Indoor air exposure to coal and wood combustion emissions associated with a high lung cancer rate in Xuan Wei, China

Residents of Xuan Wei County in China have unusually high lung cancer mortality that cannot be attributed to tobacco use or occupational exposure. They are exposed to smoke from unvented, open pit coal or wood fires (often used for cooking and heating). The variation in lung cancer rates among communes within the county suggests that indoor combustion of smoky coal may be the prime determinant of lung cancer. To characterize the air in Xuan Wei homes, samples of air particles and semivolatile organic compounds were collected from homes located in two communes; one commune has a high rate of lung cancer, and the other has a low rate. Samples collected in the commune where the lung cancer rate is high and where smoky coal is the predominant fuel contained high concentrations of small particles with high organic content; organic extracts of these samples were mutagenic. Samples from homes in the wood-burning commune, which has a low rate of lung cancer, consisted mostly of larger particles of lower organic content and mutagenicity. The smoky coal sample was a mouse skin carcinogen and was a more potent initiator of skin tumors in comparison to the wood or smokeless coal sample.     

Evaluation of genotoxic and non-genotoxic effects of organic air pollution using in vitro bioassays

In this study, organic extracts of total suspended particles (TSP) and the particulate matter (PM) with the size below 2.5 microm (PM(2.5)) combined with organic extracts of the gas phase (GP) collected at two urban and two background localities were analyzed with a bacterial genotoxicity test, SOS chromotest, and an in vitro test for the dioxin toxicity determination, using a modified cell-line of rat hepatoma H4IIE.luc. In addition, the samples of TSP and GP were analyzed for PAHs contents. The PAHs concentrations and both of the toxic activities at the urban localities were much higher than ones at the background localities. Predominantly, traffic was a source of the urban air pollution there which was also confirmed by the evaluation of portions of certain PAHs (BaP/BPE, PYR/BaP) at the localities. On the other hand, the background localities were apparently affected by a long-distance transport of the pollutants from urban and industrial centers. The results of the bioassays indicated potential health risks for the population exposed to the organic air pollutants, especially at the urban localities. Based on the collected samples, distribution of the organic pollutants with the toxic effects in the air was evaluated. The significant portion of the direct genotoxins was bound to the particles larger than 2.5 microm. On the contrary, the indirect genotoxins were bound predominantly to the particles with the size below 2.5 microm. However, in the urban air they may be also bound to the larger particles, as well. While the direct genotoxicity may be related with the presence of PAH-derivatives as well as some polar organic pollutants, the indirect genotoxicity is related with the detected carcinogenic PAHs. But besides the above specified pollutants it is also necessary to consider the presence of other toxic components of the complex organic air pollution mixture that may also show potential health risks. This study demonstrates application of the combination of the screening bioassays for the evaluation of organic air pollution and identification of its health risks.     

Waste wood recycling as animal bedding and development of bio-monitoring tool using the CALUX assay

Animal bedding made of waste wood samples from seven different plants in Japan were chemically analyzed in terms of persistent organic pollutants (POPs) including polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/DFs), coplanar polychlorinated biphenyls (Co-PCBs), drin compounds, chlordane compounds and various inorganic toxic compounds (Cr, Cu, As, B, Cd and Pb) to investigate the chemical characteristics and levels of contamination. Further investigation was conducted to determine the success of applying the Chemically Activated Luciferase Expression (CALUX) bioassay to the waste wood samples in combination with a cleanup procedure for the detection of dioxin-like compounds in order to develop the CALUX bioassay as a rapid and cost-effective screening/monitoring method and a contributive tool to risk management in the waste wood recycling process. For the cleanup procedure, crude extracts from wood samples were prepared by dimethylsulfoxide (DMSO)/n-hexane extraction, and then the extracts were processed by silica gel-44% sulfuric acid reflux treatment at 70 degrees C for 60 min to yield the bioassay fractions. The presence of POPs and inorganic toxic compounds were confirmed in most of the litter samples. In particular, Co-PCBs in one sample (litter dust) showed a high concentration level (1200000 pg/g, 240 pg TEQ/g), suggesting the potential for contamination from demolition waste. The CALUX assay-determined TEQs (CALUX-TEQs) were significantly high in the sample after DMSO/n-hexane extraction, probably due to labile aryl hydrocarbon receptor (AhR) ligands such as PAHs; however, they were remarkably reduced through a single silica gel-44% sulfuric acid reflux treatment. The ratio between CALUX-TEQ values and WHO toxicity equivalent values (WHO-TEQ) obtained by congener-specific chemical analysis ranged from 0.058 to 22 and show comparatively good agreement. Underestimation in some samples, however, was observed where WHO-TEQ values of Co-PCBs contributed greatly to total WHO-TEQ values. Reasons for this gap could be lower CALUX assay-determined relative potencies (REPs) than the WHO-TEFs for these congeners or AhR-antagonistic effects of non dioxin-like PCBs which coexist at higher concentration than Co-PCBs. The CALUX assay is proposed as a promising application in the recycling process of wooden materials.     

