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William S Beckett

Publications and source records attributed to William S Beckett.

15 recordsLinked to original sources
PubMed2006

Implications for occupational exposure to particulate matter.

The demonstrated effects of lower levels of ambient particles on cardiovascular and respiratory system morbidity and mortality were initially surprising in light of current concepts of occupational particle exposure and acute and chronic cardiopulmonary effects. Specifically, the exposure levels, as defined by the weight of the particles per liter of breathing air, at which recognized disease occurs under workplace conditions are considerably higher than the observed levels of ambient particles associated with serious adverse health effects. The possible reasons for this difference have not been adequately addressed. To further address this question, a re-examination of workplace exposure-response relationships is needed, which may include emphasis on measuring exposures to fine and ultrafine particles rather than to total particle mass concentration alone.

Air Pollutants↗
PubMed2006

Low-level ozone exposure and respiratory symptoms in infants.

OBJECTIVE: Recent studies indicate that the U.S. Environmental Protection Agency (EPA) ozone standards may not protect sensitive individuals. In this study we examined respiratory effects of ozone in infants who may be vulnerable, particularly if they are children of asthmatic mothers. DESIGN: Women delivering babies at one of five hospitals in southwestern Virginia between 1994 and 1996 were invited to participate in a cohort study; 780 women enrolled. Ambient air quality data (ozone and particulate matter) were collected at a central monitoring site. PARTICIPANTS: This analysis is of 691 infants followed for approximately 83 days between 10 June and 31 August 1995 and/or 1996 ; they contributed a total of 52,421 infant-days of follow-up. Mothers were interviewed at enrollment and approximately biweekly to report infants' daily symptoms. Repeated measures logistic regression models were run separately for wheeze, difficulty breathing, and cough. Ozone metrics included 24-hr average, peak 1-hr, and maximum 8-hr average. Analyses were repeated for the 61 infants whose mothers had asthma. RESULTS: For every interquartile-range increase in same-day 24-hr average ozone, likelihood of wheeze increased 37% [95% confidence interval (CI), 2-84%]. Among infants of asthmatic mothers, same-day 24-hr average ozone increased likelihood of wheeze 59% (95% CI, 1-154%) and of difficulty breathing 83% (95% CI, 42-136%). Maximum 8-hr ozone and peak 1-hr ozone were associated with difficulty breathing, but not wheeze, in infants of asthmatic mothers. Ozone was not associated with cough. CONCLUSIONS: At levels of ozone exposure near or below current U.S. EPA standards, infants are at increased risk of respiratory symptoms, particularly infants whose mothers have physician-diagnosed asthma.

Cohort Studies↗
PubMed2005

Comparing inhaled ultrafine versus fine zinc oxide particles in healthy adults: a human inhalation study.

RATIONALE: Zinc oxide is a common, biologically active constituent of particulate air pollution as well as a workplace toxin. Ultrafine particles (< 0.1 microm diameter) are believed to be more potent than an equal mass of inhaled accumulation mode particles (0.1-1.0 microm diameter). OBJECTIVES: We compared exposure-response relationships for respiratory, hematologic, and cardiovascular endpoints between ultrafine and accumulation mode zinc oxide particles. METHODS: In a human inhalation study, 12 healthy adults inhaled 500 microg/m3 of ultrafine zinc oxide, the same mass of fine zinc oxide, and filtered air while at rest for 2 hours. MEASUREMENTS AND MAIN RESULTS: Preexposure and follow-up studies of symptoms, leukocyte surface markers, hemostasis, and cardiac electrophysiology were conducted to 24 hours post-exposure. Induced sputum was sampled 24 hours after exposure. No differences were detected between any of the three exposure conditions at this level of exposure. CONCLUSIONS: Freshly generated zinc oxide in the fine or ultrafine fractions inhaled by healthy subjects at rest at a concentration of 500 microg/m3 for 2 hours is below the threshold for acute systemic effects as detected by these endpoints.

