Evaluation of a possible association of urban air toxics and asthma

Profile of Acute Asthma Exacerbation in Drug Users

The characteristics of patients who use heroin, cocaine, or both and present with acute asthma exacerbations have not been well studied. In this retrospective study, we aimed to study the demographic characteristics of this patient population, the characteristics of their asthma attack, and the risk factors for the need for invasive mechanical ventilation in this patient population. We reviewed the charts of patients discharged from an inner-city hospital with a diagnosis of acute asthma exacerbation. Individuals who used either heroin or cocaine or both within 24 hours of presenting to the emergency department were identified as a cohort of drug users. The rest were classified as non-drug users. Both groups were compared, and a univariate analysis was performed. To assess the predictive value of drug use for the need for intubation in the presence of confounding factors, logistic regression analysis was performed to identify whether using cocaine or heroin or both was an individual predictor for the need for invasive ventilation. Data from 218 patients were analyzed. Drug users (n = 85) were younger (mean age in years 43.9 vs. 50.5, P < 0.01), predominantly male (63.5% vs. 33.8%, P < 0.01), and more likely to be cigarette smokers (90.6% vs. 57.6%, P < 0.01). A medical history of intubation and admissions to the intensive care unit (ICU) was more common among drug users (56.5% vs. 29.3%, P < 0.01 and 54.1% vs. 38.3%, P < 0.03, respectively). Drug use was associated with increased need for invasive mechanical ventilation (35% vs. 23.3%, P = 0.05). Non-drug users were more likely to be using inhaled corticosteroids (48.9% vs. 32.9%, P = 0.03) and had longitudinal care established with a primary care provider (50.6% vs. 68.9%, P < 0.01). After adjusting for a history of mechanical ventilation, history of ICU admission, use of systemic corticosteroids, smoking, and acute physiological assessment and chronic health evaluation 2 score, drug use remained predictive for the need for mechanical ventilation (P = 0.026). Acute asthma exacerbations triggered by cocaine and heroin should be treated aggressively because they represent a cohort with poor follow-up and undertreated asthma as outpatients and are associated with increased need for invasive mechanical ventilation and ICU admission during acute exacerbation.

Reading, Writing, and Toxics: Children's Health, Academic Performance, and Environmental Justice in Los Angeles

A significant body of previous research on environmental justice has demonstrated a disproportionate burden of environmental hazards on low-income and minority residents. In this paper we evaluate spatially indexed data on estimated respiratory and cancer risks associated with exposures to ambient air toxics to show that children of color in the Los Angeles Unified School District suffer potentially disparate health impacts, and that disparities in environmental risks may be associated with diminished school performance—even after controlling for socioeconomic and demographic covariates that generally explain much of the variation in student scores. Remediating environmental health risks in distressed neighborhoods could, therefore, improve both health and human capital.

Associations between maternal periconceptional exposure to secondhand tobacco smoke and major birth defects

BACKGROUND

While associations between secondhand smoke and a few birth defects (namely, oral clefts and neural tube defects) have been noted in the scientific literature, to our knowledge, there is no single or comprehensive source of population-based information on its associations with a range of birth defects among nonsmoking mothers.

OBJECTIVE

We utilized data from the National Birth Defects Prevention Study, a large population-based multisite case-control study, to examine associations between maternal reports of periconceptional exposure to secondhand smoke in the household or workplace/school and major birth defects.

STUDY DESIGN

The multisite National Birth Defects Prevention Study is the largest case-control study of birth defects to date in the United States. We selected cases from birth defect groups having >100 total cases, as well as all nonmalformed controls (10,200), from delivery years 1997 through 2009; 44 birth defects were examined. After excluding cases and controls from multiple births and whose mothers reported active smoking or pregestational diabetes, we analyzed data on periconceptional secondhand smoke exposure-encompassing the period 1 month prior to conception through the first trimester. For the birth defect craniosynostosis, we additionally examined the effect of exposure in the second and third trimesters as well due to the potential sensitivity to teratogens for this defect throughout pregnancy. Covariates included in all final models of birth defects with ≥5 exposed mothers were study site, previous live births, time between estimated date of delivery and interview date, maternal age at estimated date of delivery, race/ethnicity, education, body mass index, nativity, household income divided by number of people supported by this income, periconceptional alcohol consumption, and folic acid supplementation. For each birth defect examined, we used logistic regression analyses to estimate both crude and adjusted odds ratios and 95% confidence intervals for both isolated and total case groups for various sources of exposure (household only; workplace/school only; household and workplace/school; household or workplace/school).

RESULTS

The prevalence of secondhand smoke exposure only across all sources ranged from 12.9-27.8% for cases and 14.5-15.8% for controls. The adjusted odds ratios for any vs no secondhand smoke exposure in the household or workplace/school and isolated birth defects were significantly elevated for neural tube defects (anencephaly: adjusted odds ratio, 1.66; 95% confidence interval, 1.22-2.25; and spina bifida: adjusted odds ratio, 1.49; 95% confidence interval, 1.20-1.86); orofacial clefts (cleft lip without cleft palate: adjusted odds ratio, 1.41; 95% confidence interval, 1.10-1.81; cleft lip with or without cleft palate: adjusted odds ratio, 1.24; 95% confidence interval, 1.05-1.46; cleft palate alone: adjusted odds ratio, 1.31; 95% confidence interval, 1.06-1.63); bilateral renal agenesis (adjusted odds ratio, 1.99; 95% confidence interval, 1.05-3.75); amniotic band syndrome-limb body wall complex (adjusted odds ratio, 1.66; 95% confidence interval, 1.10-2.51); and atrial septal defects, secundum (adjusted odds ratio, 1.37; 95% confidence interval, 1.09-1.72). There were no significant inverse associations observed.

CONCLUSION

Additional studies replicating the findings are needed to better understand the moderate positive associations observed between periconceptional secondhand smoke and several birth defects in this analysis. Increased odds ratios resulting from chance (eg, multiple comparisons) or recall bias cannot be ruled out.

High-Throughput Determination of Mercury in Tobacco and Mainstream Smoke from Little Cigars

A method was developed that utilizes a platinum trap for mercury from mainstream tobacco smoke, which represents an improvement over traditional approaches that require impingers and long sample preparation procedures. In this approach, the trapped mercury is directly released for analysis by heating the trap in a direct mercury analyzer. The method was applied to the analysis of mercury in the mainstream smoke of little cigars. The mercury levels in little cigar smoke obtained under Health Canada Intense smoking machine conditions ranged from 7.1 × 10(-3) to 1.2 × 10(-2) mg/m(3). These air mercury levels exceed the chronic inhalation minimal risk level corrected for intermittent exposure to metallic mercury (e.g., 1 or 2 h per day, 5 days per week) determined by the Agency for Toxic Substances and Disease Registry. Multivariate statistical analysis was used to assess associations between mercury levels and little cigar physical design properties. Filter ventilation was identified as the principal physical parameter influencing mercury concentrations in mainstream little cigar smoke generated under ISO machine smoking conditions. With filter ventilation blocked under Health Canada Intense smoking conditions, mercury concentrations in tobacco and puff number (smoke volume) were the primary physical parameters that influenced mainstream smoke mercury concentrations.

