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Biomedical subjects

B P Leaderer

Publications and source records attributed to B P Leaderer.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of parental reports of smoking and residential air nicotine concentrations in children.

BACKGROUND: Using questionnaires to assess children's residential exposure to environmental tobacco smoke (ETS) may result in misclassification from recall and response bias. Questionnaire data have frequently been validated against urinary cotinine measurements, but rarely against actual measurements of residential air nicotine. OBJECTIVE: To compare questionnaire reported smoking with air nicotine concentrations in a large population of children and with urinary cotinine levels in a subpopulation; and to assess the potential impact of the symptom status of the children on the agreement between different measures of exposure. METHODS: The authors assessed residential exposure to ETS in 347 German, 335 Dutch, and 354 Swedish preschool and schoolchildren by questionnaire and air nicotine measurements, and in a subset of 307 German children by urinary cotinine measurements. They then compared the different measures of ETS exposure. RESULTS: In all countries, air nicotine concentrations increased with increasing questionnaire reported smoking in a dose-response fashion. Specificity and negative predictive values of questionnaire reports for nicotine concentrations were excellent. Sensitivity and positive predictive values were moderate to good. Excluding occasional smokers, the overall percentage of homes misclassified was 6.9%, 6.7%, and 5.1% in Germany, the Netherlands, and Sweden, respectively. Similar results were found for the agreement of urinary cotinine concentrations with questionnaire reports and air nicotine levels. There was no indication of underreporting by parents of symptomatic children. CONCLUSION: Despite some misclassification, questionnaire reports are an inexpensive and valid estimate of residential ETS exposure among preschool and school children.

Adult↗
PubMed2005

Indoor nitrous acid and respiratory symptoms and lung function in adults.

BACKGROUND: Nitrogen dioxide (NO2) is an important pollutant of indoor and outdoor air, but epidemiological studies show inconsistent health effects. These inconsistencies may be due to failure to account for the health effects of nitrous acid (HONO) which is generated directly from gas combustion and indirectly from NO2. METHODS: Two hundred and seventy six adults provided information on respiratory symptoms and lung function and had home levels of NO2 and HONO measured as well as outdoor levels of NO2. The association of indoor HONO levels with symptoms and lung function was examined. RESULTS: The median indoor HONO level was 3.10 ppb (IQR 2.05-5.09), with higher levels in homes with gas hobs, gas ovens, and in those measured during the winter months. Non-significant increases in respiratory symptoms were observed in those living in homes with higher HONO levels. An increase of 1 ppb in indoor HONO was associated with a decrease in forced expiratory volume in 1 second (FEV1) percentage predicted (-0.96%; 95% CI -0.09 to -1.82) and a decrease in percentage FEV1/forced vital capacity (FVC) (-0.45%; 95% CI -0.06 to -0.83) after adjustment for relevant confounders. Measures of indoor NO2 were correlated with HONO (r = 0.77), but no significant association of indoor NO2 with symptoms or lung function was observed. After adjustment for NO2 measures, the association of HONO with low lung function persisted. CONCLUSION: Indoor HONO levels are associated with decrements in lung function and possibly with more respiratory symptoms. Inconsistencies between studies examining health effects of NO2 and use of gas appliances may be related to failure to account for this association.

Adult↗
PubMed2004

The influence of air conditioning, humidity, temperature and other household characteristics on mite allergen concentrations in the northeastern United States.

