Toxic Equivalent Quantity Research Articles

Assessment of Polycyclic Aromatic Hydrocarbons in School Playground Soils in Urban Gwangju, South Korea

Soil samples from school playground of Gwangju City were analyzed for 16 polycyclic aromatic hydrocarbons (PAHs), and the soil contamination status and the potential cancer risk for students and adults were investigated. Soil samples were collected from 57 sites from 5 districts of Gwangju City in the summer of 2013. Regardless of the sampling site, the ∑PAHs concentrations ranged from 13.2 to 145.5ng/g (mean 51.2ng/g). Four and five-ring PAHs were predominant in the soil samples while the fraction of two-ring PAHs was the lowest. Seven carcinogenic PAHs contributed ~55% of ∑PAHs in school playground soils. The benzo[a]pyrene (46.4%) and dibenz[a,h]anthracene (41.2%) were the major contributors to toxic equivalent quantity. The strong correlation between carcinogenic PAHs suggested that they originated from the same source either vehicular emission or coal combustion, because they are markers of these pollution sources. The mean cancer risk for students (3.61×10-7) and adults (8.41×10-6) was in the U.S. EPA safety range (<10-6).

DIOXINS IN THE ENVIRONMENT AND THE BODY OF ANIMALS NEAR LANDFILL: TO THE METHODOLOGY OF PUBLIC HEALTH RISK EVALUATION

For the first time dioxins (including 2,3,7,8-tetrachlorodibenzo-p-dioxin, TCDD) were revealed by high resolution chromatography-mass spectrometry in tissues of animals (rodents and fish) and abiotic samples (soil, sediment, snow) from the biotopes near the landfill with solid wastes ("Salariyevo", New Moscow). Profiles of congeners in soil samples, snow and sediment were well comparable. Parameters of "toxic equivalency quantity" (WHO-TEQ98) greatly exceeded the levels registered in Vietnam dioxin-contaminated areas (territories of ecocide) known to produce a so-called dioxin pathology among population. As to the MPC for soil the observed levels near landfill were almost 38 times higher than the standards set in Russia. The consequences of the pollutants influence on the state of animals reflected the manifestations of toxic effects on the whole organism and the chromosome apparatus, in correlations with the parameters of dioxins (WHO-TEQ98) and/or TCDD in their tissues and objects in their natural habitat. Changes of cytogenetic status of fish and rodents, morphometric parameters of fish age dynamics, the emergence of individuals with abnormal head structure - correspond to pathological processes and conditions that determine the pathogenesis of human dioxin pathology. Analysis of the data obtained illustrates the possibility of creating a universal methodical approach for screening the hazards of dioxins' low dozes for human health.

Micro-pollutants in sediment samples in the middle Danube region, Serbia: occurrence and risk assessment.

This is the first comprehensive study on the occurrence of 940 semi-volatile organic compounds including sterols, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), pesticides, plasticizers, and other emerging compounds in 10 river and canal sediments collected in northern Serbia. For quantification of investigated compounds GC-MS-MS (selected reaction monitoring) and GC-MS (using both selected ion monitoring and total ion monitoring) methods were used. The number of detected compounds was in the range of 85-117, while the sum of the concentrations varied from 959μg/kg dry-wt to 84,445μg/kg dry-wt. Sterols were quantified with high frequency in nearly 100% of investigated samples suggesting that the studied rivers and canals have been contaminated by sewage. Regarding persistent organic compounds, p,p'-DDE, p,p'-DDD, and o,p'-DDT were the dominant members of organochlorine pesticides (OCPs). The concentration range of 11 quantified pesticides of 452 analyzed was from 0.564 to 61.6μg/kg dry-wt, while the concentration range of 47 quantified PCBs of 90 analyzed was from 0.928 to 32.1μg/kg dry-wt. OCPs (DDE, DDD, and γ-HCH) and several PAHs (fluoranthene, pyrene, phenanthrene, chrysene, benzo(a)anthracene, benzo(a)pyrene) exceeded the maximum values of the sediment quality guidelines. Contents of domestic compounds comprise a large proportion of the total contaminant concentration. Overall, the study reveals that river sediments in Vojvodina Province were moderately polluted mainly by domestic wastewater. The toxic equivalent quantity (TEQ) relative to benzo(a)pyrene and 2,3,7,8-tetrachlorodibenzodioxin for seven carcinogenic PAHs and six quantified dioxin-like PCBs ranged from 3.59 to 103μg TEQ/kg and from 0.001×10-3 to 2.10×10-3μg TEQ/kg, respectively, and were in the range or lower than the literature published data.