Long-term dynamics of death rates of emphysema, asthma, and pneumonia and improving air quality

BACKGROUND

The respiratory tract is a major target of exposure to air pollutants, and respiratory diseases are associated with both short- and long-term exposures. We hypothesized that improved air quality in North Carolina was associated with reduced rates of death from respiratory diseases in local populations.

MATERIALS AND METHODS

We analyzed the trends of emphysema, asthma, and pneumonia mortality and changes of the levels of ozone, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and particulate matters (PM2.5 and PM10) using monthly data measurements from air-monitoring stations in North Carolina in 1993-2010. The log-linear model was used to evaluate associations between air-pollutant levels and age-adjusted death rates (per 100,000 of population) calculated for 5-year age-groups and for standard 2000 North Carolina population. The studied associations were adjusted by age group-specific smoking prevalence and seasonal fluctuations of disease-specific respiratory deaths.

RESULTS

Decline in emphysema deaths was associated with decreasing levels of SO2 and CO in the air, decline in asthma deaths-with lower SO2, CO, and PM10 levels, and decline in pneumonia deaths-with lower levels of SO2. Sensitivity analyses were performed to study potential effects of the change from International Classification of Diseases (ICD)-9 to ICD-10 codes, the effects of air pollutants on mortality during summer and winter, the impact of approach when only the underlying causes of deaths were used, and when mortality and air-quality data were analyzed on the county level. In each case, the results of sensitivity analyses demonstrated stability. The importance of analysis of pneumonia as an underlying cause of death was also highlighted.

CONCLUSION

Significant associations were observed between decreasing death rates of emphysema, asthma, and pneumonia and decreases in levels of ambient air pollutants in North Carolina.

Ambient air toxics and asthma prevalence among a representative sample of US kindergarten-age children

BACKGROUND

Criteria pollutants have been associated with exacerbation of children's asthma, but the role of air toxics in relation to asthma is less clear. Our objective was to evaluate whether exposure to outdoor air toxics in early childhood increased asthma risk or severity.

METHODS

Air toxics exposure was estimated using the 2002 National Air toxics Assessment (NATA) and linked to longitudinal data (n=6950) from a representative sample of US children born in 2001 and followed through kindergarten-age in the Early Child Longitudinal Study-Birth Cohort (ECLS-B).

RESULTS

Overall, 17.7% of 5.5 year-olds had ever been told by a healthcare professional they had asthma, and 6.8% had been hospitalized or visited an emergency room for an asthma attack. Higher rates of asthma were observed among boys (20.1%), low-income (24.8%), and non-Hispanic black children (30.0%) (p≤0.05). Air toxics exposure was greater for minority race/ethnicity (p<0.0001), low income (p<0.0001), non-rural area (p<0.001). Across all analyses, greater air toxics exposure, as represented by total NATA respiratory hazard index, or when limited to respiratory hazard index from onroad mobile sources or diesel PM, was not associated with a greater prevalence of asthma or hospitalizations (p trend >0.05). In adjusted logistic regression models, children exposed to the highest respiratory hazard index were not more likely to have asthma compared to those exposed to the lowest respiratory hazard index of total, onroad sources, or diesel PM.

CONCLUSIONS

Early childhood exposure to outdoor air toxics in a national sample has not previously been studied relative to children's asthma. Within the constraints of the study, we found no evidence that early childhood exposure to outdoor air toxics increased risk for asthma. As has been previously reported, it is evident that there are environmental justice and disparity concerns for exposure to air toxics and asthma prevalence in US children.

Health effects of ozone focusing on childhood asthma: what is now known--a review from an epidemiological point of view

Protecting the health of children and the environment is an essential objective for the health policies of any modern society, being also crucial for a sustainable development, according to the World Health Organization. Evaluating the risk of developing childhood asthma is one of the four priority issues identified by the European Commission, according to the European Union Environment and Health Action Plan. Accordingly, this review aimed to update information concerning the effects of exposure to ozone on childhood asthma, thus helping in the development of strategies for further research. Studies have been demonstrating strong associations between the exposure to ozone and asthma. However, the complexity of exposure patterns, the changes in the vulnerability of children at various stages of development, and the practical limitations of research, lead to a still incomplete understanding of the ozone impact on the health of children. Difficulties on the interpretation of epidemiological studies to evaluate chronic effects are mainly due to an absence of studies designed specifically to address this question and to inherent limitations in characterizing exposure. The more rigorous studies provided new evidences for chronic effects of ozone on small airway function and possibly on asthma, but substantial uncertainties remain.

The longitudinal relationship between parental reports of asthma and anxiety and depression symptoms among two groups of Puerto Rican youth

OBJECTIVES

This study aims to examine the relationship between parental reports of child asthma and levels and slopes of anxiety and depression symptoms among two contrasting groups of Puerto Rican youth, and to determine whether asthma is a special risk above and beyond parents' reports of other youths' medical conditions.

METHODS

Two probability samples of youth in San Juan and Caguas, Puerto Rico (n=673) and in the south Bronx, New York (n=598), and their caretakers were interviewed in three yearly assessments. Parental reports of their children's asthma during each assessment were used to indicate whether youth had intermittent (PR=34%, NY=23%) or persistent (PR=7%, NY=16%) asthma. Youths' depression and anxiety symptoms were assessed using self reports to the DISC-IV. Information on youths' medical comorbidity was gathered through parental reports.

RESULTS

Multilevel analyses adjusting for comorbid medical conditions indicated that parental reports of youths' intermittent and persistent asthma were related to higher levels, but similar slopes, of anxiety and depression among youth in New York. In Puerto Rico, youth with persistent asthma experienced less improvement in anxiety over time than youth without asthma, but no other associations were found.

CONCLUSION

Having asthma, based on parental reports, represents a risk factor for Puerto Rican youths' internalizing symptoms, even after adjusting for comorbid medical conditions. This risk is more pronounced among youth living in New York, which highlights the importance of considering the social context in which youth develop and minority status when examining associations between physical health risk factors and mental health.

Outdoor air pollution and asthma in children

BACKGROUND

Asthma, a chronic inflammatory disease of the airways, is associated with reversible airway obstruction and hyperresponsiveness to triggers; clinical symptoms include wheezing, episodic cough, shortness of breath, and increased mucous production. Ambient or outdoor environmental exposure to ozone, particulate matter, sulfur dioxide, and nitrogen oxides has been well documented to exacerbate asthma. Children appear to be most vulnerable to the harmful effects of ambient air pollutants. As their lungs are not completely developed, children may experience greater exposure to environmental pollutants than adults and the higher doses of varied composition may remain in their lungs for a greater duration. Altogether, the negative effects of air pollutants on pulmonary function place children at a greater risk of air pollutant-induced exacerbation of asthma for the duration of their lives.

OBJECTIVES

The aim of this review was to assess recently published literature regarding the influence of air pollution on asthma in children.

METHODS

For this work, we reviewed articles found in PubMed using the key words "outdoor air pollution, asthma, and children" which were published between 2006 and 2009. Only those articles that had a full version available in PubMed were analyzed.

RESULTS

We reviewed studies published between 2006 and 2009 examining the effect of outdoor air pollution on asthma in children. In total, we evaluated 25 articles; of these, 9 were published in 2006, 3 in 2007, 8 in 2008, and 5 in 2009. Of these 25 studies, 1 was a clinical trial, 6 were cross-sectional, 4 were case-control (2 with a case-crossover design), 12 were cohort prospective, and 2 were cohort retrospective studies with varied follow-up times ranging from 10 days to 7 years. The ages of children also differed, ranging from birth to 18 years of age.