BACKGROUND: Information about the influence of housing and occupant characteristics on mite allergen concentrations is crucial to determine which methods could be used to decrease exposure of susceptible subjects. OBJECTIVES: To identify housing and occupant characteristics that are associated with mite allergen concentrations in house dust collected from living rooms and mattresses. METHODS: We collected dust samples from 750 homes in the northeastern US. The influence of various characteristics on concentrations of mite allergens (Der p 1 and Der f 1) was studied using multiple linear regression analysis. RESULTS: Some characteristics, like absence of air conditioners, the presence of mold or mildew, and a lower temperature were consistently associated with higher concentrations of both mite allergens in dust from all sampling locations. However, none of these factors changed Der p 1 or Der f 1 concentrations by more than a factor of 2. People of white ethnic background had roughly two times higher mite allergen concentrations, while family income, family size, and education level only marginally influenced mite allergen concentrations. CONCLUSIONS: Various housing characteristics have some influence on mite allergen concentrations, and could possibly be used to decrease exposure of susceptible subjects. However, only a limited percentage of the variation in mite allergen concentrations was explained by these characteristics.

Air Conditioning↗
PubMed2001

Carbon monoxide as a tracer for assessing exposures to particulate matter in wood and gas cookstove households of highland Guatemala.

Kitchen-area 22-h gravimetric PM2.5 and passive diffusion stain-tube carbon monoxide (CO) concentrations were measured in homes with open fire and improved wood cookstoves in two studies. In the first study (Guat-2), which also studied homes with gas cookstoves, three samples were collected per stove condition from each of three test houses. In the second study (Guat-3), one sample was collected per house from 15 open fire and 25 improved-stove houses. CO personal samples were also taken for mother and child in both studies. Spearman correlation coefficients (R) between kitchen-area CO and PM2.5 levels in homes using open fires or impoved wood cookstoves were high ranging from 0.92 (Guat-2) to 0.94 (Guat-3), as were those between the personal samples for mother and child ranging from 0.85 (Guat-3) to 0.96 (Guat-2). In general, the correlations were lower for less-polluted conditions. The study found that CO is a good proxy for PM2.5 in homes using open fires or planchas (improved wood cookstove with chimney) but not under gas stove use conditions. It also determined that mother personal CO is a good proxy for child's (under 2 years of age) personal CO and that area CO measurements are not strongly representative of personal CO measurements. These results generally support the use of Draeger CO passive diffusion tubes as a proxy for PM2.5 in such cases where a single type of emission source is the predominant source for CO and PM2.5.

Air Pollution, Indoor↗
PubMed2001

A childhood asthma severity scale: symptoms, medications, and health care visits.

BACKGROUND: Although there are current measures to evaluate childhood asthma severity for clinical diagnosis and treatment, there is no standard valid measure to evaluate childhood asthma severity for large-scale epidemiologic studies. OBJECTIVES: To develop and test a childhood asthma severity scale (CHAS) for clinimetric validity and to determine differences in symptoms, medication use, and health care visits by participant characteristics. METHODS: Eight hundred ninety-seven actively asthmatic children under the age of 12 years were selected from a general population of children. Children were selected from a screening questionnaire administered at six Connecticut hospitals that serve large minority populations in Bridgeport, New Haven, Hartford, and Danbury and one hospital serving south central Massachusetts. Twelve-month baseline data for a prospective cohort study of childhood asthma severity were collected on a monthly basis through home interviews. Home interviews addressed questions on daily symptoms, medication use, and health care visits. A severity scale was constructed using three dimensions: symptoms, medication use, and health care visits. RESULTS: CHAS has sufficient preliminary content, construct, and predictive validity. Despite similarities in symptoms, there were health care utilization and medication differentials according to race and ethnicity, insurance status, family income, and maternal education. CONCLUSIONS: CHAS is a potentially useful measure of asthma severity for large-scale epidemiologic studies. It seems that CHAS has sufficient clinimetric properties.

Anti-Asthmatic Agents↗
PubMed2001

The relation between fungal propagules in indoor air and home characteristics.

