Concentrations In Dust Samples Research Articles

Presence, source attribution, and human exposure to organophosphate esters in indoor dust from various microenvironments in Nigeria

Very few studies have reported the presence of the organophosphate esters (OPEs) in African indoor microenvironments. We therefore document here, the concentrations, profiles, and human exposure to eight organophosphate esters (OPEs) for the first time in indoor dust from various microenvironments in Nigeria, specifically: cars/buses (n = 10), homes (n = 20), offices (n = 20), and medical centres (n = 14). The concentrations of OPEs in these indoor dust samples were among the lowest reported internationally. Concentrations of ∑8OPEs varied substantially between individual samples and the predominant OPEs were: tris(2-butoxyethyl) phosphate (TBOEP) (detection frequency (DF) = 90–100%), tris(1-chloro-2-propyl) phosphate (TCIPP) (DF = 100%), and 2-ethylhexyl-diphenyl phosphate (EHDPP) (DF = 100%). There were no significant differences (P˃0.05) between ∑8OPEs concentrations in dust samples from cars/buses (average = 295 ng/g), offices (231 ng/g), homes (277 ng/g), and medical centres (127 ng/g). Concentrations of chlorinated OPEs: tris(2-chloroethyl) phosphate (TCEP), TCIPP, and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) were significantly correlated with those of triphenyl phosphate (TPhP), EHDPP, and TBOEP. Estimated daily intakes (EDI) of target OPEs via indoor dust ingestion and dermal absorption were lower than the corresponding reference dose (RfD) values, indicating that exposure to the studied OPEs in the indoor environment does not pose a significant health risk for the general population in Nigeria, even under a high-end exposure scenario.

Characterization of Chemical and Bacterial Concentrations in Floor Dust Samples in Southeast Texas Households.

Indoor dust can be a major source of heavy metals, nutrients, and bacterial contamination in residential environments and may cause serious health problems. The goal of this research is to characterize chemical and bacterial contaminants of indoor, settled house dust in the Houston Metropolitan region. To achieve this, a total of 31 indoor dust samples were collected, along with household survey data, which were subsequently analyzed for elemental and bacterial concentrations. Microscopic and geospatial analysis was conducted to characterize and map potential hotspots of contamination. Interestingly Cd, Cr, Cu, Pb, and Zn concentrations of all 31 indoor dust samples were significantly enriched and exceeded soil background concentrations. Furthermore, As, Cd, Pb, and Zn concentrations in the dust samples were significantly correlated to the enteric bacterial load concentrations. Human health assessment revealed that cancer risk values via ingestion for Cd, Cr, and Ni were greater than the acceptable range. Of our 31 dust sample isolates, three Gram-negative and 16 Gram-positive pathogenic bacteria were identified, capable of causing a wide range of diseases. Our results demonstrate that both chemical and bacterial characterization of indoor dust coupled with spatial mapping is essential to assess and monitor human and ecological health risks.

Organophosphate esters in indoor and outdoor dust from Iraq: Implications for human exposure

Concentrations of 6 organophosphate esters (OPEs) were determined in 60 indoor (ID) and outdoor (OD) dust samples collected from 20 homes from Basrah, Iraq. From each home, two ID samples were collected, one from elevated surfaces (ESD) and one from the floor (FD) of the living room; while the OD samples were collected from the front yard of the same house. Total Σ6OPEs concentrations in dust samples ranged between 681 and 17900 ng/g with median concentrations of 5950, 3590 and 1550 ng/g in ESD, FD and OD samples, respectively. Chlorinated OPEs were the most abundant compounds, contributing mean percentages of 88%, 85% and 78% to Σ6OPEs in ESD, FD and OD, respectively, with tris (1-chloro-2-propyl) phosphate (TCIPP) dominant. Concentrations of our target OPEs in ESD significantly exceeded those in FD (p < 0.05) for tris (2-chloroethyl) phosphate (TCEP) and tris (1,3-dichloro-2-propyl) phosphate (TDCIPP). Ratios of median concentrations of OPEs in ID:OD ranged from 1.5 for tri-n-butyl phosphate (TNBP) to 8.0 for TCEP, indicating the significance of indoor sources. Concentrations of chlorinated OPEs in ID were moderately correlated (R = 0.522–0.591, P < 0.05) with those in OD samples, suggesting interchange of OPEs between the two environments. Concentrations of OPEs in OD from houses with a contiguous front yard car porch exceeded those in OD from houses without a car porch and were significantly higher (P < 0.05) for TCEP, TCIPP and 2-ethylhexyl diphenyl phosphate (EHDPP). Emissions from parked cars and the associated home are likely sources of OPEs in the OD area. Based on the concentrations reported here, the estimated daily intake (EDI) for the Iraqi population through house dust ingestion are all well below the relevant reference dose (RfD) values.