Levels, congener profiles, and dietary intake assessment of polychlorinated dibenzo-p-dioxins/dibenzofurans and dioxin-like polychlorinated biphenyls in beef, freshwater fish, and pork marketed in Guangdong Province, China

Persistent organic pollutants such as polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (DL-PCBs) consisting of non-ortho and mono-ortho PCBs are suggested to be very hazardous and have adverse effects on human health. However, their levels and congener profiles in retail foods marketed in Guangdong Province of China have not been elucidated thus far. Thus, in this study, 226 individual samples of beef, freshwater fish, and pork marketed across four regions of Guangdong Province were randomly collected during 2013–2015 to determine their levels of PCDD/Fs and DL-PCBs. The results showed that the total toxic equivalency quantities (TEQs) of most samples were below the maximum limits except for the 26 samples collected from the vicinities of pollution areas. The median total TEQs of these three categories were 0.174, 0.488, and 0.113pgTEQ/g fw, respectively, which indicated that the contamination status of the studied foods was not serious. For congener profiles, significantly different patterns were observed in three food groups, but with the same major TEQ contributors being 2,3,4,7,8-PeCDF in beef, freshwater fish, and pork. Regional differences of congener profiles in each food group were also found in this study, which might be attributed to the regionally different distributions of PCDD/Fs and DL-PCBs in environment media.The dietary exposures of four population subgroups (girls, boys, male adults, and female adults) to PCDD/Fs and DL-PCBs via three food groups were estimated to assessed the potential risks. They were all lower than the provisional tolerable monthly intake (PTMI, 70pgTEQ/kgbw/month) established by Joint FAO/WHO Expert Committee on Food Additive. In these food categories, the exposure to PCDD/Fs and DL-PCBs via freshwater fish was the highest one, which accounted for about 20% of PTMI, indicating that it was the major route to expose dioxin compounds.

Size distributions, PAHs and inorganic ions of exhaust particles from a heavy duty diesel engine using B20 biodiesel with different exhaust aftertreatments

Abstract Exhaust particle emissions from a heavy duty diesel engine using B20 biodiesel (20% biodiesel blend with 80% diesel by volume) were investigated, and the engine was equipped with three kinds of exhaust aftertreatment devices: DOC (diesel oxidation catalyst), DOC + DPF (diesel particle filter), and DOC + CDPF (catalyzed diesel particle filter). Particle mass, particle number and size distribution, and PAHs (polycyclic aromatic hydrocarbons) and inorganic ions in the particle emissions from the engine were studied. Compared with the engine without exhaust aftertreatments, DOC decreased nucleation mode particle number by 19.83%, while accumulation mode particles exhibited slight changes. The DOC + DPF reduced the total particle number by 82.54%, while the DOC + CDPF reduced it by 91.71%. Compared with the engine without exhaust aftertreatments, the three aftertreatments were shown to reduce total PAH emissions. DOC + DPF and DOC + CDPF can decrease total TEQ (toxicity equivalent quantity) effectively with a sharp decrease in PAH mass. The DOC increased the TEQ of particles by 46.9%. The catalyst in the DOC increased some high molecular weight PAHs such as BaA, BbF + BkF, and BaP, which led to the increase in TEQ. The DOC increased the total inorganic ions by 2%, while the DOC + DPF and DOC + CDPF decreased inorganic ions by 89.5% and 82.9%, respectively. Catalysts in DOC and CDPF promotes the formation of SO 4 2− and NO 3 − , which leads to higher inorganic ion emissions with DOC than no aftertreatments and higher inorganic ion emissions with a DOC + CDPF than with a DOC + DPF.

