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Rationale: Recent U.S. data suggest an increased risk of work-related asthma among health care workers, yet only a few specific determinants have been elucidated.Objectives: To evaluate associations of asthma prevalence with occupational exposures in a cross-sectional survey of health care professionals.Methods: A detailed questionnaire was mailed to a random sample (n=5,600) of all Texas physicians, nurses, respiratory therapists, and occupational therapists with active licenses in 2003. Information on asthma symptoms and nonoccupational asthma risk factors obtained from the questionnaire was linked to occupational exposures derived through an industry-specific job-exposure matrix.Measurements: There were two a priori defined outcomes: (1) physician-diagnosed asthma with onset after entry into health care ("reported asthma") and (2) "bronchial hyperresponsiveness-related symptoms," defined through an 8-item symptom-based predictor.Main Results: Overall response rate was 66%. The final study population consisted of 862 physicians, 941 nurses, 968 occupational therapists, and 879 respiratory therapists (n=3,650). Reported asthma was associated with medical instrument cleaning (odds ratio [OR], 2.22; 95% confidence interval [CI], 1.34-3.67), general cleaning (OR, 2.02; 95% CI, 1.20-3.40), use of powdered latex gloves between 1992 and 2000 (OR, 2.17; 95% CI, 1.27-3.73), and administration of aerosolized medications (OR, 1.72; 95% CI, 1.05-2.83). The risk associated with latex glove use was not apparent after 2000. Bronchial hyperresponsiveness-related symptoms were associated with general cleaning (OR, 1.63; 95% CI, 1.21-2.19), aerosolized medication administration (OR, 1.40; 95% CI, 1.06-1.84), use of adhesives on patients (OR, 1.65; 95% CI, 1.22-2.24), and exposure to a chemical spill (OR, 2.02; 95% CI, 1.28-3.21).Conclusions: The contribution of occupational exposures to asthma in health care professionals is not trivial, meriting both implementation of appropriate controls and further study. [ABSTRACT FROM AUTHOR]

This study assessed potential biases introduced by using maternal proxies for reporting work hazards, illness symptoms, and acute agricultural injuries in studies of migrant farmworker families. A convenience sample of 79 mother/spouse and mother/oldest child pairs was obtained from a two-year cohort study of migrant farmworker families from Starr County, Texas. Pairs completed an interviewer-administered survey including 27 close-ended items describing work history, illness symptoms, and acute injuries during the 2001 migration season. Data analysis included prevalence, sensitivity, and specificity measures. Maternal proxy reports of subjective symptoms of a spouse or child were approximately 50% lower than spouse or child self-reports. Sensitivity and specificity of mothers' responses regarding hazard items were higher for spouses than for children. For items measuring illness symptoms, sensitivity of mothers' responses for spouses and oldest child pairs was generally less than 30%; however, specificity was generally above 90%. For acute agricultural injury, the mother/spouse sensitivity was 75%, the mother/child 40%, and specificities were 100% and 97%, respectively. Sensitivity and specificity for mother/ spouse pairs was generally higher than mother/child pairs for work hazards, illness symptoms and acute injuries. While mothers may be acceptable proxies for spouses in this population, efforts should be made to collect data directly from adolescent children in studies of agricultural injuries. [ABSTRACT FROM AUTHOR]

The choice of dopaminergic therapy in early Parkinson disease (PD) is an important clinical decision, yet factors influencing this decision have not been extensively studied. We sought to investigate the factors that may be associated with the choice of dopaminergic therapy at the NINDS Exploratory Trials in PD (NET-PD) Long-Term Study-1 (LS1). NET-PD LS1 was a clinical trial of creatine versus placebo in participants with early, mild PD on stable doses of dopaminergic therapy. Baseline data from 1616 out of the 1741 participants were evaluated using univariable and multivariable logistic or generalized logit regression analyses for available factors associated with the choice of dopaminergic therapy. The dopaminergic therapy choice was determined as: (i) therapy that subjects recalled taking 180days before the study; (ii) therapy at baseline; and (iii) the longest duration of therapy reported by participants. Younger age, higher education level, longer length of time since PD diagnosis and use of an adjunctive, non-dopaminergic or monoamine oxidase inhibitor medication were associated with more frequent use of dopamine agonist compared to levodopa or combination therapy., (Copyright © 2016 Elsevier B.V. All rights reserved.)

The psychostimulants considered the gold standard in the treatment of attention deficit hyperactivity disorder, one of the most common childhood disorders, are also finding their way into the hands of healthy young adults as brain augmentation to improve cognitive performance. The possible long-term effects of psychostimulant exposure in adolescence are considered controversial, and thus, the objective of this study was to investigate whether the chronic exposure to the psychostimulant amphetamine affects the behavioral diurnal rhythm activity patterns of female adolescent Wistar-Kyoto (WKY) rat. The hypothesis of this study is that change in diurnal rhythm activity pattern is an indicator for the long-term effect of the treatment. Twenty-four rats were divided into two groups, control (N = 12) and experimental (N = 12), and kept in a 12:12-h light/dark cycle in an open-field cage. After 5-7 days of acclimation, 11 days of consecutive non-stop behavioral recordings began. On experimental day 1 (ED1), all groups were given an injection of saline. On ED2 to ED7, the experimental group was injected with 0.6 mg/kg amphetamine followed by 3 days of washout from ED8 to ED10, and amphetamine re-challenge on ED11 similar to ED2. The locomotor movements were counted by the computerized animal activity monitoring system, and the cosinor statistical test analysis was used to fit a 24-h curve of the control recording to the activity pattern after treatment. The horizontal activity, total distance, number of stereotypy, vertical activity, and stereotypical movements were analyzed to find out whether the diurnal rhythm activity patterns were altered. Data obtained using these locomotor indices of diurnal rhythm activity pattern suggest that amphetamine treatment significantly modulates the locomotor diurnal rhythm activity pattern of female WKY adolescent rats.

Given disproportionate burden of physical inactivity among US Hispanics and emerging interests in the potential role of the built environment on physical activity, we tested the hypothesis that residing in a more walkable block group is associated with increased physical activity in a cohort of Mexican-American adults. 10,183 Mexican-American adults from Houston, TX, USA were studied. Physical activity was assessed through self-report. Geographical information systems were used to create a "walkability index" (WI). We examined the relationship between WI and physical activity using regression models. Findings for the entire study population suggested a direct association between neighborhood walkability and physical activity that approached statistical significance (High WI vs. Low WI: OR = 1.16; 95% CI 0.95-1.40). Furthermore, participants who lived in a higher WI neighborhood were more likely to meet physical activity guidelines in 2 groups: (1) men whose recreational physical activity included walking (High WI vs. Low WI: OR = 5.43; 95% CI 1.30-22.73) and (2) men whose only recreational physical activity was (High WI vs. Low WI: OR = 9.54; 95% CI 1.84-49.60). Our findings suggest gender differences in the association between the built environment and physical activity in Mexican-American adults. Attempts to encourage walking among Mexican-American adults may be easier in high-walkability neighborhoods than in low-walkability neighborhoods.