Occurrence of extended-spectrum beta-lactamase-producing Enterobacteriaceae, microbial loads, and endotoxin levels in dust from laying hen houses in Egypt

BackgroundPoultry houses are often highly contaminated with dust, which might contain considerable amounts of microorganisms and endotoxins. The concentrations of microorganisms and endotoxins in dust from laying hen houses in Egypt are unknown. However, to estimate the risks for birds, the environment, and people working in laying hen houses, it is important to gather information about the composition of these dusts. Here we report the microbial loads, the occurrence of antimicrobial-resistant bacteria, and endotoxin concentrations in dust samples from 28 laying hen farms in Dakahliya Governorate, Egypt, and discuss the results relevant to the literature.ResultsPooled settled dust samples (n = 28) were analyzed for total viable counts of bacteria and fungi (CFU/g), the occurrence of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae, Salmonella spp., and methicillin-resistant Staphylococcus aureus (MRSA), and endotoxin concentrations (ng/g). The means and standard deviations of total viable counts were 7.10 × 108 ± 2.55 × 109 CFU/g for bacteria and 5.37 × 106 ± 7.26 × 106 CFU/g for fungi. Endotoxin levels varied from 2.9 × 104 to 6.27 × 105 ng/g. None of the tested samples contained Salmonella spp. or MRSA. In contrast, by direct plating, Enterobacteriaceae were found frequently (57%; n = 16), and suspected ESBL-producing Enterobacteriaceae occurred in 21% (n = 6) of the sampled barns. Using an enrichment method, the detection of Enterobacteriaceae and suspected ESBL-producing Enterobacteriaceae increased to 20 and 16 positive barns, respectively. Taking results from both methods into account, Enterobacteriaceae and suspected ESBL-producing Enterobacteriaceae were detected in 23 barns Overall, 100 ESBL suspected isolates (Escherichia coli, n = 64; Enterobacter cloacae, n = 20; and Klebsiella pneumoniae n = 16) were identified to species level by MALDI-TOF MS. Isolates from 20 barns (71% positive barns) were confirmed as ESBL producing Enterobacteriaceae by the broth microdilution test.ConclusionsDust in Egyptian laying hen houses contains high concentrations of microorganisms and endotoxins, which might impair the health of birds and farmers when inhaled. Furthermore, laying hens in Egypt seem to be a reservoir for ESBL-producing Enterobacteriaceae. Thus, farmers are at risk of exposure to ESBL-producing bacteria, and colonized hens might transmit these bacteria into the food chain.

Assessment of source and health risk of metal(loid)s in indoor/outdoor dust of university dormitory in Lanzhou City, China.

The pollution of metal(loid)s from indoor and outdoor dust is of great concern because of its impact on human health. The concentrations of nine metal(loid)s (Mn, Cu, Zn, Cd, Cr, Ni, Pb, Hg, and As) were investigated in indoor and outdoor dust samples of university dormitories in winter and summer seasons in Lanzhou City, China. This study revealed the variations of metal(loid) concentrations in dust samples with the seasonal scale and floor heights. The results showed that the concentrations of some metal(loid)s (Cu, Cd, Ni, Pb, and As) in dust samples collected in winter were higher than those of the dust samples collected in summer. The Hg in indoor dust was mainly derived from building materials and indoor human activities. Additionally, the concentrations of some metal(loid)s (Hg, Mn, As, Cu, Cd) in dust samples varied with the height of the floors from ground level. The concentrations of Hg in dust samples collected on upper floors (9-16th floors) were higher than those collected on down floors (1-8th floors), while Mn and As were the opposite of that. Cu and Cd concentrations increased as the floor height increased. Our results demonstrated that the adults and the children (particularly the children) endured potential health risks due to exposure to metal(loid)s from both indoor and outdoor dust in the studied area.