CONCLUSIONS

All studies reviewed in this work indicate that outdoor air pollution affects the appearance and exacerbation of asthma in children. Although these findings are of great interest, the limitations of noted works make future investigations of the effect of air pollution on asthma in children essential.

Relationship between polycyclic aromatic hydrocarbon-DNA adducts, environmental tobacco smoke, and child development in the World Trade Center cohort

BACKGROUND

Polycyclic aromatic hydrocarbons (PAHs), including benzo[a]pyrene (BaP), are air pollutants released by the World Trade Center (WTC) fires and urban combustion sources. BaP-DNA adducts provide a measure of PAH-specific genetic damage, which has been associated with increased risk of adverse birth outcomes and cancer. We previously reported that levels of BaP-DNA adducts in maternal and umbilical cord blood obtained at delivery were elevated among subjects who had resided within 1 mile of the WTC site during the month after 9/11; and that elevated blood adducts in combination with in utero exposure to environmental tobacco smoke (ETS) were significantly associated with decreased fetal growth.

OBJECTIVE

Our aim was to assess possible effects of prenatal exposure to WTC pollutants on child development.

METHODS

After 11 September 2001, we enrolled a cohort of nonsmoking pregnant women who delivered at three lower Manhattan hospitals. We have followed a subset of children through their third birthdays and measured cognitive and motor development using the Bayley-II Scales of Child Development (BSID-II).

RESULTS

In multivariate analyses, we found a significant interaction between cord blood adducts and in utero exposure to ETS on mental development index score at 3 years of age (p = 0.02, n = 98) whereas neither adducts nor ETS alone was a significant predictor of (BSID-II) cognitive development.

CONCLUSION

Although limited by small numbers, these results suggest that exposure to elevated levels of PAHs in conjunction with prenatal ETS exposure may have contributed to a modest reduction in cognitive development among cohort children.

Towards a multidisciplinary and integrated strategy in the assessment of adverse health effects related to air pollution: the case study of Cracow (Poland) and asthma

Complex interaction between anthropogenic activities, air quality and human health in urban areas, such as in Cracow sustains the need for the development of an interdisciplinary and integrated risk-assessment methodology. In such purpose, we propose a pilot study performed on asthmatics and based on a combined use of a biomarker, such as metallothionein 2A (MT-2A) in the characterization of human exposure to one or a mixture of pollutants and of Geographical Information Systems (G.I.S.) which integrates climatic and urban anthropogenic parameters in the assessment of spatio-temporal dispersion of air pollutants. Considering global incidence of air pollution on asthma and on peripheral blood lymphocytes MT-2A expression should provide a complementary information on biological risks linked to urban anthropogenic activities. Such study would help for the establishment of a sustainable development in urban areas that can maintain the integrity of air quality and preserve human health.

Different effects of urban and rural environments in the respiratory status of Greek schoolchildren

We hypothesized that asthma symptoms and lung function of schoolchildren living in Athens urban area are adversely affected as compared to others living in a rural environment, over a period of 8 years. We recruited 478 and 342 children aged 8-10 years living within a short radius around the urban and rural area monitoring stations, respectively. Respiratory health was assessed by a parent-completed questionnaire in three phases: 1995-1996 (phase-1), 1999-2000 (phase-2), 2003-2004 (phase-3) and by spirometry in phases-1 and 2. Reported asthma and wheeze did not differ in the two areas, whereas cough was more prevalent in the urban area in phase-1. Children from the rural environment had lower levels of percent-predicted forced vital capacity (FVC%) in phase-1 and higher of percent-predicted-forced expiratory flow at mid-FVC (FEF(50)%) in both phases. Independent associations were detected between FVC% as-well-as FEF(50)% and residential area. High FVC% was associated with outdoor systemic athletic activities; there was lower FVC% growth in the urban versus the rural area. Nitrogen dioxide and sulfur dioxide were higher in the urban area, whereas ozone concentrations differed less between the two areas. These results suggest that long-term exposure to urban environment is associated with sub-clinical airway narrowing and slower rate of FVC growth.

A summary of recent findings on birth outcomes and developmental effects of prenatal ETS, PAH, and pesticide exposures

Inner-city minority populations are high-risk groups for adverse birth outcomes and also more likely to be exposed to environmental contaminants, including environmental tobacco smoke (ETS), benzo[a]pyrene B[a]P, other ambient polycyclic aromatic hydrocarbons (global PAHs), and residential pesticides. The Columbia Center for Children's Environmental Health (CCCEH) is conducting a prospective cohort study of 700 northern Manhattan pregnant women and newborns to examine the effects of prenatal exposure to these common toxicants on fetal growth, early neurodevelopment, and respiratory health. This paper summarizes results of three published studies demonstrating the effects of prenatal ETS, PAH, and pesticides on birth outcomes and/or neurocognitive development [Perera FP, Rauh V, Whyatt RM, Tsai WY, Bernert JT, Tu YH, et al. Molecular evidence of an interaction between prenatal environment exposures on birth outcomes in a multiethnic population. Environ Health Perspect 2004;12:630-62; Rauh VA, Whyatt RM, Garfinkel R, Andrews H, Hoepner L, Reyes A, et al. Developmental effects of exposure to environmental tobacco smoke and material hardship among inner-city children. Neurotoxicol Teratol 2004;26:373-85; Whyatt RM, Rauh V, Barr DB, Camann DE, Andrews HF, Garfinkel R, et al. Prenatal insecticide exposures, birth weight and length among an urban minority cohort. Environ Health Perspect, in press]. To evaluate the effects of prenatal exposure to ETS, PAHs, and pesticides, researchers analyzed questionnaire data, cord blood plasma (including biomarkers of ETS and pesticide exposure), and B[a]P-DNA adducts (a molecular dosimeter of PAHs). Self-reported ETS was associated with decreased head circumference (P = 0.04), and there was a significant interaction between ETS and adducts such that combined exposure had a significant multiplicative effect on birth weight (P = 0.04) and head circumference (P = 0.01) after adjusting for confounders. A second analysis examined the neurotoxic effects of prenatal ETS exposure and postpartum material hardship (unmet basic needs in the areas of food, housing, and clothing) on 2-year cognitive development. Both exposures depressed cognitive development (P < 0.05), and there was a significant interaction such that children with exposure to both ETS and material hardship exhibited the greatest cognitive deficit (7.1 points). A third analysis found that cord chlorpyrifos, and a combined measure of cord chlorpyrifos, diazinon, and propoxur-metabolite, were inversely associated with birth weight and/or length (P < 0.05). These results underscore the importance of policies that reduce exposure to ETS, air pollution, and pesticides with potentially adverse effects on fetal growth and child neurodevelopment.

