Indoor and outdoor BTX levels in German cities

On the basis of the ongoing study INGA (INdoor exposure and Genetics in Asthma), Germany's most detailed and standardized epidemiological study on indoor exposure to both allergens in house dust and volatile compounds in the air of the home environment has been performed. The purpose of this paper is to describe the spatial and seasonal variability of indoor and outdoor BTX (Benzene, toluene, ethyl benzene, ortho-xylene, meta- and para-xylene) concentrations for the study period from June 1995 to November 1996. Within this framework, air concentrations of volatile organic compounds (BTX) were measured in 204 households in Erfurt (Eastern Germany) and 201 households in Hamburg (Western Germany). BTX sampling was conducted over one week using OVM 3500 passive diffusion sampling devices in the indoor (living room and bedroom) and outdoor environment (outside the window of the living room). Indoor and outdoor median BTX concentrations in Erfurt were slightly, but significantly higher than those in Hamburg. This gap was most pronounced in the levels of indoor toluene (37.3 microg/m3 for Erfurt and 20.5 microg/m3 for Hamburg, P < 0.0001). In both cities, winter indoor and outdoor concentrations for the five compounds exceeded the summer values. Outdoor concentrations of ethyl benzene and ortho-xylene were very low (50% < L.D.). In general, the indoor BTX air concentrations were significantly higher than the outdoor concentra- tions, the lowest I/O ratios were found in the case of benzene. Living room and bedroom values for the five compounds were highly correlated (Spearman coefficient 0.5-0.9). Despite the better insulation of the homes in West Germany, no indication for the expected higher indoor concentrations of BTX in the West could be found. The strong and yet undiscovered indoor source for toluene in East Germany might lead to a further increase in the indoor air load in those homes in the East, which undergo renovations which will lead to improved insulation.

Beta(1-->3)-glucan in house dust of German homes: housing characteristics, occupant behavior, and relations with endotoxins, allergens, and molds

beta(1-->3)-Glucans are potent proinflammatory agents that have been suggested to play a role in indoor-related respiratory health effects. The aim of this study was to assess whether beta(1-->3)-glucan concentrations in house dust are correlated with levels of endotoxins, allergens, and culturable mold spore counts in house dust. Further, the associations of beta(1-->3)-glucan with housing characteristics and occupant behavior were assessed. beta(1-->3)-Glucan was measured in settled house dust from living room floors of 395 homes of two German cities, Erfurt and Hamburg, with a specific enzyme immunoassay. Concentrations ranged from below the limit of detection to 19,013 microg/m(2) (22,588 microg/g dust). Concentrations per square meter were found to be correlated with endotoxins, mite and cat allergens, and culturable mold spores. Correlations were weaker when concentrations were expressed per gram of dust, indicating that variance in concentrations of all factors is largely determined by the amount of dust sampled. Associations between beta(1-->3)-glucan, housing characteristics, and occupant behavior were found for concentrations per square meter but not for concentrations per gram of dust. The following characteristics were associated with a significant increase in beta(1-->3)-glucan levels: carpets in the living room [means ratio (MR) = 1.9-2.1], keeping a dog inside (MR = 1.4), use of the home by four or more persons (MR = 1.4), use of the living room for > 180 hr/week (MR = 2.1), lower frequency of vacuum cleaning (MR = 1.6-3.0) and dust cleaning (MR = 1.2 and 1.4, respectively), and presence of mold spots during the past 12 months (MR = 1.4). We conclude that that the amount of dust sampled can be used as a proxy for hygiene and that beta(1-->3)-glucan concentrations per square meter are related to the amount of dust sampled.

Case-control study on lung cancer and residential radon in western Germany

In a 1990-1996 case-control study in western Germany, the authors investigated lung cancer risk due to exposure to residential radon. Confirmed lung cancer cases from hospitals and a random sample of community controls were interviewed by trained interviewers regarding different risk factors. For 1 year, alpha track detectors were placed in dwellings to measure radon gas concentrations. The evaluation included 1,449 cases and 2,297 controls recruited from the entire study area and a subsample of 365 cases and 595 controls from radon-prone areas of the basic study region. Rate ratios were estimated by using conditional logistic regression adjusted for smoking and for asbestos exposure. In the entire study area, no rate ratios different from 1.0 were found; in the radon-prone areas, the adjusted rate ratios for exposure in the present dwelling were 1.59 (95% confidence interval (CI): 1.08, 2.27), 1.93 (95% CI: 1.19, 3.13), and 1.93 (95% CI: 0.99, 3.77) for 50-80, 80-140, and >140 Bq/m3, respectively, compared with 0-50 Bq/m3. The excess rate ratio for an increase of 100 Bq/m3 was 0.13 (-0.12 to 0.46). An analysis based on cumulative exposure produced similar results. The results provide additional evidence that residential radon is a risk factor for lung cancer, although a risk was detected in radon-prone areas only, not in the entire study area.