Origin and distribution of trace elements in the campus dust of Xi’an, China

The concentrations of As, Ba, Co, Cr, Cu, Mn, Ni, Pb, V, and Zn in dust samples from kindergartens, primary schools, secondary schools, and universities in Xi'an City have been determined by X-ray fluorescence spectrometry. The element concentrations in dust samples collected from the campuses were higher than background levels, in particular for Pb, Zn, Cr, Cu, Co, and Ba. Summary statistics and enrichment factors allowed for the differentiation between contributions from local soil and from anthropogenic sources. The results of a multivariate spatial correlation-principal component analysis demonstrated that metal concentrations could be related to natural and anthropogenic sources separately and in combination. Source apportionment based on multiple linear regression indicated that 67% of the trace elements could be ascribed to natural and traffic sources, 13% to industrial sources, 19% to construction activities, and an additional 1% to traffic and industrial sources.

Polybrominated diphenyl ethers and novel brominated flame retardants in indoor dust of different microenvironments in Beijing, China

The occurrence levels of eight polybrominated diphenyl ethers (PBDEs) and four novel brominated flame retardants (NBFRs) were determined and compared in indoor dust from different microenvironments (21 homes, 23 offices and 16 day care centers) in Beijing, China. Concentrations of ∑8PBDEs in dust were 430–17,000 ng/g, 690–8600 ng/g, and 90–2300 ng/g for homes, offices, and day care centers, respectively, and were dominated by BDE-209. Concentrations of ∑4NBFRs ranged from 310 to 17,000 ng/g, 300 to 4300 ng/g, and not detected to 500 ng/g for homes, offices, and day care centers, respectively, and were dominated by bis(2-ethylhexyl)-3,4,5,6-tetrabromophthalate (BEH-TEBP) and decabromodiphenylethane (DBDPE) across microenvironments. The results showed an increasing detection and elevated concentration of NBFRs (especially BEH-TEBP), indicating that monitoring of NBFRs in dust samples should be of concern in future studies. A notable finding was that the BFR concentrations in dust samples from day care centers were generally one order of magnitude lower than those from homes and offices in the present study. This implies that previous estimates of toddler exposure via dust ingestion on data from homes may be overestimated. Concentrations of BDE-209 and ∑8PBDEs were found to be significantly higher in elevated surface dust than floor dust from day care centers. The estimates of daily intakes of BFRs via dust ingestion for Chinese adults and toddlers using Monte Carlo analysis were 2–5 orders of magnitude lower than the corresponding reference daily intakes.

Environmental Pollution and Related Hazards at Agbara Industrial Area, Ogun State

This study aimed at assessing the environmental pollution and related hazards of industries at Agbara, Ogun State, Nigeria. A total of five sampling points were identified and selected at random. Environmental samples were collected on a weekly basis for duration of 10 weeks. Air pollutants measured were CO2, CO, NO, NOx, VOCs, H2S, SO2, NH3, PM2.5 andPM10 using standard procedure. Dust and plant samples were also collected and analyzed for heavy metals (Pb, Cr, Cd, Cu and Zn) using the Atomic Absorption Spectrophotometer (AAS). Data was evaluated for descriptive and inferential statistics using SPSS for Windows version 22.0. Air pollution data were also subjected to SPE-risk model. The results of highest measured air parameters were: CO (5.50 ± 2.32 ppm), CO2 (3.00 ± 2.05%), NOx (0.90 ± 0.32 ppm), NO (0.60 ± 0.52 ppm), PM10 (0.40 ± 0.52 mg/m3) and PM2.5 (0.20 ± 0.42 mg/m3). The results of heavy metal concentrations in dust samples were: 57.40 ± 13.28 mg/kg for Cu, 45.36 ± 12.37 mg/kg for Cr, 22.80 ± 17.36 mg/kg for Zn, 13.76 ± 3.08 mg/kg for Pb and 0.32 ± 0.36 mg/kg for Cd. Metal concentrations in plants were: Cu (70.07 ± 16.24 mg/kg), Zn (67.69 ± 14.50 mg/kg), Cr (22.46 ± 9.35 mg/kg), Pb (13.76 ± 3.08 mg/kg) and Cd (2.25 ± 3.04 mg/kg). This study revealed the concentrations of CO2, NOx and NO higher than the World Health Organization (WHO) permissible standards while Pb, Cu, Cr, Cd and Zn values in dust samples were also found above the National Environmental Standards and Regulations Enforcement Agency (NESREA) and the WHO standards. Results of SPE-RISK model indicated that CO2, CO, Pb, Cu and Zn posed the greatest health risks, while the Principal Component Analysis (PCA) indentified pollutant sources from industrial and vehicle exhaust.