Removal Efficiency and Risk Assessment of Polycyclic Aromatic Hydrocarbons in a Typical Municipal Wastewater Treatment Facility in Guangzhou, China.

The loading and removal efficiency of 16 US EPA polycyclic aromatic hydrocarbons (PAHs) were examined in an inverted A2/O wastewater treatment plant (WWTP) located in an urban area in China. The total PAH concentrations were 554.3 to 723.2 ng/L in the influent and 189.6 to 262.7 ng/L in the effluent. The removal efficiencies of ∑PAHs in the dissolved phase ranged from 63 to 69%, with the highest observed in naphthalene (80% removal). Concentration and distribution of PAHs revealed that the higher molecular weight PAHs became more concentrated with treatment in both the dissolved phase and the dewatered sludge. The sharpest reduction was observed during the pretreatment and the biological phase. Noncarcinogenic risk, carcinogenic risk, and total health risk of PAHs found in the effluent and sewage sludge were also assessed. The effluent BaP toxic equivalent quantities (TEQBaP) were above, or far above, standards in countries. The potential toxicities of PAHs in sewage effluent were approximately 10 to 15 times higher than the acceptable risk level in China. The health risk associated with the sewage sludge also exceeded international recommended levels and was mainly contributed from seven carcinogenic PAHs. Given that WWTP effluent is a major PAH contributor to surface water bodies in China and better reduction efficiencies are achievable, the present study highlights the possibility of utilizing WWTPs for restoring water quality in riverine and coastal regions heavily impacted by PAHs contamination.

The Vernix Caseosa is the Main Site of Dioxin Excretion in the Human Foetus

Dioxins are highly toxic to foetuses and prenatal exposure leads to adverse health effects; however, the metabolic pathways involved in dioxin excretion are poorly understood. We determined the dynamics of maternal-to-foetal dioxin transfer during normal pregnancy and how foetuses eliminate polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, and non-ortho polychlorinated biphenyls. Dioxin levels in maternal blood, cord blood, placenta, vernix caseosa, meconium, and amniotic fluid were analysed by high-resolution gas chromatography/mass spectrometry. The average levels of total dioxins, expressed as picograms of toxic equivalency quantity per gram of lipid and in parentheses, dioxin fraction, with maternal blood levels arbitrarily set as 100%, were as follows: maternal blood, 15.8 (100%); placenta, 12.9 (81.5%); cord blood, 5.9 (37.2%); vernix caseosa, 8.4 (53.2%); meconium, 2.9 (18.2%); and amniotic fluid, 1.5 (9.2%). Similar proportions were observed for each dioxin congener. Thus, the highest content of foetal dioxins was observed in the vernix caseosa, indicating that this is the major site of dioxin excretion in human foetuses.

Vertical distribution, composition profiles, sources and toxicity assessment of PAH residues in the reclaimed mudflat sediments from the adjacent Thane Creek of Mumbai

A study on vertical distribution of magnetic susceptibility, carcinogenic and endocrine disrupting PAHs was performed in the reclaimed mudflat sediments adjacent to the Thane Creek of Mumbai. The 5-rings PAHs and ΣC-PAHs were more dominant at 120cm depth contributing 52.23% and 60.19% respectively to ∑PAHs. The average ratio values of LMW/HMW PAHs (0.58); Fla/(Fla+Pyr) (0.50); Ant/(Ant+Phe) (0.50); BaA/(Chry+BaA) (0.48); BaP/BghiP (2.06), Phe/Ant (1.03) and BaA/Chr (0.93) indicate that the PAH contamination might have raised due to inefficient combustion and pyrogenic emissions during the open burning of solid waste in the vicinity. This was further supported by the anthropogenic ferri(o)magnetic loading over the last 100years influencing the Creek sediments. The PAHs toxicity estimation was performed by calculating the toxic equivalent quantity (TEQ) value of 8.62ng TEQ/g which was below the safe level (600ng TEQ/g) suggested by the Canadian risk-based soil criterion for protection of human health.