BACKGROUND: Questionnaires are commonly used in epidemiologic studies to obtain information about house characteristics in order to predict the household aeroallergen exposure levels. However, the reliability of the predictions made with the questionnaires has not been evaluated. To address this issue, we compared objectively measured fungal propagules including the most frequently isolated mold genera (i.e., Alternaria, Aspergillus, Cladosporium, Penicillium, etc.) in a large sample of homes and compared these measured values to the questionnaire-determined household characteristics. METHODS: As part of a prospective cohort study on the relation between residential allergen exposure and development of asthma in neonates, fungal air samples were collected from infant bedrooms and main living areas in 1000 homes in the Northeast USA, from December 1996 to January 1999. A Burkard portable air sampler was used in combination with DG-18 and MEA agars. A questionnaire was used to obtain information on host and house characteristics that may have an impact on the presence of fungal propagules in the air. This included information on observation of moisture problems (e.g., water leakage or damage, and mold or mildew growth), ventilation and heating facilities, building age and type, number of occupants, annual household income, presence of pets and pests, cleaning regimens, etc. RESULTS: The number of CFU/m3 air collected on MEA was significantly higher than on DG-18 (means, respectively, 1033.5 and 846.0 CFU/m3) (P < 0.0005). However, there was no significant difference between the numbers of CFU/m3 air collected from the main living area and from the infant bedroom. There was only a very weak relationship between the house characteristics, as described by questionnaire, and the presence of fungal propagules in indoor air. Only the temperature, relative humidity, season, and cats inside homes had a statistically significant impact on the presence of fungal propagules in indoor air. CONCLUSION: The presence of fungal propagules in indoor air cannot be reliably predicted by home characteristics. Actual measurements are required for fungal exposure assessment, and the use of only one medium to collect samples in one location in a home might be adequate to represent residential levels of fungi in indoor air.

Air Microbiology↗
PubMed2001

Risk factors for asthma prevalence among urban and nonurban African American children.

Urban residence is a risk factor for asthma. We examined multiple risk factors simultaneously among African American children. We interviewed 2409 African American mothers of newborns who had at least 1 child at home under 18 years of age. Sixteen percent reported at least 1 child with physician-diagnosed asthma. Significantly associated with an asthmatic child were maternal asthma and allergies, maternal cigarette smoking, a humidifying device, and a gas range or oven in the home. Urban residence was related to asthma but became nonsignificant once other factors were controlled for. Asthma associated with urban residence may be explained by identifiable factors.

Black or African American↗
PubMed2001

Use of health services by insurance status among children with asthma.

OBJECTIVES: It is well known that asthmatic children receiving Medicaid use the emergency department (ED) more frequently than otherwise-insured asthmatic children. However, the extent to which this difference is attributable to provider characteristics, medication use, access to primary care, and symptomatology is poorly understood. These factors were explored as independent predictors of health care utilization. METHODS: Baseline data from a prospective cohort study of childhood asthma severity were used. Subjects were recruited from seven New England hospitals. Home interviews collected data on monthly symptoms, health care visits, insurance status, as well as sociodemographics and asthma-related risk factors (n = 804). Characteristics of providers' practices, board certifications, and asthma specialty were obtained from Folio's Medical Dictionaries for Connecticut and Massachusetts. RESULTS: After adjusting for frequency of asthma-related primary care visits, primary provider practice type, use of asthma specialist, age, gender, medication use, and symptomatology, Medicaid children still used the ED more frequently for asthma services than privately insured children (RR, 1.7; 95% CI, 1.1, 2.5). In general, race/ethnicity did not modify the relationship between insurance status and health care use, except that black children receiving Medicaid were 90% (95% CI, 0.0, 0.7) less likely to have had > or = 3 routine primary care visits for asthma in the previous year than black privately insured children. White children receiving Medicaid were 2.5 (95% CI, 1.0, 6.9) times more likely to use the ED for asthma than privately insured white children. CONCLUSIONS: The results suggest that enabling, structural, and need factors do not necessarily explain observed differences in pediatric asthma health care use by insurance status. Future investigation must explore other explanatory factors such as maternal attitudes and beliefs and patient-provider communication.

Black or African American↗
PubMed2000

Particulate matter and carbon monoxide in highland Guatemala: indoor and outdoor levels from traditional and improved wood stoves and gas stoves.