Investigating the Role of Wind in the Dispersion of Heavy Metals Around Mines in Arid Regions (a Case Study from Kushk Pb-Zn Mine, Bafgh, Iran).

The Kushk Pb-Zn mine is located in Central Iran and it has been in operation for the last 75years. To investigate the role of wind dispersion of heavy metal pollutants from the mine area, dust samples were collected during 1year and topsoil samples were collected around the mine. Results showed that the topsoil is polluted with Pb and Zn to about 1500m away from the mine. It was also found that there was not a significant difference between the metal concentrations in topsoil and dust samples. The Pb and Zn concentrations in the dust samples exceeded 200mgkg-1 and their lateral dispersion via wind was estimated to be about 4km away from the mine. It has been shown that a combination of mining activities and mechanical dispersion via water and wind have caused lateral movement of heavy metals in this area.

Polybrominated diphenyl ethers (PBDEs) in car and house dust from Thailand: Implication for human exposure

ABSTRACTThis study examines concentrations of tri- to hexa-bromodiphenylethers (BDEs 17, 28, 47, 49, 66, 85, 99, 100, 153 and 154; Σ10PBDEs (polybrominated diphenyl ethers)) in car (n = 30) and house dust samples (n = 53) collected from different provinces in Thailand. The specific objectives of this study were: (i) to monitor levels of tri- to hexa-bromodiphenylethers (BDEs 17, 28, 47, 49, 66, 85, 99, 100, 153 and 154; Σ10PBDEs) in vehicle and residential dust sampled from various provinces in Thailand; (ii) to compare PBDE concentrations with those detected for domestic and automobile dust in studies from other countries and (iii) to estimate exposure of the Thai population to the target PBDEs via dust ingestion. Levels of Σ10PBDEs in vehicle and domestic dust were 0.68–38 and 0.59–260 ng g−1, respectively. BDEs 99 and 47 were the most abundant congeners in all automobile and residential dust samples. A t-test analysis indicated that Σ10PBDE concentrations in dust samples from dwellings exceeded significantly those from cars (p = 0.001). Furthermore, contents in dust of all PBDEs studied, except for BDE-28, were significantly higher in homes than in vehicles (p = 0.000–0.004). Principal Component Analysis (PCA) demonstrated no differences in PBDE congener patterns between Thai house and automobile dust, but revealed some subtle differences in the congener pattern between household dust samples in Thailand and those reported previously for the United Kingdom. Estimated environmental exposure of Thai adults and children for BDE-99 via dust ingestion were well within a chronic oral reference dose (RfD) for BDE-99 (100 ng/kg bw/day) proposed by the United States Environmental Protection Agency (US EPA).

Occurrence and distribution of organophosphate flame retardants (OPFRs) in soil and outdoor settled dust from a multi-waste recycling area in China

