Polybrominated diphenyl ether (PBDE) concentrations and resulting exposure in homes in California: relationships among passive air,surface wipe and dust concentrations,and temporal variability

Polybrominated diphenyl ethers (PBDEs) are used as flame retardants in furniture foam, electronics, and other home furnishings. A field study was conducted that enrolled 139 households from California, which has had more stringent flame retardant requirements than other countries and areas. The study collected passive air, floor and indoor window surface wipes, and dust samples (investigator collected using an HVS3 and vacuum cleaner) in each home. PentaBDE and BDE209 were detected in the majority of the dust samples and many floor wipe samples, but the detection in air and window wipe samples was relatively low. Concentrations of each PBDE congener in different indoor environmental media were moderately correlated, with correlation coefficients ranging between 0.42 and 0.68. Correlation coefficients with blood levels were up to 0.65 and varied between environmental media and age group. Both investigator‐collected dust and floor wipes were correlated with serum levels for a wide range of congeners. These two sample types also had a relatively high fraction of samples with adequate mass for reliable quantification. In 42 homes, PBDE levels measured in the same environmental media in the same home 1 year apart were statistically correlated (correlation coefficients: 0.57–0.90), with the exception of BDE209 which was not well correlated longitudinally.     

Comparisons of polybrominated diphenyl ether and hexabromocyclododecane concentrations in dust collected with two sampling methods and matched breast milk samples

Household dust from 19 Swedish homes was collected using two different sampling methods: from the occupant's own home vacuum cleaner after insertion of a new bag and using a researcher-collected method where settled house dust was collected from surfaces above floor level. The samples were analyzed for 16 polybrominated diphenyl ether (PBDE) congeners and total hexabromocyclododecane (HBCD). Significant correlations (r = 0.60-0.65, Spearman r = 0.47-0.54, P < 0.05) were found between matched dust samples collected with the two sampling methods for ∑OctaBDE and ∑DecaBDE but not for ∑PentaBDE or HBCD. Statistically significantly higher concentrations of all PBDE congeners were found in the researcher-collected dust than in the home vacuum cleaner bag dust (VCBD). For HBCD, however, the concentrations were significantly higher in the home VCBD samples. Analysis of the bags themselves indicated no or very low levels of PBDEs and HBCD. This indicates that there may be specific HBCD sources to the floor and/or that it may be present in the vacuum cleaners themselves. The BDE-47 concentrations in matched pairs of VCBD and breast milk samples were significantly correlated (r = 0.514, P = 0.029), indicating that one possible exposure route for this congener may be via dust ingestion. PRACTICAL IMPLICATIONS: The statistically significant correlations found for several individual polybrominated diphenyl ether (PBDE) congeners, ∑OctaBDE and ∑DecaBDE between the two dust sampling methods in this study indicate that the same indoor sources contaminate both types of dust or that common processes govern the distribution of these compounds in the indoor environment. Therefore, either method is adequate for screening ∑OctaBDE and ∑DecaBDE in dust. The high variability seen between dust samples confirms results seen in other studies. For hexabromocyclododecane (HBCD), divergent results in the two dust types indicate differences in contamination sources to the floor than to above-floor surfaces. Thus, it is still unclear which dust sampling method is most relevant for HBCD as well as for ∑PentaBDE in dust and, further, which is most relevant for determining human exposure to PBDEs and HBCD.     

Bioreactivity of particulate matter in Beijing air: results from plasmid DNA assay

An in vitro plasmid assay was employed to study the bioreactivity of PM (particulate matter) in Beijing air. It was found that the TD20 (toxic dose of PM causing 20% of plasmid DNA damage) of Beijing PM can be as low as 28 microg ml(-1) and as high as >1000 microg ml(-1). Comparison of the physical properties, such as morphology and size distribution, and oxidative potential indicates that the PM(2.5) (particulate matter with an aerodynamic diameter of 2.5 microm or less) has a stronger oxidative capacity than PM(10) (particulate matter with an aerodynamic diameter of 10 microm or less), and that the higher number percentages of soot aggregates and lower number percentages of mineral and fly ashes are associated with the higher oxidative capacity. Although the mass of PM(10) during dust storms is commonly 5 times higher than that during non-dust storm episodes, the oxidative capacity of PM(10)s of dust storms is much lower than that of the non-dust storm PM(10)s. The water-soluble fractions and intact whole particle solutions of Beijing airborne particles produce similar plasmid assay results, demonstrating that the bioreactivity of Beijing airborne particles is mainly sourced from the water-soluble fraction. In the samples with stronger bioreactivity, the total analyzed water soluble Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As and Pb (ppm) concentrations are higher. The water soluble zinc shows a good negative correlation with TD20s, suggesting that the water-soluble zinc is probably the major element responsible for the plasmid DNA damage.     