Simultaneous removal of SO2 and PAHs by adding calcium-based additives during sewage sludge incineration in a fluidized bed incinerator

In this paper, the simultaneous removal of sulfur dioxide (SO2) and polycyclic aromatic hydrocarbons (PAHs) by adding calcium-based additives [CaO, Ca(OH)2, and CaCO3] during sewage sludge incineration was investigated in a fluidized bed incinerator. The effects of the types, CaO/S (mole ratio) and particle size of calcium-based additives on PAHs or PAHs Toxic Equivalent Quantity concentrations (TEQs) were also considered. The experimental results indicated that CaO had a better performance of reducing SO2 and PAHs emission, and the removal efficiencies of SO2, PAHs and PAHs TEQs at 850 °C were 86.89, 38.88 and 75.19%, respectively. Meanwhile, the increase of CaO/S and decrease of particle size were beneficial for suppressing PAHs formation and capturing SO2. Moreover, the adsorption and catalytic effect of calcium-based additives were regarded as inhibiting PAHs formation.

Spatial and Temporal Variation of PM2.5 and Atmospheric PCDD/Fs in Northern Taiwan during Winter Monsoon and Local Pollution Episodes

ABSTRACTWinter monsoonal air masses traveling from Inner Mongolia to downwind nations can transport cold temperature and air pollutants. This study investigated the effects of the long-range transport (LRT) of air pollutants by northeastern monsoons and local pollution (LP) episodes on atmospheric PM2.5, polychlorinated dibenzo-p-dioxin (PCDD), and polychlorinated dibenzofuran (PCDF) concentrations in northern Taiwan during the winters of 2014 and 2015. Air samples were collected in rural (Rural Site 1 was mountainous; Rural Site 2 was coastal) and urban (Urban Site 1 was urban; Urban Site 2 was suburban) areas in northern Taiwan as well as at a background site (Lulin Mountain) in central Taiwan. Atmospheric PCDD/F concentrations measured at different sites ranged from 11.0 ± 2.70 to 39.7 ± 22.7 fg international toxicity equivalency quantity (I-TEQ) m–3 in 2014 and 7.99 ± 5.58 to 17.5 ± 12.3 fg I-TEQ m–3 in 2015. During LRT and LP, the proportion of PCDFs was higher than that of PCDDs. Rural Site 1 (122 pg I-TEQ g–1) and Urban Site 2 (82.4 pg I-TEQ g–1) had the highest PCDD/F content in PM2.5 during LRT and LP, respectively. The proportion of PCDD increased when neither event occurred. Principal component analysis revealed relationships between the component variance of PCDD/Fs and the sampling site altitude. The results of potential source contribution function (PSCF) suggested that the cold-air masses reaching Taiwan via LRT were most likely arriving from northern China, with pollutants collected along their routes. Wind speed and direction and geographical factors affected the accumulation of air pollutants in the atmosphere during LP.

A full-scale study on thermal degradation of polychlorinated dibenzo- p-dioxins and dibenzofurans in municipal solid waste incinerator fly ash and its secondary air pollution control in China.

Degradation of polychlorinated dibenzo- p-dioxins and dibenzofurans in municipal solid waste incinerator fly ash is beneficial to its risk control. Fly ash was treated in a full-scale thermal degradation system (capacity 1 t d-1) to remove polychlorinated dibenzo- p-dioxins and dibenzofurans. Apart from the confirmation of the polychlorinated dibenzo- p-dioxin and dibenzofuran decomposition efficiency, we focused on two major issues that are the major obstacles for commercialising this decomposition technology in China, desorption and regeneration of dioxins and control of secondary air pollution. The toxic equivalent quantity values of polychlorinated dibenzo- p-dioxins and dibenzofurans decreased to <6 ng kg-1 and the detoxification rate was ⩾97% after treatment for 1 h at 400 °C under oxygen-deficient conditions. About 8.49% of the polychlorinated dibenzo- p-dioxins and dibenzofurans in toxic equivalent quantity (TEQ) of the original fly ash were desorbed or regenerated. The extreme high polychlorinated dibenzo- p-dioxin and dibenzofuran levels and dibenzo- p-dioxin and dibenzofuran congener profiles in the dust of the flue gas showed that desorption was the main reason, rather than de novo synthesis of polychlorinated dibenzo- p-dioxins and dibenzofurans in the exhaust pipe. Degradation furnace flue gas was introduced to the municipal solid waste incinerator economiser, and then co-processed in the air pollution control system. The degradation furnace released relatively large amounts of cadmium, lead and polychlorinated dibenzo- p-dioxins and dibenzofurans compared with the municipal solid waste incinerator, but the amounts emitted to the atmosphere did not exceed the Chinese national emission limits. Thermal degradation can therefore be used as a polychlorinated dibenzo- p-dioxin and dibenzofuran abatement method for municipal solid waste incinerator source in China.