A prospective, multicenter phase I trial was undertaken by the North American Clinical Trials Network (NACTN) to investigate the pharmacokinetics and safety of, as well as obtain pilot data on, the effects of riluzole on neurological outcome in acute spinal cord injury (SCI). Thirty-six patients, with ASIA impairment grades A-C (28 cervical and 8 thoracic) were enrolled at 6 NACTN sites between April 2010 and June 2011. Patients received 50 mg of riluzole PO/NG twice-daily, within 12 h of SCI, for 14 days. Peak and trough plasma concentrations were quantified on days 3 and 14. Peak plasma concentration (Cmax) and systemic exposure to riluzole varied significantly between patients. On the same dose basis, Cmax did not reach levels comparable to those in patients with amyotrophic lateral sclerosis. Riluzole plasma levels were significantly higher on day 3 than on day 14, resulting from a lower clearance and a smaller volume of distribution on day 3. Rates of medical complications, adverse events, and progression of neurological status were evaluated by comparison with matched patients in the NACTN SCI Registry. Medical complications in riluzole-treated patients occurred with incidences similar to those in patients in the comparison group. Mild-to-moderate increase in liver enzyme and bilirubin levels were found in 14-70% of patients for different enzymes. Three patients had borderline severe elevations of enzymes. No patient had elevated bilirubin on day 14 of administration of riluzole. There were no serious adverse events related to riluzole and no deaths. The mean motor score of 24 cervical injury riluzole-treated patients gained 31.2 points from admission to 90 days, compared to 15.7 points for 26 registry patients, a 15.5-point difference (p=0.021). Patients with cervical injuries treated with riluzole had more-robust conversions of impairment grades to higher grades than the comparison group.

Methylphenidate (MPD) is one of the most prescribed pharmacological agents, which is also used for cognitive enhancement and recreational purposes. The objective of this study was to investigate the repetitive dose-response effects of MPD on circadian rhythm of locomotor activity pattern of female WKY rats. The hypothesis is that a change in the circadian activity pattern indicates a long-lasting effect of the drug. Four animal groups (saline control, 0.6, 2.5, and 10.0 mg/kg MPD dose groups) were housed in a sound-controlled room at 12:12 light/dark cycle. All received saline injections on experimental day 1 (ED 1). On EDs 2-7, the control group received saline injection; the other groups received 0.6, 2.5, or 10.0 mg/kg MPD, respectively. On ED 8-10, injections were withheld. On ED 11, each group received the same dose as EDs 2-7. Hourly histograms and cosine statistical analyses calculating the acrophase (ϕ), amplitude (A), and MESOR (M) were applied to assess the 24-h circadian activity pattern. The 0.6 and 2.5 mg/kg MPD groups exhibited significant (p < 0.05) change in their circadian activity pattern on ED 11. The 10.0 mg/kg MPD group exhibited tolerance on ED 11 and also a significant change in activity pattern on ED 8 compared to ED 1, consistent with withdrawal behavior (p < 0.007). In conclusion, chronic MPD administration alters circadian locomotor activity of adult female WKY rats and confirms that chronic MPD use elicits long-lasting effects.

Cocaine is one of well-known drugs of abuse, and many children experience early exposure to cocaine. Because of an immature neuronal system in adolescents, they may react differently to repeated cocaine administration compared to adults. Most of the published papers report the effect of cocaine on adult male rats and this paper focused on the effects of cocaine on the 24 h locomotor activity rhythm patterns activity of adolescent Sprague Dawley (SD) female rats. Changes in the locomotor activity rhythm patterns could indicate that cocaine elicits long-term changes in the clock genes of the body that regulate different physiological processes. The objective of this study was to investigate whether cocaine in adolescent female rats modulated their daily activity pattern. Animals were divided into control (saline), 3.0, 7.5, 15.0 mg/kg cocaine groups. On experimental day 1 (ED 1), all groups were given saline injection. From ED 2 to ED 7, either saline or cocaine (3.0, 7.5, or 15.0 mg/kg) was given daily. ED 8 to ED 10 were the washout days, where no injection was given. On ED 11, the animals were injected with saline or with the same dose of cocaine as they were treated on ED 2 to ED 7. Each animal's locomotor activities was recorded nonstop following saline or cocaine injection for 11 consecutive days using the open field assay. In conclusion, it was observed that all three groups receiving repeated cocaine administration (3.0, 7.5, and 15.0 mg/kg) displayed significantly altered locomotor activity rhythm patterns.

Objectives: Potential gains in life expectancy (PGLEs) that give proper consideration to competing risks are an effective indicator for measuring the impact of multiple causes of death on a defined population. This study aimed to assess PGLE by hypothetically reducing the major causes of death in the USA from 2001 to 2008., Study Design: PGLEs due to the reduction and elimination of heart disease, cancer, Alzheimer's disease, kidney disease or human immunodeficiency virus/acquired immunodeficiency syndrome (HIV/AIDS) were calculated by age, gender and race., Methods: Age-specific mortality rates for the above diseases from the National Center for Health Statistics were used, and multiple decremental life tables were constructed to compute the corresponding PGLEs., Results: PGLEs due to the elimination of heart disease, cancer or HIV/AIDS decreased from 2001 to 2008, but PGLEs due to the elimination of Alzheimer's disease or kidney disease increased over time. For heart disease, PGLE in 2001-2008 for all races was 2.78-2.15 for females vs 2.41-2.06 for males. For cancer, PGLE in 2001-2008 for all races was 2.97-2.81 for females vs 3.02-2.85 for males. HIV/AIDS has a greater impact on people of working age, whereas Alzheimer's disease has a greater impact on the elderly population. To compare the impacts of these diseases on life expectancy, partial multiple decremental life tables were constructed, and PGLEs were computed by a partial reduction or complete elimination of various causes of death for the entire life span as well as for certain working ages., Conclusion: This study outlined a picture of how each category of diseases could affect life expectancy in the US population by age, race or sex. The findings may assist in evaluating current public health improvements, and also provide useful information for directing future research and disease control programmes., (Copyright © 2013 The Royal Society for Public Health. Published by Elsevier Ltd. All rights reserved.)