Distribution of 12 organophosphate flame retardants (OPFRs) was determined in soil and outdoor settled dust samples collected from a multi-waste (electronic, plastic, and rubber wastes and abandoned household-appliances and vehicles) recycling area, that encompassed different modes of operation i.e. open (ORS) and semi-closed recycling (SCRS). Among the twelve OPFRs analyzed, eleven were detected at a frequency of 75%–100% in all soil and dust samples. In soil samples, ΣOPFR concentrations were significantly higher at ORS (122–2100ng/g) than at SCRS (58.5–316ng/g) and nearby farmlands (37.7–156ng/g). The ΣOPFR concentrations in dust samples were higher than those in soil samples with spatial distribution similar to that observed for soil, decreasing from ORS (1390–42,700ng/g) to SCRS (914–7940ng/g). Tris(2-chloroisopropyl) phosphate (TCIPP) was the major OPFRs in both soil (<MDL–1370ng/g) and dust (39.9–16,300ng/g) samples. Chlorinated OPFRs [TCIPP, tris(1,3-dichloroisopropyl) phosphate (TDCIPP) and tris(2-chloroethyl) phosphate (TCEP)] and aryl-OPFRs [triphenyl phosphate (TPHP), tris(methylphenyl) phosphate (TMPP)] exhibited spatial difference between ORS and SCRS. Principle component analysis (PCA) of OPFR concentrations revealed that TCIPP, TDCIPP, TPHP, TMPP originated from similar sources. TMPP was assessed to pose eco-toxicological risk (risk quotient values: RQs) in the soil ecosystem. The median estimated daily intake (EDI) of OPFRs via soil and outdoor settled dust ingestion (based on average ingestion rate) was 3.14×10−1ng/kgbw/day for adults at ORS. Our results suggest that waste recycling is an important source of chlorinated- and aryl-OPFRs in the environment.

Biomonitoring of atmospheric heavy metals pollution using dust deposited on date palm leaves in southwestern Iran

Heavy metals in dust are causing health problems in humans and other organisms. The main objectives of this study were to determine (1) the concentrations and the sources of heavy metals including Zn, Cu, Pb, Fe, Ni, Cr, Co and Mn, and (2) the contamination levels of metals in the dust of Bushehr (an urban area) and Assaluyeh (an industrial area) located in the province of Bushehr, southwestern Iran. Also, the transect between the two cities was investigated as a non-urban area. Fifty dust samples deposited on date palm leaves and 50 surface soil samples were collected. The mean concentrations of heavy metals in dust from the three areas were found to be higher than those of the nearby soils except for Co in Assaluyeh and Pb in Bushehr. Zn, Cu and Pb concentrations in dust samples from industrial and urban areas were higher than those in samples taken from the non-urban area. The results indicated minimal pollution levels of Mn, Fe and Cr, minimal to moderate levels of Co, moderate levels of Ni, moderate to significant levels of Cu, significant levels of Zn, and significant to very high levels of Pb in dust. The two main sources of different heavy metals in atmospheric dust deposited on date palm leaves were identified based on principal component analysis, cluster analysis and correlation analysis. Zn, Cu, and Pb seem to have anthropogenic sources, whereas Fe, Ni, Cr, Co, and Mn in atmospheric dust presumably derive from non-anthropogenic sources. In general, the implementation of environmental standards and improvement of the public transportation system are required to reduce the hazardous pollutants released into the atmosphere.

Factors Controlling the Deposition of Airborne Metals on Plant Leaves in a Subtropical Industrial Environment

This study was conducted in an industrial city (Bilaspur) representative of subtropical area in central India. In order to assess the metal deposition on plant, concentrations of six target metals (i.e., Fe, Mn, Pb, Cu, Cd, and Cr) in both plant leaf and dust (deposited on its surface) samples were measured from six different sites. Metal concentrations in dust samples were found on the order of Fe＞Mn＞Cr＞Pb＞Cu＞Cd. In contrast, the concentration of metals in plant leaves were seen on the order of Fe＞Mn＞Cr＞Cd＞Cu＞Pb. As such, Cd showed significantly high concentration in leaves relative to their corresponding dust samples. A high accumulation potential for Fe and Cd was seen from Butea monosperma, while Mn and Pb were accumulated noticeably in Pongamia pinnata and Butea monosperma. Likewise, Cr and Cu were enriched in Calotropis procera, Alstonia scholaris, and Butea monosperma. The overall results of our study suggest that the foliar uptake pattern should vary considerably by an interactive role between plant and metal types.

Poly- and perfluoroalkyl substances (PFASs) in indoor dust and food packaging materials in Egypt: Trends in developed and developing countries.

