Toxic Equivalency Factors Research Articles

The Acute Toxicity of Tetrodotoxin and Tetrodotoxin⁻Saxitoxin Mixtures to Mice by Various Routes of Administration.

Tetrodotoxin (TTX) is a potent neurotoxin associated with human poisonings through the consumption of pufferfish. More recently, TTX has been identified in bivalve molluscs from diverse geographical environments, including Europe, and is therefore recognised as an emerging threat to food safety. A recent scientific opinion of the EFSA Panel on Contaminants in the Food Chain recognised the need for further data on the acute oral toxicity of TTX and suggested that, since saxitoxin (STX) and TTX had similar modes of action, it was possible that their toxicities were additive so could perhaps be combined to yield one health-based guideline value. The present study determined the toxicity of TTX by various routes of administration. The testing of three different mixtures of STX and TTX and comparing the experimentally determined values to those predicted on the basis of additive toxicity demonstrated that the toxicities of STX and TTX are additive. This illustrates that it is appropriate to treat TTX as a member of the paralytic shellfish group of toxins. Since the toxicity of TTX was found to be the same as STX by feeding, a molar toxicity equivalence factor of 1.0 for TTX can be applied.

Integrating data gap filling techniques: A case study predicting TEFs for neurotoxicity TEQs to facilitate the hazard assessment of polychlorinated biphenyls

The application of toxic equivalency factors (TEFs) or toxic units to estimate toxic potencies for mixtures of chemicals which contribute to a biological effect through a common mechanism is one approach for filling data gaps. Toxic Equivalents (TEQ) have been used to express the toxicity of dioxin-like compounds (i.e., dioxins, furans, and dioxin-like polychlorinated biphenyls (PCBs)) in terms of the most toxic form of dioxin: 2,3,7,8-tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD). This study sought to integrate two data gap filling techniques, quantitative structure–activity relationships (QSARs) and TEFs, to predict neurotoxicity TEQs for PCBs. Simon et al. (2007) previously derived neurotoxic equivalent (NEQ) values for a dataset of 87 PCB congeners, of which 83 congeners had experimental data. These data were taken from a set of four different studies measuring different effects related to neurotoxicity, each of which tested overlapping subsets of the 83 PCB congeners. The goals of the current study were to: (i) evaluate an alternative neurotoxic equivalent factor (NEF) derivations from an expanded dataset, relative to those derived by Simon et al. and (ii) develop QSAR models to provide NEF estimates for the large number of untested PCB congeners. The models used multiple linear regression, support vector regression, k-nearest neighbor and random forest algorithms within a 5-fold cross validation scheme and position-specific chlorine substitution patterns on the biphenyl scaffold as descriptors. Alternative NEF values were derived but the resulting QSAR models had relatively low predictivity (RMSE ∼0.24). This was mostly driven by the large uncertainties in the underlying data and NEF values. The derived NEFs and the QSAR predicted NEFs to fill data gaps should be applied with caution.

Environmental Exposures to PCDDs, PCDFs, and PCBs and Mechanism of Steatohepatitis in the Anniston Community Health Survey II

PCDDs, PCDFs, and some PCBs activate the aryl hydrocarbon receptor (AhR); but non-dioxin like (NDL) PCBs do not. We previously reported a high prevalence of suspected nonalcoholic steatohepatitis (NASH) associated with PCB exposures in the Anniston Community Health Survey (ACHS). Here, we determine if dioxins and NDL PCB exposures were associated with serologic biomarkers of NASH in the subgroup of ACHS-II participants with suspected liver disease. The total dioxin toxic equivalency (TEQ) was determined by summing the TEQs for serum PCBs, PCDDs, and PCDFs using WHO toxic equivalency factors. Disease biomarkers were measured by ELISA or Milliplex. Subjects were categorized as having suspected liver disease if serum cytokeratin 18 was elevated. Linear regression models examined associations between TEQ or ΣNDL PCBs with NASH biomarkers in the suspected liver disease subgroup. In 345 adult participants, the prevalence of suspected liver disease was 62%. These subjects were at risk for NASH due to a high prevalence of overweight/obesity and diabetes. Suspected liver disease was significantly associated with male sex, non-Hispanic White race/ethnicity, increased liver enzymes, and a trend towards increased diabetes. Both TEQ and ΣNDL PCBs were associated with altered intermediary metabolism biomarkers (increased LDL, VLDL, phospholipids; and decreased HOMA-IR). TEQ was also associated with decreased HOMA-B. TEQ was associated with increased TNFα, IL-12 and CXCL11; while ΣNDL PCBs was associated with increased IL-13. Both TEQ and ΣNDL PCBs were positively associated with TGFβ. Neither exposure biomarker was positively associated with either CK18 or transaminases. In ACHS-II participants with suspected liver disease we found associations with altered biomarkers of liver intermediary metabolism, inflammation, fibrosis, and synthetic function; but not cell death. The potential role of the AhR, dioxins, and NDL PCBs in NASH progression warrants further investigation.