Relationships among polycyclic aromatic hydrocarbon-DNA adducts, proximity to the World Trade Center, and effects on fetal growth

Polycyclic aromatic hydrocarbons (PAHs) are toxic pollutants released by the World Trade Center (WTC) fires and various urban combustion sources. Benzo[a]pyrene (BaP) is a representative member of the class of PAHs. PAH-DNA adducts, or BaP-DNA adducts as their proxy, provide a measure of chemical-specific genetic damage that has been associated with increased risk of adverse birth outcomes and cancer. To learn whether PAHs from the WTC disaster increased levels of genetic damage in pregnant women and their newborns, we analyzed BaP-DNA adducts in maternal (n = 170) and umbilical cord blood (n = 203) obtained at delivery from nonsmoking women who were pregnant on 11 September 2001 and were enrolled at delivery at three downtown Manhattan hospitals. The mean adduct levels in cord and maternal blood were highest among newborns and mothers who resided within 1 mi of the WTC site during the month after 11 September, intermediate among those who worked but did not live within this area, and lowest in those who neither worked nor lived within 1 mi (reference group). Among newborns of mothers living within 1 mi of the WTC site during this period, levels of cord blood adducts were inversely correlated with linear distance from the WTC site (p = 0.02). To learn whether PAHs from the WTC disaster may have affected birth outcomes, we analyzed the relationship between these outcomes and DNA adducts in umbilical cord blood, excluding preterm births to reduce variability. There were no independent fetal growth effects of either PAH-DNA adducts or environmental tobacco smoke (ETS), but adducts in combination with in utero exposure to ETS were associated with decreased fetal growth. Specifically, a doubling of adducts among ETS-exposed subjects corresponded to an estimated average 276-g (8%) reduction in birth weight (p = 0.03) and a 1.3-cm (3%) reduction in head circumference (p = 0.04). The findings suggest that exposure to elevated levels of PAHs, indicated by PAH-DNA adducts in cord blood, may have contributed to reduced fetal growth in women exposed to the WTC event.

Molecular evidence of an interaction between prenatal environmental exposures and birth outcomes in a multiethnic population

Inner-city, minority populations are high-risk groups for adverse birth outcomes and also are more likely to be exposed to environmental contaminants, including environmental tobacco smoke (ETS), benzo[a]pyrene (BaP), and other polycyclic aromatic hydrocarbons (PAHs) found in urban air. In a sample of nonsmoking African-American and Dominican women, we evaluated the effects on birth outcomes of prenatal exposure to ETS, using questionnaire data and plasma cotinine as a biomarker of exposure, and environmental PAHs using BaP-DNA adducts as a molecular dosimeter. We previously reported that among African Americans, high prenatal exposure to PAHs estimated by prenatal personal air monitoring was associated with lower birth weight (p = 0.003) and smaller head circumference (p = 0.01) after adjusting for potential confounders. In the present analysis, self-reported ETS was associated with decreased head circumference (p = 0.04). BaP-DNA adducts were not correlated with ETS or dietary PAHs. There was no main effect of BaP-DNA adducts on birth outcomes. However, there was a significant interaction between the two pollutants such that the combined exposure to high ETS and high adducts had a significant multiplicative effect on birth weight (p = 0.04) and head circumference (p = 0.01) after adjusting for ethnicity, sex of newborns, maternal body mass index, dietary PAHs, and gestational age. This study provides evidence that combined exposure to environmental pollutants at levels currently encountered in New York City adversely affects fetal development.

Traffic related air pollution and incidence of childhood asthma: results of the Vesta case-control study

STUDY OBJECTIVE

The Vesta project aims to assess the role of traffic related air pollution in the occurrence of childhood asthma.

DESIGN AND SETTING

Case-control study conducted in five French metropolitan areas between 1998 and 2000. A set of 217 pairs of matched 4 to 14 years old cases and controls were investigated. An index of lifelong exposure to traffic exhausts was constructed, using retrospective information on traffic density close to all home and school addresses since birth; this index was also calculated for the 0-3 years age period to investigate the effect of early exposures.

MAIN RESULTS

Adjusted on environmental tobacco smoke, personal and parental allergy, and several confounders, lifelong exposure was not associated with asthma. In contrast, associations before age of 3 were significant: odds ratios for tertiles 2 and 3 of the exposure index, relative to tertile 1, exhibited a positive trend (1.48 (95%CI = 0.7 to 3.0) and 2.28 (1.1 to 4.6)), with greater odds ratios among subjects with positive skin prick tests.

CONCLUSIONS

These results suggest that traffic related pollutants might have contributed to the asthma epidemic that has taken place during the past decades among children.

Respiratory symptoms and peak expiratory flow in children with asthma in relation to volatile organic compounds in exhaled breath and ambient air

Indoor volatile organic compounds (VOCs) have been associated with asthma, but there is little epidemiologic work on ambient exposures, and no data on relationships between respiratory health and exhaled breath VOCs, which is a biomarker of VOC exposure. We recruited 26 Hispanic children with mild asthma in a Los Angeles community with high VOC levels near major freeways and trucking routes. Two dropped out, three had invalid peak expiratory flow (PEF) or breath VOC data, leaving 21. Children filled out symptom diaries and performed PEF maneuvers daily, November 1999-January 2000. We aimed to collect breath VOC samples on asthma episode and baseline symptom-free days, but six subjects only gave samples on symptom-free days. We analyzed 106 breath samples by GC-MS. Eight VOCs were quantifiable in >75% of breath samples (benzene, methylene chloride, styrene, tetrachloroethylene, toluene, m,p-xylene, o-xylene, and p-dichlorobenzene). Generalized estimating equation and mixed linear regression models for VOC exposure-response relationships controlled for temperature and respiratory infections. We found marginally positive associations between bothersome or more severe asthma symptoms and same day breath concentrations of benzene [odds ratio (OR) 2.03, 95% confidence interval (CI) 0.80, 5.11] but not other breath VOCs. Ambient petroleum-related VOCs measured on the same person-days as breath VOCs showed notably stronger associations with symptoms, including toluene, m,p-xylene, o-xylene, and benzene (OR 5.93, 95% CI 1.64, 21.4). On breath sample days, symptoms were also associated with 1-h ambient NO(2), OR 8.13 (1.52, 43.4), and SO(2), OR 2.36 (1.16, 4.81). Consistent inverse relationships were found between evening PEF and the same ambient VOCs, NO(2), and SO(2). There were no associations with O(3). Given the high traffic density of the region, stronger associations for ambient than for breath VOCs suggest that ambient VOC measurements were better markers for daily exposure to combustion-related compounds thought to be causally related to acute asthma. Alternatively, the low sample size of symptom responses (15-21 responses per 108 breath samples) may have led to the nonsignificant results for breath VOCs.

Genetic susceptibility to nickel-induced acute lung injury

Human exposure to insoluble and soluble nickel compounds is extensive. Besides wide usage in many industries, nickel compounds are contained in cigarette smoke and, in low levels, in ambient particulate matter. Soluble nickel particulate, especially nickel sulfate (NiSO(4)), has been associated with acute lung injury. To begin identifying genes controlling susceptibility to NiSO(4), mean survival times (MSTs) of eight inbred mouse strains were determined after aerosol exposure. Whereas A/J (A) mice were sensitive, C57BL/6J (B6) mice survived nearly twice as long (resistant). Their offspring were similarly resistant, demonstrating heritability as a dominant trait. Quantitative trait locus (QTL) analysis of backcross mice generated from these strains identified a region on chromosome 6 significantly linked to survival time. Regions on chromosomes 1 and 12 were suggestive of linkage and regions on chromosomes 8, 9, and 16 contributed to the response. Haplotype analysis demonstrated that QTLs on chromosomes 6, 9, 12, and 16 could explain the MST difference between the parental strains. To complement QTL analysis results, cDNA microarray analysis was assessed following NiSO(4) exposure of A and B6 mice. Significant expression changes were identified in one or both strains for >100 known genes. Closer evaluation of these changes revealed a temporal pattern of increased cell proliferation, extracellular matrix repair, hypoxia, and oxidative stress, followed by diminished surfactant proteins. Certain expressed sequence tags clustered with known genes, suggesting possible co-regulation and novel roles in pulmonary injury. Together, results from QTL and microarray analyses of nickel-induced acute lung injury survival allowed us to generate a short list of candidate genes.