Object: Pulmonary complications are the most common acute systemic adverse events following spinal cord injury (SCI), and contribute to morbidity, mortality, and increased length of hospital stay (LOS). Identification of factors associated with pulmonary complications would be of value in prevention and acute care management. Predictors of pulmonary complications after SCI and their effect on neurological recovery were prospectively studied between 2005 and 2009 at the 9 hospitals in the North American Clinical Trials Network (NACTN)., Methods: The authors sought to address 2 specific aims: 1) define and analyze the predictors of moderate and severe pulmonary complications following SCI; and 2) investigate whether pulmonary complications negatively affected the American Spinal Injury Association (ASIA) Impairment Scale conversion rate of patients with SCI. The NACTN registry of the demographic data, neurological findings, imaging studies, and acute hospitalization duration of patients with SCI was used to analyze the incidence and severity of pulmonary complications in 109 patients with early MR imaging and long-term follow-up (mean 9.5 months). Univariate and Bayesian logistic regression analyses were used to analyze the data., Results: In this study, 86 patients were male, and the mean age was 43 years. The causes of injury were motor vehicle accidents and falls in 80 patients. The SCI segmental level was in the cervical, thoracic, and conus medullaris regions in 87, 14, and 8 patients, respectively. Sixty-four patients were neurologically motor complete at the time of admission. The authors encountered 87 complications in 51 patients: ventilator-dependent respiratory failure (26); pneumonia (25); pleural effusion (17); acute lung injury (6); lobar collapse (4); pneumothorax (4); pulmonary embolism (2); hemothorax (2), and mucus plug (1). Univariate analysis indicated associations between pulmonary complications and younger age, sports injuries, ASIA Impairment Scale grade, ascending neurological level, and lesion length on the MRI studies at admission. Bayesian logistic regression indicated a significant relationship between pulmonary complications and ASIA Impairment Scale Grades A (p = 0.0002) and B (p = 0.04) at admission. Pulmonary complications did not affect long-term conversion of ASIA Impairment Scale grades., Conclusions: The ASIA Impairment Scale grade was the fundamental clinical entity predicting pulmonary complications. Although pulmonary complications significantly increased LOS, they did not increase mortality rates and did not adversely affect the rate of conversion to a better ASIA Impairment Scale grade in patients with SCI. Maximum canal compromise, maximum spinal cord compression, and Acute Physiology and Chronic Health Evaluation-II score had no relationship to pulmonary complications.

Object: The aim of this multicenter, prospective study was to determine the spectrum, incidence, and severity of complications during the initial hospitalization of patients with spinal cord injury., Methods: The study was conducted at 9 university-affiliated hospitals that comprise the clinical centers of the North American Clinical Trials Network (NACTN) for Treatment of Spinal Cord Injury. The study population comprised 315 patients admitted to NACTN clinical centers between June 25, 2005, and November 2, 2010, who had American Spinal Injury Association (ASIA) Impairment Scale grades of A-D and were 18 years of age or older. Patients were managed according to a standardized protocol., Results: The study population was 79% male with a median age of 44 years. The leading causes of injury were falls (37%) and motor vehicle accidents (28%). The distribution of initial ASIA grades were A (40%), B (16%), C (15%), and D (29%). Fifty-eight percent of patients sustained 1 or more severe, moderate, or mild complications. Complications were associated with more severe ASIA grade: 84% of patients with Grade A and 25% of patients with Grade D had at least 1 complication. Seventy-eight percent of complications occurred within 14 days of injury. The most frequent types of severe and moderate complications were respiratory failure, pneumonia, pleural effusion, anemia, cardiac dysrhythmia, and severe bradycardia. The mortality rate was 3.5% and was associated with increased age and preexisting morbidity., Conclusions: Knowledge of the type, frequency, time of occurrence, and severity of specific complications that occur after spinal cord injury can aid in their early detection, treatment, and prevention. The data are of importance in evaluating and selecting therapy for clinical trials.

In the immediate period after traumatic spinal cord injury (SCI) a variety of secondary injury mechanisms combine to gradually expand the initial lesion size, potentially leading to diminished neurological outcomes at long-term follow-up. Riluzole, a benzothiazole drug, which has neuroprotective properties based on sodium channel blockade and mitigation of glutamatergic toxicity, is currently an approved drug that attenuates the extent of neuronal degeneration in patients with amyotrophic lateral sclerosis. Moreover, several preclinical SCI studies have associated riluzole administration with improved functional outcomes and increased neural tissue preservation. Based on these findings, riluzole has attracted considerable interest as a potential neuroprotective drug for the treatment of SCI. Currently, a Phase I trial evaluating the safety and pharmacokinetic profile of riluzole in human SCI patients is being conducted by the North American Clinical Trials Network (NACTN) for Treatment of Spinal Cord Injury. The current review summarizes the existing preclinical and clinical literature on riluzole, provides a detailed description of the Phase I trial, and suggests potential opportunities for future investigation. Clinical trial registration no.: NCT00876889.

The North American Clinical Trials Network (NACTN) for the Treatment of Spinal Cord Injury is a consortium of 10 neurosurgery departments, a data management center, and a pharmacological center. The NACTN was established with the goal of bringing recent molecular and cell-based discoveries in neuroprotection and regeneration from the laboratory into clinical trials that optimize meaningful data outcomes and maximum safety to patients. The requirements of planning and executing clinical trials in spinal cord injury (SCI) and the steps that the NACTN has taken to address these requirements are discussed and illustrated in articles in this issue of the Journal of Neurosurgery: Spine. The progress that the NACTN has made in meeting these goals can be summarized as organizing a network of hospitals capable of enrolling a sufficient number of patients for conducting Phase I and II trials; creating a Data Management Center and a database of the natural history of recovery after SCI (at the time of this writing 485 patients were enrolled in the database); creating a database of the incidence and severity of complications that occur during acute and subacute treatment after SCI; developing a Pharmacological Center capable of performing pharmacokinetic and pharmacodynamic studies of therapeutic drugs; completing enrollment of 36 patients in NACTN's first clinical trial, a Phase I study of riluzole, a neuroprotective drug; and performing pharmacokinetic and pharmacodynamic studies of riluzole in acute SCI.

Circadian pattern of activity regulates many aspects of mammalian physiology and behavior to particular times of the day by entraining the circadian clocks to external environmental signals. Since circadian rhythms are sensitive to many pharmacological agents, it is important to understand if the repetitive use of psychostimulants such as amphetamine will alter the circadian rhythm behavioral activity pattern. The present study uses male Sprague-Dawley rats to study the long-term effects of amphetamine on the locomotor circadian rhythm activity pattern. Rats were randomly assigned to a testing cage that recorded their locomotor activity nonstop for eleven days using the open field assay, as follows: one day of baseline activity was recorded and then the experimental group was injected with amphetamine (0.6mg/kg) for 6days, no treatment for 3days (i.e., washout days) and then re-challenged with amphetamine for one more day while the control group was treated similarly with saline. The Cosine Curve Statistical Analysis (CCSA) test was used to fit a 24-hour curve to activity pattern. Results indicate that repetitive daily amphetamine injections cause behavioral sensitization and a significant change of circadian rhythm of locomotor activity pattern, and elicit behavioral expectation to receive the drug or expression of withdrawal during the washout days. The results suggest that either changes in circadian rhythm caused sensitization and withdrawal or sensitization and withdrawal caused the change in circadian rhythm activity., (Published by Elsevier B.V.)