Mutagenic and carcinogenic potency of extracts of diesel and related environmental emissions: Summary and discussion of the results

The proposed conversion from gasoline powered automobiles to diesel powered vehicels has prompted the Environmental Protection Agency to evaluate the potential health effects associated with exposure to diesel emissions. At present, there is no direct epidemiological link between this exposure and human health. Therefore, a research program was constructed to compare the health effects associated with diesel emissions with those from other emission sources for which epidemiological information was available. The emission sources chosen were cigarette smoke, roofing tar, and coke oven. An additional comparative emission source which was a gasoline catalyst engine. Respirable particles from a variety of combustion sources have the potential of being carcinogenic and mutagenic. The objective of these studies was to determine the relative biological activity of the organic material adsorbed on these particles in both in vitro mutagenesis and in vitro and in vivo bioassays. The organic extracts from the following series of emission sources were quantitatively bioassayed in a matrix of tests for their carcinogenic and mutagenic activity: (1) a light-duty Oldsmobile diesel 350 engine; (2) a heavy-duty Caterpillar diesel engine; (3) a light-duty Nissan engine; (4) a Volkswagen Rabbit diesel engine; (5) cigarette smoke; (6) roofing tar; (7) coke oven; and (8) a gasoline catalyst Mustang. The test matrix consisted of the following bioassay: reverse mutation in Salmonella typhimurium; mitotic recombination in Saccharomyces cerevisiae; DNA damage in Syrian hamster embryo cells (SHE); sister chromatid exchange in CHO cells; gene mutation in L5178Y mouse lymphoma cells, Balb/c 3T3 mouse embryo fibroblasts and CHO cells; viral enhancement of SHE cells; oncogenic transformation in Balb/c 3T3 cells; and skin tumor initiation in SENCAR and C57 black mice. The results of this test matrix are discussed.     

Mutagenic and carcinogenic potency of diesel and related environmental emissions: Salmonella bioassay

Due to the expected increase in the percentage of diesel vehicles in the United States, the Environmental Protection Agency must evaluate the health effects associated with exposure to diesel emissions. Respirable particles from a variety of combustion sources have the potential of being carcinogenic and mutagenic. The objective of these studies was to determine the relative biological activity of the organic material adsorbed on these particles in in vitro mutagenesis bioassays. The organic extracts from the following series of emission sources were bioassayed in the Salmonella assay for mutagenic activity: (1) a light-duty Oldsmobile diesel 350 engine; (2) a heavy-duty Caterpillar diesel engine; (3) a light-duty Nissan engine; (4) a Volkswagen Rabbit diesel engine; (5) cigarette smoke; (6) roofing tar; (7) coke oven; and (8) a gasoline catalyst Mustang. This paper provides a comparison of these sources within the Salmonella bioassay and also demonstrates how bacterial systems can be used as a quality assurance measure in in vivo testing.     

Evaluation of techniques used in the preparation of diesel extract samples for mutagenicity studies

Diesel exhaust particles were used to compare methods and techniques used in the preparation of particulate matter for microbial mutagenesis testing. Investigated in this study were extraction, concentration, and solvent exchange methodologies as they affected recovery of mutagenic material from diesel samples using a Salmonella typhimurium plate incorporation assay. Solvent removal methods applicable for use in determining the mass concentration of extracts were also evaluated. Results indicated that particle samples Soxhlet extracted with dichloromethane yielded higher levels of mutagenic activity than did comparative samples utilizing sonication. No difference was seen between rotary evaporation or Kuderna-Danish macro concentration of extracts to volumes > 50 mL. In comparison of micro concentration techniques to volumes < 10 mL, vortex evaporation was found to be more efficient than a modified micro Kuderna-Danish method in recovery of mass and mutagenicity. Solvent exchanged samples were found to yield higher recoveries of mutagenic activity than samples taken to dryness and then reconstituted in the bioassay solvent. A dry mass weighing procedure utilizing desiccation was found to be more acceptable than either the use of an infrared heat lamp or nitrogen blowdown for solvent removal.     