Effects of transplacental exposure to environmental pollutants on birth outcomes in a multiethnic population

Inner-city, minority populations are high-risk groups for adverse birth outcomes and also are more likely to be exposed to environmental contaminants, including environmental tobacco smoke (ETS), polycyclic aromatic hydrocarbons (PAHs), and pesticides. In a sample of 263 nonsmoking African-American and Dominican women, we evaluated the effects on birth outcomes of prenatal exposure to airborne PAHs monitored during pregnancy by personal air sampling, along with ETS estimated by plasma cotinine, and an organophosphate pesticide (OP) estimated by plasma chlorpyrifos (CPF). Plasma CPF was used as a covariate because it was the most often detected in plasma and was highly correlated with other pesticides frequently detected in plasma. Among African Americans, high prenatal exposure to PAHs was associated with lower birth weight (p = 0.003) and smaller head circumference (p = 0.01) after adjusting for potential confounders. CPF was associated with decreased birth weight and birth length overall (p = 0.01 and p = 0.003, respectively) and with lower birth weight among African Americans (p = 0.04) and reduced birth length in Dominicans (p < 0.001), and was therefore included as a covariate in the model with PAH. After controlling for CPF, relationships between PAHs and birth outcomes were essentially unchanged. In this analysis, PAHs and CPF appear to be significant independent determinants of birth outcomes. Further analyses of pesticides will be carried out. Possible explanations of the failure to find a significant effect of PAHs in the Hispanic subsample are discussed. This study provides evidence that environmental pollutants at levels currently encountered in New York City adversely affect fetal development.

Environmental air toxics: role in asthma occurrence?

The National Urban Air Toxics Research Center (NUATRC) hosted its first scientific workshop in 1994 that focused on possible relationships between air toxics and asthma. From that meeting came recommendations for future research including a need for more complete individual personal exposure assessments so that determinations of personal exposures to pollutants could be made. In the spring of 2001, NUATRC held a second such workshop to review progress made in this area during the intervening 7 years. Peer-reviewed articles from the workshop are published in this issue of (italic)Environmental Health Perspectives Supplements(/italic). As in 1994, academic, government, and industry scientists participated. Dave Guinnup of the Environmental Protection Agency discussed the nature of air toxics, their definition, and the basis for federal regulation. George Leikauf from the University of Cincinnati reviewed the 1994 workshop and subsequent research in this field. Current research funded by NUATRC that is addressing individual personal exposure was presented by Clifford Weisel (Environmental and Occupational Health Sciences Institute, University of Medicine and Dentistry of New Jersey), Patrick Kinney (Columbia University) and Candis Claiborn (Washington State University). David Corry from Baylor College of Medicine highlighted new insights into asthma pathogenesis while Stephen Redd from the Centers for Disease Control presented an overview of asthma epidemiology as well as the societal costs of the disease. Mary White (Agency for Toxic Substances and Disease Registry) discussed recent epidemiologic investigations by public health agencies into community concerns about asthma and hazardous air pollutants. David Peden (University of North Carolina) reviewed scientific studies into the links between asthma and air toxics as well as criteria air pollutants. In a session on occupational asthma, Lee Petsonk (National Institute for Occupational Safety and Health) discussed risk factors for work-related asthma, whereas Ralph Delfino (University of California, Irvine) addressed limitations of extrapolating from occupational asthma to asthma in the general population. These presentations were followed by panel discussions focusing on future research programs, both for NUATRC and similar research institutions. Recommendations for future research included improved assessments of personal exposure to air toxics as well as research focused on specific hazardous air pollutants. The latter recommendation was based on medical literature that suggests certain pollutants from the list of 188 air toxics are most likely to adversely affect respiratory health.

Hazardous air pollutants and asthma

Asthma has a high prevalence in the United States, and persons with asthma may be at added risk from the adverse effects of hazardous air pollutants (HAPs). Complex mixtures (fine particulate matter and tobacco smoke) have been associated with respiratory symptoms and hospital admissions for asthma. The toxic ingredients of these mixtures are HAPs, but whether ambient HAP exposures can induce asthma remains unclear. Certain HAPs are occupational asthmagens, whereas others may act as adjuncts during sensitization. HAPs may exacerbate asthma because, once sensitized, individuals can respond to remarkably low concentrations, and irritants lower the bronchoconstrictive threshold to respiratory antigens. Adverse responses after ambient exposures to complex mixtures often occur at concentrations below those producing effects in controlled human exposures to a single compound. In addition, certain HAPs that have been associated with asthma in occupational settings may interact with criteria pollutants in ambient air to exacerbate asthma. Based on these observations and past experience with 188 HAPs, a list of 19 compounds that could have the highest impact on the induction or exacerbation of asthma was developed. Nine additional compounds were identified that might exacerbate asthma based on their irritancy, respirability, or ability to react with biological macromolecules. Although the ambient levels of these 28 compounds are largely unknown, estimated exposures from emissions inventories and limited air monitoring suggest that aldehydes (especially acrolein and formaldehyde) and metals (especially nickel and chromium compounds) may have possible health risk indices sufficient for additional attention. Recommendations for research are presented regarding exposure monitoring and evaluation of biologic mechanisms controlling how these substances induce and exacerbate asthma.

Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research

Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass. Community studies should focus on air toxics expected to have adverse respiratory effects based on biological mechanisms, particularly irritant and immunological pathways to asthma onset and exacerbation.

Addressing community concerns about asthma and air toxics

People with asthma who live near or downwind from a source of toxic emissions commonly express concerns about the possible impact of hazardous air pollution on their health, especially when these emissions are visible or odorous. Citizens frequently turn to their local and state health departments for answers, but health departments face many challenges in addressing these concerns. These challenges include a lack of asthma statistics at the local level, limited exposure information, and a paucity of scientific knowledge about the contributions of hazardous air pollutants to asthma induction or exacerbation. Health agencies are creatively developing methods to address these challenges while working toward improving asthma surveillance data at the state and local levels. Recent community health investigations suggest that hazardous air pollutants that are occupational asthmagens or associated with odors may deserve more attention. In seeking to address community concerns about hazardous air pollution and asthma, community health investigations may also help to fill gaps in our scientific knowledge and identify areas for further research or environmental intervention. The solutions to community problems associated with environmental contamination and asthma, however, require sustained, coordinated efforts by public and private groups and citizens. Public health agencies can make a unique contribution to this effort, but additional resources and support will be required to develop information systems and epidemiologic capacity at the state and local levels.