PFASs concentrations in dust samples collected from three microenvironments in Cairo ranged from 1.3 to 69 ng g(-1) with FTOHs being dominant. The 8:2 FTOH was detected in all samples. Among the FOSAs and FOSEs the MeFOSE was dominant while among ionic PFASs, PFOS and PFOA were most prominent. The concentrations of PFASs were among the lowest worldwide. Correlations between worldwide concentrations of PFOS + PFOA and country development indexes highlight higher usage and human exposure in more developed countries. Food packaging was analyzed for PFSAs, PFCAs and PAPs. The 6:2 and 8:2 monoPAPs were found to be above the MDL in 18% of the samples. PFOA was detected in 79% of the samples with median concentration of 2.40 ng g(-1). PFOS was detected in 58% of the samples with median concentration of 0.29 ng g(-1) while PFHxS and PFDS were below detection limit. Different human exposure scenarios were estimated.

Consideration of Analysis Method of Asbestos and Existing Condition for Fibrous Materials in Domestic Air

Dust samples collected from air in metropolitan areas of Busan and Ulsan were analyzed by phase contrast microscopy, phase contrast dispersion microscopy and SEM. Asbestos concentration in dust samples was lower than detection limit. Many fibrous materials were observed in dust samples, but most of them were organic fibers. Inorganic fibers such as rock fiber, ceramic fiber and gypsum were contained in the samples and non-fibrous minerals such as quartz, calcite and feldspar were also occasionally observed. Domestic law requires that asbestos in air dust is mainly analyzed by phase contrast microscopy. From this study, however, precise analysis of asbestos was almost impossible by this method only. As indicated in JIS method of Japan, therefore, count and identification of asbestos were more efficient by dispersion staining method after removing organic materials in samples by low temperature incinerator.

A survey of cyclic and linear siloxanes in indoor dust and their implications for human exposures in twelve countries

Siloxanes are used widely in a variety of consumer products, including cosmetics, personal care products, medical and electrical devices, cookware, and building materials. Nevertheless, little is known on the occurrence of siloxanes in indoor dust. In this survey, five cyclic (D3–D7) and 11 linear (L4–L14) siloxanes were determined in 310 indoor dust samples collected from 12 countries. Dust samples collected from Greece contained the highest concentrations of total cyclic siloxanes (TCSi), ranging from 118 to 25,100ng/g (median: 1380), and total linear siloxanes (TLSi), ranging from 129 to 4990ng/g (median: 772). The median total siloxane (TSi) concentrations in dust samples from 12 countries were in the following decreasing order: Greece (2970ng/g), Kuwait (2400), South Korea (1810), Japan (1500), the USA (1220), China (1070), Romania (538), Colombia (230), Vietnam (206), Saudi Arabia (132), India (116), and Pakistan (68.3). TLSi concentrations as high as 42,800ng/g (Kuwait) and TCSi concentrations as high as 25,000ng/g (Greece) were found in indoor dust samples. Among the 16 siloxanes determined, decamethylcyclopentasiloxane (D5) was found at the highest concentration in dust samples from all countries, except for Japan and South Korea, with a predominance of L11; Kuwait, with L10; and Pakistan and Romania, with L12. The composition profiles of 16 siloxanes in dust samples varied by country. TCSi accounted for a major proportion of TSi concentrations in dust collected from Colombia (90%), India (80%) and Saudi Arabia (70%), whereas TLSi predominated in samples collected from Japan (89%), Kuwait (85%), and South Korea (78%). Based on the measured median TSi concentrations in indoor dust, we estimated human exposure doses through indoor dust ingestion for various age groups. The exposure doses ranged from 0.27 to 11.9ng/kg-bw/d for toddlers and 0.06 to 2.48ng/kg-bw/d for adults.

Indoor determinants of dustborne allergens in Mexican homes.