Area 22-h average carbon monoxide (CO), total suspended particulates (TSP), particles less than 10 microns in diameter (PM10), and particles less than 2.5 microns in diameter (PM2.5) measurements were made in three test homes of highland rural Guatemala in kitchens, bedrooms, and outdoors on a longitudinal basis, i.e. before and after introduction of potential exposure-reducing interventions. Four cookstove conditions were studied sequentially: background (no stove in use); traditional open woodstove, improved woodstove with flue (plancha), and bottled-gas (LPG) stove. With nine observations each, kitchen PM2.5 levels were 56 micrograms/m3 under background conditions, 528 micrograms/m3 for open fire conditions, 96 micrograms/m3 for plancha conditions, and 57 micrograms/m3 for gas stove conditions. Corresponding PM10/TSP levels were 173/174, 717/836, 210/276, 186/218 micrograms/m3. Corresponding CO levels were 0.2, 5.9, 1.4, 1.2 ppm. Comparisons with other studies in the area indicate that the reductions in indoor concentrations achieved by improved wood-burning stoves deteriorate with stove age. Mother and child personal CO and PM2.5 measurements for each stove condition demonstrate the same trend as area measurements, but with less differentiation.

Adult↗
PubMed2000

Using nicotine measurements and parental reports to assess indoor air: the PIAMA birth cohort study. Prevention and Incidence of Asthma and Mite Allergy.

We used two methods to collect data on indoor smoking exposure of 3-month-old infants. First, parents of approximately 100 children completed a questionnaire. We then measured nicotine in the air of the living rooms in smoking and non-smoking households with a passive sampler for a period of 2 weeks, several months after the questionnaire had been completed. Smoking habits reported in the questionnaire generally with reported number of cigarettes smoked during the measurement weeks, and with nicotine concentrations in the air. These results suggest that exposure classification based on questionnaire data is likely to be reasonably valid.

Air↗
PubMed1999

Healthy women's PEF variations with ambient summer concentrations of PM10, PM2.5, SO42-, H+, and O3.

The relationship between ambient air pollution and daily change in peak expiratory flow (PEF) was studied in a sample of 473 nonsmoking women (age 19 to 43 yr) in Virginia over summers 1995- 1996. Daily 24-h averages of particulate matter (PM2.5 and PM10), fine particulate sulfate (SO42-) and strong acid (H+), hourly ozone (O3), and select meteorologic variables (e.g., temperature) were collected at a regional outdoor monitoring site. Subjects took PEF measurements twice daily for a 2-wk period using a standard MiniWright peak flow meter. Concurrent measures for summer periods of 24-h PM2.5 (micrograms/m3) ranged from 3.5 to 59.7; H+ (nmol/m3) from 0 to 250; maximal daily 8-h average O3 (ppb) from 17.0 to 87.6. Morning PEF decrements were significantly associated with H+ and PM2. 5. An increase of 50 etamol/m3 of H+ and 10 micrograms/m3 of PM2.5 related to decreases of 0.89 (95% CI = 0.21 to 1.57) and 0.73 (95% CI = 0.07 to 1.38) L/min in morning PEF, respectively. Ozone was the only exposure related to evening PEF with 5-d cumulative lag exposure showing the greatest effect; 7.65 L/ min (95% CI = 2.25 to 13.0) decrease per 30 ppb O3 increase. Separate physiologic effects were observed for summer ambient concentrations of two different pollutants (PEF decrements related to PM2.5 in morning and O3 in evening) at concentrations below the new U.S. EPA 24-h ambient air quality standard for PM2.5 and 8-h standard for O3.

Adult↗
PubMed1999

Indoor, outdoor, and regional summer and winter concentrations of PM10, PM2.5, SO4(2)-, H+, NH4+, NO3-, NH3, and nitrous acid in homes with and without kerosene space heaters.

