Determination of microcontaminants in sediments by on-line solid-phase extraction-gas chromatography-mass spectrometry

Two simple and straightforward analytical procedures for the screening of sediment samples are reported. They involve extraction with ethyl acetate or methanol and subsequent analysis by means of gas chromatography-mass spectrometry (GC-MS) using large-volume injection (LVI) or solid-phase extraction (SPE). The latter, which was originally developed for the analysis of aqueous samples, can be used without any modification. In general, 10 ml of organic solvent were added to 2 g of sediment, and the mixture was shaken and allowed to stand overnight. The methanolic extracts were then diluted in water and subjected to preconcentration and analysis using on-line SPE-GC-MS. The ethyl acetate extracts were injected directly into the GC using LVI. Both methods were used for the detection and identification of microcontaminants during a monitoring study of the river Nitra (Slovak Republic). They included polyaromatic hydrocarbons (PAHs), chlorofluorohydrocarbons, alkoxylated and alkylated phenols and benzothiazole derivatives. Semi-quantitative profiles of the contaminants were constructed and provisionally interpreted. The results indicate that SPE-GC-MS, and also LVI-GC-MS, have good potential for a rapid screening of sediment samples and the identification of microcontaminants. The analytical procedures pose no problems, and the on-line set-up is user-friendly.     

Levels of dioxin-like compounds in sewage sludge determined with a bioassay based on EROD induction in chicken embryo liver cultures

A bioassay for the detection of dioxin-like compounds was used to estimate levels in sewage sludge from Swedish sewage treatment plants (STPs). The sludge extracts were HPLC-separated into three fractions containing a) monoaromatic/aliphatic, b) diaromatic (e.g. polychlorinated biphenyls [PCBs], polychlorinated dibenzodioxins and polychlorinated dibenzofurans [PCDDs/Fs]), and c) polyaromatic compounds (e.g. polycyclic aromatic hydrocarbons [PAHs]). The bioassay, which is based on EROD (7-ethoxyresorufin O-deethylase) induction in cultured chicken embryo livers detected dioxin-like activity in all unfractionated extracts and in the di- and polyaromatic fractions of all sludge extracts, but not in the monoaromatic/aliphatic fractions. The levels ranged between 6 and 109 pg bio-TEQ/g sludge (d.w.). In sediment samples from rural lakes in Sweden, levels of about 5 pg bio-TEQ/g (d.w.) have been found. The polyaromatic fractions of the sludge samples were potent in the bioassay, probably due to various PAHs and other polyaromatics in the sludge. The levels of six PAHs that are screened for in the sludge at Swedish STPs accounted for only 3-10% of the observed EROD-induction by the polyaromatic fractions. Consequently, many other polyaromatic EROD-inducing compounds were present in the sludge. Inclusion of a biological test like the chicken embryo liver bioassay in the screening of sludge would improve the ability to detect the presence of bioactive dioxin-like compounds. A theoretical estimation of bio-TEQ concentrations in farm-soil following long-term application of sludge with bio-TEQ concentrations similar to those observed in this investigation indicated that the bio-TEQ levels in soil would increase very slowly over time. The chicken embryo liver bioassay proved useful in assessing levels of dioxin-like compounds in sewage sludge and it gives valuable complementary information to chemical analysis data.     

Residues of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides in organically-farmed vegetables

