking. Further studies are needed to explore the association between SHS exposure and ND among smokers to guide treatment and policy development.

Self-reported head injury and risk of late-life impairment and AD pathology in an AD Center cohort

Aims: To evaluate the relationship between self-reported head injury and cognitive impairment, dementia, mortality, and Alzheimers disease (AD)-type pathological changes. Methods: Clinical and neuropathological data from participants enrolled in a longitudinal study of aging and cognition (n = 649) were analyzed to assess the chronic effects of self-reported head injury. Results: The effect of self-reported head injury on the clinical state depended on the age at assessment: for a 1-year increase in age, the OR for the transition to clinical mild cognitive impairment (MCI) at the next visit for participants with a history of head injury was 1.21 and 1.34 for the transition from MCI to dementia. Without respect to age, head injury increased the odds of mortality (OR = 1.54). Moreover, it increased the odds of a pathological diagnosis of AD for men (OR = 1.47) but not women (OR = 1.18). Men with a head injury had higher mean amyloid plaque counts in the neocortex and entorhinal cortex than men without. Conclusions: Self-reported head injury is associated with earlier onset, increased risk of cognitive impairment and dementia, increased risk of mortality, and AD-type pathological changes.