Identification of a mutagenic chlorination by-product produced from (E)-1, 3-dichloropropene (a component of nematocide DD) by using high resolution LC/MS and multivariate analysis

The estimated domestic usage of DD (a typical nematocide) has been the greatest among all the agricultural chemicals in Japan. DD is involved in a document which is used to establish tap water quality standard in Japan. The document indicates that DD is potentially detectable in raw water for tap waters. DD in raw water will be treated with chlorine at waterworks, which raises concerns about formation of mutagenic chlorination by-products through the treatment. The objective of this work was to identify a mutagenic chlorination by-product by using high resolution mass spectrometers and multivariate analyses. Mutagenicity of the chlorination by-product was evaluated with the Ames Salmonella mutagenicity assay. (E)-1,3-Dichloropropene (DCP) was used as a model compound of DD. The mutagenicity of chlorine treated model aqueous solutions of DD increased with increasing chlorine dosages up to 3.00 mol-Cl2/mol-DCP. From the chlorine treated aqueous solutions of DD, 1,3-dichloroacetone (DCA) was identified as a major mutagen by a cochromatography with an authentic standard, precursor ion analyses and first-generation product ion analyses with the high resolution mass spectrometers. The mutagenicity of DCA against TA100 strain without microsomal activation was 160,000 net revertant colony/μmol (the toxicity equivalent factor was 0.14). Based on the mutagenicity of the chlorine treated DCP sample, the specific mutagenicity of DCA, and the DCA concentration in the sample, the mutagenic contribution of DCA to the chlorine treated DCP sample was calculated. High contribution (98%) clearly shows that DCA is a major mutagen in the chlorine treated DCP sample. Because the exploration of DCA was performed by using the unrealistic high concentration samples of DCP and chlorine, formation of DCA in the practical concentration samples (0-200 μg-DCP/L, 0.10 or 1.27 mg-Cl2/L) was examined. It was proven that DCA formation reaction takes place in the practical concentrations of DCA and chlorine.

Evaluation of the fuel potential of sewage sludge mixtures with beech sawdust and lignite

Sewage sludge (SS) from municipal wastewater treatment has drawn serious attention of scientists around the world in the attempt to find feasible disposal methods. Therefore, in this work, a solution for valorisation of SS as solid fuel is proposed based on an advanced compositional investigation of SS versus conventional solid fuels, namely, lignite (L) and beech sawdust (BS). A characterisation in terms of proximate analysis and ultimate analysis was performed for the studied materials, both to SS, L, and BS as single fuel and to bi-component mixture formulas of SS and L/BS, in variable proportions of 30:70, 50:50, and 70:30. SS:BS based blends had higher hydrogen (from 4.43 wt. % to 5.14 wt. %) and carbon (from 30.76 wt. % to 40.12 wt. %) contents than the SS:L mixtures, very close to the one for BS (5.5 wt. % for hydrogen and 44.00 wt. % for carbon), indicating a more efficient release of energy during combustion. The combustion behaviour of SS and its blends with L and BS was also studied by thermogravimetric analysis (DSC-TGA) by heating the samples from ambient temperature up to 1100 °C at a rate of 20 °C/min under a nitrogen inert atmosphere. Analysis showed differences among SS, L, and BS, and the improvements were observed in the SS combustion profile after the addition of L or BS. The best potential as an alternative fuel was showed by the blends SS+L in a proportion of 30%:70% and SS+BS as a 30%:70% mixture. Additional information regarding the environmental risk induced by SS was obtained through the determination of the content of dioxines, furans, and carcinogenic polycyclic aromatic hydrocarbons of dried sewage sludge and the calculation of the toxicity equivalent factor. The values were within acceptable limits, and therefore, the proposed solution for valorization of waste sewage sludge offers a feasible way to reduce the anthropogenic impact and to enhance the durable development of the society.

Effects of polychlorinated biphenyls (PCB) on California sea lion (Zalophus californianus) lymphocyte functions upon in vitro exposure

Polychorinated biphenyl (PCB) congeners are a cause for concern due to their persistence in the environment, their lipophilic properties that cause them to bio-accumulate in top predators, and their adverse effects on mammalian health. For example, the common urogenital carcinoma reported in California sea lions (Zalophus californianus) (CSL) is associated with high tissue levels of PCBs, but the mechanisms responsible for this association are unknown. This study investigated the effect of exposure to six PCB congeners and a congener mix at low and environmentally relevant concentrations on NK cell-like and T cell activity using in vitro assays on cryopreserved lymph node mononuclear cells isolated from dead CSL. Non dioxin-like congeners 153 and 180 increased lymphocyte proliferation at 5 and 10 ppm, while congener 138 decreased proliferation by up to 43% at 15 ppm. Dioxin-like PCBs 118 and 169 did not affect lymphocyte proliferation, while the effects of congener 105 depended on the mitogen concentration; these did not correlate with their predicted toxic equivalent factors. NK cell-like activity was affected only by the highest concentration of PCBs tested; it was increased by non-dioxin-like congeners 138 and 153, and decreased by dioxin-like congener 169. The PCB congener mix suggested that the effects of PCB congeners were not simply additive. Our results concur with effects of PCBs reported for other pinniped's lymphocytes and add further experimental support to the observation that dioxin-like PCBs are not the most toxic congeners for marine mammals, contrary to effects in other species. This is the first evidence of in vitro suppression of NK cell-like cytotoxicity by a dioxin-like congener in a pinniped. More importantly, the observed results suggest that PCBs can modulate the CSL immune system, increasing exposed individuals’ susceptibility to viral and oncogenic challenges.