The residues of polyaromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) in soils from organic farms and their uptake by four varieties of organic-produced potatoes and three varieties of organic carrots from England were investigated. Samples of the soils, crop peels and cores were all Soxhlet-extracted in triplicate, cleaned up by open-column chromatography and analysed by a multi-residue analytical method using gas chromatography with mass selective detection. The concentrations of PAHs, PCBs and OCPs in soils from organic farms ranged from 590+/-43 to 2301+/-146 microg/kg, 3.56+/-0.73 to 9.61+/-1.98 microg/kg and 52.2+/-4.9 to 478+/-111 microg/kg, respectively. Uptake by different crop varieties were 8.42+/-0.93 to 40.1+/-4.9 microg/kg sigmaPAHs, 0.83+/-0.19 to 2.68+/-0.94 microg/kg sigmaPCBs and 8.09+/-0.83 to 133+/-27 microg/kg sigmaOCPs. Residue uptake from soils depended on plant variety; Desiree potato and Nairobi carrot varieties were more susceptible to PAH contamination. Likewise, uptake of PCBs and OCPs depended on potato variety. There were significant positive correlations between the PCB and OCP concentrations (P<0.05) in soils and carrots but no significant correlation was found between the concentrations of any contaminants in soils and potatoes. Peeling carrots and potatoes was found to remove 52-100% of the contaminant residues depending on crop variety and the properties of the contaminants. Soil-crop bioconcentration factors (BCFs) decreased with increasing logK(ow) for PAHs up to about 4.5 and for PCBs up to about 6.5, above which no changes were discernible for either class of contaminants. No relationship was observed between soil-crop BCFs and logK(ow) for OCPs, most likely because their concentrations were low and variable.     

A high efficiency all glass sampling and concentration device for adsorptive semivolatile organics

A low-volume, inert sampling and enrichment device for semivolatile organic vapors is described. The device consists of two concentric fused silica capillaries. A small portion of the inter-capillary volume, cooled with a burst of compressed carbon dioxide, serves as a trap for the semivolatile organics. The low mass of the trap permits rapid sampling and desorption cycles suitable for applications requiring fast monitoring of semivolatile chemicals. The device is devoid of switching valves in the sampling train and consequently does not suffer from analyte loss due to irreversible adsorption or interference resulting from cross contamination. The device was successfully used for sampling low concentrations of highly adsorptive nitroaromatic compounds and is applicable for polychlorinated dibenzo-p-dioxins (PCDDs) and polyaromatic hydrocarbons (PAHs).     

Pressure-assisted ozonation of PCB and PAH contaminated sediments

Sediment contamination by recalcitrant organics such as polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) is prevalent and of a great concern. Remediation efforts are hampered by the hydrophobic nature of the contaminants that limits their availability as well as by the sediment matrix that limits their exposure to treatment agents. Using contaminated sediment samples from the Passaic River, St. Louis River, Waukegan Harbor, and Wells National Estuarine Research Reserve, this research demonstrated a new ozonation technique that incorporates rapid, successive cycles of pressurization (690 kPa) and depressurization, enabling more effective treatment than conventional ozonation would. Conventional ozonation reached maximum 60% and 40% removal of PAHs from the Passaic River (40 mg kg(-1) initially) and St. Louis River sediment (520 mg kg(-1) initially), respectively, in 1h; however, removals ceased despite prolonged treatment for 2h. The pressure-assisted technique removed 96% of PAHs from both river sediments within 1h; it completely removed both PAHs (16 mg kg(-1) initially) and PCBs (5.1 mg kg(-1) initially) from the Waukegan Harbor sediment in 0.5 h. The heightened treatment is explained by soil aggregate fracturing upon pressure cycles that exposes the contaminants as well as by the confluence of hydrophobic contaminants and O(3) at the gas-liquid interface in the presence of microbubbles. The technique is expected to accelerate O(3) treatment of a wide range of organic contaminants, and it may provide treatment to dredged and stored contaminated sediment.     

Uptake of PAHs into polyoxymethylene and application to oil-soot (lampblack)-impacted soil samples

Polyoxymethylene (POM) is a polymeric material used increasingly in passive sampling of hydrophobic organic contaminants such as PAHs and PCBs in soils and sediments. In this study, we examined the sorption behavior of 12 PAH compounds to POM and observed linear isotherms spanning two orders of magnitude of aqueous concentrations. Uptake kinetic studies performed in batch systems for up to 54 d with two different volume ratios of POM-to-aqueous phase were evaluated with coupled diffusion and mass transfer models to simulate the movement of PAHs during the uptake process and to assess the physicochemical properties and experimental conditions that control uptake rates. Diffusion coefficients of PAHs in POM were estimated to be well correlated with diffusants' molecular weights as D(POM) proportional, variant(MW)(-3), descending from 2.3 x 10(-10) cm(2) s(-1) for naphthalene to 7.0 x 10(-11) cm(2) s(-1) for pyrene. The uptake rates for PAHs with log K(ow)<5.8 were controlled by the POM phase and the hydrophobicity of PAH compounds. For more hydrophobic PAH compounds, the aqueous boundary layer played an increasingly important role in determining the overall mass transfer rate. The POM partitioning technique was demonstrated to agree well with two other procedures for measuring PAH soil-water distribution coefficients in oil-soot (lampblack) containing soil samples.     