Availability and plant uptake of heavy metals from contaminated dredged material placed in flooded and upland disposal environments

The availability and plant uptake of heavy metals was evaluated from contaminated dredged material placed in flooded and upland disposal environments using a solid-phase plant bioassay. The objective of the study was to verify previous dredged material research results and to develop a plant bioassay procedure that could indicate phytotoxicity and bioaccumulation of heavy metals in contaminated dredged material. The plant bioassay indicated more uptake and bioaccumulations of cadmium and, to a lesser extent, zinc when contaminated dredged material was placed in an upland environment where the sediment was allowed to air-dry. Placing the contaminated dredged material in a flooded (reduced) environment lowered the availability and plant uptake of cadmium and, to a lesser extent, zinc. Factors that influenced the availability and plant uptake of heavy metals from contaminated sediments included sediment oxidation-reduction potential, organic matter content, total sulfur content, and pH. The plant bioassay showed phytotoxicity and bioaccumulation of arsenic under a flooded environment. Placing the arsenic-contaminated sediment in an upland environment reduced both the phytotoxicity and bioaccumulation of arsenic in the freshwater marsh plant Cyperus esculentus.     

Evaluation of chemical and ecotoxicological characteristics of biodegradable organic residues for application to agricultural land

The use of organic waste and compost as a source of organic matter and nutrients is a common practice to improve soil physico-chemical properties, meanwhile reducing the need for inorganic fertilisers. Official guidelines to assess sewage sludge and compost quality are mostly based on total metal content of these residues. Measurement of the total concentration of metals may be useful as a general index of contamination, but provides inadequate or little information about their bioavailability, mobility or toxicity when the organic residue is applied to the soil. However, ecotoxicity tests provide an integrated measure of bioavailability and detrimental effects of contaminants in the ecosystem. In the present study, three different types of biodegradable organic residues (BORs) have been considered: sewage sludge from municipal wastewater treatment (SS), compost from the organic fraction of unsorted municipal solid waste (MSWC), and garden waste compost (GWC). The BORs were subjected to chemical characterisation and total metal quantification (Cd, Cr, Cu, Ni, Pb and Zn), in order to verify their suitability for land application. Water leachability was determined through the DIN 38414-S4 method, while the modified BCR sequential extraction procedure was used for metal speciation. Ecotoxicity of the BORs was studied by direct and indirect bioassays. Direct toxicity bioassays were: plant growth tests with cress (Lepidium sativum L.) and barley (Hordeum vulgare L.), and earthworm (Eisenia fetida) mortality. On the other hand, indirect exposure bioassays, with leachate from the residues, took into account: luminescent bacteria (Vibrio fischeri), seed germination (L. sativum and H. vulgare) and Daphnia magna immobilization. As far as total metal concentration is concerned, with particular reference to Zn, SS resulted neither suitable for the use in agriculture nor compatible to be disposed of as an inert material into landfill, according to the Directive 1999/31/EC. Zinc in SS was mainly present in exchangeable form (28.5%), appearing as highly bioavailable. As a consequence, SS exhibited either high ecotoxicity effects with the indirect exposure bioassays or significant mortality with the earthworm bioassay. Total content of metals in MSWC allowed its classification as "stabilised biowaste", according to 2nd draft [DG Env.A.2. Working document of Biological treatment of biowaste - 2nd draft. Directorate-General Environment, Brussels, 12th February; 2001. accessed in:http://europa.eu.int/comm/environment/waste/facts_en.htm, at 10/09/2002] while leachate, on the basis of the concentration of these contaminants, could be classified as "inert waste". This residue showed significant ecotoxicity effects with direct exposure bioassays as well as with the luminescent bacteria bioassay. However, it resulted less toxic than SS. Finally, GWC could be classified as a Class 2 compost, with no detectable toxic effects on the organisms used in the bioassays, except for the luminescent bacteria. In this case, an EC(50) of 73.0% was observed. Considering the results, the use of a battery of toxicity test in conjunction with chemical analysis should be suggested, in order to correctly assess possible environmental risks deriving from disposal or land application of biodegradable organic residues.     