Effect of relative humidity on the aerosolization and total inflammatory potential of fungal particles from dust‐inoculated gypsum boards

The aim of this study was to investigate the effect of relative humidity (RH) on the aerosolization and total inflammatory potential (TIP) of microbial particles released from gypsum boards inoculated with dust samples from homes. After microbial colonization, the gypsum boards were incubated at either high or low RH. The aerosolized particles (0.54–19.8 μm), culturable fungi, β‐glucan and the TIP of the aerosolized particles were quantified. Despite the colonization of several fungal groups, Penicillium dominated the aerosolized fraction. Higher emission rates of particles and culturable fungi were found from low RH compared with high RH in both the inhalable and particulate matter <1 μm (PM₁) fractions, and the TIP was accordingly higher. However, for the aerosolized fractions, the TIP or concentration β‐glucan relative to the number of fungi or particles present was higher from high RH compared with low RH. Despite the low number of culturable fungi in PM₁, this fraction showed a high TIP, and the concentration of β‐glucan correlated strongly with the TIP of this fraction. The individual particles of the aerosolized PM₁ fraction were more inflammatory than the larger particles of the inhalable fraction, and β‐glucan may be an important contributor to the inflammatory potential of the aerosolized particles.     

Characterization and variability of endotoxin and 3-hydroxy fatty acids in an office building during a particle intervention study

Air and dust samples were collected on two floors of an office building during a double-blind particle intervention study to examine spatial and temporal variability of airborne endotoxin over a period of weeks, and to characterize endotoxin activity and lipopolysaccharide (LPS) content in carpet and chair dust. Air samples were collected on multiple days within and across weeks. Dust samples were collected from carpets and chairs one day per week for three weeks. Endotoxin was measured using a Limulus assay. Dust samples were analyzed for LPS by determination of 3-hydroxy fatty acids (3-OHFAs) using gas chromatography-mass spectrometry. The geometric mean (geometric standard deviation) for 96 indoor air samples was 0.24 (1.6) EU/m3. Significant within-floor spatial variation of airborne endotoxin was found (P < 0.0001, n = 80). Temporal variability of airborne endotoxin was not significant across weeks. Mean (+/- SD) endotoxin levels in carpet dust (59 +/- 9.3 EU/mg dust, n = 12) and in chair dust (38 +/- 7.7 EU/mg dust, n = 10) were significantly different (P < 0.001). Carbon chain length-dependent differences in 3-OHFA levels by dust source and floor were found. Enhanced air filtration did not significantly affect airborne endotoxin (P = 0.62); however, total dust mass and total endotoxin in carpet dust samples increased significantly after enhanced surface cleaning (P < 0.01). These findings suggest that spatial variability, dust source, and surface cleaning may influence building occupant exposures to endotoxin.     

Influence of ventilation systems and related energy consumption on inhalable and respirable dust concentrations in fattening pigs confinement buildings

In this paper are presented the results of experimental analysis of the influence of ventilation systems and related energy consumption on inhalable and respirable dust concentrations in fattening pigs confinement buildings. The application of different under pressure ventilation systems in reducing and controlling dust concentrations was analyzed. Optimal ventilation systems designs and the ranges of airflow velocities were defined and discussed.Airflow velocities in the finishing room, under floor, roof and both ventilations, ranged from: 0.01 to 0.10, 0.01 to 0.10 and 0.02 to 0.10 m/s, respectively.The average inhalable dust concentrations during the reference regime (no ventilation), as well as second (floor-), third (roof-) and fourth (both ventilations) regime were: 20, 20, 25 and 17 particles/cm³, respectively. The average respirable dust concentrations during the reference regime, as well as second, third and fourth regime were: 18, 19, 23 and 16 particles/cm³, respectively.Significant decrements of inhalable (F = 44.35, P ≪ 0.01) and respirable (F = 43.82, P ≪ 0.01) dust concentration, in the finishing fattening pig house, were achieved only with the fourth regime (both ventilations).     