Twenty-four-hour samples of PM10 (mass of particles with aerodynamic diameter < or = 10 microm), PM2.5, (mass of particles with aerodynamic diameter < or = 2.5 microm), particle strong acidity (H+), sulfate (SO42-), nitrate (NO3-), ammonia (NH3), nitrous acid (HONO), and sulfur dioxide were collected inside and outside of 281 homes during winter and summer periods. Measurements were also conducted during summer periods at a regional site. A total of 58 homes of nonsmokers were sampled during the summer periods and 223 homes were sampled during the winter periods. Seventy-four of the homes sampled during the winter reported the use of a kerosene heater. All homes sampled in the summer were located in southwest Virginia. All but 20 homes sampled in the winter were also located in southwest Virginia; the remainder of the homes were located in Connecticut. For homes without tobacco combustion, the regional air monitoring site (Vinton, VA) appeared to provide a reasonable estimate of concentrations of PM2.5 and SO42- during summer months outside and inside homes within the region, even when a substantial number of the homes used air conditioning. Average indoor/outdoor ratios for PM2.5 and SO42- during the summer period were 1.03 +/- 0.71 and 0.74 +/- 0.53, respectively. The indoor/outdoor mean ratio for sulfate suggests that on average approximately 75% of the fine aerosol indoors during the summer is associated with outdoor sources. Kerosene heater use during the winter months, in the absence of tobacco combustion, results in substantial increases in indoor concentrations of PM2.5, SO42-, and possibly H+, as compared to homes without kerosene heaters. During their use, we estimated that kerosene heaters added, on average, approximately 40 microg/m3 of PM2.5 and 15 microg/m3 of SO42- to background residential levels of 18 and 2 microg/m3, respectively. Results from using sulfuric acid-doped Teflon (E.I. Du Pont de Nemours & Co., Wilmington, DE) filters in homes with kerosene heaters suggest that acid particle concentrations may be substantially higher than those measured because of acid neutralization by ammonia. During the summer and winter periods indoor concentrations of ammonia are an order of magnitude higher indoors than outdoors and appear to result in lower indoor acid particle concentrations. Nitrous acid levels are higher indoors than outdoors during both winter and summer and are substantially higher in homes with unvented combustion sources.

Air Pollutants↗
PubMed1998

Correlates of residential wiring code used in studies of health effects of residential electromagnetic fields.

The home wiring code is the most widely used metric for studies of residential electromagnetic field (EMF) exposure and health effects. Despite the fact that wiring code often shows stronger correlations with disease outcome than more direct EMF home assessments, little is known about potential confounders of the wiring code association. In a study carried out in southern Connecticut in 1988-1991, the authors used strict and widely used criteria to assess the wiring codes of 3,259 homes in which respondents lived. They also collected other home characteristics from the tax assessor's office, estimated traffic density around the home from state data, and interviewed each subject (2,967 mothers of reproductive age) for personal characteristics. Women who lived in very high current configuration wiring coded homes were more likely to be in manual jobs and their homes were older (built before 1949, odds ratio (OR) = 73.24, 95% confidence interval (CI) 29.53-181.65) and had lower assessed value and higher traffic densities (highest density quartile, OR = 3.99, 95% CI 1.17-13.62). Because some of these variables have themselves been associated with health outcomes, the possibility of confounding of the wiring code associations must be rigorously evaluated in future EMF research.

Adult↗
PubMed1996

Asthma among Puerto Rican Hispanics: a multi-ethnic comparison study of risk factors.

For a study of childhood asthma we interviewed 9,276 mothers during 1993-1994, ascertaining whether they had asthmatic children younger than 18 yr of age and asking about genetic and environmental risk factors for asthma. Independent risk factors for asthma in 7,776 children were: Hispanic and African American ethnicity, maternal history of asthma, lower socioeconomic status (SES) of the mother, and the presence of a cigarette smoker in the household. Hispanic ethnicity was also a strong risk factor for asthma in the mother. The prevalence of asthma among children of Hispanic (mainly Puerto Rican) mothers with one or more children older than 9 mo of age was 18.4%, for blacks it was 1 1.3%, and for non-Hispanic whites it was 7.4%. The marked increased risk for asthma in children of Hispanic mothers was not explained by SES or maternal age. In addition, increased risk for asthma in these children was not associated with higher reporting of environmental tobacco smoke (ETS) exposure. In this study of asthma in primarily Puerto Rican Hispanics, the risk of physician-diagnosed asthma as reported by mothers was significantly associated with Hispanic ethnicity, and it was not confounded by SES or active smoking in the home.