Lung cancer in lifetime nonsmoking men - results of a case-control study in Germany

Epidemiological studies of lung cancer among nonsmoking men are few. This case-control study was conducted among lifetime nonsmoking men between 1990 and 1996 in Germany to examine lung cancer risk in relation to occupation, environmental tobacco smoke, residential radon, family history of cancer and previous lung disease. A total of 58 male cases with confirmed primary lung cancer and 803 male population controls who had never smoked more than 400 cigarettes in their lifetime were personally interviewed by a standardized questionnaire. In addition, 1-year radon measurements in the living and bedroom of the subjects' last dwelling were carried out. Unconditional logistic regression was used to calculate odds ratios (OR) and 95% confidence intervals (CI). Having ever worked in a job with known lung carcinogens was associated with a two-fold significantly increased lung cancer risk (OR = 2.2; CI = 1.0-5.0), adjusted for age and region. The linear trend test for lung-cancer risk associated with radon exposure was close to statistical significance, demonstrating an excess relative risk for an increase in exposure of 100 Bq m(-3)of 0.43 (P = 0.052). Nonsignificantly elevated effects of exposure to environmental tobacco smoke in public transportation and in social settings were observed. No associations with a family history of cancer or previous lung diseases were found. Our results indicate that occupational carcinogens and indoor radon may play a role in some lung cancers in nonsmoking men.

A cluster of childhood leukaemias near two neighbouring nuclear installations in Northern Germany: prevalence of chromosomal aberrations in peripheral blood lymphocytes

PURPOSE

Between 1990 and 1991 a leukaemia cluster was observed in children living close to the combined site of a nuclear power plant and a nuclear research facility in Elbmarsch, a region in Lower Saxony (Germany). We aim to investigate the prevalence of presumably radiation-induced chromosomal aberrations in peripheral blood lymphocytes of children in Elbmarsch and children of a control region in order to find out whether there was an uncontrolled release of radioactive material which resulted in a substantial exposure.

MATERIALS AND METHODS

The frequency of dicentric and ring chromosomes in lymphocytes of the peripheral blood in 42 children in Elbmarsch and 30 children in Plön was investigated. Children in both groups had been permanent residents of the study area.

RESULTS

The mean frequency of dicentric and ring chromosomes in Elbmarsch was 14/32580 cells (=0.430 x 10(-3); 95% CI 0.24-0.70 x 10(-3) cells), and in Plön it was 17/24065 cells (=0.706 x 10(-3); 95% CI 0.42-1.10 x 10(-3) cells).

CONCLUSIONS

No difference in the frequency of dicentric and ring chromosomes was observed between children in Elbmarsch living close to a combined site of a nuclear power plant and a nuclear research facility and children living in the control area Plön. The power of the study to detect a threefold or higher increase in the aberration frequency was at least 0.86.

Histopathologic findings of lung carcinoma in German uranium miners

BACKGROUND

This study evaluates the histopathology of lung carcinoma in relation to underground radon exposure.

METHODS

Two hundred forty uranium miners of the former Wismut Company in Eastern Germany with histologically or cytologically confirmed primary lung carcinoma were recruited from 3 study clinics between 1991 and 1995. Information on smoking history was obtained by personal interviews, whereas job histories were derived from original payrolls provided by the Wismut Company. Quantitative estimates of occupational radon exposure were based on a job-exposure matrix.

RESULTS

Squamous cell carcinoma (SqCC) was the predominant cell type (43%), followed by adenocarcinoma (AC; 26%), small cell lung carcinoma (SCLC; 23%), and other cell types (8%). Nearly all patients were smokers. Time since first occupational exposure was 42 years on average, the mean cumulative radon exposure 506 working level months. Adenocarcinoma appeared to be more likely than both SCLC and SqCC among miners with low cumulative radiation exposure, long time since first exposure, an older age at diagnosis, and among ex- and never-smokers. In current smokers, lung carcinomas developed at a much lower level of radiation exposure than in ex- and never-smokers. The increase in the relative frequency of SCLC and SqCC at the expense of AC with increasing cumulative radiation exposure was more pronounced among ex- and never-smokers and seemed to be masked among current smokers.