Polybrominated diphenyl ether (PBDE) concentrations in house dust are related to hormone levels in men

Despite documented widespread human exposure to polybrominated diphenyl ethers (PBDEs) through dietary intake and contact with or inhalation of indoor dust, along with growing laboratory evidence for altered endocrine function following exposure, human studies of PBDE exposure and endocrine effects remain limited. We conducted a preliminary study within an ongoing study on the impact of environmental exposures on male reproductive health. We measured serum hormone levels and PBDE concentrations (BDE 47, 99 and 100) in house dust from 24 men recruited through a US infertility clinic. BDE 47 and 99 were detected in 100% of dust samples, and BDE 100 was detected in 67% of dust samples, at concentrations similar to those reported in previous US studies. In multivariable regression models adjusted for age and BMI, there was a statistically significant inverse relationship between dust PBDE concentrations and free androgen index. Dust PBDE concentrations were also strongly and inversely associated with luteinizing hormone (LH) and follicle stimulating hormone (FSH), and positively associated with inhibin B and sex hormone binding globulin (SHBG). Finally, consistent with limited recent human studies of adults, PBDEs were positively associated with free T4. In conclusion, the present study provides compelling evidence of altered hormone levels in relation to PBDE exposures estimated as concentrations in house dust, and that house dust is an important source of human PBDE exposure, but more research is urgently needed.     

CFD modelling of ventilation and dust flow behaviour above an underground bin and the design of an innovative dust mitigation system

To mitigate dust contamination in the mine intake roadway, Computational Fluid Dynamics (CFD) study was first conducted to understand the ventilation and respirable dust flow behaviour above the bin. Based on the modelling results, two possible solutions were proposed for dust control, one is modifying the ventilation system to dilute the respirable dust particles, and the other is using water mist dust droppers to suppress and capture the majority of the dust particles. Modelling results indicated that respirable dust particles could be significantly diluted at the operators’ breathing level by increasing the ventilation volume from the horizontal air intake, where 10–13 m³/s of air flow rate was suggested to be a preferable quantity. The mechanism of respirable dust capture using water mist was investigated from classical theory and two phase flow theory, respectively, both of which demonstrated a good dust mitigation effect was achievable. CFD models were employed to investigate the flow behaviour of water mists when sprays were oriented at different directions above the bin. An innovative design of dust control system employing water mist technology with four nozzles was proposed and subsequently built for field implementation. An independent field dust evaluation demonstrated that a reduction up to 68% of respirable dust particles has been achieved in the vicinity of the underground bin, and an average of 40% respirable dust reduction along the belt roadway. The successful application of the new dust mitigation system also demonstrates its potential use in underground longwall faces, roadway development and subsurface tunnel excavations by roadheader.     

Exposure matrices of endotoxin, (1 → 3)-β-d-glucan, fungi, and dust mite allergens in flood-affected homes of New Orleans

This study examined: (i) biocontaminant levels in flooded homes of New Orleans two years after the flooding; (ii) seasonal changes in biocontaminant levels, and (iii) correlations between biocontaminant levels obtained by different environmental monitoring methods. Endotoxin, (1 → 3)-β-d-glucan, fungal spores, and dust mite allergens were measured in 35 homes during summer and winter. A combination of dust sampling, aerosolization-based microbial source assessment, and long-term inhalable bioaerosol sampling aided in understanding exposure matrices. On average, endotoxin found in the aerosolized fraction accounted for < 2% of that measured in the floor dust, suggesting that vacuuming could overestimate inhalation exposures. In contrast, the (1 → 3)-β-d-glucan levels in the floor dust and aerosolized fractions were mostly comparable, and 25% of the homes showed aerosolizable levels even higher than the dust-borne levels. The seasonal patterns for endotoxin in dust and the aerosolizable fraction were different from those found for (1 → 3)-β-d-glucan, reflecting the temperature and humidity effects on bacterial and fungal contamination. While the concentration of airborne endotoxin followed the same seasonal trend as endotoxin aerosolized from surfaces, no significant seasonal difference was identified for the concentrations of airborne (1 → 3)-β-d-glucan and fungal spores. This was attributed to the difference in the particle size; smaller endotoxin-containing particles can remain airborne for longer time than larger fungal spores or (1 → 3)-β-d-glucan-containing particles. It is also possible that fungal aerosolization in home environments did not reach its full potential. Detectable dust mite allergens were found only in dust samples, and more commonly in occupied homes. Levels of endotoxin, (1 → 3)-β-d-glucan, and fungi in air had decreased during the two-year period following the flooding as compared to immediate measurements; however, the dust-borne endotoxin and (1 → 3)-β-d-glucan levels remained elevated. No conclusive correlations were found between the three environmental monitoring methods. The findings support the use of multiple methods when assessing exposure to microbial contaminants.     