Adolescent↗
PubMed1995

Measurement of exposure to environmental tobacco smoke in pregnant women.

The authors compared three methods used to measure exposure to environmental tobacco smoke in pregnant women: personal air monitor, urine cotinine, and questionnaire. Environmental tobacco smoke exposure assessment methods were compared for agreement using Cohen's Kappa and the Spearman rank order correlation coefficient. Women who reported exposure had significantly higher levels of air nicotine concentration compared with women who reported no exposure, but urine cotinine did not differ. Air nicotine was more highly correlated with home exposure (r = 0.34) than work exposure (r = 0.18). Urine cotinine correlated with work exposure (r = 0.14) but neither home nor social exposure. Agreement was "fair" (Kappa = 0.29) when self-reported exposure was compared with air monitor, but agreement was "poor" when urine cotinine was compared with self-report (Kappa = 0.08) and air monitor (Kappa = 0.10). In low environmental tobacco smoke exposure environments, all three methods for measuring exposure may have a role, although modification to monitoring protocols will be needed to improve monitoring sensitivity and exposure classification.

Adult↗
PubMed1995

The accuracy of environmental tobacco smoke exposure measures among asthmatic children.

This study determined the reliability and validity of parent-reported measures of environmental tobacco smoke (ETS) exposure among 91 asthmatic children. Test-retest reliability assessments were conducted for environmental, biological and parent-reported measures of ETS exposure. All measures except a urine cotinine assay resulted in satisfactory levels of reliability. The parent-reported measures of ETS exposure were compared to the environmental filter measure of nicotine as well as submitted to a construct validity test. Parent-reported home exposure to ETS proved moderately and significantly correlated to the filter measure. Approximately 80% of all hypothetical constructs agreed with the observed relationships for convergent, divergent and discriminant validity. It was concluded that middle class Caucasian parents' reports of their asthmatic child's residential ETS exposure are reliable and valid. These parent-reported measures should be valuable tools for epidemiological investigations and for clinical programs designed to reduce asthmatic children's residential exposure to ETS.

Adult↗
PubMed1995

Effect of nitrous acid on lung function in asthmatics: a chamber study.

Nitrous acid, a component of photochemical smog and a common indoor air pollutant, may reach levels of 100 ppb where gas stoves and unvented portable kerosene heaters are used. Nitrous acid is a primary product of combustion and may also be a secondary product by reaction of nitrogen dioxide with water. Because the usual assays for nitrogen dioxide measure several oxides of nitrogen (including nitrous acid) together, previous studies of indoor nitrogen dioxide may have included exposure to and health effects of nitrous acid. To assess the respiratory effects of nitrous acid exposure alone, we carried out a double-blinded crossover chamber exposure study with 11 mildly asthmatic adult subjects. Each underwent 3-hr exposures to 650 ppb nitrous acid and to filtered room air with three 20-min periods of moderate cycle exercise. Symptoms, respiratory parameters during exercise, and spirometry after exercise were measured. A statistically significant decrease in forced vital capacity was seen on days when subjects were exposed to nitrous acid. This effect was most marked at 25 min and 85 min after exposure began. Aggregate respiratory and mucous membrane symptoms were also significantly higher with nitrous acid. We conclude that this concentration and duration of exposure to nitrous acid alters lung mechanics slightly, does not induce significant airflow obstruction, and produces mild irritant symptoms in asthmatics.

Adolescent↗