P. Paoletti

PREVALENCE RATES OF RESPIRATORY SYMPTOMS IN ITALIAN GENERAL POPULATION SAMPLES EXPOSED TO DIFFERENT LEVELS OF AIR POLLUTION

We surveyed two general population samples aged 8 to 64 living in the unpolluted, rural area of the Po Delta (northern Italy) (n = 3289) and in the urban area of Pisa (central Italy) (n = 2917). Each subject filled out a standardized interviewer-administered questionnaire. The Pisa sample was divided into three groups according to their residence in the urban-suburban areas and to outdoor air pollution exposure (automobile exhaust only or industrial fumes as well). Significantly higher prevalence rates of all the respiratory symptoms and diseases were found in Pisa compared with the Po Delta. In particular, rhinitis and wheezing symptoms were higher in all the three urban zones; chronic cough and phlegm were higher in the zone with the automobile exhaust and the additional industrial exposure. Current smoking was more frequent in the rural area, but the urban smokers had a higher lifetime cigarette consumption. Childhood respiratory trouble and recurrent respiratory illnesses were evenly distributed. Exposure to parental smoking in childhood and lower educational level were more frequent in Po Delta, whereas familial history of respiratory/allergic disorders and work and indoor exposures were more often reported in the city. Multiple logistic regression models estimating independently the role of the various risk factors showed significant odds ratios associated with residence in Pisa for all the symptoms but chronic phlegm. For example, those living in the urban-industrial zone had an odds ratio of 4.0 (4.3-3.7) for rhinitis and 2.8 (3.0-2.6) for wheeze with respect to those living in the Po Delta.(ABSTRACT TRUNCATED AT 250 WORDS)

Skin prick test reactivity to common aeroallergens in relation to total IgE, respiratory symptoms, and smoking in a general population sample of northern Italy.

Skin prick test (SPT) reactivity to common airborne allergens and its relationships to sex, age, smoking habits, and respiratory symptoms/ diseases were evaluated in a general population sample (n= 2841, 8–75 years of age) living in the Po delta area (northern Italy). Subjects completed a standardized questionnaire and underwent prick tests (12 local allergens, a negative and a positive control) and determination of total serum IgE. Atopy was evaluated by measuring the maximal diameter for each allergen, after subtracting that of the negative control. Thirty‐one percent of subjects showed a positive skin response at a 3‐mm threshold. Pollens, Dermatophagoides pteronyssinus, and D. farinae caused the highest frequencies of reactions. Young people and those who had never smoked had higher prevalence rates of SPT reactivity. Asthma, asthma symptoms, and rhinitis were significantly associated with SPT reactivity in both sexes (cough only in females) and with the number of positive reactions. IgE values were also significantly associated with SPT reactivity. In conclusion, our findings indicate that almost one‐third of the general population of an Italian rural area is skin test positive, emphasizing the importance of assessing atopy in respiratory epidemiologic surveys.

The Po River Delta Respiratory Epidemiological Survey: an analysis of factors related to level of total serum IgE

The purpose of the present study was to analyse whether sex, age, skin test reactivity, cigarette smoking and occupational exposure were related to the total serum immunoglobulin (Ig)E concentrations (kU x L[-1]), in a general population sample. We studied 1,905 subjects (915 males, 990 females) of a general population sample (n=2,841, 8-73 yrs) participating in the second cross-sectional respiratory epidemiological survey in the rural Po Delta area (near Venice, North Italy). Distribution of total serum IgE concentrations was skewed, thus a log-transformation was performed to obtain a Gaussian shape. Significantly higher values of IgE were found in males compared to females. In general, a peak of IgE concentration was found at 8-14 yrs. IgE values tended to be lower in older than younger adults. Significantly higher serum IgE levels were shown in subjects with a positive skin-prick test index (ST+) than in those with a negative skin-prick test index (ST-). There was a significant relationship of total IgE levels with skin reactivity to pollens and house-dust mites. In both sexes higher values of IgE were found in current smokers than in ex-nonsmokers, regardless of skin-test reactivity. There was no significant difference in IgE values between ex- and nonsmokers. Passive smoking and occupational exposure were significantly related to increased IgE values. Our results confirm that in a general population sample immunoglobulin E concentrations are related not only to skin-prick test reactivity to common aeroallergens, but also to other risk factors for chronic obstructive lung diseases, such as sex, active/ passive smoking and occupational exposure.

The Po River Delta epidemiological study of obstructive lung disease: sampling methods, environmental and population characteristics.