Granulometry and the content of toxic and potentially toxic elements in vacuum-cleaner collected, indoor dusts of the city of Warsaw

Twenty-seven sites, together with 23 household dust sample sites, representing the home environment, and four public room dust sample sites, representing working environment (mainly offices) have been described in this paper. The latter were examined to obtain an approximate reference to the home environment data. All the samples were collected between May and July 1997 by a vacuum-cleaner method, in the city of Warsaw, Poland. The granulometry of the dusts was determined by their separation into seven fractions in the range 8-500 microm. The concentrations of Cr, Ni, Cu, Zn, Pb, Br and Fe in the samples were investigated in fractions 8-32, 32-63 and 63-125 microm by the EDXRF technique. The results showed higher concentrations of these elements in finer fractions (8-32 microm). The Pb content in the household dusts was found to be unexpectedly low, ranging from 120 microg g(-1) for the 63-125 microm fraction, up to 210 microg g(-1) for the 8-32 microm fraction. Car exhausts could not be determined clearly as the main source of Pb in the indoor household dusts due to the lack of a Pb-Br intercorrelation. In these dusts, only Cr and Zn showed a remarkably high content of 90-100 and 1020-1070 (microg g(-1)), respectively. In the household dusts, strong intercorrelations were present in the three analysed fractions for the metal pairs: Pb-Zn, Pb-Cu, Fe-Cr, and Cu-Cr (weaker). The working environment rooms showed a higher degree of dustiness by 300%, as compared to the dwellings. The dusts collected in the working environment rooms showed slightly higher concentrations of Ni and by 50-100% higher concentrations of: Cu, Zn, Pb, Br than the analysed household dusts.     

Airborne fungal cell fragments in homes in relation to total fungal biomass

Fungal exposure may induce respiratory symptoms. The causative agents are compounds in the fungal cell wall. Fragments of microbes may be present in air samples but are not measurable using conventional spore counting or by the determination of viable organisms. This study assesses the proportion of fungal cell biomass and endotoxin in different particle size fractions in air samples from homes. Air samples were collected from 15 homes using a cyclone sampler, collecting particles in three aerodynamic size fractions: <1.0, 1.0–1.8, and >1.8 μm. N‐Acetylhexosaminidase (NAHA) was determined as a marker of fungal cell biomass. Endotoxin was determined using the Limulus amebocyte lysate method. NAHA and endotoxin in the size range <1.0 μm comprised up to 63% (mean 22.7%) and 96.3% (mean 22.6%) of the total concentrations, respectively. There were significant relationships between the amounts of NAHA and endotoxin in the total amount and in the size fraction >1.8 μm but not in the smaller fractions. The results demonstrate significant amounts of fungal cell biomass and endotoxin in particles <1.0 μm. Homes with reported mold damage had a lower concentration of NAHA in particles <1.0 μm than homes without mold damage. To assess airborne exposure for diagnostic and preventive purposes, measurement techniques that include this fraction should be considered.     