煤矸石堆积下多环芳烃的淋溶污染特征

淋溶是使有害物质析出的主要途径之一。为查明煤矸石堆放淋溶造成的有机污染效应,对不同风化强度煤矸石进行了动态淋溶模拟实验,系统研究了煤矸石中US EPA优先控制的16种多环芳烃（PAH16）的析出规律和迁移方式。获得煤矸石中多环芳烃（PAHs）淋溶特征如下：煤矸石堆积期遭受短期降雨（500~1 600 mm）作用后,煤矸石溶出的PAH16总质量浓度达125.6~451.2 ng/L。PAH16溶出量初期较高,在一定降雨期后又达到峰值,酸雨条件下,煤矸石山淋溶出的PAH16可由线性累加转为指数快速累加的趋势。淋溶液中优势组分为萘、二氢苊、芴和菲,4种组分之和占所测PAHs总量的80%~90%。煤矸石溶出的PAHs环数分布为2环〉3环〉4环〉5环、6环。迁移方式上,2环PAHs多以溶解相迁移,3环PAHs主要以颗粒态迁移,存在少量溶解形式,而4环以上PAHs则以颗粒相形式迁移。     

空气中多环芳烃的研究现状

本文比较系统地讨论了空气中多环芳烃（ＰＡＨｓ）的研究现状。重点介绍了空气颗粒物及气相中多环芳烃的采样分析新办法，城市大气及居民室内外空气中多环芳烃的污染状况及其来源，简单介绍了人体接触多环芳烃的水平，指标及空气中多环芳烃的健康风险评价的研究概况。共引文献１２９篇。     

Impact of soil organic matter on the distribution of polycyclic aromatic hydrocarbons (PAHs) in soils

The knowledge on the distribution of hydrophobic organic contaminants in soils can provide better understanding for their fate in the environment. In the present study, the n-butanol extraction and humic fractionation were applied to investigate the impact of SOM on the distribution of polycyclic aromatic hydrocarbons (PAHs). The results indicated that 80.5%-94.8% of the target PAHs could be extracted by n-butanol and 63.1%-94.6% of PAHs were associated with fulvic acid (FA). Concentrations of un-extracted PAHs increased significantly with the increasing soil organic matter (SOM), however, such an association was absent for the extractable fractions. The results suggested that the sequestration played a critical role in the accumulation of PAHs in soils. SOM also retarded the diffusion of PAHs into the humin fractions. It implied that sequestration in SOM was critical for PAH distribution in soils, while the properties of PAH compounds also had great influences.     

The stable carbon isotope composition of atmospheric PAHs

A method for compound-specific stable carbon isotope analysis of atmospheric polycyclic aromatic hydrocarbons (PAHs) in carbonaceous aerosols is described. Atmospheric aerosol samples containing PAHs (C-10 to C-20) were collected on filters using a high-volume sampling technique, solvent extracted, taken through a cleanup procedure, separated by gas chromatography, oxidized to CO₂ on-line, and introduced into an isotope ratio mass spectrometer for analysis. The method can be used to determine the isotope composition of a few nanograms of PAHs. This technique was used to analyse and compare the isotope composition of atmospheric PAHs from standards, as well as two samples from urban and rural locations. Isotopic variability in atmospheric PAHs is greater than measurement uncertainties which makes this a potentially useful technique for source identification when used together with concentration measurements.     

