Multipollutant exposures and health responses to particulate matter

Quantitative determination of volatile organic compounds in indoor dust using gas chromatography-UV spectrometry

A novel technique, gas chromatography-UV spectrometry (GC-UV), was used to quantify volatile organic compounds (VOCs) in settled dust from 389 residences in Sweden. The dust samples were thermally desorbed in an inert atmosphere and evaporated compounds were concentrated by solid phase micro extraction and separated by capillary GC. Eluting compounds were then detected, identified, and quantified using a diode array UV spectrophotometer. Altogether, 28 compounds were quantified in each sample; 24 of these were found in more than 50% of the samples. The compounds found in highest concentrations were saturated aldehydes (C5-C10), furfuryl alcohol, 2,6-di-tert-butyl-4-methylphenol (BHT), 2-furaldehyde, and benzaldehyde. Alkenals were also found, notably 2-butenal (crotonaldehyde), 2-methyl-propenal (methacrolein), hexenal, heptenal, octenal, and nonenal. The concentrations of each of the 28 compounds ranged between two to three orders of magnitude, or even more. These results demonstrate the presence of a number of VOCs in indoor dust, and provide, for the first time, a quantitative determination of these compounds in a larger number of dust samples from residents. The findings also illustrate the potential use of GC-UV for analysing volatile compounds in indoor dust, some of which are potential irritants (to the skin, eyes or respiratory system) if present at higher concentrations. The potential use of GC-UV for improving survey and control of the human exposure to particle-bound irritants and other chemicals is inferred.

Correlation of environmental factors with asthma and rhinitis symptoms in Tulsa, OK

BACKGROUND

Airborne allergens, pollutants, and climatic changes are known to influence the symptoms of asthma patients.

OBJECTIVE

To correlate airborne fungal spore and pollen concentrations, meteorological data, and airborne pollutants with asthma and rhinitis symptoms to develop predictive models for asthma severity.

METHODS

Patients from the Tulsa community participated in this study from September 1 to October 31, 2000, by filling out daily symptom diaries and measuring morning and evening peak expiratory flow rates. Air samples were collected using a volumetric spore trap. Meteorological variables and maximum and average pollutants were also included in the analysis. Linear regression analyses were performed for all environmental variables and symptom scores. Forward stepwise multiple regression analyses were performed to determine sets of variables that could be used to predict the conditions of increased symptom severity.

RESULTS

Twenty-four patients participated in this study. The predominant spore types included Cladosporium, ascospores, and basidiospores. The predominant pollen type was Ambrosia. September was unusually hot and dry in Tulsa, but 161 mm of precipitation fell in October, primarily during the last 11 days. Two periods of peak symptoms occurred during the study, the first during the peak week of Ambrosia and the second after a 22 degrees C drop in temperature over 6 days. Numerous environmental variables showed significant correlations with symptom scores; however, there was no single predictive model for all symptoms.

CONCLUSIONS

Ambrosia pollen and other environmental variables, including ozone levels, were significantly correlated with asthma and rhinitis symptoms.

Microorganisms and volatile organic compounds in airborne dust from damp residences

Airborne dust samples from damp (n = 9) and control (n = 9) residences were analyzed for microorganisms (molds and bacteria), bacterial markers (3-hydroxy fatty acids and muramic acid), and adsorbed volatile organic compounds (VOCs). The number of mold species was greater in the damp residences than in the controls (23 vs.18) and nine mold species were found only in damp residences. The levels of 3-hydroxy fatty acids and muramic acid correlated better in damp residences than in controls, indicating that damp conditions affect the bacterial flora of airborne dust. Identifications made by culture and microscopy of the major molds found, i.e. Aspergillus, Cladosporium, and Penicillum, coincided with the identification of VOCs known to be produced by these species. A number of additional VOCs irritating to the skin, eyes, or respiratory tract were also found. The results from this pilot study illustrate the diversity of microorganisms and VOCs present in the indoor environment and suggest that analysis of airborne dust may help to assess human exposure to microorganisms and chemical compounds.