CONCLUSION

The authors' data suggest that all cell types were associated with radon exposure, but high radiation exposure tended to increase the proportion of SCLC and SqCC.

Lung cancer and cigarette smoking in women: a multicenter case-control study in Europe

The association between cigarette smoking and lung cancer risk in women was investigated within the framework of a case-control study in 9 centres from 6 European countries. Cases were 1,556 women up to 75 years of age with histologically confirmed primary lung cancer; 2, 450 controls with age distribution similar to cases were selected. The predominant cell type was adenocarcinoma (33.5%), with similar proportions for squamous-cell type (26.4%) and small-cell carcinoma (22.3%). Overall, smoking cigarettes at any time was associated with a 5-fold increase in lung cancer risk (odds ratio 5.21, 95% confidence interval 4.49-6.04); corresponding figures for current smoking habits were 8.94, 7.54-10.6. The association showed a dose-response relationship with duration of the habit and daily and cumulative lifetime smoking. A significant excess risk of 70% was associated with every 10 pack-years smoked. After 10 years of smoking cessation, the relative risk decreased to 20% compared to current smokers. The following characteristics were associated with a higher relative risk: inhalation of smoke, smoking non-filter cigarettes, smoking dark-type cigarettes and starting at young age. The association was observed for all major histological types, being the strongest for small-cell type carcinoma, followed by squamous-cell type and the lowest for adenocarcinoma. The proportion of lung-cancer cases in the population attributable to cigarette smoking ranged from 14% to 85%. We concluded that women share most features of the association between cigarette smoking and lung cancer observed in men.

Daily mortality and fine and ultrafine particles in Erfurt, Germany part I: role of particle number and particle mass

Increases in morbidity and mortality have been observed consistently and coherently in association with ambient air pollution. A number of studies on short-term effects have identified ambient particles as a major pollutant in urban air. This study, conducted in Erfurt, Germany, investigated the association of mortality not only with ambient particles but also with gaseous pollutants and indicators of sources. Part I of this study concentrates on particles. Data were collected prospectively over a 3.5-year period from September 1995 to December 1998. Death certificates were obtained from the local authorities and aggregated to daily time series of total counts and counts for subgroups. In addition to standard data for particle mass with diameters < or = 2.5 microm (PM2.5)* or < or = 10 microm (PM10) from impactors, a mobile aerosol spectrometer (MAS) was used to obtain size-specific number and mass concentration data in six size classes between 0.01 microm and 2.5 microm. Particles smaller than 0.1 microm were labeled ultrafine particles (three size classes), and particles between 0.1 and 2.5 microm were termed fine particles (three size classes). Concentrations of the gases sulfur dioxide (SO2), nitrogen dioxide (NO2), and carbon monoxide (CO) were also measured. The daily average total number concentration was 18,000 particles/cm3 with 88% of particles below 0.1 pm and 58% below 0.03 microm in diameter. The average mass concentration (PM2.5) was 26 microg/m3; of this, 75% of particles were between 0.1 and 0.5 microm in diameter. Other average concentrations were 38 microg/m3 for PM10, 17 microg/m3 for SO2, 36 microg/m3 for NO2, and 600 microg/m3 for CO. Ambient air pollution demonstrated a strong seasonality with maximum concentrations in winter. Across the study period, fine particle mass decreased, whereas ultrafine particle number was unchanged. The proportion of ultrafine particles below 0.03 microm diameter increased compared with the proportion of other particles. During the study, concentrations of SO2 and CO also decreased, whereas the concentration of NO2 remained unchanged. The data were analyzed using Poisson regression techniques with generalized additive modeling (GAM) to allow nonparametric adjustment for the confounders. Both the best single-day lag and the overall association of multiple days fitted by a polynomial distributed lag model were used to assess the lag structure between air pollution and death. Mortality increased in association with level of ambient air pollution after adjustment for season, influenza epidemics, day of week, and weather. In the sensitivity analyses, the results proved stable against changes of the confounder model. We saw comparable associations for ultrafine and fine particles in a distributed lag model where the contribution of the previous 4 to 5 days was considered. Furthermore, the data suggest a somewhat more delayed association of ultrafine particles than of fine particles if single-day lags are considered. The associations tended to be stronger in winter than in summer and at ages below 70 years compared to ages above 70 years. Analysis of the prevalent diseases mentioned on death certificates revealed that the overall association for respiratory diseases was slightly stronger than for cardiovascular diseases. In two-pollutant models, associations of ultrafine and fine particles seemed to be largely independent of each other, and the risk was enhanced if both were considered at the same time. Furthermore, when the associations were summed for the six size classes between 0.01 and 2.5 microm, the overall association was clearly stronger than the associations of the individual size classes alone. Associations were observed for SO2, NO2, and CO with mortality despite low concentrations of these gases. These associations disappeared in two-pollutant models for NO2 and CO, but they remained stable for SO2. The persistence of the SO2 effect was interpreted as artifact, however, because the SO2 concentration was much below levels at which effects are usually expected. Furthermore, the results for SO2 were inconsistent with those from earlier studies conducted in Erfurt. We conclude that both fine particles (represented by particle mass) and ultrafine particles (represented by particle number) showed independent effects on mortality at ambient concentrations. Comparable associations for gaseous pollutants were interpreted as artifacts of collinearity with particles from the same sources.