Polycyclic aromatic hydrocarbons in the surface soils from outskirts of Beijing, China

Surface soils from the outskirts of Beijing were analyzed for 16 priority polycyclic aromatic hydrocarbons (PAHs) using gas chromatography and mass spectrometry (GC-MS). The distribution map of total PAHs content was obtained as a contour plot. The concentration range of 16 PAHs varied by over two orders of magnitude from 0.016 microg g-1 in rural to 3.884 microg g-1 in suburban soils with the relatively standard deviation of 70.5%, showing large differences in the extent of PAHs pollution at the various sampling sites. It was notable that the concentration of BaP was 0.005-0.270 microg g-1 with a mean of 0.055 microg g-1. In general, the distribution of PAHs centered on the high molecular weight PAHs known to be carcinogenic. The 4-6 ring PAHs represented about 66% in rural samples and 70% in suburban soils of the total PAHs found. There was relatively good relationship among most of the individual PAHs and the compounds of Pyr, BaA, Flu, BbF, BaP, Chr and Ph gave strong correlation (r>0.8) with the sum of PAHs. The selected marked compounds, a principal component analysis (PCA) and special PAHs compound ratios (Ph/An vs Flu/Pyr; summation operator COMB/ summation operator EPA-PAHs) suggest the pyrogenic origins, especially traffic exhausts, are the dominant sources of PAHs in Beijing outskirts soils.     

Characterization of polycyclic aromatic hydrocarbons from the diesel engine by adding light cycle oil to premium diesel fuel

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L(-1), respectively. The total benzo(a)pyrene equivalent (BaPeq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L(-1), respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaPeq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.     

Natural attenuation/phytoremediation in the vadose zone of a former industrial sludge basin

The natural attenuation of polyaromatic hydrocarbons (PAHs) in the vadose zone of a naturally revegetated former industrial sludge basin (0.45 ha) was examined. This was accomplished by comparing the concentration of 16 PAH contaminants present in sludge collected below the root zone of plants with contaminants present at 3 shallower depths within the root zone. Chemical analysis of 240 samples from 60 cores showed the average concentration of total and individual PAHs in the 0-30 cm, 30-60 cm, and bottom of the root zone strata were approximately 10, 20, and 50%, respectively, of the 16, 800 ppm average total PAH concentration in deep non-rooted sludge. Statistically significant differences in average PAH concentrations were observed between each strata studied and the non-rooted sludge except for the concentrations of acenaphthene and chrysene present at the bottom of the root zone in comparison to sludge values. The rooting depth of the vegetation growing in the basin was dependent on both vegetation type and plant age. Average rooting depths for trees, forbs (herbaceous non-grasses), and grasses were 90, 60, and 50 cm, respectively. The deepest root systems observed (100-120 cm) were associated with the oldest (12-14 year-old) mulberry trees. Examination of root systems and PAH concentrations at numerous locations and depths within the basin indicated that plant roots and their microbially active rhizospheres fostered PAH disappearance; including water insoluble, low volatility compounds, i.e. benzo(a)pyrene and benzo(ghi)perylene. The reduced concentration of PAHs in the upper strata of this revegetated former sludge basin indicated that natural attenuation had occurred. This observation supports the concept that through appropriate planting and management practices (phytoremediation) it will be possible to accelerate, maximize, and sustain natural processes, whereby even the most recalcitrant PAH contaminants (i.e. benzo(a)pyrene) can be remediated over time.     

An independent prediction of the effect of dissolved organic matter on the transport of polycyclic aromatic hydrocarbons

The transport of polycyclic aromatic hydrocarbons (PAH) in porous media in the presence of dissolved organic matter (DOM) was predicted with a transport bicontinuum model using independently obtained relationships to derive transport parameters for describing the effect of PAH binding to the DOM. The sorption constants of PAHs to soil and their binding constants to DOM were derived from basic correlations with K(ow) (indicator of hydrophobicity). The kinetic (rate) constants were derived from previously published correlations with K(p) (sorption constant). The independently obtained sorption and rate constants were corrected for binding to DOM and were used to predict the breakthrough curves (BTC) of contaminants in the presence and the absence of DOM. Column results confirmed the independently predicted BTC of PAHs in the presence of DOM that did not sorb to the solid phase, as well as the effect of DOM on the rate of the sorption and desorption processes. These findings confirm the ability to quantitatively describe how DOM facilitates transport of contaminants in the subsurface using independently derived parameters.     