Emissions of polycyclic aromatic hydrocarbons (PAHs) during hydrothermally treated municipal solid waste combustion for energy generation

Hydrothermal treatment (HT) is one of the efficient approaches for upgrading municipal solid waste (MSW). In the present study, emission characteristics of polycyclic aromatic hydrocarbons (PAHs) from hydrothermally treated municipal solid waste (H-MSW) combustion alone and H-MSW/coal co-combustion were investigated at different temperatures. The results showed that for all fuel combustion, the majority of PAHs were 3- or 4-ring PAHs. In addition, flue gas had the highest yields of PAHs followed by fly ash and bottom ash, while the ring number of dominated PAHs in fly ash was higher than those in flue gas and bottom ash. Compared to MSW, H-MSW combustion generated less PAHs at the value of 1131.95–7649.24μg/g. The blending of H-MSW and coal reduced total PAH emissions and positive interactions were observed between H-MSW and coal during co-combustion. The toxicity equivalent quantity (TEQ) values of the PAHs from combustion were in the order MSW>H-MSW>H-MSW/coal, which was consistent with the total PAH emissions. The present study illustrated that significant reduction of PAH emissions and toxicity from combustion could be achieved by HT and the blending of H-MSW and coal.

Occurrence and distribution of polycyclic aromatic hydrocarbons in surface sediments of San Diego Bay marinas

Polycyclic aromatic hydrocarbons (PAHs) have garnered much attention due to their bioaccumulation, carcinogenic properties, and persistence in the environment. Investigation of the spatial distribution, composition, and sources of PAHs in sediments of three recreational marinas in San Diego Bay, California revealed significant differences among marinas, with concentrations in one site exceeding 16,000ngg−1. ‘Hotspots’ of PAH concentration suggest an association with stormwater outfalls draining into the basins. High-molecular weight PAHs (4–6 rings) were dominant (>86%); the average percentage of potentially carcinogenic PAHs was high in all sites (61.4–70%) but ecotoxicological risks varied among marinas. Highly toxic benzo(a)pyrene (BaP) was the main contributor (>90%) to the total toxic equivalent quantity (TEQ) in marinas. PAHs in San Diego Bay marina sediments appear to be derived largely from pyrogenic sources, potentially from combustion products that reach the basins by aerial deposition and stormwater drainage from nearby streets and parking lots.

Composition and sources of polycyclic aromatic hydrocarbons in cryoconites of the Tibetan Plateau glaciers

Dark-colored cryoconite can absorb substantial solar radiation, reduce the surface albedo of glaciers, and thus greatly accelerate glacier melting. Organic matters in cryoconites such as polycyclic aromatic hydrocarbons (PAHs) are kind of the light absorbing compositions. In this study, 15 PAHs containing 3–7 rings were identified in 61 cryoconites samples collected from seven glaciers over the Tibetan Plateau (TP). The average concentration of total PAHs in cryoconites samples was in the range of 6.67–3906.66ngg−1 dry weight. The highest average total PAH concentration was found in the southeastern TP, followed by the northern TP. The central TP contained the lowest amount of PAHs. Moreover, correlation analysis showed that total organic carbon (TOC) and grain size were only a minor factor for the accumulation of PAHs in cryoconites of the TP. Factor analysis and diagnostic ratios indicated that the PAHs were produced mainly from the incomplete combustion of coal, fossil fuels and biomasses. The exhaust gas of locomotives also contributed to the accumulation of PAHs in the glaciers. The PAHs in these seven glaciers showed low toxic equivalent quantity (TEQ), and thus had low biological risk. Nevertheless, the pollution of PAHs in the southeastern TP needs to be addressed.

