Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust - Effect of temperature and ventilation.

Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18-16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6-40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.

A longitudinal study of sick building syndrome among pupils in relation to microbial components in dust in schools in China.

There are few longitudinal studies on sick building syndrome (SBS), which include ocular, nasal, throat, and dermal symptoms, headache, and fatigue. We studied the associations between selected microbial components, fungal DNA, furry pet allergens, and incidence and remission of SBS symptoms in schools in Taiyuan, China. The study was based on a two-year prospective analysis in pupils (N=1143) in a random sample of schools in China. Settled dust in the classrooms was collected by vacuum cleaning and analyzed for lipopolysaccharide (LPS), muramic acid (MuA), and ergosterol (Erg). Airborne dust was collected in Petri dishes and analyzed for cat and dog allergens and fungal DNA. The relationship between the concentration of allergens and microbial compounds and new onset of SBS was analyzed by multi-level logistic regression. The prevalence of mucosal and general symptoms was 33% and 28%, respectively, at baseline, and increased during follow-up. At baseline, 27% reported at least one symptom that improved when away from school (school-related symptoms). New onset of mucosal symptoms was negatively associated with concentration of MuA, total LPS, and shorter lengths of 3-hydroxy fatty acids from LPS, C14, C16, and C18. Onset of general symptoms was negatively associated with C18 LPS. Onset of school-related symptoms was negatively associated with C16 LPS, but positively associated with total fungal DNA. In general, bacterial compounds (LPS and MuA) seem to protect against the development of mucosal and general symptoms, but fungal exposure measured as fungal DNA could increase the incidence of school-related symptoms.

Asthmatic symptoms among pupils in relation to microbial dust exposure in schools in Taiyuan, China.

Microbial exposure has been indicated as significant in the development of asthma and allergy among children. The aim of the study was to test whether microbial exposure and allergens in the school environment are associated with asthmatic symptoms in pupils. Data on asthmatic symptoms and respiratory infections were collected through a questionnaire survey among 1993 pupils aged 11-15 yr in 10 randomly selected schools in Taiyuan, China. Settled dust in classrooms was analysed using tandem gas chromatography-mass spectrometry for 3-hydroxy fatty acids, marker of lipopolysaccharide (LPS) from endotoxin, muramic acid (MuA), marker of bacteria and ergosterol (Erg) for fungi, quantifying both culturable and non-culturable microbes. A total of 29.8% reported daytime attacks of breathlessness, 8.4% wheeze and 1.2% had doctor's diagnosed asthma. Generally, MuA was negatively associated with wheeze and daytime attacks of breathlessness, the latter of which was negatively associated with Erg to a weaker extent. Total concentration of LPS was positively associated with daytime attacks of breathlessness, but shorter lengths of LPS, C10, C12 and C14 LPS were negatively associated with either wheezing or daytime attacks of breathlessness. For MuA and C10 and C12 of LPS, the associations were independent of airborne allergens and classroom crowdedness, and even independent of the other two microbial markers for MuA. Microbial exposure indicated by certain chemical markers (e.g. MuA) could be protective for asthmatic symptoms, but for LPS (endotoxin), the picture is more complex, varying by different lengths of fatty acids of LPS.

Air contaminants in a submarine equipped with air independent propulsion.

The Swedish Navy has operated submarines equipped with air independent propulsion for two decades. This type of submarine can stay submerged for periods far longer than other non-nuclear submarines are capable of. The air quality during longer periods of submersion has so far not been thoroughly investigated. This study presents results for a number of air quality parameters obtained during more than one week of continuous submerged operation. The measured parameters are pressure, temperature, relative humidity, oxygen, carbon dioxide, hydrogen, formaldehyde and other volatile organic compounds, ozone, nitrogen dioxide, particulate matter and microbiological contaminants. The measurements of airborne particles demonstrate that air pollutants typically occur at a low baseline level due to high air exchange rates and efficient air-cleaning devices. However, short-lived peaks with comparatively high concentrations occur, several of the sources for these have been identified. The concentrations of the pollutants measured in this study do not indicate a build-up of hazardous compounds during eight days of submersion. It is reasonable to assume that a substantial build-up of the investigated contaminants is not likely if the submersion period is prolonged several times, which is the case for modern submarines equipped with air independent propulsion.

Assessment of microbial exposure risks from handling of biofuel wood chips and straw--effect of outdoor storage.