Continental bottled water assessment by stir bar sorptive extraction followed by gas chromatography-tandem mass spectrometry (SBSE-GC-MS/MS)

This study was aimed to determine the presence of 69 organic contaminants in 77 representative bottled waters collected from 27 countries all over the world. All water samples were contained in polyethylene terephthalate bottles. Target compounds were (1) environmental contaminants (including 13 polycyclic aromatic hydrocarbons (PAHs), 31 pesticides including organochlorine (OCPs), organophosphorus, and pyrethroids; 7 polychlorinated biphenyls (PCBs); and 7 triazines) and (2) plasticizers (including 6 phthalates and 5 other compounds). Samples were analyzed by stir bar sorptive extraction followed by gas chromatography-tandem mass spectrometry. PAHs, OCPs, PCBs, and triazines, which are indicators of groundwater pollution, were not detected in most of the samples, except for naphthalene (0.005–0.202 μg/L, n?=?16). On the other hand, plastic components were detected in 77 % of the samples. Most frequently detected compounds were dimethyl phthalate and benzophenone at concentrations of 0.005–0.125 (n?=?41) and 0.014–0.921 (n?=?32), respectively. Levels detected are discussed in terms of contamination origin and geographical distribution. Target compounds were detected at low concentrations. Results obtained showed the high quality of bottled water in the different countries around the world.     

Cell absorption induced desorption of hydrophobic organic contaminants from digested soil residue

Oral ingestion of contaminated soil is an important pathway of human exposure to hydrophobic organic contaminants (HOCs), particularly for children in developing countries. The mobilization potential of various contaminants from ingested soil is often characterized using an in vitro gastrointestinal model, based on the quantities of contaminants remaining in digestive fluid after digestion and separation. Recently, it was experimentally demonstrated that a large fraction of mobilized contaminants sorbed on the digested residue could be released if the dissolved fraction was removed by intestinal absorption. This hypothesis was further tested in this study. Soil spiked with dichlorodiphenyltrichloroethane and its metabolites (DDXs) and polycyclic aromatic hydrocarbons (PAHs) was digested using an in vitro gastrointestinal model. A human colon carcinoma cell line (Caco-2) was cultured in digestive fluid with or without soil residue (pre-equilibrated with the soil) for 2 h. A large proportion of the contaminants (37-68%) was sorbed on the digested residue. Without this residue, 66 ± 13% of DDXs and 73 ± 14% of PAHs dissolved in the fluid, as means and standard deviations, were absorbed by the cell monolayer after exposure. With both digestive fluid and residue, the sorbed fraction of PAHs and DDXs decreased by 38-92%, while the ratios of the cellular to the dissolved concentrations were 2.7-2.8 times higher than those without the residue. This supported the hypothesis that the cell absorption of dissolved HOCs induces desorption of the sorbed fraction from digestive residue, and the desorbed HOCs can be absorbed as well.     

Large-volume injection PTV-GC-MS analysis of polycyclic aromatic hydrocarbons in air and sediment samples

For the analysis of trace organic pollutants in environmental samples using a gas chromatographic (GC) instrument, large-volume injection using the programmable temperature vaporization (PTV) technique has many advantages over the traditional split/splitless injection. By increasing the injection volume from 1 or 2 microL with a split/splitless inlet to 60 microL or higher with the PTV inlet, analytical sensitivity is greatly enhanced for analytes with low concentrations. Results obtained from optimization of instrument operational parameters for analyzing polycyclic aromatic hydrocarbons (PAHs) are reported in this paper. The laboratory method detection limits for 16 PAHs and six deuterated PAH surrogates were determined using seven replicate spike samples. The initial temperature of the inlet was found to be critical in determining the analytical sensitivity of PAHs with two or three rings due to loss of these relatively highly volatile compounds during solvent vaporization. For most PAHs, the response of the mass spectrometry detector increased proportionally as the total injected volume was increased up to 150 microL. Significant interference from rubber material of the sample vial septa was observed.     