Occupational risks for lung cancer among nonsmokers

We conducted a case-control study in 12 European study centers to evaluate the role of occupational risk factors among nonsmokers. We obtained detailed occupational histories from 650 nonsmoking cases (509 females/141 males) and 1,542 nonsmoking controls (1,011 females/531 males). On the basis of an a priori definition of occupations and industries that are known (list A) or suspected (list B) to be associated with lung carcinogenesis, we calculated odds ratios (ORs) for these occupations, using unconditional logistic regression models and adjusting for sex, age, and center effects. Among nonsmoking men, an excess relative risk was observed among those who had worked in list-A occupations [OR = 1.52; 95% confidence interval (C) = 0.78-2.97] but not in list-B occupations (OR = 1.05; 95%), CI = 0.60-1.83). Among nonsmoking women, there was an elevation of risk for list-A occupations (OR = 1.50; 95% CI = 0.49-4.53), although this estimate was imprecise, given that less than 1% of cases and controls were exposed. Exposure to list-B occupations was associated with an increase in relative risk (OR = 1.69; 95% CI = 1.09-2.63) in females, but not in males. Women who had been laundry workers or dry cleaners had an OR of 1.83 (95% CI = 0.98-3.40). Our findings confirm that certain occupational exposures are associated with an increased risk for lung cancer among both female and male nonsmokers; however, knowledge on occupational lung carcinogens is biased toward agents to which mainly men are exposed.

Trends in bronchial hyperresponsiveness, respiratory symptoms and lung function among adults: West and East Germany. INGA Study Group. Indoor Factors and Genetics in Asthma

Previous studies have shown higher prevalences of bronchial hyperresponsiveness (BHR), respiratory symptoms and atopic sensitization among adults in Western Germany than in Eastern Germany. One of the aims of the joint project INGA (INdoor Factors and Genetics in Asthma) is to assess incidence, prevalence and trends for asthma, BHR and atopic diseases over a time period of 11 years (1990-2001) in the former West (Hamburg) and East Germany (Erfurt), with special reference to indoor exposure. INGA was designed as a case-control study following a cross-sectional study performed from 1990 to 1992 within the European Community Respiratory Health Survey (ECRHS). The database consisted of 1159 subjects in Hamburg and 731 subjects in Erfurt from the ECRHS (age 20-44). In 1995-1996, 107 cases (diagnosed asthma, positive specific serum IgE, positive skin prick or PD20FEV1< or =2.0 mg methacholine at ECRHS) and 106 controls (none of the previous findings) participated in Hamburg (115 cases and 109 controls in Erfurt). The methodology was identical to the ECRHS and dose-response slopes (DRS) of the methacholine challenge were calculated as an index of responsiveness. In the control group, median values of DRS were 0.028% mg(-1) (1990-1992) and 0.044 (1995-1996) (P<0.01) in Erfurt. Corresponding values for Hamburg were 0.028 and 0.022 (NS). Corresponding values within the case groups were 0.041 and 0.049 (NS) for Erfurt, and 0.069 and 0.052 (P<0.05) for Hamburg. Thus, 4 years after the first survey, we found an increased BHR in the Erfurt control group while the bronchial responsiveness remained unchanged for the Hamburg group. These trends in BHR, which indicate the expected converging tendency between East and West Germany, have to be confirmed within the next INGA-survey in 2000-2001.

Lung cancer risk of workers in shoe manufacture and repair

BACKGROUND

The occupational lung cancer risk in manufacturing and repair of shoes was studied by pooling of two major case-control studies from Germany.