Administration, Inhalation↗
PubMed2005

Occupational asbestos exposure and predictable asbestos-related diseases in India.

BACKGROUND: India imports nearly 100,000 metric tons of asbestos per year, and small-scale asbestos (chrysotile and tremolite) mining and milling contributes nearly 5%-10% of the total national usage. The industry is relatively young, having started in the 1950s and 1960s. METHODS: Surveys of asbestos-exposed workers have identified significant occupational exposures, early pleural and parenchymal changes on chest radiograph, and decrements in lung function. RESULTS AND CONCLUSIONS: Based on knowledge of past and current exposures to asbestos in industry, we can predict a future occurrence of clinical asbestos-related diseases-pleural changes, pulmonary fibrosis, bronchogenic carcinoma, and diffuse malignant mesothelioma. These cases of asbestos related disease are expected to occur in asbestos exposed workers from mining, milling, and manufacturing as well as in those with secondary exposures to asbestos-containing materials, including construction and maintenance workers, users of asbestos-containing consumer products, and the occupants of asbestos-containing buildings.

Asbestos, Serpentine↗
PubMed2005

Indoor heating sources and respiratory symptoms in nonsmoking women.

BACKGROUND: Secondary heating appliances are important indoor sources of air pollution, including particulate matter, nitrogen dioxide (NO2), and sulfur dioxide (SO2). We hypothesized that the use of secondary heating sources increases respiratory symptoms in women living in nonsmoking households and specifically that concentrations of SO2 and NO2 emitted from heating sources are associated with respiratory symptoms. METHODS: Mothers who delivered babies at 12 hospitals in Connecticut and Virginia (1993-1996) were enrolled. There were 888 women who contributed symptom and exposure information during the winter heating season (15 October to 15 April), for a total of 9783 reporting periods (median = 12 reporting periods per woman, interquartile range 11-12). Adjusted rate ratios (RRs) of effects of source use and measured concentrations on rate of days with symptoms were obtained using generalized estimating equations for a log-linear Poisson model, controlling age, education, race, history of allergies, number of children, dwelling type, and residence state. RESULTS: In adjusted models, each hour-per-day increase in kerosene heater use is associated with an increase in wheezing (RR = 1.06; 95% confidence interval (CI) = 1.01-1.11). Each hour of fireplace use is associated with increased cough (1.05; 1.01-1.09), sore throat (1.04; 1.00-1.08), and marginally with chest tightness (1.05; 0.99-1.12). Each 10 ppb increase in SO2 (a proxy for sulfate aerosol) is associated with increased wheezing (1.57; 1.10-2.26) and chest tightness (1.32; 1.01-1.71). CONCLUSIONS: Emissions from fireplaces, gas space heaters, and kerosene heaters may contribute to respiratory symptoms in a population of nonsmoking women.

Air Pollution, Indoor↗
PubMed2005

Clinical activities in an academic hospital-based occupational medicine program.

OBJECTIVES: The objectives of this article are to characterize the clinical activities encountered by a large academic hospital-based occupational medicine program and to discuss their implications for occupational medicine residency training and the training of practicing physicians. METHODS: Clinical activities from July 1, 1996, to December 31, 2004, were retrieved from computerized databases and categorized. All morbidity coding was performed using the same classification scheme and resource. RESULTS: The largest volume of clinical activities included patients seen for physical examinations, work-related injury and illness care, and substance abuse testing. The most frequently encountered workers' compensation cases were musculoskeletal. CONCLUSIONS: Although medical surveillance examinations, toxic exposure assessments, and other specialty services were available, the demand for such services was relatively low.

Hospitals, University↗
PubMed2004

Prediction of residential pet and cockroach allergen levels using questionnaire information.