Alteration of steroidogenesis in H295R cells by organic sediment contaminants and relationships to other endocrine disrupting effects

A novel bioassay with the human adrenocortical carcinoma cell line H295R can be used to screen for endocrine disrupting chemicals that affect the expression of genes important in steroidogenesis. This assay was employed to study the effects of organic contaminants associated with the freshwater pond sediments collected in the Ostrava-Karvina region, Czech Republic. The modulation of ten major genes involved in the synthesis of steroid hormones (CYP11A, CYP11B2, CYP17, CYP19, 17betaHSD1, 17betaHSD4, CYP21, 3betaHSD2, HMGR, StAR) after exposure of H295R cells to sediment extracts was investigated using quantitative real-time polymerase chain reaction (PCR). Crude sediment extracts, containing high concentrations of polycyclic aromatic hydrocarbons (PAHs) and moderate amounts of polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) significantly stimulated expression of the CYP11B2 gene (up to 10-fold induction), and suppressed expression of 3betaHSD2 and CYP21 genes. A similar pattern was observed with the extracts after treatment with concentrated sulfuric acid to remove labile chemicals (including PAHs) leaving only persistent PCBs, OCPs and potentially PCDD/Fs. Comparison of the results with other mechanistically based bioassays (arylhydrocarbon receptor, AhR, mediated responses in H4IIE-luc cells, and estrogen receptor mediated effects in MVLN cells) revealed significant endocrine disrupting potencies of organic contaminants present in the sediments (most likely antiestrogenicity). Pronounced effects were observed particularly in sediment extracts from the Pilnok Pond which harbors an unusual intersexual population of the narrow-cawed crayfish Pontastacus leptodactylus (Decapoda, Crustacea). This pilot study provided the first experimental evidence of the wider application of the H295R bioassay for screening complex environmental samples, and the results support the hypothesis of chemical-induced endocrine disruption in intersexual crayfish.     

Mutagenic activity of diesel emission particulate extracts and isolation of the mutagenic fractions

Mutagenic activity in diesel emission particulate extracts was detected by the Salmonella typhimurium/microsome assay. Direct-acting mutagens as well as promutagens requiring metabolic activation were detected. The extracts were fractionated into acidic, basic, and neutral fractions, and the neutral fraction was chromatographed into seven subfractions. Differences in the mutagenic potency of these fractions and subfractions were determined by the Salmonella assay. Fractions containing as yet unidentified compounds, but not polynuclear aromatic hydrocarbons, were found to make a major contribution to mutagenic activity of the extracts.     

Preparation and characterization of diesel exhaust particles for biological experiments

Bioassays of diesel engine exhaust components are being conducted at IITRI to determine toxic and carcinogenic potentials of the exhaust. The bioassay method, intracheal instillation of saline suspensions of test materials in hamsters, requires preparation of stable suspensions of test materials. A method to prepare suspensions of whole particle diesel exhaust in saline has been developed. The diesel exhaust particle material was supplied to IITRI as a dry, loose powder by the U.S. EPA from a light duty diesel test engine. Preliminary characterizations of the powders indicated aggregation of exhaust particles had occurred both before and during capture on collection substrates. Flake-like sheets and hollow spheres of aggregated particles up to 150 μm in sie present in the powders. Therefore, the powder were ball-milled to geometric particle sizes more amenable to the animal administration technique to be employed. Grinding, suspension preparation and particle concentration assaying methods have been developed. Particle (geometric) size and morphological characterizations have also been performed on the as-received powders and prepared suspensions. A method to prepare emulsions (liquid-liquid suspensions) of the dichloromethane extracts of whole particle diesel exhaust has also been developed.     