METHODS

Some 4184 incident hospital-based cases of primary lung cancer and 4253 population controls, matched for sex, age, and region of residence were intensively interviewed with respect to their occupational and smoking history. Based on the occupational coding and a free text search, all individuals who had ever worked in shoe manufacturing or repair for at least half a year were identified. Shoemaker-years were calculated as the cumulated duration of working in shoe manufacturing or repair. Odds ratios (OR) and 95% confidence intervals (CI) were calculated via conditional logistic regression. Additional adjustment for smoking and occupational asbestos exposure was used.

RESULTS

Seventy-six cases and 42 controls who had ever worked in shoe manufacture or repair (OR = 1.89, 95% CI: 1.29-2.78). After adjustment for smoking, this risk was lowered to 1.69 (95% CI: 1.09-2.62). Further adjustment for asbestos exposure only slightly changed the risk estimates upwards. The smoking adjusted OR in males was 1.50 (95% CI: 0.93-2.41) and 2.91 (95% CI: 0.90-9.44) in females. Logistic regression modeling showed a positive dose-effect relationship between duration of exposure in shoe manufacture and repair and lung cancer risk. The odds ratio for 30 years of exposure varied between 1.98 and 2.24 depending on the model specified.

CONCLUSIONS

The study demonstrates an increased lung cancer risk for shoemakers and workers in shoe manufacturing. The risk seems to double after being 30 years in these occupations.

Decline of ambient air pollution and respiratory symptoms in children

Several regional cross-sectional studies have shown a consistently higher prevalence of respiratory disorders in children with exposure to total suspended particulates (TSP) than in children living in less polluted areas. The aim of the present study was to investigate the temporal changes in the prevalence of nonasthmatic respiratory symptoms and diseases in children living in three areas of East Germany during a phase of strong improvement in ambient air quality. Groups of 2,470 and 2,814 school children between 5 and 14 yr, respectively, participated in two regional cross-sectional studies in 1992-1993 and 1995-1996. In the three areas (Hettstedt, Bitterfeld, and Zerbst) examined in the study, the annual mean TSP decreased from 65, 48, and 44 microg/m(3), respectively, in 1993 to 43, 39, and 36 microg/m(3) in 1995. In the same time interval, the crude prevalence of bronchitis in the three respective areas decreased from 62%, 52%, and 50% to 47%, 40%, and 39%. During the 3-yr period between the two regional studies, prevalence decreased significantly for bronchitis (odds ratio [OR]: 0.55; confidence interval [CI]: 0.49 to 0.62), for otitis media (OR: 0.83; CI: 0.73 to 0.96), for frequent colds (OR: 0.74; CI: 0.64 to 0.86), and for febrile infections (OR: 0.76; CI: 0.66 to 0.88) after adjustment for several potential predictors. In conclusion, we found that the prevalence of nonasthmatic respiratory symptoms decreased from the first period to the second period in all three study areas.

Lung cancer and exposure to man-made vitreous fibers: results from a pooled case-control study in Germany

BACKGROUND

To investigate the association between lung cancer and occupational exposure to man-made vitreous fibers (MMVF), a pooled analysis of two case-control studies was conducted in the years 1988-1994.

METHODS

The case series consisted of 3498 males who were histologically or cytologically verified primary lung cancer cases. 3541 male population controls were drawn at random from the general population and matched to cases by sex, age, and place of residence. To examine the relationship between MMVF and lung cancer we asked all study subjects who worked for at least 6 months as construction and installation workers whether they ever installed or removed insulations and what kind of insulation material they used.

RESULTS

Some 304 (8.7%) cases and 170 (4.8%) controls reported to have insulated with glass wool or mineral wool mats. Coded as ever/never exposed, the odds ratio was 1.48 (95% CI: 1.17-1.88), adjusted for smoking and asbestos. To be sure to exclude any confounding effect of asbestos, we tried to identify those cases and controls who insulated with glass wool or mineral wool mats only and never reported any asbestos exposure. For this group we calculated an odds ratio of 1.56 (95% CI: 0.92-2.65), after adjustment for smoking. An elevated risk was also estimated on the basis of an expert rating which was done for a subgroup of cases and controls. Ever exposure to MMVF (but not to asbestos) in this subgroup yielded an odds ratio of 1.30 (95% CI: 0.82-2.07).

CONCLUSIONS

Our study provides some indication for an excess risk of man-made vitreous fibers. This result also persists after adjustment for smoking and asbestos.