Relationship between indoor and outdoor bio-aerosols collected with a button inhalable aerosol sampler in urban homes

This field study investigated the relationship between indoor and outdoor concentrations of airborne actinomycetes, fungal spores, and pollen. Air samples were collected for 24 h with a button inhalable aerosol sampler inside and outside of six single-family homes located in the Cincinnati area (overall, 15 pairs of samples were taken in each home). The measurements were conducted during three seasons - spring and fall 2004, and winter 2005. The concentration of culturable actinomycetes was mostly below the detection limit. The median indoor/outdoor ratio (I/O) for actinomycetes was the highest: 2.857. The indoor of fungal and pollen concentrations followed the outdoor concentrations while indoor levels were mostly lower than the outdoor ones. The I/O ratio of total fungal spores (median=0.345) in six homes was greater than that of pollen grains (median=0.025). The low I/O ratios obtained for pollen during the peak ambient pollination season (spring) suggest that only a small fraction penetrated from outdoor to indoor environment. This is attributed to the larger size of pollen grains. Higher indoor concentration levels and variability in the I/O ratio observed for airborne fungi may be associated with indoor sources and/or higher outdoor-to-indoor penetration of fungal spores compared to pollen grains. Practical Implication This study addresses the relationship between indoor and outdoor concentrations of three different types of bio-aerosols, namely actinomycetes, fungal spores, and pollen grains. The results show that actinomycetes are rare in indoor and outdoor air in Midwest, USA. Exposure to pollen occurs mainly in the outdoor air even during peak pollen season. Unexpectedly high fungal spore concentrations were measured outdoors during winter. The presented pilot database on the inhalable levels of indoor and outdoor bio-aerosols can help apportion and better characterize the inhalation exposure to these bio-aerosols. Furthermore, the data can be incorporated into existing models to quantify the penetration of biological particles into indoor environments from outdoors.     

Brominated flame retardants in the Arctic environment — trends and new candidates

Polybrominated diphenyl ethers (PBDEs) containing two to 10 bromines are ubiquitous in the Arctic, in both abiotic and biotic samples. Hexabromocyclododecane (HBCD) is also ubiquitous in the Arctic, with the γ-HBCD isomer predominating in air, the α-HBCD isomer predominating in biota and similar concentrations of α-, β- and γ-HBCD found in marine sediments. Other brominated flame retardants (BFRs) found in some Arctic samples are polybrominated biphenyls (PBBs), tetrabromobisphenol A (TBBPA), 1,2-bis(2,4,6-tribromophenoxy)ethane (BTBPE), hexabromobenzene (HxBBz), pentabromoethylbenzene (PBEB), pentabromotoluene (PBT), and 1,2-dibromo-4-(1,2-dibromoethyl)cyclohexane (TBECH). Temporal trends of tetra- to heptaBDEs and HBCD show increasing concentrations or a tendency to levelling off depending on the matrix (air, sediment, biota) and location, but no uniform picture for the Arctic emerges. BDE-209 concentrations are increasing in air. PBDEs and HBCD spatial trends in seabirds and marine mammals are similar to those seen previously for polychlorinated biphenyls (PCBs), with highest concentrations found in organisms from East Greenland and Svalbard. These trends indicate western Europe and eastern North America as important source regions of these compounds via long range atmospheric transport and ocean currents. Latitudinal trends showed lower concentrations and fluxes of PBDEs at higher latitudes. The tetra-hexaBDEs and α-HBCD biomagnify in Arctic food webs. Results for BDE-209 are more conflicting, showing either only low or no biomagnification potential. PBDE and HBCD concentrations are lower in terrestrial organisms and higher in marine top predators such as some killer whale populations in Alaska and glaucous gulls from the Barents Sea area. Higher concentrations are seen near populated areas indicating local sources. Findings of BTBPE, HxBBz, PBEB, PBT and TBECH in seabirds and/or marine mammals indicate that these compounds reach the Arctic, most probably by long range atmospheric transport and accumulate in higher trophic level organisms and that increasing use as PBDE replacements will lead to increasing concentrations.     

Linear alkylbenzene sulfonates in indoor floor dust

A method was developed to analyse linear alkylbenzene sulfonates (C10-C13 LAS) in vacuumed floor dust in office buildings by the use of HPLC chromatography. Floor dust was sampled with a specially designed vacuum cleaner and fractionated into fibres and particles. The content of LAS in the particle fraction of floor dust sampled from seven different public buildings varied between 34 microg LAS g(-1) dust and 1,500 microg LAS g(-1) dust, while the content of the fibre fractions was generally higher with up to 3,500 microg LAS g(-1) dust. The use of a cleaning agent with LAS resulted in increases approximately 30% of the amount of LAS in the floor dust after floor wash relative to just before floor wash. However, the most important source of LAS in the indoor floor dust appeared to be residues of detergent in clothing. Thus, a newly washed shirt contained 2,960 microg LAS g(-1) clothing. The analysis of the office dust samples indicated that LAS (and probably other detergents) might be of importance for the indoor environment.     