Handling of biofuels may release dust particles containing high concentrations of Hazardous microorganisms, thus representing a potential occupational health problem. We analysed the microbial dustiness of baled straw (cultivated both conventionally and ecologically) and of wood chips from piles that had been stored outdoors for up to 11 months by using total spore counting, cultivation, and measuring of endotoxin and chemical markers of fungal biomass, lipopolysaccharide, and peptidoglycan. The bacterial dustiness of straw was much greater than of wood chips whereas the fungal dustiness did not differ much. In general, samples taken from the inner part of each biofuel material were dustier than samples taken from the surface, except for fungal and bacterial biomass in wood chips and total fungi and fungal biomass in ecological straw. A considerable increase of bacterial dustiness occurred during storage over summer. Dust from ecological straw contained considerably less of bacterial components than from conventional straw and, in addition, exhibited a less pronounced increase upon storage over summer. In summary, biofuels represent sustainable energy resources of growing economic importance but may at the same time pose significant health problems. We found that storage of biofuels outdoors over summer increased the microbiological dustiness and should therefore be avoided, and that ecological straw contained less of microbe-containing dust than conventional straw and should be preferred since it reduces the exposure to harmful microbiological agents.

Elevated concentrations of endotoxin in indoor air due to cigarette smoking.

Exposure to environmental tobacco smoke (ETS) is an important worldwide public health issue. The present study demonstrates that cigarette smoke can be a major source of endotoxin (lipopolysaccharide, LPS) in indoor environments. Gas-chromatography/mass-spectrometry was used to determine 3-hydroxy fatty acids as markers of endotoxin in air-borne house dust in homes of smokers and non-smokers. Air concentrations of endotoxin were 4-63 times higher in rooms of smoking students than in identical rooms of non-smoking students. The fact that cigarette smoke contains large amounts of endotoxin may partly explain the high prevalence of respiratory disorders among smokers and may also draw attention to a hitherto neglected risk factor of ETS.

Characterizing microbial exposure with ergosterol, 3-hydroxy fatty acids, and viable microbes in house dust: determinants and association with childhood asthma.

The authors assessed determinants of ergosterol, 3-OH fatty acids (FAs), and viable microbes in vacuum cleaner dust, and investigated the association between these microbial markers and childhood asthma. The authors studied the homes of 36 children who were new cases of childhood asthma and the homes of 36 controls. Home characteristics explained 34% to 44% of the variation in levels of different microbial groups. Determinants of 3-OH FAs were a lower level of cleanliness, having a fireplace, having livestock, and moisture damage; determinants of viable bacteria were the level of home repair needed and the material used in the building frame of the home. Ergosterol was associated with the presence of livestock and the practice of cleaning rugs outside; viable fungi was associated with the material used in the building frame, visible mold, and the practice of cleaning rugs outside. Exposure to mesophilic actinomycetes was nonsignificantly associated with risk of asthma. The authors concluded that the variation of microbial levels in dust could be explained relatively well by home characteristics, and suggested that exposure to mesophilic actinomycetes may increase the risk of new asthma.

Extremely low electrical current generated by porcine small intestine smooth muscle alters bacterial autolysin production.

The effect of extremely low electrical currents, identical to those generated by the gut smooth muscle, on bacterial autolysin production in vitro was tested in the present study. When stimulated with these electrical currents, the bacteria Pediococcus pentosaceus 16:1 produced groups of peptidoglycan hydrolases that differed from those produced by the unstimulated (control) bacteria. The autolysins synthesized by the P. pentosaceus 16:1 under extremely low electrical currents were effective against peptidoglycans from the cell walls of various lactic acid bacteria strains, whereas the autolysins from the control bacteria acted exclusively against P. pentosaceus 16:1 cell walls. Thus, it can be predicted that in vivo the electrical currents generated by the intestinal smooth muscles, which can be recorded as the myoelectrical migrating complexes, could regulate lactic acid bacteria strain growth in the gut.

Large particles are responsible for elevated bacterial marker levels in school air upon occupation.

Muramic acid (Mur) is found in bacterial peptidoglycan (PG) whereas 3-hydroxy fatty acids (3-OH FAs) are found in Gram-negative bacterial lipopolysaccharide (LPS). Thus Mur and 3-OH FAs serve as markers to assess bacterial levels in indoor air. An initial survey, in a school, demonstrated that the levels of dust, PG and LPS (pmol m(-3)) were each much higher in occupied rooms than in the same rooms when unoccupied. In each instance, the Mur content of dust was increased and the hydroxy fatty acid distribution changed similarly suggesting an alteration in the bacterial population. Here, findings are compared with results from two additional schools. Follow-up aerosol monitoring by particle size was also performed for the first time for all 3 schools. The particle size distribution was shown to be quite different in occupied versus unoccupied schoolrooms. Within individual classrooms, concentrations of airborne particles [greater-than-or-equal]0.8 [micro sign]m in diameter, and CO(2) were correlated. This suggests that the increased levels of larger particles are responsible for elevation of bacterial markers during occupation. Release of culturable and non-culturable bacteria or bacterial aggregates from children (e.g. from flaking skin) might explain this phenomenon.