A longitudinal study on chronic obstructive lung disease (AOD) has been started in the Po River Delta in northern Italy. The first cross-sectional study was conducted in this previously unpolluted rural area before the start of operation of a large thermoelectric power plant (2,649 megawatt). A significant output of air pollutants is expected. This will permit us to carry out a “natural experiment” to study the effects of air pollutants (SO2 and suspended particulates). A multistage stratified cluster design was chosen. Stratification was based on age and socio-economic characteristics (SES) of households, and was performed in two steps, using the different indices computed from the census data. Geographic zones represented four areas of different predicted pollution exposure, once the plant started operating. There were 3,289 subjects in the selected age group (8–64) who agreed to participate (78%); only 11% refused to participate. The participants were representative of the clusters and SES. Participants had slightly fewer employed males, who did not participate due to work. The stratification and staging method allowed us to keep an acceptable level of precision and efficiency in the sample. In fact age-related differences were not found among the SES strata and geographic zones; various socio-economic characteristics, verified from the questionnaire information, were consistent with the SES stratification. Differences between geographic zones were related to the number of households of different SES within clusters; however this reflects the characteristics of the general population in the area.

Risk factors for chronic obstructive pulmonary disease in a North Italian rural area

To assess the role of risk factors for chronic obstructive lung disease (COPD) by multiple logistic models, the data of the first cross-sectional epidemiological survey in the unpolluted rural area of the Po River Delta were analyzed (n=2382; 20–64 years). Each subject filled out a standardized questionnaire; 94% of the subjects were also able to perform forced expirograms. Dependent variables were chronic respiratory symptoms, asthma, abnormal parameters of flow-volume curve (ABNFVC), and a complex characterized by chronic phlegm and/or any wheeze and/or dyspnea grade 2+ and/or diagnosis of asthma and/or an FEV1/FVC ratio less than 60% (ANYABN). Independent variables were: age, ever cigarette smoking (SMK) and lifetime cigarette consumption expressed as pack-years, childhood respiratory infections (CRI), adolescence-adulthood respiratory infections (ARI), familial history for COPD (FCOPD) or for asthma/allergies (FASTHMA), work exposure to dusts/chemicals (EXPO), low socio-economic conditions (SES). A significant relationship with almost all dependent variables was shown by pack-years, ARI and age in both sexes. In males, FCOPD was related to chronic mucus hypersecretion and to ABNFVC, FASTHMA was associated with wheeze and ANYABN. EXPO was related to dyspnea and asthmatic symptoms in both sexes and also to bronchitic symptoms in males. CRI was a significant contributor for asthma symptoms in males, for ANYABN in females. SES had no significant association. In conclusion, our findings show that, beside lifetime cigarette smoking, other host — or environment — related conditions are important risk factors for COPD, suggesting the need for a more thorough strategy for prevention.

Respiratory effects of occupational exposure to tobacco dust.

Few investigations of the respiratory effects of occupational exposure to tobacco dust have been carried out and the threshold limit value has not well been established. A cross sectional survey on a sample of 223 male and female workers at a cigar and cigarette factory in Lucca (Tuscany) showed a significantly higher prevalence of wheezing, attacks of shortness of breath with wheezing, dyspnoea, and rhinitis than in a reference population. A trend towards a decrease in forced end expiratory flows according to smoking habit and work duration was evident. Positive skin prick tests were observed in 26% of men and 23% of women and were positively associated with duration of work and negatively with cigarette smoking. Thin interstitial space involvement was observed on chest x ray examination in almost half the female workers with more than 35 years exposure. These findings suggest that prolonged exposure to tobacco dust may have negative health effects and that it is advisable to establish a threshold limit value for tobacco dust different from that of inert dust.

Effects of the home environment on respiratory symptoms of a general population sample in middle Italy

The effects of home environment characteristics were evaluated in a multistage, stratified, cluster sample (N = 3,866) of the general population who lived in the district of Pisa (middle Italy). Each subject completed a standardized interviewer-administered questionnaire that contained questions about respiratory symptoms/diseases and risk factors (e.g., type of heating, fuels used for cooking and heating). Cough and asthma were significantly more frequent in men who did not smoke and who did not use natural gas for cooking and heating. Attacks of shortness of breath accompanied by wheeze, dyspnea, and cardiovascular conditions in female nonsmokers were associated with use of a stove or forced-air circulation for heating; the type of fuel used did not affect this result. Multiple logistic models, which accounted for independent effects of age, smoking status, pack-years, childhood respiratory illness, education, zone of residence, and work exposure to dusts, chemicals, or fumes, showed significantly increased odds ratios for (a) cough and phlegm in males (associated with bottled gas for cooking), (b) wheeze and shortness of breath with wheeze in females (associated with the use of a stove or forced-air circulation). These results, which confirm our previous observations in an unpolluted rural area of north Italy, indicate that characteristics of the home environment, as assessed by questionnaire, may be linked to mild adverse health effects, i.e., respiratory symptoms, in the general population. The results also identify the need to better characterize the dose-response relationship in indoor air pollution monitoring studies that include subsamples of this population.