DNA-binding studies with diesel exhaust particle extract

This study examines whether chemical components from diesel exhaust particulates react with DNA to form covalently bound adducts. Experiments in this report describe the in vitro reaction of purified DNA with a dichloromethane extract of diesel exhaust particulates in the absence or presence of enzyme activation by rat liver microsomes. The reactivity of the particle extract was compared to that of benzo[a]pyrene metabolites using low temperature fluorescence techniques which detect small quantities of polycyclic aromatic compounds bound to DNA. Incubation of DNA with the particle extract in the presence of microsomal enzymes produced no detectable fluorescent adducts in contrast to model experiments using benzo[a]pyrene. However, addition of the particle extract to incubation mixtures containing benzo[a]pyrene markedly decreased formation of benzo[a]pyrene-DNA adducts because the particle extract inhibits microsomal enzymes which activate benzo[a]pyrene and other polycyclic aromatic hydrocarbons. In the absence of microsomal enzymes, fluorescent material was detected in DNA exposed to high concentrations of the particle extract, but probably not as a result of covalent binding because the mutagenic activity of the particle extract remained unchanged during prolonged incubation with DNA. This stability is in contrast to the rapid decrease in mutagenic activity of benzo[a]pyrene-4,5-oxide during incubation with DNA. Thus, direct mutation of bacteria by the particle extract may require activation by bacterial enzymes as is known to occur with nitroaromatic compounds.     

Evaluation of the water genotoxicity from Santos Estuary (Brazil) in relation to the sediment contamination and effluent discharges

The genotoxic activity of water samples collected in 9 different sites within the area of the Santos estuary was preliminary evaluated, and related to previous data on the genotoxicity of sediments and the contents of PAHs in both water and sediment samples. The liquid discharge of a steel mill (coke plant), known to be mutagenic, was chemically analyzed to determine its PAH content. For the water evaluation we employed the Salmonella/microsome assay with the strains TA98 and TA100 with and without S9 mix in the plate incorporation method. The water was filtered with an AP20 membrane before being extracted with XAD4 at natural and acidic pH. The industrial effluent was filtered in 0.45 microm membranes before being extracted with the liquid/liquid method. Both membranes containing the particulate material were extracted using ultrasonication. PAHs were found associated with the suspended particles present in the industrial effluent in accordance with mutagenicity data previously reported. In relation to the estuarine waters, sites 1 and 5 presented low levels of mutagenic activity only in the filtered water (liquid fraction) extracts. At site 3, both the filtered water and particulate solids presented also low mutagenicity. Results show that the mutagenic activity observed in water could not be directly related to the genotoxic activity and PAHs contents of the bottom sediments.     

Mutagenic and carcinogenic potency of extracts from diesel related environmental emissions: Simultaneous morphological transformation and mutagenesis in BALB/c 3t3 cells

Particulate extracts from six different environmental emission sources were assayed for genotoxic activity in mouse BALB/c 3T3 clone A31-1 cells. All compounds were tested simultaneously for both transforming and mutagenic (induction of ouabain-resistance) potential with and without exogenous metabolic activation in the form of a 9000 × g postmitochondrial hepatic supernatant fraction from Aroclor-1254 induced Fischer 344 rats. Dichloromethane particulate extracts from the exhaust of two light duty diesel engines (Oldsmobile and Nissan), one heavy duty diesel engine (Caterpillar) and one late model gasoline engine (Mustang II) were assayed in an identical manner to particulate extracts from the emissions of a roofing tar pot and a coke oven. No clear dose-dependent responses were observed, but several of the samples showed significant transforming and mutagenic activity. A qualitative ranking system showed the activity of these particulate extracts for either mutagenesis or transformation was: coke oven = Mustang II gasoline engine > Nissan diesel engine > roofing tar. Particulate extracts from the Oldsmobile diesel engine and the Caterpillar diesel engine showed essentially no activity.     

Mutagenic properties of PM2.5 urban pollution in the Northern Italy: The nitro-compounds contribution