Five epidemiological studies on transport and asthma: objectives, design and descriptive results

A case-control study was conducted in five French metropolitan areas in order to assess the role of traffic-related air pollution in the occurrence of childhood asthma. This paper presents the study design and describes the distribution of key exposure variables. A set of 217 pairs of matched 4- to 14-year-old cases and controls were investigated (matching criteria: city, age, and gender). Current and past environmental smoke exposures, indoor allergens or air pollution sources, and personal and family atopy were assessed by standard questionnaires. When possible, direct measurements were done to check the validity of this information, on current data: skin prick tests, urine cotinine, house dust mites densities, personal exposures to, and home indoor concentrations of NO(x) and PM(2.5). Cumulative exposure to traffic-related pollutants was estimated through two indices: "traffic density" refers to a time-weighted average of the traffic density-to-road distance ratio for all home and school addresses of each child's life; "air pollution" index combines lifelong time-activity patterns and ambient air concentration estimates of NO(x), using an air dispersion model of traffic exhausts. Average current PM(2.5) personal exposure is 23.8 microg/m3 (SD=17.4), and average indoor concentrations=22.5 microg/m3 (18.2); corresponding values for NO(2) are 31.4 (13.9) and 36.1 (21.4) microg/m3. Average lifelong calculated exposures to traffic-related NO(x) emissions are 62.6 microg/m3 (43.1). The five cities show important contrasts of exposure to traffic pollutants. These data will allow comparison of lifelong exposures to indicators of traffic exhausts between cases and controls, including during early ages, while controlling for a host of known enhancers or precipitators of airway chronic inflammation and for possible confounders.

Mucin apoprotein expression in COPD

Mucins, which are complex glycoproteins that provide the viscoelastic properties of mucus that are essential for the protection of the airways, are characterized by a variable-number tandem repeats (VNTR) region that may undergo alternate splicing during transcription. Such transcripts may yield multiple proteins via diverse post-translational modifications involving glycosylation (within each VNTR). Fifteen distinct mucin genes have been identified, with several mapping to chromosomal clusters (ie, 7q22 and 11p15.5), possibly having evolved by gene duplication. The deduced protein sequences can be subdivided into both membrane-associated mucins and secreted mucins. Membrane-associated mucins consist of cytoplasmic, transmembrane, and extracellular domains. The membrane-associated mucins MUC1, MUC4, and MUC11 have been localized to the lung. In addition to VNTRs, secreted mucins possess repeated cysteine-rich D-domains (which are important in polymerization). Secreted mucins that are localized to the lung include MUC2 (in cells with and without secretory granules), MUC5AC (in surface and submucosal mucous cells), MUC5B and MUC8 (in submucosal mucous cells), and MUC7 (in submucosal serous cells). Currently, little is known about the regulation of mucins in COPD patients. Recent studies with acrolein and cigarette smoke have suggested that MUC5AC is inducible (accompanied by epidermal growth factor [EGF] ligand formation and the activation of EGF receptor-dependent pathways), whereas MUC5B is constitutively expressed (increasing through gland enlargement). Similarly, little is known about the genetic determinants that control mucus hypersecretion, but preliminary findings in animal models suggest that intrastrain differences in acrolein-induced mucin formation are amenable to genetic analysis. As our understanding of the functional genomics of mucin biology increases, further clinical targets and therapeutic strategies are likely to emerge.

Dose-related protection from nickel-induced lung injury in transgenic mice expressing human transforming growth factor-alpha

To determine the role of transforming growth factor-alpha (TGF-alpha) in protecting the lung from aerosolized nickel injury, transgenic mouse lines expressing human TGF-alpha in the pulmonary epithelium, under control of the human surfactant protein-C gene promoter, were tested. Higher expressing TGF-alpha transgenic mouse lines, expressing distinct levels of TGF-alpha, survived longer than nontransgenic control mice. Increased survival correlated with levels of TGF-alpha expression in the lung. After 72 h of nickel exposure (70 microg Ni/m3), transgenic lines with intermediate levels of the TGF-alpha expression demonstrated attenuation of lung injury. The highest expressing line (line 28) demonstrated reduced lung inflammation and edema, reduced lung wet-to-dry weight ratios, decreased bronchoalveolar lavage (BAL) protein and neutrophils, reduced interleukin (IL)-1beta, interleukin-6, and macrophage inflammatory protein-2, and maintained surfactant protein-B (SP-B) levels compared with nontransgenic controls. In the TGF-alpha transgenic mouse model, TGF-alpha protects against nickel-induced acute lung injury, at least in part, by attenuating the inflammatory response, reducing pulmonary edema, and preserving levels of SP-B.

Segregation and black/white differences in exposure to air toxics in 1990

I examined non-Hispanic Black and non-Hispanic White differences in exposure to noncriteria air pollutants in 44 U.S. Census Bureau-defined metropolitan areas with populations greater than one million, using data on air toxics concentrations prepared for the U.S. Environmental Protection Agency as part of its Cumulative Exposure Project combined with U.S. census data. I measured differences in exposure to air toxics through the calculation of a net difference score, which is a statistical measure used in income inequality analysis to measure inequality over the whole range of exposures. The scores ranged from 11.52 to 83.60. In every metropolitan area, non-Hispanic Blacks are more likely than non-Hispanic Whites to be living in tracts with higher total modeled air toxics concentrations. To assess potential reasons for such a wide variation in exposure differences, I performed a multiple regression analysis with the net difference score as the dependent variable. Independent variables initially included were as follows: the dissimilarity index (to measure segregation), Black poverty/White poverty (to control for Black/White economic differences), population density and percentage of persons traveling to work who drive to work (alone and in car pools), and percentage of workforce employed in manufacturing (factors affecting air quality). After an initial analysis I eliminated from the model the measures of density and the persons driving to work because they were statistically insignificant, they did not add to the predictive power of the model, and their deletion did not affect the other variables. The final model had an R(2) of 0.56. Increased segregation is associated with increased disparity in potential exposure to air pollution.

Acute lung injury: functional genomics and genetic susceptibility

Initiated by numerous factors, acute lung injury is marked by epithelial and endothelial cell perturbation and inflammatory cell influx that leads to surfactant disruption, pulmonary edema, and atelectasis. This syndrome has been associated with a myriad of mediators including cytokines, oxidants, and growth factors. To better understand gene-environmental interactions controlling this complex process, the sensitivity of inbred mouse strains was investigated following acute lung injury that was induced by fine nickel sulfate aerosol. Measuring survival time, protein and neutrophil concentrations in BAL fluid, lung wet-to-dry weight ratio, and histology, we found that these responses varied between inbred mouse strains and that susceptibility is heritable. To assess the progression of acute lung injury, the temporal expression of genes and expressed sequence tags was assessed by complementary DNA microarray analysis. Enhanced expression was noted in genes that were associated with oxidative stress, antiprotease function, and extracellular matrix repair. In contrast, expression levels of surfactant proteins (SPs) and Clara cell secretory protein (ie, transcripts that are constitutively expressed in the lung) decreased markedly. Genome-wide analysis was performed with offspring derived from a sensitive and resistant strain (C57BL/6xA F(1) backcrossed with susceptible A strain). Significant linkage was identified for a locus on chromosome 6 (proposed as Aliq4), a region that we had identified previously following ozone-induced acute lung injury. Two suggestive linkages were identified on chromosomes 1 and 12. Using haplotype analysis to estimate the combined effect of these regions (along with putative modifying loci on chromosomes 9 and 16), we found that five loci interact to account for the differences in survival time of the parental strains. Candidate genes contained in Aliq4 include SP-B, aquaporin 1, and transforming growth factor-alpha. Thus, the functional genomic approaches of large gene set expression (complementary DNA microarray) and genome-wide analyses continue to provide novel insights into the genetic susceptibility of lung injury.