Sources and concentrations of indoor nitrogen dioxide in Hamburg (west Germany) and Erfurt (east Germany)

Here we report indoor and outdoor concentrations of NO2 for Erfurt and Hamburg and assess the contribution of the most important indoor sources (e.g. the presence of gas cooking ranges, smoking) and outdoor sources (traffic exhaust emissions). We examined the relative contribution of the different sources of NO2 to the total indoor NO2 levels in Erfurt and Hamburg. NO2 indoor concentrations in Hamburg were slightly higher than those in Erfurt (i.e. living room: 15 microg m(-3) for Erfurt and 17 microg m(-3) for Hamburg). A linear regression model including the variables, place of residence, season and outdoor NO2 levels, location of the home within the city, housing and occupant characteristics accounted for 38% of the NO2 variance. The most important predictors of indoor NO2 concentrations were gas in cooking followed by other characteristics, such as ventilation or outdoor NO2 level. Residences in which gas was used for cooking, or in which occupants smoked, had substantially higher indoor NO2 concentrations (41 or 18% increase, respectively). An increase in the outdoor NO2 concentration from the 25th to the 75th-percentile (17 microg m(-3)) was associated with a 33% increase in the living room NO2 concentration. Multiple regression analysis for both cities separately illustrated that use of gas for cooking was the major indoor source of NO2. This variable caused a similar increase in the indoor NO2 levels in each city (43% in Erfurt and 47% in Hamburg). However, outdoor sources of NO2 (motor vehicle traffic) contributed more to indoor NO2 levels in Hamburg than in Erfurt.

Associations between mortality and air pollution in central Europe

Increased mortality has been observed in association with elevated concentrations of air pollutants in European cities and in the United States. We reassessed the effects of particulate matter in Central Europe. Mortality and air pollution data were obtained for a highly polluted region of the Czech Republic and a rural region in Germany. Poisson regression analyses were conducted considering trend, season, meteorology, and influenza epidemics as confounders in both a parametric and a nonparametric approach. The Czech Republic had a 3.8% increase in mortality [95% confidence interval (CI), 0.8-6.9%] in association with 100 microg/m(3) total suspended particles (TSP) (lagged 2 days) for the time period 1982-1994. During the last 2 years of study, 68% of the TSP consisted of particulate matter [less than/equal to] 10 microm in aerodynamic diameter (PM(10)). An increase of 100 microg/m(3) TSP (lagged 1 day) was associated with a 9.5% increase in mortality (CI, 1.2-18.5%) and 100 microg/m(3) PM(10 )(lagged 1 day) showed a 9.8% increase in mortality (CI, 0.7-19.7%). We found no evidence for an association between mortality and particulate matter in the rural area in Germany at the Czech border. Data from the coal basin in the Czech Republic suggested an increase in mortality associated with the concentration of particulate matter in a highly polluted setting in Central Europe that is consistent with the associations observed in other western European cities and in the United States.

Models for retrospective quantification of indoor radon exposure in case-control studies

In epidemiologic studies on lung cancer risk due to indoor radon the quantification of individual radon exposure over a long time period is one of the main issues. Therefore, radon measurements in one or more dwellings, which in total have been inhabited by the participants for a sufficient time-period, are necessary as well as consideration of changes of building characteristics and ventilation habits, which influence radon concentration. Given data on 1-y alpha-track measurements and personal information from 6,000 participants of case-control studies in West and East Germany, an improved method is developed to assess individual radon exposure histories. Times spent in different rooms of the dwelling, which are known from a personal questionnaire, are taken into account. The time spent outside the house (average fraction 45%) varies substantially among the participants. Therefore, assuming a substantially lower radon exposure outside the dwelling, the residence time constitutes an important aspect of total radon exposure. By means of an analysis of variance, important determinants of indoor radon are identified, namely constant conditions such as type of house (one family house or multiple dwelling), type of construction (half-timbered, massive construction, lightweight construction), year of construction, floor and type of basement, and changeable conditions such as heating system, window insulation, and airing habits. A correction of measurements in former dwellings by factors derived from the analysis is applied if current living conditions differ from those of the participants at the time when they were living in the particular dwellings. In rare cases the adjustment for changes leads to a correction of the measurements with a factor of about 1.4, but a reduction of 5% on average only. Exposure assessment can be improved by considering time at home and changes of building and ventilation conditions that affect radon concentration. The major concern that changes in ventilation habits and building conditions lead to substantial errors in exposure (and therefore risk) assessment cannot be confirmed in the data analyzed.

Indoor determinants of Der p 1 and Der f 1 concentrations in house dust are different

BACKGROUND

Exposure to mite allergens is a major risk factor for sensitization and the development of asthma. Der p 1 and Der f 1 content in homes and probably the proportion of both antigens is highly variable even in the same geographical area.