PM2.5 is the breathable fraction of the particulate matter and some adverse health effects, such as respiratory functionality, cardiological diseases and cancer, can be in some measure attributable to this risk factor exposure. Some of the most carcinogen compounds transported by PM2.5 are nitro-compounds. In this study, a strengthened in vitro bioassay — able to predict the mutagenic/carcinogenic activity of the environmental mixtures — was conducted on PM2.5 organic extracts to define the nitro-compounds burden. PM2.5 air pollution was daily monitored, during 2006, in three cities located in the Northern part of Italy (Torino, Pavia and Verona) and the mutagenic properties of the PM2.5 organic extracts were assessed with the Ames test. The bacterial used in this study were three Salmonella typhimurium strains: TA98, nitroreductase-less mutant TA98NR and YG1021 carrying a nitroreductase-producing plasmid. The annual PM2.5 mean level measured in Torino was 46.5 (± 31.6) μg/m³, in Pavia 34.8 (± 25.1) μg/m³, and in Verona 37.3 (± 27.8) μg/m³, while the mutagenicity expressed as TA98 net reverants/m³ was 28.0 (± 22.1), 28.3 (± 24.9), and 34.2 (± 30.9) respectively. Monthly pool bioassays, conducted with the three different strains, showed a greater mutagenic response of the YG1021 in each city. The relationship among the mutagenic answers for YG1021:TA98:TA98NR was about 6:3:1 (p < 0.001). Over nitroreductase activity enhanced the response of 2.2, 2.0 and 1.7 times for Torino, Pavia, and Verona (ANOVA Torino p < 0.05) respectively. Without nitroreductase activity the genotoxicity was limited. These biological findings are able to describe a relevant role played by the nitro compounds in the mutagenic properties of the urban PM2.5 in the Padana plain; moreover the bacterial nitroreductase plays a predominant role in DNA interaction primarily for Torino PM2.5 extracts.     

Diesel particulate extracts in bacterial test systems

The Ames bacterial mutagenicity test system was used to evaluate parameters which may affect the mutagenic activity of diesel particulate extracts. The optimal extraction conditions, extractability of mutagens by simulated biological fluids and the effect of collection method were investigated. The role of solvent was examined by extracting diesel particles with methanol, acetone, cyclohexane, ethyl acetate, n-hexane, dichloromethane, benzene and a benzene-ethanol mixture. Of these, the dichloromethane extract exhibited the highest activity in the Ames test, although methanol yielded the largest extractable mass. Diesel particles were also extracted by dimethyl sulfoxide (DMSO) and four other simulated biological fluids for 48 h at 25, 37, and 45°C to study the effects of temperature. The mutagenic activity of the DMSO extract began to decline at temperatures higher than 37°C after 8 h of incubation. Fetal calf serum was the only simulated biological fluid which eluted mutagenic activity from the particles. No activity was detected in the 0.5% bovine serum albumin, simulated lung surfactant and saline extracts. Diesel particles collected by electrostatic precipitation (ESP) and filtration were studied. The mutagenic activities of both extracts were comparable when expressed as revertants per mg of particle. After the extracts were separated into nine fractions by a solvent partitioning scheme, the majority of the activity was found in the neutral-nonpolar II, neutral polar, strong acid and weak acid fractions. The acid salt fraction from the ESP sample was inactive. These results demonstrate that differences in the extraction conditions can result in differences in the mutagenic activity of diesel particulate extract. Since the mutagens in the extracts are not readily extractable by simulated biological fluids, the question of bioavailability of mutagens in diesel particles must be considered in the final assessment of their potential effects in biological systems and organisms.     

Genetic biomonitoring of an urban population exposed to mutagenic airborne pollutants

Biomonitoring studies have increased as a consequence of risks and effects to human health on exposure to environmental contaminants, mainly air pollutants. Genetic biomarkers are useful tools for the early assessment of exposure to occupational and environmental pollution. The objective of the present study was to investigate genotoxic effects on people residing and/or working downwind from an oil refinery in southern Brazil and the mutagenic activity of airborne particulate matter (PM10). Samples of peripheral blood and buccal mucosa cells were evaluated using the single-cell gel electrophoresis assay (comet assay) and the micronucleus (MN) assay, respectively. PM10 samples were collected in the target site and the organic matter extraced with dichloromethane was assessed for mutagenic activity in the Salmonella/microsome assay. The exposed group (n = 37) was compared to a reference group (n = 37) of subjects living in an urban area with limited traffic and industrial influence, located far from the main industrial areas. All PM10 organic extracts showed mutagenic positive responses and the effect decreased in the presence of S9 mix indicating that the predominant compounds present were direct-acting mutagens. The responses of YGs strains are consistent with aromatic amines and nitroarenes being present in the PM10 extracts. The group in the area under the influence of the oil refinery (exposed group) showed significantly higher DNA damage in lymphocytes than the reference group. The MN frequencies in buccal mucosa were very low for both groups and no difference between groups was observed. No association was found between age and tobacco smoking habit and level of DNA damages measured by the comet assay. The results indicate that the comet assay was a sensitive tool to detect DNA damage in subjects under the influence of an oil refinery, with marked genotoxic activity in the atmospheric environment.     