Characterization of Polycyclic Aromatic Hydrocarbons from the

Abstract

Diesel fuels governed by U.S. regulations are based on the index of the total aromatic contents. Three diesel fuels, containing various fractions of light cycle oil (LCO) and various sulfur, total polyaromatic, and total aromatic contents, were used in a heavy-duty diesel engine (HDDE) under transient cycle test to assess the feasibility of using current indices in managing the emissions of polycyclic aromatic hydrocarbons (PAHs) from HDDE. The mean sulfur content in LCO is 20.8 times as much as that of premium diesel fuel (PDF). The mean total polyaromatic content in LCO is 28.7 times as much as that of PDF, and the mean total aromatic content in LCO is 2.53 times as much as that of PDF. The total polyaromatic hydrocarbon emission factors in the exhaust from the diesel engine, as determined using PDF L3.5 (3.5% LCO and 96.5% PDF), L7.5 (7.5% LCO and 92.5% PDF), and L15 (15% LCO and 85% PDF) were 14.3, 25.8, 44, and 101 mg L^?1, respectively. The total benzo(a)pyrene equivalent (BaP_eq) emission factors in the exhaust from PDF, L3.5, L7.5, and L15 were 0.0402, 0.121, 0.219, and 0.548 mg L^?1, respectively. Results indicated that using L3.5 instead of PDF will result in an 80.4% and a 201% increase of emission for total PAHs and total BaP_eq, respectively. The relationships between the total polyaromatic hydrocarbon emission factor and the two emission control indices, including fuel polyaromatic content and fuel aromatic content, suggest that both indices could be used feasibly to regulate total PAH emissions. These results strongly suggest that LCO used in the traveling diesel vehicles significantly influences PAH emissions.     

A case study for wintertime observation of atmospheric particulates by an eye-safe laser radar

Atmospheric particulates were monitored on a typical high concentration day in early winter in Osaka, Japan, using a compact and portable eye-safe laser radar system. The height of mixing layer was about 0.4 km at 8:00 and gradually increased to 0.8 km at 14:00. The development of the layer was in inverse proportion to the decrease of particulates near the ground surface. Analysis of particulates collected with high-volume air samplers showed that concentrations of elemental carbon (EC), lead and ammonium ion near the surface decreased significantly from morning to midday, while concentrations of sulfate, nitrate, sodium and calcium ions were almost constant. The results obtained in the preliminary study suggest that anthropogenic particulates such as EC and lead are on the rise with development of mixing layer from morning to midday.     

Polycyclic aromatic hydrocarbons in cigarette sidestream smoke particulates from a Taiwanese brand and their carcinogenic relevance

Polycyclic aromatic hydrocarbons (PAHs) adsorbed on cigarette sidestream smoke particulates (CSSPs) have been regarded as important contributors to lung carcinogenesis in never smokers. However, limited information is available on PAH levels in cigarette sidestream smoke. Here we determine the concentrations of 22 PAHs, including 16 US EPA priority PAHs, in CSSPs generated from a high market-share domestic brand in Taiwan. Five of the 22 PAHs are undetectable. The remaining 17 PAHs constitute about 0.022% of the total mass of CSSPs. Near one fifth of the PAH mass come from IARC group 1 and group 2 carcinogens. Carcinogenic potency is equivalent to 144 ng benzo[a]pyrene per cigarette converted according to potency equivalency factors (PEFs). The CSSP condensate could activate AhR activity and induce AhR target gene expression. High concentrations of CSSPs also exhibited AhR-independent cytotoxicity. However, mixing the 17 PAHs as the composition in the CSSP condensate could not reconstitute either capacity. Since AhR activation and cytotoxicity are important mechanisms underlying carcinogenic potency, the results suggest that other component compounds play a more active role in carcinogenesis. The approach of individual PAH profiling plus PEF conversion commonly used in risk assessment is likely to underestimate the risk caused by environmental cigarette smoke exposure.