Quantitative measurement of airborne cockroach allergen in New York City apartments

We designed and tested a sampling and analysis system for quantitative measurement of airborne cockroach allergen with sufficient sensitivity for residential exposure assessment. Integrated 1-week airborne particle samples were collected at 10-15 LPM in 19 New York City apartments in which an asthmatic child who was allergic to cockroach allergen resided. Four simultaneous air samples were collected in each home: at heights of 0.3 and 1 m in the child's bedroom and in the kitchen. Extracts of air samples were analyzed by ELISA for the cockroach allergen Bla g2, modified by amplifying the colorimetric signal generated via use of AMPLI-Q detection system (DAKO Corporation, Carpinteria, CA, USA). Settled dust samples were quantified by conventional ELISA. Of the homes where cockroach allergen was detected in settled dust, Bla g2 also was detected in 87% and 93% of air samples in the bedroom and kitchen, respectively. Airborne Bla g2 levels were highly correlated within and between the bedroom and kitchen locations (P < 0.001). Expressed as picogram per cubic meter, the room average geometric mean for Bla g2 concentrations was 1.9 pg/m3 (95% CI 0.63, 4.57) and 3.8 pg/m3 (95% CI 1.35, 9.25) in bedrooms and kitchens, respectively. This method offers an attractive supplement to settled dust sampling for cockroach allergen exposure health studies. PRACTICAL IMPLICATIONS: Until now, cockroach allergen exposures have usually been assessed by collection and analysis of settled dust, on the assumption that airborne cockroach allergen cannot be reliably measured. In this study, a sensitive and quantitative method for measuring indoor airborne exposures to cockroach allergens involving a 7-day integrated total suspended particulate (TSP) sample collected at approximately 10-15 l/min was developed. Investigators are now empowered with an alternative exposure assessment method to supplement their studies and the understanding of allergen aerodynamics in the homes of children with asthma. We report airborne cockroach allergen in apartments, suggesting an ongoing burden of inhalation exposure.     

Influence of compressive strength and applied force in concrete on particles exposure concentrations during cutting processes

The objective of this research was to identify the influence of applied force (AF) and the compressive strength (CS) of concrete on particle exposure concentrations during concrete cutting processes. Five cutting conditions were selected with AF varied between 9.8 and 49 N and CS varied between 2500 and 6000 psi. For each selected cutting condition, the measured total dust concentrations (C_tot) were used to further determine the corresponding three health-related exposure concentrations of the inhalable (C_inh), thoracic (C_thor), and respirable fraction (C_res). Results show that particle size distribution was consistently in a bimodal form under all selected cutting conditions. An increase in CS resulted in an increase in coarse particle generations leading to an increase in the four measured particle exposure levels. An increase in AF resulted in an increase in exposure concentrations with a higher fraction of fine particles (i.e., C_tho and C_res) However, for particle exposure concentrations with a higher fraction of coarse particles (i.e., C_tot and C_inh), an increase in AF resulted in an initial increase, followed by a decrease in concentration. Finally, the above inferences were further confirmed through the use of fixed-effect models to determine the influence of both CS and AF on the four exposure concentrations. These results provide a reference for industries to initiate appropriate control strategies to reduce the exposure levels encountered by workers.     

Polycyclic aromatic hydrocarbons associated with particles in ambient air from urban and industrial areas

This study takes into consideration an analysis of the chemical polycyclic aromatic hydrocarbon (PAH) profile and its distribution in inhalable and respirable particulate matter in urban and industrial areas in La Plata, Argentina, and Leipzig, Germany. Representative samples from three locations in La Plata (industrial, traffic influenced and control area) and two locations in Leipzig (traffic influenced and control area) were obtained in summer and winter. The sampling of particulate matter was carried out with high volume collectors using cascade impactors to separate six size fractions. PAHs were extracted with hexane through a solid-liquid equilibrium extraction and analysed by HPLC/UV/fluorescence detection. The results showed a PAH seasonal behaviour in both regions, with lower contents in summer and higher ones in winter. Highest concentrations of total PAHs were found in the industrial area in La Plata. The size distribution of particles demonstrates the greater relevance of smaller particles. More than 50% of PAHs were associated with particles of less than 0.49 microm. Moreover, this particle size fraction was associated with traffic, whereas other sources of combustion were related also to particles between 0.49 and 0.95 microm. Considering the ratio of benzo(ghi)perylene (BgP)/benzo(a)pyrene (BaP) as an indicator for traffic influence, it was observed that La Plata City was more affected than Leipzig by the same proportion in summer and in winter. The BgP/InP (indeno(123-cd)pyrene) ratio was lower in winter than in summer in both places and indicates the presence of domestic combustion sources. It is important to point out the significance of using fingerprint compound ratios to identify possible sources of pollution with PAHs bound to particles.     

