Determinants of personal exposure to some carcinogenic substances and nitrogen dioxide among the general population in five Swedish cities.

Environmental levels of airborne carcinogenic and related substances are comparatively better known than individual exposure and its determinants. We report on a personal monitoring program involving five Swedish urban populations. The aim of the program was to investigate personal exposure to benzene, 1,3-butadiene, formaldehyde, and nitrogen dioxide (NO2). The measurements were performed among 40 inhabitants during seven consecutive days, in one urban area each year, during 2000-2008. The estimated population exposure levels were 1.95 µg/m(3) for benzene, 0.56 µg/m(3) for 1,3-butadiene, 19.4 µg/m(3) for formaldehyde, and 14.1 µg/m(3) for NO2. Statistical analysis using a mixed-effects model revealed that time spent in traffic and time outdoors contributed to benzene and 1,3- butadiene exposure. For benzene, refueling a car was an additional determinant influencing the exposure level. Smoking or environmental tobacco smoke were significant determinants of exposure to NO2, benzene, and 1,3-butadiene. Those with a gas stove had higher NO2 exposure. Living in a single-family house increased the exposure to formaldehyde significantly. In a variance component model, the between-subject variance dominated for 1,3-butadiene and formaldehyde, whereas the between-city variance dominated for NO2. For benzene, the between-subject and between-cities variances were similar.

Lung function in volunteers before and after exposure to trichloramine in indoor pool environments and asthma in a cohort of pool workers.

OBJECTIVES: Exposure to trichloramine (NCl(3)) in indoor swimming-pool environments is known to cause mucous membrane irritation, but if it gives rise to changes in lung function or asthma in adults is not known. (1) We determined lung function in volunteers before and after exposure to indoor pool environments. (2) We studied the occurrence of respiratory symptoms and asthma in a cohort of pool workers. DESIGN/METHODS/PARTICIPANTS: (1) We studied two groups of volunteers, 37 previously non-exposed healthy persons and 14 pool workers, who performed exercise for 2 h in an indoor pool environment. NCl(3) in air was measured during pool exposures and in 10 other pool environments. Filtered air exposures were used as controls. Lung function and biomarkers of pulmonary epithelial integrity were measured before and after exposure. (2) We mailed a questionnaire to 1741 persons who indicated in the Swedish census 1990 that they worked at indoor swimming-pools. RESULTS: (1) In previously non-exposed volunteers, statistically significant decreases in FEV(1) (forced expiratory volume) and FEV(%) (p=0.01 and 0.05, respectively) were found after exposure to pool air (0.23 mg/m(3) of NCl(3)). In pool workers, a statistically significant decrease in FEV(%) (p=0.003) was seen (but no significant change of FEV(1))(.) In the 10 other pool environments the median NCl(3) concentration was 0.18 mg/m(3). (2) Our nested case/control study in pool workers found an OR for asthma of 2.31 (95% CI 0.79 to 6.74) among those with the highest exposure. Exposure-related acute mucous membrane and respiratory symptoms were also found. CONCLUSIONS: This is the first study in adults showing statistically significant decreases in lung function after exposure to NCl(3). An increased OR for asthma among highly exposed pool workers did not reach statistical significance, but the combined evidence supports the notion that current workroom exposures may contribute to asthma development. Further research on sensitive groups is warranted.

Field validation of the Ogawa diffusive sampler for NO2 and NOx in a cold climate.

A small-scale field trial in Umeå, Sweden with Ogawa samplers and a chemiluminescence instrument indicated that the NO(2) concentration was underestimated with respect to the reference monitor, if calculated according to the manufacturer's Ogawa sampling protocol. By co-locating Ogawa samplers and reference monitors at six sites in two Swedish cities, uptake rates were determined for NO(2) and NO(x) better applicable to the Swedish conditions and climate. The concentrations of NO(2) and NO(x) calculated according to the instruction manual of the sampler and using the field-determined uptake rates were compared with values derived from chemiluminescence monitors for each week over which samples were taken. When calculated according to the manufacturer's suggested protocol, the Ogawa sampler underestimated the NO(2) concentrations by 9.1% on average for all samples (N = 53), with respect to the reference monitor. In contrast, NO(x) concentrations were overestimated by a mean value of 15% for all samples (N = 45). By using the field determined uptake rates for the calculation of NO(2) and NO(x) a better estimation of the concentrations was obtained. The ratio between concentrations determined with the Ogawa samplers and chemiluminescence monitors was then 1.02 for all measurements of NO(2) and 1.00 for NO(x). Precision, expressed as the mean coefficient of variation, was 6.4% for six, 6-replicate measurements of NO(2) and 3.7% for five, 6-replicate measurements of NO(x).

Potential dermal exposure to methyl methacrylate among dental technicians; variability and determinants in a field study.