Assessment of respiratory symptoms and asthma prevalence in a U.S.-Mexico border region

The authors studied children who were 10-12 yr of age and who resided in sister cities in a U.S.-Mexico border region to determine the prevalence of asthma and respiratory symptoms. The relationship of symptoms to ambient levels of particulate matter less than 10 microm in diameter (PM10), and to several indoor environmental conditions, was assessed. The study was conducted in the border cities of Ambos Nogales (Nogales, Arizona [United States], and Nogales, Sonora [Mexico]). At the beginning of the 11-wk study, during the autumn of 1996, 631 students and their parents completed baseline questionnaires. While in school, the children completed daily symptom diaries and daily peak expiratory flow maneuvers. PM10 values and daily temperatures were also measured. The authors found that the prevalence of self-reported asthma among 5th-grade students was comparable on both sides of the border (i.e., 7.6% on the Arizona side and 6.9% on the Sonora side). Wheezing was a frequent complaint (29.5-35.6%), as was cough (16.8-29.6%). Smoking in the home was common on both sides of the border, and it was associated with a greater occurrence of self-reported asthma and respiratory complaints. Increased respiratory symptoms were also associated with increased ambient PM10 levels. The prevalence of respiratory symptoms such as wheezing and frequent cough among all children in this study, combined with the limitations inherent in self-reporting, suggest that asthma may actually be more prevalent than has been previously reported.

'EUROPART'. Airborne particles in the indoor environment. A European interdisciplinary review of scientific evidence on associations between exposure to particles in buildings and health effects

The relevance of particle mass, surface area or number concentration as risk indicators for health effects in non-industrial buildings has been assessed by a European interdisciplinary group of researchers (called EUROPART) by reviewing papers identified in Medline, Toxline, and OSH. Studies dealing with dermal effects or cancer or specifically addressing environmental tobacco smoke, house dust-mite, cockroach or animal allergens, microorganisms and pesticides were excluded. A total of 70 papers were reviewed, and eight were identified for the final review: Five experimental studies involving mainly healthy subjects, two cross-sectional office studies and one longitudinal study among elderly on cardiovascular effects. From most studies, no definite conclusions could be drawn. Overall, the group concluded that there is inadequate scientific evidence that airborne, indoor particulate mass or number concentrations can be used as generally applicable risk indicators of health effects in non-industrial buildings and consequently that there is inadequate scientific evidence for establishing limit values or guidelines for particulate mass or number concentrations.

Exposure to environmental tobacco smoke and risk of lung cancer in non-smoking women from Moscow, Russia

The association between exposure to ETS and the risk of lung cancer in life-time non-smoking women was investigated by means of a hospital based case-control study in Moscow, Russia. The main importance of our study is that it was conducted on a population with a specific smoking pattern from which no information is available on health effects of ETS. A total of 189 incident cases of histologically confirmed lung cancer were identified in 2 principal cancer treatment hospitals in Moscow. A total of 358 female oncology patients from the same hospitals were selected as controls. The controls matched by the hospitals to the cases were similarly restricted to never-smokers. Women diagnosed with cancer of the upper respiratory organs were ineligible for selection as controls. Personal interviews of cases and controls were conducted in the hospital wards, using a closed-form structured questionnaire. An elevated risk of lung cancer was observed in women whose husbands smoked. The odds ratio (OR) adjusted by age and education for husband's smoking was 1.53 (95% CI, 1.06-2.21). Smoking by other members of the family, by colleague's, or by fathers in the women's childhood do not affect the risk of lung cancer. The risk is higher for women whose husbands smoke "papirosy" (OR 2.12; 95% CI, 1.32-3.40), a special Russian type of cigarettes with a long mouthpiece, and usually very high levels of tar (> 30 mg/cig) and nicotine (> 1.8 mg/cig). Our study suggests that the association between exposure to ETS of the spouse and risk of lung cancer in non-smoking women is somewhat stronger for squamous-cell carcinoma (OR, 1.94; 95% CI, 0.99-3.81) than for adenocarcinoma (OR, 1.52; 95% CI, 0.96-2.39).

Methods for assessing the extent of exposure and effects of air pollution

BACKGROUND AND OBJECTIVES

In many places in Europe, the ambient air pollution exceeds the levels considered to be safe for health. The objective of the paper is to review and summarise the methods of assessment of its impact on health, and to indicate the contributions of various research disciplines, particularly environmental epidemiology.

METHODS

The framework for assessment of impact is based on a four stage model: assessment of release of pollutant; assessment of exposure; assessment of the consequence; and risk estimation.

RESULTS

Epidemiology is crucial in providing the data for the assessment of consequence. The criteria that determine the use of epidemiological studies for this task include lack of bias, correct control of confounding, and measured estimates of exposure. At present, those criteria are easier to satisfy for studies of short term effects on health than for the delayed consequences of exposure, or exposure accumulated over a prolonged period. Combinations of results from various populations through meta-analysis of existing studies or conducting multicentre studies is often necessary to increase the reliability of the consequence assessment stage.