Presumptive identification of asbestos in urban air

Chrysotile asbestos can be selectively stained with fluorochrome Coriphosphine O. The fluorescent staining technique positively distinguishes chrysotile from amosite, crocidolite and from man-made mineral fibers, like glass wool. As ubiquitous urban particulates do not interfere, the staining method allows the presumptive identification of asbestos fibers by light (fluorescent) microscopy in presence of a large excess of non-asbestos particles or fibers.Sometimes a slight interference from antigorite, a parent mineral of asbestos occurs. Investigations are in progress to establish if the few fluorescent points observed for this mineral may in fact correspond to asbestos fibers, in which case a link between fluorochrome uptake and physiological behaviour might be further sought.The current practice of sampling asbestos in occupational air, where asbestos represents a significant fraction of the particulates, is by collecting dust on organic membranes, mostly Nucleopore. The dust deposit is counted using phase contrast microscopy. Under these conditions, when asbestos is relatively abundant and overall samples of a few hundred micrograms can be collected, gravimetric evaluation using X-ray diffraction techniques is also possible.     

Organophosphate and phthalate esters in settled dust from apartment buildings in Stockholm

In this study, the occurrence of nine phthalate diesters (phthalates) and 14 organophosphorus flame retardants (PFRs) was investigated in 62 house dust samples collected from 19 buildings in Stockholm area during the year 2008. Eight phthalates were detected in almost all samples, with median concentrations ranging from 0.47 μg/g to 449 μg/g with di(2‐ethylhexyl) phthalate being the most abundant compound. Twelve PFRs were detected with median concentrations ranging from 0.19 μg/g to 11 μg/g. Within this class of compounds, the most abundant were tris(2‐chloroisopropyl) and tris(2‐butoxyethyl) phosphate. Both classes of compounds were also measured in the air of the apartments, but no correlation between air and dust concentrations could be found. Based on these measurements, exposure, via house dust ingestion and air inhalation, was calculated for adults and toddlers, and compared to published limit values in order to estimate potential health risks. In an extreme exposure scenario for toddlers, di(2‐ethylhexyl) phthalate, tris(2‐chloroethyl) phosphate, tris(2‐butoxyethyl) phosphate, and tributyl phosphate were close to the reference dose for chronic oral exposure or the tolerable daily intake. Standard Reference Material SRM 2585 was used as a quality control sample, and the levels of diisononyl and diisodecyl phthalates were determined in this material.     

Evaluation of a procedure to isolate culturable microorganisms from carpet dust

Details of a method to isolate culturable bacteria and fungi from carpet dust were evaluated to isolate the greatest numbers of these agents. Four broad groups were evaluated: mesophilic and thermophilic bacteria and moderately hydrophilic and xerophilic fungi. Features studied included: 1) mixing time; 2) addition of glass beads; 3) length of time dust settled before suspensions were plated; 4) relative concentrations of microorganisms in the fibrous and fine dust fractions; and 5) storage temperature and period. The findings are preliminary because of the small number of samples, but a votexing time of at least 2 min with glass beads gave the best results in terms of the highest estimate of the concentration of culturable bacteria or fungi. Microorganisms were retrievable-from the upper portion of a suspending liquid for at least 30 min with little detectable change in concentration. Both bacteria and fungi were more abundant in the fine than the fibrous dust fraction. No significant losses were observed for samples stored up to 25 days at 5 degrees C or 25 degrees C. This procedure optimized measurement of total concentration, but may not identify the range of genera and species in dust if microorganisms present in small numbers and as single units are underrepresented relative to those in clusters and aggregates.