Evaluation of the methyl ester O-methyl acetate derivative of muramic acid for the determination of peptidoglycan in environmental samples by ion-trap GC-MS-MS.

Muramic acid (MA) is a unique amino sugar that is a constituent of the peptidoglycan (PG) present in prokaryotic cell walls. MA can serve as a marker for quantifying bacterial load, e.g. in indoor environments, by using gas chromatography-tandem mass spectrometry (GC-MS-MS). We demonstrated recently that the methyl ester O-methyl acetate (MMA) derivative can be used to detect MA in house dust by ion-trap GC-MS-MS. However, since the MMA derivative is not formed from free MA quantification was not optimal. Here we report 1) significant improvements in sample preparation of the MMA derivative and 2) an evaluation of the performance of derivative, using for comparison the alditol acetate derivative, the gold standard in quantitative trace analysis of MA in complex matrices. The MMA derivative was analysed using an MS instrument with internal ionization and the alditol acetate derivative was analysed using an instrument with external ionization. 13C-labelled cyanobacteria, containing MA in their PG, were used as the internal standard. A linear relationship was found between the two methods in studies on 27 parallel samples of airborne dust from school classes collected on filters. Although the analytical sensitivity of the MMA derivatives was somewhat slightly lower than of the alditol acetate derivative, this may be due to differences in yield of derivative, sample clean-up efficiency, or different performance of the GC columns or MS instruments. However preparation of the MMA derivative is quick and compatible with preparation of methyl esters of 3-hydroxy fatty acids (used as markers of Gram negative endotoxin) allowing the levels of both markers to be determined in the same dust sample. In conclusion, the MMA procedure can be used to determine MA in environmental samples with good reproducibility provided the concentration of the 13C-labelled MA internal standard in the cyanobacteria is first determined with an alternative method.

Characterization of the microbial community in indoor environments: a chemical-analytical approach.

An integrated procedure is presented whereby gas chromatography-ion trap mass spectrometry is used to determine chemical markers of gram-negative bacterial lipopolysaccharide (3-hydroxy fatty acids with 10 to 18 carbon atoms), gram-positive bacteria (branched-chain fatty acids with 15 and 17 carbon atoms), bacterial peptidoglycan (muramic acid), and fungal biomass (ergosterol) in samples of settled house dust. A hydrolysate of (13)C-labeled cyanobacterial cells is used as an internal standard for the first three markers. These analyses require two dust samples, one for 3-OH fatty acids, branched-chain fatty acids, and muramic acid and another for ergosterol. The method may be used to characterize microbial communities in environmental samples.

Increased levels of bacterial markers and CO2 in occupied school rooms.

Our group previously demonstrated that carbon dioxide (CO2) levels in heavily occupied schools correlate with the levels of airborne bacterial markers. Since CO2 is derived from the room occupants, it was hypothesized that in schools, bacterial markers may be primarily increased in indoor air because of the presence of children; directly from skin microflora or indirectly, by stirring up dust from carpets and other sources. The purpose of this project was to test the hypothesis. Muramic acid (Mur) is found in almost all bacteria whereas 3-hydroxy fatty acids (3-OH FAs) are found only in Gram-negative bacteria. Thus Mur and 3-OH FA serve as markers to assess bacterial levels in indoor air (pmol m(-3)). In our previous school studies, airborne dust was collected only from occupied rooms. However, in the present study, additional dust samples were collected from the same rooms each weekend when unoccupied. Samples were also collected from outside air. The levels of dust, Mur and C10:0, C12:0, C14:0, and C16:0 3-OH FAs were each much higher (range 5-50 fold) in occupied rooms than in unoccupied school rooms. Levels in outdoor air were much lower than that of indoor air from occupied classrooms and higher than the levels in the same rooms when unoccupied. The mean CO2 concentrations were around 420 parts per million (ppm) in unoccupied rooms and outside air; and they ranged from 1017 to 1736 ppm in occupied rooms, regularly exceeding 800-1000 ppm, which are the maximum levels indicative of adequate indoor ventilation. This indicates that the children were responsible for the increased levels of bacterial markers. However, the concentration of Mur in dust was also 6 fold higher in occupied rooms (115.5 versus 18.2 pmole mg(-1)). This further suggests that airborne dust present in occupied and unoccupied rooms is quite distinct. In conclusion in unoccupied rooms, the dust was of environmental origin but the children were the primary source in occupied rooms.