OBJECTIVE

We investigated specific indoor determinants of Der p 1 and Der f 1 concentrations in house dust of two German cities, Erfurt and Hamburg (n = 405 homes).

METHODS

Mite allergen levels were determined using monoclonal antibodies against Der p 1 and Der f 1 by the ELISA method. Indoor relative humidity and temperature were monitored continuously in the homes over 1 week. The characteristics of homes and occupants were assessed by questionnaire to obtain information on factors which may have an impact on the mite antigen concentration in house dust. These determinants were studied by multivariate regression analysis.

RESULTS

The correlation between concentrations of Der p 1 and Der f 1 inside the homes was weak (r = 0.29-0.35), indicating that different determinants are relevant. Concentrations of the allergens were significantly higher on lower floors (ratios 2-8 times, Der p 1, Der f 1), on old mattresses (ratios 3-13 times, Der p 1, Der f 1), in post-war buildings (ratio 6 times, Der p 1), for non-central heating (ratio 2 times, Der p 1), for old carpets (ratio 3 times, Der p 1) and for the presence of a dog in the house (ratio 3 times, Der f 1). Furthermore, mite concentration increases with raising relative humidity (ratio 1.03 per 1%, Der p 1) and with decreasing temperature (ratio 0.86 per 1 degrees C, Der p 1) indoors.

CONCLUSION

Both Der p 1 and Der f 1 concentrations should be measured in house dust, since they are only weakly correlated and have different determinants.

Gas cooking, respiratory health and white blood cell counts in children

The use of gas stoves has been associated with respiratory symptoms of chronic airway inflammation and higher rates of respiratory infections. We used data from a 1992/93 survey of 2,198 East German school children (aged 5 to 14) to assess whether gas cooking increases respiratory symptoms and is associated with a chronic inflammatory process reflected by an increase in white blood cell (WBC) count in children who do not exhibit signs of an acute respiratory infection. We found increases for the respiratory symptoms 'cough without cold' [odds ratio (OR) = 1.68; 95% confidence interval (CI), 1.18-2.39], 'cough in the morning' (OR = 1.58; CI, 1.23-2.04) and 'cough during the day or at night' (OR = 1.42; CI, 1.13-1.78) in children living in homes with gas ranges, but lifetime prevalence of asthma, bronchitis, wheeze, and the prevalence of acute infections were not affected. Furthermore, we examined WBC levels in a subgroup of 1,134 children for whom blood samples were available and who did not suffer from an acute infection. We observed small increases in the risk of having WBC counts above the 75th or 90th percentile (8300 or 9800 cell counts per microliter) when children were exposed to gas cooking after adjustment for age, gender, and passive smoking (OR = 1.30; CI, 0.98-1.73, and OR = 1.38; CI, 0.91-2.10). The strongest effect estimates for chronic inflammation were found for those children likely to have been exposed at higher levels, that is when stoves had no fans, in smaller homes, and for children spending more time indoors.

Occupational lung cancer risk for men in Germany: results from a pooled case-control study

Occupational exposures such as crystalline silica, diesel engine exhaust, polycyclic aromatic hydrocarbons, and man-made mineral fibers are strongly suspected to increase lung cancer risk. Two case-control studies in Germany conducted between 1988 and 1996 were pooled for a joint analysis. A total of 3,498 male cases and 3,541 male population controls, frequency matched for age and region, were included in the study. The lifelong history of all jobs and industries was coded and occupational exposures were evaluated by expert rating. Odds ratios, crude and adjusted for smoking and asbestos exposure, were calculated by conditional logistic regression. Job-related evaluation showed a statistically significant increased odds ratio adjusted for smoking among farmers; forestry workers, fishermen, and livestock workers; miners and quarrymen; chemical processors; cabinet makers and related wood workers; metal producers and processors; bricklayers and carpenters; road construction workers, pipelayers and well diggers; plasterers, insulators, and upholsterers; painters and lacquerers; stationary engine and heavy equipment operators; transport workers and freight handlers; and service workers. With regard to specific occupational exposures, elevated odds ratios (OR) (95% confidence intervals (CI)) for lung cancer risk adjusted for smoking and asbestos exposure were observed for man-made mineral fibers (OR = 1.48, 95% CI 1.17, 1.88); crystalline silica (OR = 1.41, 95% CI 1.22, 1.62); diesel engine exhaust (OR = 1.43, 95% CI 1.23, 1.67); and polycyclic aromatic hydrocarbons (OR = 1.53, 95% CI 1.14, 2.04). The risk of asbestos exposure, adjusted for smoking was also increased (OR = 1.41, 95% CI 1.24, 1.60).