Urban air pollution and health inequities: a workshop report

Over the past three decades, an array of legislation with attendant regulations has been implemented to enhance the quality of the environment and thereby improve the public's health. Despite the many beneficial changes that have followed, there remains a disproportionately higher prevalence of harmful environmental exposures, particularly air pollution, for certain populations. These populations most often reside in urban settings, have low socioeconomic status, and include a large proportion of ethnic minorities. The disparities between racial/ethnic minority and/or low-income populations in cities and the general population in terms of environmental exposures and related health risks have prompted the "environmental justice" or "environmental equity" movement, which strives to create cleaner environments for the most polluted communities. Achieving cleaner environments will require interventions based on scientific data specific to the populations at risk; however, research in this area has been relatively limited. To assess the current scientific information on urban air pollution and its health impacts and to help set the agenda for immediate intervention and future research, the American Lung Association organized an invited workshop on Urban Air Pollution and Health Inequities held 22-24 October 1999 in Washington, DC. This report builds on literature reviews and summarizes the discussions of working groups charged with addressing key areas relevant to air pollution and health effects in urban environments. An overview was provided of the state of the science for health impacts of air pollution and technologies available for air quality monitoring and exposure assessment. The working groups then prioritized research needs to address the knowledge gaps and developed recommendations for community interventions and public policy to begin to remedy the exposure and health inequities.

Effect of exposure to nitrogen dioxide on alveolar macrophage-mediated immunosuppressive activity in rats

Nitrogen dioxide (NO2), a major component of air pollutants, induces inflammatory responses in the lungs. Resident alveolar macrophages (AM) play an immunosuppressive role in the lungs via suppression of lymphocyte proliferation, and nitric oxide (NO) plays a crucial role in this immunosuppressive activity. Microenvironmental changes within the alveoli during inflammatory responses, however, can inhibit this immunosuppressive activity of AM. The present study was designed to clarify the effect of NO2 exposure on the immunosuppressive activity of and NO production by AM in rats. Wistar rats were exposed to 10 ppm NO2 for 3, 14 or 28 days, after which bronchoalveolar lavage fluid (BALF) was taken as a sample of the alveolar microenvironment. Suppression of concanavalin A-induced lymphocyte proliferation and NO production by AM were markedly inhibited by BALF from NO2-exposed rats (NO2-BALF). The inhibitory effect of NO2-BALF at 28-days exposure was stronger than that of NO2-BALF at 3 or 14 days exposure. In conclusion, AM-mediated immunosuppressive activity was inhibited by the NO2-induced changes of the alveolar microenvironment through the inhibition of NO production.

Suspended particulate matter in indoor air: adjuvants and allergen carriers

The overall purpose of this study was to investigate how airborne house dust particles may contribute to an allergic immune response, and thereby also to asthma and other respiratory symptoms. The following aims were set: first, to quantify and characterize indoor suspended particulate matter (SPM) with regard to amount, as well as elemental and size distribution, second, to identify possible mechanisms by which SPM may affect the allergic immune response. A vast majority of the particles in SPM samples from homes in Oslo were found to be less than 2.5 microm in diameter. This PM(2.5) fraction contained, in addition to a large amount of sulfur aerosols and silicates, a lot of soot particles. Most of these were less than 1 microm in diameter. Using an immunogold labeling technique, we found that these soot particles carried cat, dog and birch allergens on their surface. These results show that indoor SPM contains a lot of potential allergen carriers, i.e. soot particles (carbon aggregates), most of them less that 1 microm in diameter and therefore able to transport allergens deep into the respiratory tree. We further found that diesel exhaust particles (DEP), which is likely the main soot component of SPM, adsorbed several well-known allergens in vitro. Furthermore, SPM was found to elicit a local lymph node inflammatory response, and to have an adjuvant activity on the production of IgE antibodies to ovalbumin (OA).

Prevalence of cocaine use and its impact on asthma exacerbation in an urban population

OBJECTIVES

To assess the prevalence of cocaine use, and its impact on severity of presentation, among adults presenting to the emergency department (ED) with asthma. A secondary aim was to assess the use of various asthma treatment modalities, with reference to the 1997 National Asthma Education and Prevention Program (NAEPP) guidelines.

METHODS

All adults aged 18 to 55 years who presented to the ED of this institution with an asthma attack, were approached about participating in the study, which required giving informed consent, answering a facilitated questionnaire, and giving a urine sample for drug screening.

RESULTS

Patients were enrolled during a 7-month period. A total of 163 patients were approached to enter the study; 116 patients consented to participate in the study, with 103 submitting complete urine samples. Thirty-seven patients refused to participate, and 10 were excluded. Sixty-eight percent of the patients were women, with a mean age of 33 years. African-Americans made up 89% of the total group. Thirty-five percent were cigarette smokers. Urine cocaine tests were positive in 13 of 103 (13%); 6 of 103 (5.8%) were positive for opiates. In the cocaine-positive group, 5 of 13 patients (38%) were admitted to the hospital, including two patients requiring intubation and mechanical ventilation. Of the total group, 23 of 103 patients (22%) were admitted, and 5 of those 23 admitted patients (22%) were cocaine-positive. Length of stay was significantly longer (5 vs 2.5 days, p < 0.05) in the cocaine-positive admitted patients. Forty-six percent of all patients reported using inhaled corticosteroids (ICS), with 39% of admitted patients using them. Thirty-two percent of all patients had obtained three or more refills of their beta(2)-agonist inhaler in the previous month.

CONCLUSIONS

The prevalence of cocaine use may be much higher than the 13% shown in this study, because of patients' refusal to participate in the study. Second, the severity of exacerbation appears to be worse in the cocaine-positive group. Finally, the majority of patients presenting did not use ICS in accordance with the NAEPP guidelines.

Neuroepithelial bodies of pulmonary airways serve as a reservoir of progenitor cells capable of epithelial regeneration

Remodeling of the conducting airway epithelium is a common finding in the chronically injured lung and has been associated with increased risk for developing lung cancer. Pulmonary neuroendocrine cells and clusters of these cells termed neuroepithelial bodies (NEBs) play a central role in each of these processes. We previously developed an adult mouse model of airway injury and repair in which epithelial regeneration after naphthalene-induced Clara cell ablation occurred preferentially at airway branch points and gave rise to nascent Clara cells. Continued repair was accompanied by NEB hyperplasia. We now provide the following evidence that the NEB microenvironment serves as a source of airway progenitor cells that contribute to focal regeneration of the airway epithelium: 1) nascent Clara cells and NEBs localize to the same spatial domain; 2) within NEB, both Clara cell secretory protein- and calcitonin gene-related peptide-immunopositive cells are proliferative; 3) the NEB microenvironment of both the steady-state and repairing lung includes cells that are dually immunopositive for Clara cell secretory protein and calcitonin gene-related peptide, which were previously identified only within the embryonic lung; and 4) NEBs harbor variant Clara cells deficient in cytochrome P450 2F2-immunoreactive protein. These data suggest that the NEB microenvironment is a reservoir of pollutant-resistant progenitor cells responsive to depletion of an abundant airway progenitor such as the Clara cell.