Carcinogenic and endocrine-disrupting PAHs in the aquatic ecosystem of India

The quantification studies of 17 carcinogenic and endocrine-disrupting polycyclic aromatic hydrocarbons (PAHs) in the Mithi River polluting the Mahim Creek near Mumbai were performed to understand their sources and probable ecological risk. The overall concentration level of ΣPAHs was 157.96±18.99μgL-1, while that of carcinogenic PAHs (ΣC-PAHs) was 81.31±9.75μgL-1, which corresponds to 51.5% of the ΣPAHs. The source analysis of PAH pollution was made on the basis of different PAH ratios. It was observed that the probable PAH contamination was due to pyrogenic inputs arising due to the combustion of grass, wood, and coal as well as due to the combustion of diesel and gasoline. Toxicity and biological risk assessment was made using toxic equivalent quantity (TEQ) for various C-PAHs. The results of our study showed that the mean BaP concentration in the Mithi River water (8.61μgL-1) was above the European Directive 2008/105/EC Environmental Quality Standards (EQS) value of 0.05μgL-1, while the levels of benzo(k)fluoranthene (BkF) + benzo(b)fluoranthene (BbF) (21.54μgL-1) and benzo(g,h,i)perylene (BghiP) + indeno(1,2,3,-c,d) pyrene (InP) (18.27μgL-1) were significantly higher than that set by the EQS (0.03 and 0.002μgL-1, respectively), showing that the ecological integrity of the river and the adjoining creek is possibly at risk.

Suppression of PCDD/Fs during thermal desorption of PCBs-contaminated soil.

Thermal treatment of polychlorinated biphenyls (PCBs) contaminated soil was shown in earlier work to generate new PCBs, as well as polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). In this study, this thermal desorption was conducted with addition of three distinct inhibitors, including ammonium sulphate, urea and calcium oxide, to inhibit the formation of PCDDs and PCDFs when remediating PCBs-contaminated soil. Experiments were conducted for 40min at 400°C after adding 1wt.% of inhibitor. Both the total PCDD/Fs and international toxic equivalent quantity (I-TEQ) reduced when inhibitors were introduced. Of the three compounds tested, CaO shows the highest inhibition efficiency, 92.2% for total PCDD/Fs and 95.6% for I-TEQ. The amount of CaO added also influences the suppression efficiency of PCDD/Fs. These results suggest that promoting desorption and destruction of precursors is probably the mechanism of suppression.

Risk assessment and uncertainty analysis of PAHs in the sediments of the Yangtze River Estuary, China

To better explore the concentration of polycyclic aromatic hydrocarbons (PAHs) in the sediments of the Yangtze River Estuary (YRE), 16 priority PAHs were analyzed based on sampling data obtained in February 2011. The results showed that the total concentrations of PAHs in sediments of the YRE varied from 65.07 to 668.98ng·g−1. The results of toxic equivalent quantities of benzo[a]pyrene and the sediment quality guideline quotient suggested that PAHs had little or no adverse effects on the environment. The cancer risk results showed that the cancer risk at all sites exceeded 10−6, with 73% of sites exceeding 10−4, suggesting that people remain at risk of cancer as a result of their exposure to carcinogenic PAHs. However, the result of hazard index results showed that the non-cancer risks were substantially lower than one, indicating that PAHs in these sediments likely pose little or no adverse health threats to local inhabitants.

Particle- and gas-phase PAHs toxicity equivalency quantity emitted by a non-road diesel engine with non-thermal plasma technology.