Effects of Daily Cigarette Consumption on Respiratory Symptoms and Lung Function in a General Population Sample of North-Italian Men

We assessed the respiratory effects of the number of cigarettes smoked daily (CIGD) in 748 male smokers of a general population sample living in the unpolluted area of the Po Delta (Italy). A standardized questionnaire, flow-volume curves (V/V), the diffusing capacity of carbon monoxide (DLCO) and the slope of the alveolar plateau of nitrogen (DN2%/l) were used. Subjects were divided according to the median value of the observed distribution of CIGD (1-19, 20+) and according to the tertile values of the observed distribution of pack-years (an index representing lifetime cigarette consumption; 1-7, 8-21, 22+). In those with a higher CIGD, the prevalence rate of chronic phlegm was always significantly increased, while the prevalence rate of wheeze was significantly higher if they had smoked 8+ pack-years. Using analysis of variance, adjusted for pack-years, DLCO indexes, FEF75-85 and Vmax75 were significantly reduced in those with higher CIGD. When multiple logistic models, accounting for the independent effects of age and pack-years, were used, significantly increased odds ratios (ORs) for symptoms (e.g. OR = 2.0 for phlegm, OR = 1.8 for cough, OR = 1.6 for wheeze) and abnormal DLCO (OR = 1.9) or DN2%/l (OR = 1.6) were associated with a daily consumption of 10 cigarettes. In conclusion, the amount of cigarettes currently smoked may add a negative effect to that caused by lifetime cigarette consumption on respiratory symptoms and lung function. Moreover, the use of diffusing capacity in general population surveys is advisable.

Application of biomarkers in population studies for respiratory non-malignant diseases

Though the use of biomarkers has been mainly suggested for cancer studies, the possibility of its use in non malignant disease is considered. Markers of internal dose, markers of biologically effective dose and markers of early biologically effect have been typically used in basic research and, more recently, in epidemiology to characterize genotoxic carcinogenic agents. These markers (e.g. adducts to DNA or proteins) may be used mainly in the presence of chronic exposure to toxic agents (e.g. benzene or benzopyrene), additional markers such as carboxyhemoglobin, expired air to measure various VOC and heavy metals in biological fluids are also considered in the paper. Since airway obstructive disease (asthma, chronic bronchitis, emphysema) are the main disorders influenced by environmental factors (including air pollution), markers of individual susceptibility, such as atopy increased responsiveness of airways, initial level of lung function, must be considered for a more precise evaluation of the relationship between environmental exposure and health effects. Currently, the application of the determination of markers of exposure in non malignant disorders is very limited. In fact, the relationships between acute adverse respiratory effects and the exposure to air pollutants appears difficult since markers for common air pollutants are not available, and their detection appears difficult in acute conditions. Characterization of long term exposure may be performed in organ fluids (blood, urine, saliva) however it is important to recognize that concentration at that level may not reflect that observed in the target organ (e.g. lung).

The assessment of gas exchange by automated analysis of O2 and CO2 alveolar to arterial differences

SummaryA computer program to measure breath by breath alveolar pressure (PA) and alveolar to arterial difference (AaD) for O2 and CO2, by a mass-spectrometer has been implemented. The program allows the determination of alveolar gas by different methods: 1. Bohrs equation (BE); 2. ideal alveolar air equation for O2 (IDO2); 3. end-tidal (ET); 4. by the Rahns definition of ‘mean alveolar gas’, i.e., alveolar pressures are defined when instantaneous respiratory exchange ratio (IRQ) equals mean respiratory exchange ratio (MRQ). This automated technique has been used in 16 patients with chronic obstructive lung disease (COLD) and 15 patients with pulmonary embolism (APE). In both groups of patients it was always possible to find in each breath the point where IRQ=MRQ and therefore to measure AaD by RD. IDO2 was significantly lower than PAO2 by the other methods. Also ET values of O2 and CO2 were significantly different from RD and BE in both groups of patients, however the difference was consistently higher in COLD patients. The different shape of the expirograms (steeper expirograms in COLD) is responsible for this different result. RD and BE AaD characterize gas exchange more precisely than ET, because the contribution of high VA/Q units is also evaluated. This is particularly important in COLD patients.Consideration on dead space measurements are also reported both for COLD and APE patients. In conclusion this automated technique provides the assessment of gas exchange for the use in clinical respiratory physiology and for the monitoring of gas-exchange in critically ill patients.