We assessed the accuracy of questionnaire reports of cat and dog ownership and presence of cockroaches in predicting measured allergen concentrations in house dust. We collected dust samples in the homes of 932 newborns living in New England. Dust samples were taken from the main living area and the infant's bedding. Allergen content of house dust was measured by enzyme-linked immunosorbent assays (ELISA) and related to questionnaire information on past and current cat and dog ownership and presence of cockroaches. Allergen levels were dichotomized using the limit of detection and the following cut points: 1.0 microg/g and 8.0 microg/g for cat, 2.0 microg/g and 10.0 microg/g for dog, and 2 U/g and 8 U/g for cockroach allergen. For the upper cut point, both specificity and sensitivity of questionnaire-reported cat and dog ownership and presence of cockroaches were high. For the limit of detection and lower cut point, specificity was high (> 80%), whereas sensitivity was low, particularly for current cat and dog ownership (21-60%). Taking pet ownership during the preceding 2 years into account increased the sensitivity by 10%, but it remained relatively poor. In conclusion, questionnaire-reported pet ownership and presence of cockroaches predicts allergen levels above the upper cut point but is a relatively poor measure of allergen exposure above the limit of detection and the lower cut point. Knowledge of past pet ownership can improve pet allergen exposure assessment by means of questionnaire. However, for epidemiologic purposes, measured concentrations of allergens are necessary.

Adult↗
PubMed2004

Variable response to long-term corticosteroid therapy in chronic beryllium disease.

OBJECTIVES: Chronic beryllium disease (CBD) shares many of its characteristics with sarcoidosis and is often treated with corticosteroids. There is limited available literature regarding the effect of long-term corticosteroid therapy on the natural history of CBD. METHODS AND MATERIALS: We conducted an observational retrospective study of six patients with CBD who received prolonged corticosteroid treatment with a mean pulmonary function test follow-up period of 10.1 years. Five of the six patients were exposed to beryllium at the same workplace. The diagnosis in four of the six cases was confirmed by a positive beryllium lymphocyte proliferation test result on blood or BAL fluid. Periodic pulmonary function tests were analyzed in relation to removal from beryllium exposure and treatment with corticosteroids. MEASUREMENTS AND RESULTS: Two broad patterns of response were noted in these patients. The first pattern seen in two patients showed no improvement in FVC or diffusion capacity of the lung for carbon monoxide (Dlco) with corticosteroids. However, a significant improvement in these parameters was noted on cessation of beryllium exposure in one of the two patients. The second pattern showed an initial improvement in FVC and Dlco with corticosteroids, which was not sustained. An improvement was noted on stopping beryllium exposure. CONCLUSIONS: The response to long-term corticosteroids in CBD, quite like that in sarcoidosis, is variable. Significant lung function improvement may be seen following cessation of beryllium exposure.

Adult↗
PubMed2003

Association of low-level ozone and fine particles with respiratory symptoms in children with asthma.

CONTEXT: Exposure to ozone and particulate matter of 2.5 microm or less (PM2.5) in air at levels above current US Environmental Protection Agency (EPA) standards is a risk factor for respiratory symptoms in children with asthma. OBJECTIVE: To examine simultaneous effects of ozone and PM2.5 at levels below EPA standards on daily respiratory symptoms and rescue medication use among children with asthma. DESIGN, SETTING, AND PARTICIPANTS: Daily respiratory symptoms and medication use were examined prospectively for 271 children younger than 12 years with physician-diagnosed, active asthma residing in southern New England. Exposure to ambient concentrations of ozone and PM2.5 from April 1 through September 30, 2001, was assessed using ozone (peak 1-hour and 8-hour) and 24-hour PM2.5. Logistic regression analyses using generalized estimating equations were performed separately for maintenance medication users (n = 130) and nonusers (n = 141). Associations between pollutants (adjusted for temperature, controlling for same- and previous-day levels) and respiratory symptoms and use of rescue medication were evaluated. MAIN OUTCOME MEASURES: Respiratory symptoms and rescue medication use recorded on calendars by subjects' mothers. RESULTS: Mean (SD) levels were 59 (19) ppb (1-hour average) and 51 (16) ppb (8-hour average) for ozone and 13 (8) microg/m3 for PM2.5. In copollutant models, ozone level but not PM2.5 was significantly associated with respiratory symptoms and rescue medication use among children using maintenance medication; a 50-ppb increase in 1-hour ozone was associated with increased likelihood of wheeze (by 35%) and chest tightness (by 47%). The highest levels of ozone (1-hour or 8-hour averages) were associated with increased shortness of breath and rescue medication use. No significant, exposure-dependent associations were observed for any outcome by any pollutant among children who did not use maintenance medication. CONCLUSION: Asthmatic children using maintenance medication are particularly vulnerable to ozone, controlling for exposure to fine particles, at levels below EPA standards.