Methyl methacrylate (MMA) is a commonly used chemical in dental work that can cause dermatitis. Nineteen dental technicians participated in a field study in which potential dermal exposure to MMA and exposure determinants, including glove use and MMA vapour in the breathing zone, were repeatedly monitored during three consecutive days. Using patches placed on various parts of their hands we observed that the fingers and palms of the dental technicians were exposed to MMA, and their forefingers were significantly more exposed than their ring fingers; this is based on pooled data for both left and right hands (p = 0.04). The exposure variability was greater between workers than within worker (i.e. day-to-day variability), but the between worker variability was to some extent explained by a model which included the tested determinants. Neither the amount of MMA vapours in the breathing zone nor glove use was consistently correlated with the dermal exposure. Thus, the effects of glove use and the distribution of exposure to MMA on the hands in working environments needs to be further investigated.

Ozone air levels adjacent to a dental ozone gas delivery system.

OBJECTIVE: Ozone (O3) has been suggested as an anti-microbial treatment in dentistry, with an ozone gas delivery system introduced for the treatment of fissure and root caries. The aim of this study was to investigate the sealing capacity of the novel delivery system and its re-suction capacity during accidental displacement of the cup at different stages of ozone delivery. MATERIAL AND METHODS: Ozone leakage was studied in vitro after application on a flat metal surface and on buccal and occlusal tooth surfaces. An ozone analyzer was used to measure ozone gas concentrations adjacent to the delivering cups when adapted to the target surfaces during and after 10-20 s application cycles. The measured levels were compared with the background concentrations in the room. Measurements were performed 1) after complete ozone application cycles, 2) within the cycle before the start of the suction period, and 3) after displacements of the cup during the cycles. RESULTS: Ozone air values varied between 8 and 166 microgram/meter-3 for the flat metal surface and between 0 and 108 microgram/meter-3 for the tooth surfaces. Ozone leakage levels were 7.6 microgram/m-3 for the flat and and 7.4 microgram/meter-3 and 5.6 microgram/meter-3 for the buccal and occlusal surfaces, respectively, and 5.2 microgram/meter-3 and 9.8 microgram/meter-3 for the premolar and molar surfaces, respectively. Cycles with displacement showed significantly higher leakage levels than continuous complete cycles (p=0.03). CONCLUSIONS: Ozone application cycles with displacements showed significantly higher leakage levels than continuous complete cycles. The largest ozone delivery cups showed the highest leakage values. A change in background levels was seen with similar change in adjacent ozone levels. The overall measured ozone leakage values were low after normally functioning delivery cycles and after repeated displacements. The delivery system can be considered safe.

Can NO(2) be used to indicate ambient and personal levels of benzene and 1,3-butadiene in air?

The aim of this study was to investigate the relation between two toxic volatile organic compounds, 1,3-butadiene and benzene, and a commonly used indicator of vehicle exhaust fumes, NO(2). This was to see if NO(2) can be used to indicate personal exposure to carcinogenic substances or at least estimate ambient levels measured at a stationary point. During the winter of 2001, 40 randomly selected persons living in the City of Umea (in the north of Sweden) were recruited to the study. Personal measurements of 1,3-butadiene, benzene and NO(2) were performed for one week, and were repeated for 20 of the 40 participants. Additional information was gathered using a diary kept by each participant. During the same time period weekly stationary measurements were performed at one urban background station and one street station in the city centre. The results from the personal measurements showed a negligible association of NO(2) with 1,3-butadiene (r= 0.06) as well as with benzene (r= 0.10), while the correlation coefficient between 1,3-butadiene and benzene was high and significant (r= 0.67). In contrast to the personal measurements, the stationary measurements showed strong relations between 1,3-butadiene, benzene and NO(2) both within and in-between the street and urban background station. This study supports NO(2) as a potential indicator for 1,3-butadiene and benzene levels in streets or urban background air, while the weak relations found for the personal measurements do not support the use of NO(2) as an indicator for personal 1,3-butadiene and benzene exposure.

Validation of the Willems badge diffusive sampler for nitrogen dioxide determinations in occupational environments.

The Willems badge, a diffusive sampler for nitrogen dioxide, has previously been validated for ambient air measurements. This paper describes the laboratory and field validation of the Willems badge for personal sampling under working environment conditions. The mean sampling rate in the laboratory tests was 46 ml min(-1), with an RSD of 12%. No statistically significant effects on sampling rate of the sampling time, concentration of NO2 or relative humidity were found. A slightly decreased sampling rate was observed at low wind velocity. This was also confirmed during static sampling, which makes the sampler less appropriate for static sampling indoors. No back diffusion was observed. Storage of the samplers for two weeks before or after exposure did not affect the sampling rate. Our analysis is based on a modified colorimetric method, performed by FIA (flow injection analysis). This technique was compared to ion chromatography analysis. The use of ion chromatography lowered the detection limit from 11 to 2 microg m(-3) for an 8 h sample, and furthermore enabled the detection of other anions. In conclusion, the diffusive sampler was found to perform well for personal measurements in industrial environments.