Prevalence of asthma and respiratory symptoms in south-central Durban, South Africa

The prevalence of asthma and respiratory symptoms in south-central Durban, one of the most heavily polluted areas of South Africa, has been determined using a cross-sectional survey of 213 households in the communities of Merewent (97% Indians) and Austerville (98% coloreds). The study population consisted of 367 children (less than 17 years old) and 693 adults. About 10% of the children and 12% of adults reported doctor diagnosed asthma. The self-reported prevalence rates for wheezing (3740%) and attacks of shortness of breath with wheeze (16-28%) were much higher than that for doctor diagnosed asthma and common co-occurrence of the three symptoms is found. The prevalence rates for other respiratory symptoms include 33-35% for chronic cough, 31-32% for chronic phlegm, 44-50% for frequent blocked-runny nose, and 16-27% for sinusitis. Factors in the community that were associated with asthma, wheeze and shortness of breath with wheeze among the adult population included cigarette smoking, use of insecticides (coils and pump spray) and home ownership. An association between asthma among children and a number of household risk factors including dampness, carpet, pets or use of pesticides was not apparent in the community. Asthma prevalence was strongly correlated with missing of school by children (odds ratio (OR): 44; 95% confidence interval (CI): 13-141). The study serves to draw attention to a growing but neglected public health problem in urban areas of Africa.

Effect of environmental pollutants on the production of pro-inflammatory cytokines by normal human dermal keratinocytes

The effect of the environmental pollutants, diesel exhaust particles (DEP) and formaldehyde (FA), on the production of pro-inflammatory cytokines (interleukin (IL)-1alpha, IL-1beta, tumor necrosis factor (TNF)-alpha and IL-8) by normal human dermal keratinocytes (hKCs) was investigated. Normal hKCs were incubated with various concentrations of DEP (0.4, 0.8, 4, or 20 microg/ml) or FA (0.25, 0.5, 1, or 5 microg/ml), and cytokine production was then determined by enzyme-linked immunosorbent assay (ELISA). DEP (20 microg/ml) induced IL-1beta production without altering cell growth. The increased production of IL-1beta induced by this concentration of DEP was further enhanced by the presence of phorbol 12-myristate 13-acetate (PMA), although PMA alone did not affect the levels of IL-1beta. IL-8 production was also increased by DEP (0.4 and 0.8 microg/ml), which is consistent with the results that these concentrations of DEP increased the number of cells significantly after 72 h incubation. Although FA alone did not stimulate the production of IL-1beta or IL-8 by keratinocytes, FA (0.5 microg/ml and 5 microg/ml) significantly increased IL-8 and IL-1beta production, respectively, in cells stimulated with PMA. IL-1alpha production was not modulated by FA or DEP even in the presence of PMA. TNF-alpha was produced by unstimulated keratinocytes at barely detectable levels after 48 h incubation. Although basal levels of TNF-alpha in the culture supernatants were increased after stimulation with PMA, neither pollutant alone nor combination with PMA affected the levels of TNF-alpha. These in vitro findings suggest that environmental pollutants may act as modulating factors of cutaneous inflammation by affecting the ability of keratinocytes to release pro-inflammatory cytokines.

Experimental assessment of the influence of atmospheric pollutants on respiratory disease

Asthma is a chronic respiratory disease characterized by inflammation, episodes of usually reversible airways obstruction, and bronchial hyperresponsiveness. The disease has significant health, societal and economic consequences. Experimental assessment methods, including controlled human exposure studies, human and animal dosimetry, as well as animal and in vitro toxicology, can shed light on how air pollutants may cause and/or worsen asthma. A brief summary background on selected classes of air pollutants is provided and selected experimental studies that exemplify novel approaches or suggest new hypotheses are highlighted. Possible directions for future research about the effects of particles, pesticides, ambient air toxicants, and pollutant mixtures on asthma, are also outlined.

Respiratory symptoms in a susceptible population due to burning of agricultural residue

STUDY OBJECTIVES

To identify characteristics associated with respiratory symptoms due to an episode of air pollution.

DESIGN

Mail survey.

SETTING

In October 1992, the population of the city of Winnipeg was exposed to elevated levels of particulate matter (total and <10 microm size), carbon monoxide, nitrogen dioxide, and volatile organic compounds due to smoke from adjacent fields where farmers were burning agricultural residue (straw and stubble).

PARTICIPANTS

We surveyed 428 participants in the ongoing Lung Health Study (35 to 64 years old, both sexes) with mild to moderate airways obstruction (mean FEV1 percent predicted 73+/-12%), and a high level of airways hyperreactivity (23% of men and 37% of women).

RESULTS

While 37% of subjects were not bothered by smoke at all, 42% reported that symptoms (cough, wheezing, chest tightness, shortness of breath) developed or became worse due to the air pollution episode and 20% reported that they had breathing trouble. Those with symptoms were more likely to be female than male and were more likely to be ex-smokers than smokers. Subjects with asthma and chronic bronchitis were also more likely affected. The degree of airways obstruction and the level of bronchial hyperresponsiveness were not associated with increased susceptibility.

CONCLUSIONS

Gender, smoking habit, and respiratory symptoms but not bronchial hyperresponsiveness or the degree of airways obstruction are factors influencing susceptibility to symptoms due to air pollution in adult smokers and former smokers.

Air pollution and doctors' house calls: results from the ERPURS system for monitoring the effects of air pollution on public health in Greater Paris, France, 1991-1995. Evaluation des Risques de la Pollution Urbaine pour la Santé

This study examines short-term relationships between doctors' house calls and urban air pollution in Greater Paris for the period 1991-1995. Poisson regressions using nonparametric smoothing functions controlled for time trend, seasonal patterns, pollen counts, influenza epidemics, and weather. The relationship between asthma visits and air pollution was stronger for children. A relative risk (RRP95/P5) of 1.32 [95% confidence interval (CI) = 1.17-1.47)] was observed for an increase from the 5th to the 95th percentile (7-51 micrograms/m3) in daily concentrations of black smoke (BS). The risks for 24-hr sulfur dioxide and nitrogen dioxide levels were in the same range. Cardiovascular conditions, considered globally, showed weaker associations than angina pectoris/myocardial infarction, for which RRP95/P5 was 1.63 (95% CI = 1.10-2.41) in relation to ozone ambient levels. Eye conditions were exclusively related to ozone (RRP95/P5 = 1.17, 95% CI 1.02-1.33). Asthma visits and ozone showed an interaction with minimum temperature: an effect was observed only at 10 degrees C or higher. In two-pollutant models including BS with, successively, SO2, NO2, and O3, only BS and O3 effects remained stable. Along with mortality and hospital admissions, house call activity data, available on a regular basis, may be a sensitive indicator for monitoring health effects related to air pollution.

Occupational asthma

Many toxic compounds found in air emissions may induce bronchoconstriction. In the workplace, workers are exposed to these compounds, often in much higher concentrations. Some of these compounds act as sensitizers. Of these, some compounds induce asthma by producing specific IgE antibodies to the compound or its protein conjugate, while others induce asthma through yet unidentified immunologic mechanisms. Some compounds, when inhaled in high concentrations, act as irritants and produce bronchoconstriction probably by inducing acute airway inflammation. The latter condition is called Reactive Airways Dysfunction Syndrome (RADS) or irritant-induced asthma. Occupational asthma is an excellent model to study the pathogenesis and the natural history of adult onset asthma because the responsible agent can be identified, complete avoidance is possible, and exposure can be measured or estimated.