Objective: Low levels of safety climate and training have been associated with higher occurrence of occupational-related health outcomes; workplace violence and verbal abuse could be considered an early indicator of escalating psychological workplace violence. We examined whether low level of safety factors were associated with a higher prevalence of verbal abuse at the workplace., Methods: We used data from a cross-sectional survey administered among a stratified random sample of 1,000 employees from 10 of the 29 public hospitals in Costa Rica. Odds ratios (OR) and 95% confidence intervals (95%CI) were calculated using survey logistic regression models to estimate the association between safety factors and verbal abuse from the following sources: administrators, supervisors, patients, patients' relatives and coworkers., Results: There was a high prevalence of verbal abuse among the healthcare workforce from both external (i.e., patients and patients' relatives) and internal workplace sources (i.e., coworkers, supervisors and administrators). A low level of safety climate was associated with verbal abuse from all sources with associations ranging from verbal abuse from administrators (OR=6.07; 95%CI: 2.05-17.92) to verbal abuse from patients (OR=2.24; 95%CI: 1.23-4.09)., Conclusion: These results highlight the need to address organizational characteristics of the workplace that may increase the risk of verbal abuse for the future development of prevention interventions in this setting.

Objective: The objectives of the study were to detect high-risk areas and to examine how racial and ethnic status affect the geographic distribution of female breast cancer mortality in Texas. Analyses were based on county-level data for the years from 2000 to 2008., Materials and Methods: Breast cancer mortality data were obtained from the Texas Cancer Registry, and the Spatial Scan Statistics method was used to run Purely Spatial Analyses using the Discrete Poisson, Bernoulli, and Multinomial models., Results and Conclusions: Highest rates of female breast cancer mortality in Texas have shifted over time from southeastern areas towards northern and eastern areas, and breast cancer mortality at the county level is distributed heterogeneously based on racial/ethnic status. Non-Hispanic blacks were at highest risk in the northeastern region and lowest risk in the southern region, while Hispanics were at highest risk in the southern region along the border with Mexico and lowest risk in the northeastern region.

Diurnal rhythms influence many of the physiological processes that act to maintain homeostasis of the body in response to different environmental changes. Thus, disturbances in diurnal rhythms can lead to various physiological complications. Repeated exposure to psychostimulants may cause long-term effects by disturbing diurnal rhythms. The aim of the present study is to use the open field assay to determine whether repeated exposure to the psychostimulant methylphenidate (MPD) changes diurnal locomotor activity patterns of female adult Sprague-Dawley (SD) rats. As much as 31 female adult SD rats were divided into four groups. On experimental day (ED) 1, all groups were given an injection of saline. On ED 2-7, animals were injected once a day with either saline, or 0.6 mg/kg MPD, or 2.5 mg/kg MPD, or 10 mg/kg MPD depending on the group. On ED 8-10, no injections were given (washout period). On ED 11, animals were treated as they were on ED 2-7. Locomotor movements were recorded using a computerized animal activity monitoring system. The horizontal activity (HA), total distance traveled (TDT), and number of stereotypies (NOS) were analyzed by cosine curve statistical analysis (CCSA) test. The HA and TDT diurnal rhythm activity patterns of ED 2, 7, 8, and 11 were significantly different (p < 0.05) from the control recording of ED 1 according to the CCSA test. The observation obtained in this study suggests that repeated administration of MPD (all doses tested) is able to change diurnal locomotor patterns, which indicates that chronic MPD treatment exerts long-term effects.

Attention Deficit Hyperactivity Disorder (ADHD) is a common behavioral disorder of children and is treated by psychostimulants. Psychostimulant exposure to children at the time of neuronal development can cause behavioral and physiological changes continuing during adulthood. Most of the studies on psychostimulants investigate the acute effects of the drug. The objective of this study was to investigate whether acute or chronic exposure to methylphenidate (MPD), the drug most often used to treat ADHD in children, will modulate the diurnal activity pattern of young rats. Maintaining the diurnal activity pattern is a physiological process that regulates the internal homeostasis. Dose response protocol was used to study the effect of acute and chronic MPD in four young post natal day 40 (P 40) rat groups, (each N=8), as follows: saline (control) group, and 0.6, 2.5, or 10.0 mg/kg i.p. MPD groups, respectively. The experiment was performed over 11 consecutive days of continuous locomotor activity recording using the open field assay. The data evaluation was divided into four phases as follows: acute, induction, washout and expression phases. There was a dose-dependent increase in the average locomotor activity in the first few hours post-injection. Analysis of the diurnal rhythmic pattern of locomotion in the three dose groups compared to control demonstrated that only the 10.0 mg/kg MPD elicited significant changes in diurnal pattern activity in the washout and the expression phase. In addition, this study indicated that chronic MPD treatment elicits dose dependent anticipation and/or withdrawal and behavioral sensitization.

Background: Laboratory evidence is presented of significant associations between reduced maternal serum folate and vitamin B12 levels and neural tube birth defects (NTD) compared to referents., Methods: This was an incident case-control study. Cases of neural tube defects (including anencephaly and open spina bifida) diagnosed in residents within 100 miles of the US-Mexico border from January 1993 to October 2000 were eligible. Most cases were diagnosed in utero upon visits to clinics, obstetrical or genetic expert offices. Cases identified upon hospital admission or at delivery were also eligible. Cases identified after discharge were not. Controls were matched on geographic region, maternal age, race/ethnicity, gestational age, and type of health insurance (including none)., Results: Three hundred eighty-two border area residents (107 cases and 275 individually matched controls) provided biological specimens. Median folate concentrations for case mothers were 36% lower than controls (9.8 ng/mL vs. 15 ng/mL). Maternal serum folate concentrations in quartiles above 9.5 ng/mL indicated significantly reduced risk (OR = 0.4, OR = 0.3, and OR = 0.2). Likewise, the risk for NTD decreased (OR = 0.4, OR = 0.3, and OR = 0.2) in quartiles of sera B12 concentrations above 246 pg/mL., Conclusions: Physician attention is invited to significantly lower concentrations of serum folate and vitamin B12 in women with NTD-affected pregnancies. This study assayed sera samples from women while still pregnant or immediately after delivery. The confounding effect of reduced folate and B12 levels with other biological and chemical exposures will be addressed in subsequent communications.

Methylphenidate (MPD), or Ritalin, is a psychostimulant that is prescribed for an extended period of time to children and adolescents with attention deficit hyperactivity disorder. Adolescence is a time of critical brain maturation and development, and the drug exposure during this time could lead to lasting changes in the brain that endure into the adulthood. Circadian rhythms are 24 h rhythms of physiological processes that are synchronized by the master-clock, the suprachiasmatic nucleus, to keep the body stable in a changing environment. The aim of present study is to observe the effect of repeated MPD exposure on the locomotor diurnal rhythm activity patterns of female adolescent Sprague-Dawley (SD) rats using the open field assay. 31 female adolescent SD rats were divided into four groups: control, 0.6 mg/kg, 2.5 mg/kg, and 10 mg/kg MPD group. On experimental day 1, all groups were given an injection of saline. On experimental days 2-7, animals were injected once a day with either saline, 0.6 mg/kg, 2.5 mg/kg, or 10 mg/kg MPD, and experimental days 8-10 were the washout period. A re-challenge injection was given to each animal on experimental day 11 with the similar dose as the experimental days 2-7. The locomotor movements were counted by the computerized animal activity monitoring system. The data were analyzed statistically to find out whether the diurnal rhythm activity patterns were altered. The obtained data showed that repeated administrations of 2.5 mg/kg and 10 mg/kg MPD were able to change the locomotor diurnal rhythm patterns, which suggests that these MPD doses exerts long-term effects.