Polycyclic aromatic hydrocarbon (PAH) toxicity equivalency quantity (TEQ, denoted by benzo(a)pyrene equivalent (BaPeq) concentration) is more meaningful when evaluating the influence of non-road diesel engines PAH toxicity on environment. Particle- and gas-phase PAH BaPeq concentrations were calculated based on gas chromatography-mass spectrometer (GC-MS) results and toxic equivalency factors. A non-thermal plasma (NTP) reactor was applied to a non-road diesel engine to decrease PAH TEQ content. Only the gas-phase Nap BaPeq concentration increased slightly with the action of NTP at three different generator power outputs. BaP dominated the BaPeq concentration for 15 samples with, and without NTP except in the gas-phase at 4kW. Almost all medium molecular weight (MMW) and high molecular weight (HMW) PAH TEQs increased for particle- and gas-phases at 3kW power output compared to 2kW without the use of NTP. Particle-phase Nap, Acp, and AcPy (low molecular weight, LMW) TEQ were under detection at 3 and 4kW, while gas-phase BkF, IND, DBA, and BghiP (HMW) concentrations were below the limits of detection. The most abundant PAH TEQ compounds were MMW and HMW PAHs for gas- and particle-phase while they were BaA, CHR, BbF, BaP, and IND for PM aggregation. The total BaPeq emission factors were 15.1, 141.4, and 46.5μgm(-3) at three engine loads, respectively. Significant BaPeq concentration percentage reduction was obtained (more than 80 and 60%) with the use of NTP for particle- and gas-phases. A high TEQ content was observed for PM aggregation (38.8, 98.4, and 50.0μgkg(-1)) which may have caused secondary PAH toxicity emissions. With the action of NTP, the breakup of MMW and HMW into LMW PAHs led to reduction of some PAH concentrations.

Influence of non-detect data-handling on toxic equivalency quantities of PCDD/Fs and dioxin-like PCBs: A case study of major fish species purchased in Korea

It has been known that substitution is not a suitable method to address non-detect (ND) data and can result in significant errors. However, reports of reliable statistical methods for handling ND data of polychlorinated dibenzo-p-dioxin/furans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) in fish are rare. This work examines US-EPA's recommended statistical methods and traditional substitution-based methods for handling ND data in PCDD/F and DL-PCB datasets obtained from 240 fish samples. The Kaplan-Meier (KM) method was confirmed as a suitable statistical approach for dealing with our fish datasets. The results of the KM and substitution methods were compared; a significant difference was found in TEQs derived from KM and substitution for PCDD/Fs, suggesting that the handling of ND data is a critical issue for PCDD/Fs. For example, the substitution by ½LOD resulted in 20–25% overestimation of PCDD/F TEQs for fish samples with ND data (60–70%). In conclusion, the use of KM method is preferable for average TEQs, and if the use of KM is not applicable, substitution by zero is preferred. Based on this conclusion, the characteristics of fish contamination by PCDD/Fs and DL-PCBs in Korea were investigated.

Characteristics, sources, and health risk of polycyclic aromatic hydrocarbons in urban surface dust: a case study of the city of Xi'an in Northwest China.

Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants. Urban surface dust is an important carrier of PAHs. To investigate the characteristics, sources, and health risk of PAHs in urban surface dust, this study collected urban surface dust samples from Xi'an, the largest city in Northwest China and one of the cities with severe smog occurrences in China. The total concentration of 16 US EPA priority PAHs (∑16PAHs) ranged from 5.0 to 48mg/kg, with an average of 14mg/kg. The seven carcinogenic PAHs accounted for 21 to 65% of the ∑16PAHs. Higher levels of PAHs were found in its industrial, traffic, and mixed commercial and traffic districts. The PAHs were dominated by four-ring PAHs, and the predominant components were Fla, Phe, Chy, and Pyr. Multivariate statistical analyses showed that the PAHs originated mainly from the combustion of fossil fuel as well as coal and wood, and petroleum emission. The toxic equivalency quantities (TEQs) of urban surface dustborne PAHs ranged from 0.25 to 8.3mg/kg, with a mean of 1.8mg/kg. The 95% upper confidence limit of incremental lifetime cancer risk (ILCR) due to human exposure to urban surface dustborne PAHs was 8.2 × 10(-5) for children and 7.3 × 10(-5) for adults.