Deposition and biological availability of diesel particles and their associated mutagenic chemicals

To estimate the human health risk of inhaled diesel particles, it is necessary to know their deposition and retention in the respiratory tract and the rate of dissociation of mutagenic compounds associated with the particles. The deposition of a chain aggregate aerosol of ⁶⁷Ga₂O₃ with size and shape characteristics similar to diesel exhaust particles has been evaluated using Beagle dogs. Approximately one-third of the inhaled activity is deposited in the respiratory tract with most of the particles deposited in the lung. The mutagenic activity present in dichloromethane, dog serum, dog lung lavage fluid, saline, dipalmitoyl lecithin (DPL) and albumin following incubation of these fluids with diesel exhaust particles was determined in the Ames Salmonella system. As observed by other investigators, large quantities of mutagenic activity were removed by dichloromethane. A very small amount of mutagenic activity was removed by the serum and lavage fluid over a 3-day incubation period. No activity was detected following elution with the other solvents. The finding that minimal mutagenic activity could be demonstrated in the biological media following incubation with diesel exhaust particles may be due to a lack of removal of mutagens from the particles or an inactivation of removed mutagens by protein binding or other processes.     

Assessing the genotoxicity of urban air pollutants in Varanasi City using Tradescantia micronucleus (Trad-MCN) bioassay

In the present study Tradescantia micronucleus (Trad-MCN) bioassay was performed to assess the genotoxicity of air pollutants in Varanasi City. The experiment was performed during October 2006 to April 2007. For Tradescantia micronucleus (Trad-MCN) bioassay four sites were selected, three in the city having different traffic characteristics and one control site virtually free from traffic intervention. Twenty young Tradescantia pallida inflorescences were collected from each sampling site during the study period and micronuclei frequencies were determined in early tetrads of pollen mother cells and expressed as MCN/100 tetrads. During the same period the concentration of different air pollutants were also measured. Tradescantia micronucleus (Trad-MCN) bioassay showed that the plants kept in areas having higher traffic emissions evidence higher micronuclei frequencies than samples kept at control site. The study indicates that in situ biomonitoring using higher plants may be useful for characterizing genotoxic air pollutants in areas even without any sophisticated instrument.     

Levels of household particulate matter and environmental tobacco smoke exposure in the first year of life for a cohort at risk for asthma in urban Syracuse, NY

The Syracuse, NY, AUDIT (Assessment of Urban Dwellings for Indoor Toxics) study was designed to quantify asthma agent levels in the inner-city homes of a birth cohort whose mothers had a diagnosis of asthma. Risk of exposure to particulate matter (PM), particle number and tobacco smoke was assessed in 103 infants' homes. Repeat measurements were made in 44% of the homes. Infants also were examined on a quarterly basis during the first year of life to monitor their respiratory health and urine cotinine levels. Overall geometric mean (GM) values for PM(2.5) of 21.2 μg/m(3) and for PM(10) of 31.8 μg/m(3) were recorded in homes at visit 1. GM values for PM(2.5) and PM(10) in smoking homes were higher at 26.3 and 37.7 μg/m(3), while values in non-smoking homes were 12.7 and 21.2 μg/m(3) respectively. Fifty-four percent of mothers (55/103) smoked at some point in pregnancy (39% smoked throughout pregnancy). Environmental tobacco smoke (ETS) exposure occurred in 68% of homes during the infants' first year. Significant to this study was the size- and time-resolved monitoring of PM at 140 home visits and the classification of PM count data. PM number counts ranged from continuously low levels (little indoor activity) to continuously high counts (constant indoor activity), and recorded apparent instances of prolonged repeated cigarette smoking. Wheezing in the first year of life was recorded for 38% of the infants (39/103). Adjusted logistic regression modeling demonstrated that elevated levels of indoor PM(2.5) (≥ 15 μg/m(3)) were a significant risk factor for infant wheezing after controlling for infant gender, mothers' age and education level, season of home visit and presence of carpeting (OR 4.21; 95% CI 1.36-13.03; p=0.013). An elevated level of the nicotine metabolite cotinine in infant urine also was associated with infant wheezing after adjusting for infant gender, mothers' age and education level (OR 5.10; 95% CI 0.96-27.24; p=0.057). ETS exposure was pervasive in the AUDIT cohort and a risk for developing infants in this urban population.