Background: We collected sample data on radon concentrations concurrently in the air, water, and soil in the northern part of the Texas-Mexico border (both sides) popularly known as Paso Del Norte., Methods: These field data were used to statistically correlate relative contributions of yard soil, tap water, location, and house features to concentrations of radon indoors., Results: Indoor air radon concentrations in some homes were up to nine-fold the limit recommended by the US Environmental Protection Agency (USEPA). Concentrations of radon in tap water were up to nearly three-fold the recommended limit. Apartments and manufactured homes had generally greater concentrations of indoor radon. Statistically significant associations were indicated between indoor radon air levels and radon in the soil (P < 0.001); radon in the water and radium in water (P = 0.016); radon air levels and apartment living (P = 0.010); and mobile homes vs. wood, brick, and stucco construction (P = 0.016)., Conclusion: Radon soil gas, apartment living, and the aluminum plank wall environment of mobile homes were associated with elevated indoor radon in the homes studied. Physician's attention is invited to the potential nontrivial risk from radon, as it becomes trapped inside enclosed structures. This article is intended to serve as a resource for primary care physicians who want to better understand the distribution and contributing factors for indoor radon. The Surgeon General recommends every US home be tested for radon as of January 13, 2005.

Methylphenidate (MPD) is becoming a drug of abuse among adult professionals and students, alike. Yet, few studies have investigated its long-term effects on the adult population. We hypothesized that prolonged administration of MPD leads to changes in the diurnal horizontal activity (HA) pattern, an effect persisting beyond acute drug effects. Four groups of adult male Sprague-Dawley rats (N=32) were divided into a saline/control, 0.6, 2.5, or 10.0 mg/kg MPD group. Each group was treated with saline on experimental day 1, followed by six consecutive days of designated treatment (days 2-7), then, after three consecutive days of washout (days 8-10), each group was re-challenged with its respective treatment (day 11). Activity was monitored continuously throughout the 11 experimental days. There was a dose-dependent increase in HA in the first hour post-injection. The 0.6 mg/kg MPD group exhibited changes in diurnal activity pattern only during the wash-out period. The 2.5 mg/kg MPD group exhibited the most profound changes in HA after 6 days of continuous injection, washout, and MPD re-challenge (p<0.05, p=0.001, p<0.001) respectively, and the 10.0 mg/kg MPD group exhibited changes during the washout and re-challenge periods (p<0.01, p<0.001), respectively. In conclusion, prolonged administration of MPD modulated the diurnal HA pattern in a dose-dependent manner.

Objectives: This study estimated the prevalence of chronic back pain among migrant farmworker family members and identified associated work and non-work variables., Methods: Migrant farmworkers (n = 390 from 267 families) from Starr County, Texas were interviewed in their home once a year for 2 years. The original survey included items measuring demographics, smoking, sleep, farm work, and chronic back pain. For this cross-sectional analysis, multi-level logistic regression was used to identify associated work and other variables associated with chronic back pain while accounting for intraclass correlations due to repeated measures and multiple family members., Results: The prevalence of chronic back pain during the last migration season ranged from 9.5% among the youngest children to 33.3% among mothers. Variables significantly associated with chronic back pain were age (odds ratio [OR], 1.03, per year increase), depressive symptoms while migrating (OR, 8.72), fewer than 8 hours of sleep at home in Starr County (OR, 2.26), fairly bad/very bad quality of sleep while migrating (OR, 3.25), sorting crops at work (OR, 0.18), and working tree crops (OR, 11.72)., Conclusion: The role of work exposures, depressive symptoms, and sleep in chronic back pain among farmworkers warrants further examination. Refinements in outcome and exposure assessments are also needed given the lack of a standardized case definition and the variety of tasks and crops involved in farm work in the United States.

Background: There is a lack of research on ethnic disparities in survival among patients with non-Hodgkin lymphoma (NHL), although these disparities have been documented for patients with many other tumors., Methods: A retrospective cohort of 13,321 patients diagnosed with incident NHL at age > or = 65 years from 1992 to 1999 were identified from the Surveillance, Epidemiology, and End Results (SEER)-Medicare linked database with 11 years of follow-up. Of these patients, 11,868 were Caucasians, 533 were African Americans, and 920 were other ethnicities. A time-to-event Cox regression model was used to examine the relative risk of all-cause and disease-specific mortality., Results: A larger proportion (72.2%) of African Americans were in the poorest quartile of socioeconomic status as measured by the poverty level compared with 21.8% of Caucasians, and 43.2% of African Americans received chemotherapy compared with 52.4% of Caucasians (P < .01). Hazard ratio of all-cause and NHL-specific mortality increased significantly with age, advanced stage, higher comorbidity scores, and poorer socioeconomic status. Patients receiving either chemotherapy or radiotherapy or both were significantly less likely to die. After taking into account differences in treatment, comorbidity, and socioeconomic status, there was no statistically significant difference in the risk of all-cause (hazard ratio, 0.97; 95% confidence interval, 0.88-1.08) and disease-specific mortality (hazard ratio, 1.07; 95% confidence interval, 0.92-1.25) between African Americans and Caucasians., Conclusions: The risk of mortality in patients with NHL was associated with socioeconomic status and was reduced in patients receiving chemotherapy. No significant differences in the risk of mortality were observed between African Americans and Caucasians after controlling for factors such as treatment and socioeconomic status., ((c) 2008 American Cancer Society)

Background: Injury-related statistics in developing countries are rare., Objective: To assess the relationship between occupational and safety-related risk factors and absences from work during the preceding 6 months due to work-related injury among public hospital employees in Costa Rica., Methods: Data were used from a cross-sectional survey conducted in December 2000 among a stratified random sample of 1000 employees from 10 of the 29 public hospitals in Costa Rica. The questionnaire included sociodemographic data, occupational exposures, and organizational risk factors. A dichotomous variable was created to indicate work-injury absence. At-risk employees (n = 466) were classified as having had a work-injury absence if they reported having been absent for at least 1 day in the preceding 6 months because of a work-related injury. OR and 95% CI were calculated using unconditional logistic regression models., Results: There is a greater likelihood of injury-related absence in non-professional occupational positions (ie, auxiliary personnel (OR = 2.29) and general services employees (OR = 5.55)) than in professional positions, and in employees who show poor compliance with safety practices (OR = 2.03) and have high interference from their job task (OR = 3.79) compared with their counterparts., Conclusions: Work-injury absence appears not only to be a function of work injury, but also a function of occupation and degree of compliance with safety practices.