CONCLUSION

To assess the impact on health systematically helps to focus on actions to limit air pollutants with the greatest impacts on human health and on the most affected populations. This method allows identification of the most pertinent questions which have to be answered by studies on relations between pollution and health and on exposure of populations to air pollutants. Epidemiology has considerable potential to contribute to this research.

Quantification and characterisation of suspended particulate matter in indoor air

Quantification and characterisation of suspended particulate matter (SPM) from homes in the city of Oslo was carried out. In 29 households the dust concentrations were found to vary between 9 and 56 mug/m(3) (median value 26 mug/m (3)). In 12 of the 29 households, a thorough analysis was carried out to determine the size and element distribution of the particles using transmission electron microscopy (TEM) and X-ray microanalysis (XRMA). The vast majority of the collected particles were less than 2.5 mum in diameter, i.e. they belonged to the fine fraction. In this fraction a considerable amount of soot and sulphur particles were found, usually less than 1 mum in diameter. The coarse fraction (particles > 2.5 mum in diameter) was found to consist mainly of organic material, silicates and larger soot aggregates. Both a thorough analysis of individual particles and a "bulk analysis" (i.e. recording XRMA spectra from whole grid masks) were performed, and the two methods were found to show good agreement.

Estimated long-term ambient concentrations of PM10 and development of respiratory symptoms in a nonsmoking population

Site- and season-specific regressions of particulates less than 10 mu in diameter (PM10) on total suspended particulates (TSPs) were formed throughout California during years when both were monitored. The regressions were then applied to monitored TSPs for the years 1973 to 1987, and indirect estimates of PM10 were formed. These estimates of PM10 were validated by interpolating them to other monitoring stations. The split-halves correlation between the estimated and monitored mean concentrations, obtained when both were first cumulated for a 2-y period, was .86. Indirect estimates of PM10 at monitoring stations were interpolated, by month, to zip code centroids of home and work location and were cumulated for a cohort of 3,914 California Seventh-day Adventist (SDA) nonsmokers. Multivariate analyses, adjusted for several covariates, showed statistically significant (p < .05), but small, positive associations between PM10 and development of (a) definite symptoms of overall airway obstructive disease, (b) chronic productive cough, and (c) increased severity of airway obstructive disease and asthma. The relative risk (RR) associated with 1,000 h/y (42 d) exposure to concentrations of PM10 that exceeded 100 micrograms/m3 for development of airway obstructive disease was 1.17 (95% confidence interval [CI]: 1.02, 1.33); for development of productive cough, the RR was 1.21 (CI 1.02, 1.44); and for development of asthma, the RR was 1.30 (CI, 0.97, 1.73). Stronger associations were observed for those who were exposed occupationally to dusts and fumes. The RR of developing airway obstructive disease as an adult for those who had airway obstructive disease as a child was 1.66 (CI 1.15, 2.33).

Acute NO2 exposure alters inflammatory cell activation and particle clearance in silica-injected mice

Previous work indicates that exposure to nitrogen dioxide (NO2) at different stages of silica-induced acute inflammation alters the outcome of lung injury. C57BI/6 mice were injected intratracheally (IT) with 2.0 mg silica particles (SI) and subsequently exposed to 20 ppm NO2 (or filtered air) within 2 or 24 h after SI. The present study demonstrates that exposure of mice to NO2 within 2 h after silica injection during acellular lung injury (increased alveolar protein, albumin, lactate dehydrogenase) resulted in increases in intraalveolar and interstitial polymorphonuclear leukocytes (PMNs) as well as more advanced granulomas on d 14, 30, and 60. In contrast, exposure of mice to NO2 24 h after silica during marked lung injury and inflammatory cell influx resulted in a less severe inflammatory reaction with fewer interstitial and alveolar PMNs and decreased size and number of pulmonary granulomas. NO2 exposure 2 or 24 h after SI appeared to increase in the lavage fluid levels of lysosomal enzymes and at the same time decrease levels of PMN chemotactins. Moreover, exposure to NO2 24 h after SI significantly decreased SI accumulation in the mediastinal lymph nodes. These data suggest that NO2 modulation of SI lung injury may be due, in part, to changes in inflammatory cell activation/influx and/or altered particle disposition within the lung. These effects are dependent upon the inflammatory status of SI exposed lungs at the time NO2 is administered.