Association of beta(2)-adrenoreceptor variants with bronchial hyperresponsiveness

Because of its involvement in the regulation of airway tone, the beta(2)-adrenoreceptor is considered a candidate for bronchial hyperresponsiveness (BHR) associated with asthma. This notion is supported by several reports that have implicated the chromosomal region 5q31-q33 harboring the gene for the beta(2)-adrenoreceptor in the genetics of asthma and related phenotypes. We performed a population-based association study focusing on BHR as a qualitative trait and omitting other asthma-related phenotypes. From a German population sample of 1,150 individuals we extracted all 152 bronchohyperreactive probands, who were compared with 295 bronchonormoreactive control subjects. All individuals were genotyped for three single nucleotide polymorphisms of the beta(2)-adrenoreceptor gene resulting in variants at the amino acid positions 16, 27, and 164. The genotyping protocol used allowed the determination of haplotypes of these polymorphisms. Whereas no individual polymorphism was associated with BHR, the Gly16/Gln27/Th164 haplotype was significantly underrepresented in the case group indicating a protective effect of this haplotype with regard to BHR. Upon reanalysis by sex a significant association persisted only for female probands.

The effect of low-level blood lead on hematologic parameters in children

A health survey of school children living in polluted regions of eastern Germany provided us with data necessary to examine the effects of lead on the blood system at levels below current standards for blood lead content. Data collected for 797 children, aged 5-14 years, with low blood lead levels (GM, 33.3 microg Pb/L; range, 7.5-239 microg Pb/L) allowed us to examine the relationship between blood lead content and hematological parameters. Using linear regression analyses and controlling for a number of potential confounding factors, we found that increasing blood lead levels by 10 microg/L were associated with a small increase in the number of red blood cells and in girls with reduced MCV and MCH. The reasons for our observation, especially the gender difference, are still uncertain. In conclusion the morphology and function of erythrocytes might be sensitive parameters of low dose lead toxicity.

Indoor viable mold spores--a comparison between two cities, Erfurt (eastern Germany) and Hamburg (western Germany)

BACKGROUND

In eastern Germany, the prevalence of allergies is lower than in western Germany for both children and adults. Several reasons for this fact have been discussed, although it is still not completely understood. One purpose of the epidemiologic study "Indoor and genetic factors in asthma and allergy" (INGA) is to compare exposure to mold spores in two German cities. Therefore, 405 homes in Erfurt (east) and Hamburg (west) were visited twice by trained investigators between June 1995 and May 1997.

METHODS

Samples of settled dust were taken by vacuuming from the carpet in the living room. Sieved house dust was diluted and plated on DG18 agar. The analyses were carried out in duplicate in the same laboratory.

RESULTS

No significant difference could be shown for the total and for single genera (Alternaria, Aspergillus, Cladosporium, and Penicillium) in concentration of spores of viable fungi in settled house dust between Erfurt and Hamburg. Seasonal variation of the mold picture, with highest values in August, could be identified both indoors and outdoors.

CONCLUSIONS

Because outdoor concentration is the main influence on indoor concentration of mold spores from June to October, we recommend sampling from November to May to evaluate exposure to indoor mold spores.

Environmental tobacco smoke and lung cancer: a case-control study in Germany

To assess the association between exposure to environmental tobacco smoke (ETS) and lung cancer, the authors personally interviewed 292 lifelong nonsmoking lung cancer cases (recruited from 15 hospitals in the study area) and 1,338 nonsmoking controls (randomly selected by population registries) between 1990 and 1996 in Germany. Subjects were asked by a standardized questionnaire about exposure to ETS in childhood, by spouse, at work, and in transportation and social settings. Several indicators of these different sources of exposure were investigated, using not or low exposed subjects as the reference category. The most informative quantification index was weighted duration of exposure (hours x level of smokiness). No effect of ETS exposure during childhood and no clear effect of spousal ETS were observed. However, for the highest category of exposure, clear effects of ETS at the workplace (odds ratio (OR) = 1.93; 95% confidence interval (CI): 1.04, 3.58), in vehicles (OR = 2.64; 95% CI: 1.30, 5.36), and from all sources combined (OR = 1.39; 95% CI: 0.96, 2.01) were found. Adjustment for occupational carcinogens, radon, and diet did not appreciably change the results. These findings suggest that exposures to high levels of ETS at the workplace and in other public indoor settings appear to be important risk factors for lung cancer risk in nonsmokers.