Background: While both ionizing and nonionizing radiation are known to impair human reproductive capacity, the role of low-level domestic radiation continues to be an unsettled issue., Objectives: We examined the geostatistical distribution (residential longitude and latitude) of orofacial cleft birth cases adjusted for the underlying population distribution. Furthermore, we examined the cleft birth rates enumerated by zip codes for possible associations with levels of radium and radon in drinking water., Methods: Cleft births and unaffected live births in Harris County, Texas, from 1990 to 1994, were geocoded by residential addresses and tested for spatial clusters using the space-time clustering program SaTScan. Historical sample data on local variations in water quality facilitated the assessment of the association of orofacial cleft defect births with low-level radiation exposure., Results: A cluster of significantly greater than expected numbers of cleft defect births was identified in northwest Harris County, (relative risk = 3.0, P = 0.043), where the presence of elevated levels of radium (> 3 pCi/L) and radon (> 300 pCi/L) in the tap water has been known since the 1980s., Conclusions: Despite the ecological design of the study, lacking individual exposure measurements for cleft birth residences, there was strong suggestive evidence of an association between elevated radiation levels in tap water and elevated cleft birth prevalence rates by zip codes. Attention of physicians is invited to environmental causes as potential risk factors for orofacial cleft. This would aid in genetic counseling and the development of future preventive measures.

Purpose: This cohort study is among the first to estimate the prevalence of and examine potential risk factors for severe back pain (resulting in medical care, 4+ hours of time lost, or pain lasting 1+ weeks) among adolescent farmworkers. These youth often perform tasks requiring bent/stooped postures and heavy lifting., Methods: Of 2536 students who participated (response rate across the three public high schools, 61.2% to 83.9%), 410 students were farmworkers (largely Hispanic and migrant). Students completed a self-administered Web-based survey including farm work/nonfarm work and back-pain items relating to a 9-month period., Results: The prevalence of severe back pain was 15.7% among farmworkers and 12.4% among nonworkers. The prevalence increased to 19.1% among farm workers (n = 131) who also did nonfarm work. A multiple logistic regression for farmworkers showed that significantly increased adjusted odds ratios for severe back pain were female sex (4.59); prior accident/back injury (9.04); feeling tense, stressed, or anxious sometimes/often (4.11); lifting/carrying heavy objects not at work (2.98); current tobacco use (2.79); 6+ years involved in migrant farm work (5.02); working with/around knives (3.87); and working on corn crops (3.40)., Conclusions: Areas for further research include ergonomic exposure assessments and examining the effects of doing farm work and nonfarm work simultaneously.

This study analyzed the 1999 to 2003 database of the Center for Disease Control and Prevention (CDC) for seasonal and longer-term time trends in the sexually transmitted diseases (STDs) of chlamydia, gonorrhea, and syphilis in the United States. Linear regression was used to ascertain time trends, and a linear mixed auto-regression model was applied to determine the statistical significance of the major peaks relative to the annualized time series mean. A statistically significant increasing trend during the 5 yr span was documented only in the incidence of chlamydia. No clear annual periodicity was detected in any of the STDs; instead, significant three-month cycles were documented in all the STDs, with prominent peaks evident in March, May, August, and November. The March and May peaks could be associated with the sexual activities of young adults during spring break, which for different colleges and universities, commences as early as mid- to late-February and concludes as late as early- to mid-April, when huge numbers of sexually active youth congregate at beach resort settings. We propose the August peak is representative of summer sexual activity, in particular, of youths during school recess when adult supervision is poor. Finally, the autumn peak seems to be an expression of an endogenous annual rhythm in human reproductive biology, exemplified by elevated levels of testosterone in young males and sexual activity at this time of the year.

The Center for Disease Control (CDC) in the United States collects and maintains records of communicable (so-called notifiable) infectious diseases that cause significant morbidity and mortality and impact the national economy. This investigation focused on seasonal patterns in the primarily childhood and young adult infectious diseases of meningococcal meningitis, mumps, pertussis, typhoid fever, streptococcal toxic shock syndrome (1990 to 2003 CDC database), and varicella (1993 to 2003 CDC database). Linear regression was performed to ascertain the trend in the incidence of each disease, and multi-component cosinor analysis was applied to determine and describe periodicities. Significant decreasing trends in incidence were detected in meningococcal meningitis, mumps, typhoid fever, and streptococcal toxic shock syndrome, and increasing trends were found in pertussis and varicella. Significant annual patterns were documented in meningococcal meningitis (January peak), mumps (April peak), pertussis (August peak), varicella (April peak), typhoid fever (August peak), and in the hospital-acquired streptococcal toxic shock syndrome (February peak). Such seasonal patterns and long-term trends in infectious diseases are of practical public health significance in indicating which can benefit from timely prevention interventions.

Aims: To explore the relation between occupational and organisational factors and work related injuries (WRI) among public hospital employees in Costa Rica., Methods: A cross-sectional survey was conducted among a stratified random sample of 1000 employees from 10 of the 29 public hospitals in Costa Rica. A previously validated, self-administered questionnaire which included occupational and organisational factors and sociodemographic variables was used. From the final eligible sample (n = 859), a total of 842 (response rate 98%) questionnaires were returned; 475 workers were analysed after excluding not-at-risk workers and incomplete questionnaires. WRI were computed for the past six months., Results: Workers exposed to chemicals (RR = 1.36) and physical hazards (RR = 1.26) had higher WRI rate ratios than non-exposed workers. Employees reporting job tasks that interfered with safety practices (RR = 1.46), and a lack of safety training (RR = 1.41) had higher WRI rate ratios than their counterparts. Low levels of safety climate (RR = 1.51) and safety practices (RR = 1.27) were individually associated with an increased risk of WRI. Also, when evaluated jointly, low levels of both safety climate and safety practices showed the highest association with WRI (RR = 1.92)., Conclusions: When evaluated independently, most of the occupational exposures and organisational factors investigated were significantly correlated with an increased injury risk. As expected, some of these associations disappeared when evaluated jointly. Exposure to chemical and physical hazards, lack of safety training, and low levels of safety climate and safety practices remained significant risk factors for WRI. These results will be important to consider in developing future prevention interventions in this setting.

Very little published research describes employer compliance with EPA-mandated Worker Protection Standard (WPS) pesticide safety training and the OSHA Field Sanitation Standard among farmworker women in general and mothers specifically. A goal of both standards is limiting farmworkers' exposure to potentially hazardous agricultural pesticides. Data from a NIOSH-supported cohort study ("Injury and Illness Surveillance in Migrant Farmworker Families") allowed for examining these issues. The cohort included 267 migrant farmworker families who usually reside along the Texas-Mexico border (Starr County, Texas). Data were collected in Starr County during in-home interviews. Of 102 mothers who participated in migrant farm work during summer 2001, 57 (55.9%) reported having ever received training/instruction in the safe use of pesticides, while 47 (46.1%) reported having received training within the previous five years, as required by WPS. Of trained mothers, 91.5% to 93.6% reported that their training covered key WPS areas: (1) entry into a recently treated field, (2) pesticide related injuries/illnesses, and (3) where to go and who to contact for emergency care following exposure. Regarding access to field sanitation, 67.5% to 84.2% of 77 mothers who worked outside Texas reported employer-provided decontamination supplies (e.g., soap, wash water, towels, and toilet facilities). However, a strikingly smaller proportion (12% to 28%) of 25 mothers who worked within Texas reported access to the same resources, suggesting discrepancies in compliance across the U.S. Due to the low level of employer compliance with both WPS and OSHA mandated standards, increased enforcement and an alternate delivery of pesticide training is recommended.