Exposure to indoor allergens represents a significant risk factor for allergies and asthma in several parts of the world. In Mexico, few studies have evaluated indoor allergens, including cat, dog, and mouse allergens and the factors that predict their presence. This study evaluates the main environmental and household predictors of high prenatal allergen levels and multiple allergen exposures in a birth cohort from Mexico City. A cross-sectional study was conducted as part of a birth cohort study of 1094 infants recruited during pregnancy and followed until delivery. We collected dust samples in a subset of 264 homes and assessed environmental factors. Der p 1, Der f 1, dust mite group 2, Fel d 1, Can f 1, Rat n 1, Mus m 1, and Bla g 2 concentrations in dust samples were measured using immunoassays. To define detectable allergen levels, the lowest limits of detection for each allergen were taken as cutoff points. Overall allergen exposure was considered high when four or more allergens exceeded detectable levels in the same household. Logistic regression was used for predictive models. Eighty-five percent of homes had at least one allergen in dust over the detection limit, 52.1% had high exposure (four or more allergens above detectable limits), and 11.7% of homes had detectable levels for more than eight allergens. Der p 1, Der p 2, Mus m 1, and Fel d 1 were the most frequent allergens detected. Each allergen had both common and distinct predictors. The main predictors of a high multiple allergen index were the size of the home, pesticide use, mother's age, mother as homemaker, and season. Increased indoor environmental allergen exposure is mainly related to sociodemographic factors and household cleaning.

Distribution and health risk assessment of mercury in urban street dust from coal energy dominant Huainan City, China.

High levels of mercury contamination in urban street dust pose a great threat to human health. In this study, representative urban street dust samples in different urban zones were collected from industrial Huainan City, Eastern China. The distribution and human health risk of Hg in urban street dusts were investigated. In comparison with the soil background Hg values of Huainan and China, the average Hg concentration (0.16 ± 0.14 mg kg(-1), n = 50) was significantly elevated, with a variation ranging from 0.02 to 0.56 mg kg(-1). Among the seven different urban zones, the industrial district had the highest levels of Hg, potentially deriving predominantly from the dust emissions of the nearby Pingwei coal-fired power plant. In addition, Hg concentrations in dust samples appear to increase with the decrease of particle size. The result of health risk assessment on Hg in these urban street dusts indicated that there was no significant risk of carcinogenesis for the adults living in Huainan city.

Fungal Concentrations in Dust Samples of Animal Rearing Houses of Bangalore, India

Fungal concentrations in dust samples analyzed by molecular methods were carried out of animal rearing house at Hessaraghatta village, Bangalore. Handy air sampler EnviroTech-APM 821 was used to collect the dust samples in triplicate and sampling time was limited to eight hours. The sampled filter papers were used for the assay of DNA extracted from all the four animal rearing locations were used for PCR amplification using Universal ITS fungal identification primers PCR products were analyzed on 2% agarose gel out of four different locations were rabbit house, cow shed, poultry farm and swine house. The sequencing was then blasted against known sequences in the NCBI database to provide species identification and phylogenetic tree was also constructed with 20 closely related blast sequences. The rabbit house and cow shed dust samples did not show any amplifications even with varying conditions while poultry farm (Cladosporium oxysporium DFFSCS018) and swine house (Peniophora species1306-hpF-04) isolate samples gave amplicons of 550bp and 600bp respectively with ITS region showing 99% similarity. These studies useful for clinicians to identify the cause of the dust allergic diseases of the animal rearing house workers and suggest amendment strategies.

Phthalate Levels in Nursery Schools and Related Factors

Phthalate esters, which are known endocrine disruptors, are ubiquitously present throughout indoor environments. Leaching from building materials may be a major source of phthalate esters. In this study, we evaluated phthalate ester concentrations in dust samples from 64 classrooms located in 50 nursery schools and explored the critical factors affecting phthalate concentrations, especially with regard to building materials. Dust was sampled by a modified vacuuming method, and building materials were assessed using a portable X-ray fluorescence (XRF) analyzer to determine whether they contained polyvinyl chloride. Di-n-butyl phthalate (DBP), di(2-ethylhexyl) phthalate (DEHP), and di-isononyl phthalate (DINP) were the most frequently detected phthalates. Of these, DEHP was the most abundant phthalate, with a geometric mean of 3170 μg/g dust, and concentrations were significantly correlated with the area of polyvinyl chloride (PVC)-verified flooring. DINP, which has not been well-reported in other studies, was the second-most abundant phthalate, with a geometric mean of 688 μg/g dust, and showed a critical relationship with the number of children in the institution and the agency operating the nursery school. This is the first study to verify the sources of phthalates with an XRF analyzer and to evaluate the relationship between phthalate concentrations and PVC-verified materials.