Air Pollutants↗
PubMed2003

Asthma symptoms, severity, and drug therapy: a prospective study of effects on 2205 pregnancies.

OBJECTIVE: To prospectively examine in pregnant women whether asthma or asthma therapy influenced preterm delivery, intrauterine grown restriction (IUGR), or birthweight. METHODS: We enrolled 873 pregnant women with a history of asthma, of whom 778 experienced asthma symptoms or took medication, and 1333 women with no asthma history, including 884 women with neither asthma diagnosis nor symptoms and 449 with symptoms but no diagnosis. Asthma symptoms, medication, and severity were classified according to 2002 Global Initiative for Asthma guidelines. RESULTS: Preterm delivery was not associated with asthma diagnosis, severity, or symptoms but was associated with use of controller medications, independent of symptoms, specifically oral steroids and theophylline. Gestation was reduced by 2.22 weeks in women using oral steroids daily (P =.001) and 1.11 weeks after theophylline (P =.002). We observed a 24% (5-47%) increased risk for IUGR with each increased symptom step, which increased further in symptomatic women with no asthma diagnosis (31%, 4-65%) compared with women with neither asthma nor symptoms. CONCLUSIONS: We found no effect of asthma symptoms or severity on preterm delivery but observed increased risks associated with use of oral steroid and theophylline. Intrauterine growth restriction was associated with asthma severity, which possibly reflects a hypoxic fetal effect. Women with asthma symptoms but no diagnosis were at particular risk of undermedication and delivering IUGR infants. These observations support guidelines that advocate active management of pregnant patients with mild or moderate asthma with beta(2) agonists, with oral steroids added only if severity increases. Symptomatic patients without an asthma diagnosis might need to be equally managed.

Adult↗
PubMed2002

Early life factors contribute to the decrease in lung function between ages 18 and 40: the Coronary Artery Risk Development in Young Adults study.

Early life factors may influence pulmonary function. We measured forced expiratory volume in 1 second (FEV(1)) in 1985-1986 and 2, 5, and 10 years later in approximately 4,000 black and white men and women initially aged 18-30 years. We estimated the age pattern of FEV(1) according to family smoking status, early diagnosis of asthma, early smoking initiation, adult asthma, and cigarette smoking. FEV(1) followed a quadratic pattern from age of peak through age 40. The pattern varied by race and sex. Early smoking initiation was associated with a faster decrease in FEV(1). Smoking by family members was related to early life asthma and may have contributed to faster FEV(1) decrease by encouraging behaviors such as heavier smoking or earlier smoking initiation. Prevalence of smoking was 28% when no family member smoked, compared with 59% when four or more members smoked. The FEV(1) decline was 8.5% in never-smokers without asthma; 10.1% in nonsmoking individuals diagnosed with asthma; and 11.1% in baseline smokers who smoked 15 or more cigarettes per day. The combination of asthma and heavier smoking was synergistic (17.8% decline). This study delineates an increased rate of decline in those with asthma or in those who smoke cigarettes and implicates early life exposures as contributing to the faster rate of FEV(1) decline.

Adolescent↗