To develop a worker safety training program for its public hospital system, the Costa Rican Social Security System entered into a collaborative agreement with the University of Texas School of Public Health. A national survey to assess safety in the public hospitals revealed high rates of injury and under-reporting of injuries, as well a lack of worker safety training. A program developed based on the results of the survey was implemented using a training-of-trainers model. The program created opportunities for human resource development in occupational health in the hospital system, allowed for the sustainability of the training effort, and reduced dependency on external funding. Over 3700 workers were trained in its first three years, and 57 trainers were established in local hospitals and clinics.

Objective: To investigate the relationship between birth weight and risk of early age childhood cancer and whether racial differences in birth weight distribution could explain differences in the incidence of cancer in white, Hispanic, and black children., Methods: We compared birth weights of 268 children younger than five years old and diagnosed with cancer in the State of Texas in 1995 to the birth weights of 2680 randomly selected, age-matched population-based controls. Birth weight, sex, race/ethnicity, maternal age, smoking status, parity, and gestational age information was ascertained from the birth certificates. Logistic regression analyses were performed to evaluate the association between high birth weight (>4,000 g) and occurrence of childhood cancer., Results: Increased odds ratios (OR) were found for "total cancer cases" (OR 1.4, 95% CI 0.9-2.1), "leukemia cases" (OR 1.7, 95% CI 0.9-3.0) and "acute lymphoblastic leukemia (ALL) cases" (OR 2.2, 95% CI 1.2-4.1). Increased ORs in the former two groups were shown to be due to ALL cases. Including the race/ethnicity variable in the regression model did not affect the ORs., Conclusion: Compared to newborns who weighed between 2500 and 4000 g at birth, children who weighed >4,000 g had an increased risk of developing childhood ALL during the first five years of life. Birth weight differences does not explain the sequence of childhood cancer incidence by race/ethnicity.

Sick Building Syndrome remains a prevalent problem with patient complaints similar to typical allergy symptoms. Unlike household allergens typically found in domestic reservoirs, the allergen from a common fungus like Aspergillus fumigatus (i.e., Asp f 1) is conceivably widespread in the work environment. This project surveyed airborne levels of the Asp f 1 allergen in office and non-industrial occupational environments, as well as the dust reservoirs of A. fumigatus believed to be responsible for those levels. Airborne and bulk dust samples were collected, extracted, and assayed for Asp f 1. Concurrently, bulk dusts collected from the same locations were selectively cultured for A. fumigatus, and mesophilic fungi and bacteria. Samples were collected during both wet and dry climatological conditions from paired wet and dry building locations to examine the possibility of Asp f 1 increases due to fungal growth blooms. Very low levels of Asp f 1 were detected but only in the airborne samples (2/120 positive samples, with 3.6 ng/m3 and 1.8 ng/m3; LOD < 1.2 ng/m3). No dust samples showed even detectable traces of the allergen (LOD = 5 ng/g dust). Although A. fumigatus counts from dusts fluctuated significantly with exterior moisture events, analysis of wet versus dry period samples showed no differences in Asp f 1 levels. These results indicate that even in the presence of measurable fungal concentrations, background levels of Asp f 1 are low. Nonindustrial office buildings devoid of indoor air quality issues were not observed to have significant levels of the Asp f 1 allergen in the geographical region studied.

The identification of host factors that are predictors of changes in serum polyhalogenated biphenyl contaminants over time has been a difficult challenge in epidemiologic studies of exposed individuals. Of particular concern are age at exposure, reproductive and lactational histories, and changes in body mass index. Using both cross-sectional and longitudinal approaches, this study examined factors related to high initial serum PBB and PCB levels and changes in these levels over time among women of varying ages at exposure (n=1772; age range<1 to 45 years). In 1973, PBB exposure occurred through consumption of farm products contaminated with PBB added to cattle feed. Exposures to PCBs began in 1941 through PCB-contaminated silo sealant deteriorating into animal feed. The Michigan Department of Public Health began enrolling participants in 1977 and has continued to follow them through annual updates. At enrollment, questionnaires were administered to obtain demographic, lifestyle, and anthropometric measurements, medical/reproductive and occupational histories, and contaminated food consumption patterns. Blood samples were collected for PBB and PCB analysis at enrollment for all participants; additional serum tests were done on a subset of the population during follow-up. Median serum levels at enrollment were 2.0 ppb PBB and 5.0 ppb PCB. A decline in serum PBB level over an interval that ranged from 1 to 146 months (median=31) was observed for 44.6% of the women (median=1.0 ppb), while 12.2% showed an increase (median=1.0 ppb). PCB levels declined in 50.3% of the women (median=3.0 ppb) while 12.2% increased (median=2.0 ppb). Relative to women whose contaminant levels were stable, higher initial serum level was a predictor of decline for both PBB and PCB (OR=1.66, 95% CI 1.52-1.82; OR=3.26, 95% CI 2.58-4.12, respectively); a yearly increase in interval between tests was related to declining PCBs (OR=1.65, 95% CI 1.46-1.87). In addition, age< or =10 years at exposure (OR=1.72, 95% CI 1.03-2.86) and residence on a quarantined farm (OR=1.40, 95- CI 1.03-1.90) were predictors of a decrease in PBBs. Factors related to an increase in PBB levels were age< or =10 years at exposure (OR=0.30, 95% CI 0.10-0.96) and initial PBB level (OR=1.24, 95% CI 1.15-1.33); and for PCBs, high initial level (OR=1.34, 95% CI 1.17-1.53) and body mass index (OR=1.07, 95% CI 1.01-1.13). One or more live births during the interval between tests were not related to changing levels of either contaminant; breastfeeding data were not available for examination. Early age at exposure appears to be an important predictor of changes in serum PBB levels over time., (Copyright 2001 Academic Press.)

In response to growing concern for occupational health and safety in the public hospital system in Costa Rica, a cross-sectional survey of 1,000 hospital-based health care workers was conducted in 1997 to collect baseline data that are being used to develop worker training programs in occupational health in Costa Rica. The objectives of this survey were to: 1) describe the safety climate within the national hospital system, 2) identify factors associated with safety, and 3) evaluate the relationship between safety climate and workplace injuries and safety practices of employees. The safety climate was found to be very poor. The two most significant predictors of safety climate were training and administrative support for safety. Safety climate was a statistically significant predictor of workplace injuries and safety practices, respectively, and there was an underreporting rate of 71% of workplace injuries. These findings underscore the need for improvement of the safety climate in the public hospital system in Costa Rica.

Background: A comprehensive surveillance system for occupational injuries to adolescents does not exist in Texas, as in most states. Therefore, the magnitude, severity, nature, and source of injuries to working adolescents have not been well described in Texas., Methods: The investigators used three data sources to investigate work-related injuries and deaths in Texas: (1) Texas Workers' Compensation Commission (TWCC) claims data from 1991 through April 1996; (2) 1993 TWCC/Bureau of Labor Statistics (BLS) Annual Survey of Occupational Injuries and Illnesses; and (3) work-related fatalities identified from Texas death certificates from 1990-1995., Results: There were 9,027 injuries reported to the TWCC for adolescents 14-17 years of age during slightly more than 5 years. Injuries for which indemnity payments were made (more than 7 days out of work) occurred among 21.7% of the adolescents. Based on BLS data in 1993, of 992 non-fatal injuries involving days away from work, 35% were caused by contact with objects, 27% by bodily reaction, and 24% by falls. Two-thirds of these injuries occurred while working in eating and drinking places and grocery stores. Three-quarters of the 30 deaths from 1990-1995 were accounted for equally by motor vehicle and homicide., Conclusions: In conclusion, a substantial number of adolescents are injured or killed in the workplace each year in Texas. Although improved population-based surveillance is needed, sufficient knowledge exists to begin prevention efforts now.

The long-term health effects of human exposure to polybrominated biphenyls are not known. In this nested case-control study, we evaluated the association between site-specific cancer risk and serum polybrominated biphenyl levels among a Michigan cohort accidentally exposed to polybrominated biphenyls in 1973. The Michigan Department of Public Health has followed 3,899 people through 1993, among whom 195 primary cancers were identified in 187 persons. Controls were 696 randomly selected cancer-free individuals who were frequency matched to cases by sex and age (in 5-year strata). Baseline serum polybrominated biphenyl levels were measured using standard methods. We found an increasing dose-response relation for digestive system cancer risk with higher serum polybrominated biphenyl category [4-20 parts per billion (ppb), 21-50 ppb, and > 50 ppb] after adjustment for age, family cancer history, cigarette smoking, alcohol drinking, and baseline serum polychlorinated biphenyl level. Adjusted odds ratios (ORs) for each category were 8.23 [95% confidence interval (CI) = 1.27-53.3], 12.3 (95% CI = 0.80-191), and 22.9 (95% CI = 1.34-392), respectively. Univariate analysis for polybrominated biphenyl level and lymphoma risk also showed a dose-response relation, with corresponding ORs of 3.24 (95% CI = 0.24-95.9), 20.5 (95% CI = 1.51-608), and 32.6 (95% CI = 3.33-861).

A method is presented which links on-site electromagnetic field monitoring data with pre-existing work history data. The linkage is used to estimate cumulative and average annualized magnetic field exposure for a case-control study. On-site electromagnetic field monitoring data for 1,966 volunteer utility employees, at 59 sites in the United States and three other countries, were obtained from a large project (the EMDEX project) designed to collect, analyze, and document 60-Hz electric and magnetic field exposures for a diverse population. These data represent 9 primary work environments, and 16 job classification categories, amounting to 144 unique job categories which were consolidated using the job-exposure matrix presented into 282 three-digit Dictionary of Occupational Title (DOT) codes. The DOT code categories were then linked to lifetime occupational histories from a case-control study of leukemia. The method may be extended to link additional job titles with monitoring information. Job titles linked with electromagnetic field monitoring information provide more specific estimates of exposure intensity than previous ordinal estimates of exposure. Therefore, estimates of cumulative electromagnetic field exposure are achievable, as well as high and low level exposure estimates.

An autopsy study was conducted to investigate whether there is transplacental transfer of asbestos in humans. The asbestos burden of lung, liver, skeletal muscle, and placenta digests of 40 stillborn infants was determined using a bleach digestion method. The fibers detected in the tissue digests were characterized as to the type of asbestos, using electron microscopy, energy-dispersive x-ray analysis, and selected-area diffraction analysis. Placental digests of 45 full-term, liveborn infants were similarly processed as controls. Low levels of small, thin, uncoated asbestos fibers were detected in the placentas and organs of 37.5% of the stillborn infants (15 of 40). The fiber sizes ranged from 0.05 to 5.0 microns in length and 0.03 to 0.3 micron in width, with a mean length of 1.15 microns and a mean width of 0.069 micron. Maximum numbers of fibers were found in the lungs (mean 235,400 fibers/g; n = 10), followed by liver (mean 212,833 fibers/g; n = 6), placenta (mean 164,500 fibers/g; n = 4), and skeletal muscle (80,000 fibers/g; n = 1). The fibers were detected at all stages of gestation and showed no association with gestational age. A significant association was found between fiber presence and working mothers, and positive but nonsignificant associations were found with maternal history of drug abuse, previous abortions, and fetal maceration. No association was found between premature rupture of membranes and fiber presence. No fibers were detected in the 45 placentas of the liveborn control infants. There was a highly significant difference in the asbestos fiber counts of the placentas of the stillborn and liveborn infants (P < .001). Our studies demonstrate the presence of short and thin asbestos fibers in stillborn infants and their positive association with working mothers.

Objectives: To define the profile of 24-hour uterine activity in normal pregnancy and to correlate contraction frequency with physical activity and emotional stress diaries., Methods: One hundred nine low-risk pregnant women who delivered at term recorded uterine contractions for 24 hours twice weekly from 20-40 weeks' gestation using an ambulatory monitor and kept a physical activity and emotional stress diary. Contractions per hour were calculated for each hour of the day and week of gestation, and related to physical activity and emotional stress., Results: We analyzed 71,683 hours. No contractions were recorded in 73% of the hours, and fewer than four contractions per hour occurred in 96%. Significant inter-individual variability was noted. Contractions increased markedly with gestational age: The 95th percentile was 1.3 contractions per hour at 21-24 weeks, 2.9 at 28-32 weeks, and 4.9 at 38-40 weeks. A strong clustering of contractions occurred at night, which became pronounced after 24 weeks (night:day ratio 2:1 at 28-32 weeks). To adjust for the effects of gestational age and time of day, contractions per hour were converted to gestation- and hour-specific percentiles ("contraction percentiles"). Rest was associated with a fall in contraction percentile by 1.25, whereas coitus increased the contraction percentile by 5.52 (P < .05). No changes were noted with emotional stress., Conclusions: This study provides normative contraction data in uncomplicated pregnancy. A strong diurnal rhythm is present from 24 weeks onward, with 67% of contractions occurring at night. Contractions per hour increase with gestational age but rarely exceed three per hour before term. Rest and sexual activity have small but measurable effects on contraction frequency.

A system of programs which process data on a microcomputer for a case/comparison study is described. The procedures process the data from the abstracted case source records, to control selection, interview data management, and the selection of data subsets for analysis. The capabilities of various data processing modules are outlined, and cost estimates of an existing implementation are discussed. The microcomputer is presented as an alternative to mainframe data management.