The traffic signature on the vertical PM profile: Environmental and health risks within an urban roadside environment

In an attempt to investigate the traffic-impacted vertical aerosols profile and its relationship with potential carcinogenicity and/or mutagenicity, samples of different sized airborne particles were collected in parallel at the 1st and 5th floor of a 19 m high building located next to one of the busiest roads of Athens. The maximum daily concentrations were 65.9, 42.5 and 38.5 μg/m3, for PM10, PM2.5 and PM1, respectively. The vertical concentration ratio decreased with increasing height verifying the role of the characteristics of the area (1st/5th floor: 1.21, 1.13, 1.09 for PM10, PM2.5 and PM1, respectively). Chemically, strengthening the previous hypothesis, the collected particles were mainly carbonaceous (68%–93%) with the maximum budget of the polyaromatic hydrocarbons being recorded near the surface (1st/5th floor: 1.84, 1.07, 1.15 for PM10, PM2.5 and PM1, respectively). The detected PM-bound PAHs along with the elements as well as the carbonaceous and ionic constituents were used in a source apportionment study. Exhaust and non-exhaust emissions, a mixed source of biomass burning and high temperature combustion processes (natural gas, gasoline/diesel engines), sea salt, secondary and soil particles were identified as the major contributing sources to the PM pollution of the investigated area. With respect to the health hazards, the calculation of the Benzo[a]Pyrene toxicity equivalency factors underlined the importance of the height of residence in buildings for the level of the exposure (1st/5th floor: B[a]PTEQ: 1.82, 1.12, 1.10, B[a]PMEQ: 1.85, 1.13, 1.09 for PM10, PM2.5 and PM1, respectively). Finally, despite its verified significance as a surrogate compound for the mixture of the hydrocarbons (its contribution up to 72%, 79% on the level of the 1st and 5th floor, respectively), the importance of the incorporation of PAH species in addition to B[a]P when assessing PAH toxicity was clearly documented.

Airborne bacteria and persistent organic pollutants associated with an intense Saharan dust event in the Central Mediterranean

In this paper, we present a comprehensive taxonomic survey of the bacterial community and accurate quantification of polycyclic aromatic hydrocarbons (PAHs) associated with an intense Saharan dust advection, which impacted Central Mediterranean area in the whole 2014–2015 period. This work is part of an intensive field campaign at the EMEP regional background site of Monte Martano (Central Italy), considered well representative of long-range transport in the Central Mediterranean area. 22 samples have been characterized in their provenance region and have been considered for the chemical and biological characterization. The event described in the present paper was exceptionally intense at the sampling site allowing a detailed evaluation of the dust load on a regional scale, an estimation of the impact of PAH based on the Toxic Equivalency Factor methodology and a thorough characterization of the airborne bacterial fraction performed by High Throughput Sequencing approach. Afterward, we cultured viable bacteria and evaluated several enzymatic activities and conducted UV survival tests. Principal findings include: (i) the striking evidence that, during the Saharan dust event, a highly diverse and abundant bacterial community was associated with PAH concentrations higher than the yearly mean; (ii) the tangible presence of cultivable microbes; (iii) the proof that the isolates recovered from Saharan dust had the potential to be metabolically active and that almost all of them were able to persist following UV radiation exposure. Comparisons of results for the present case study with mean values for the 2014–2015 experimental campaign are presented. The bacterial community and chemical speciation associated with the Saharan dust advection were specific and very different from those associated with other air masses. The particular case of North-Western Atlantic, which represents one of the most typical advection route reaching the sampling site is discussed in detail.

Are ingested plastics a vector of PCB contamination in northern fulmars from coastal Newfoundland and Labrador?

While marine animals are exposed to environmental contaminants via their prey, because plastic pollution in the aquatic environment can concentrate some chemicals, ingested plastics are thought to increase the exposure of biota to contaminants. Currently, in the literature there are contradictory results relating to how higher levels of ingested plastics by birds may lead to higher levels of polychlorinated biphenyl (PCBs). To date none of these have incorporated known Toxic Equivalency Factors (TEFs) for non-ortho and mono-ortho congeners of PCB which is critical to assessing the potential effects from PCBs. We examined northern fulmars (Fulmarus glacialis) from the Labrador Sea region Canada, and the ingested plastics from these same birds for comparative PCB concentrations. We found no significant correlations between the PCB concentrations in the birds and the mass or number of retained ingested plastic pieces in the stomach, this held true when PCBs were considered by a number of different ways, including ∑4PCB, ∑PCB, lower-chlorinated, high-chlorinated, non-ortho PCB, and mono-ortho congeners. PCB concentrations were lower in plastics as compared with livers. We found significant differences in congener profiles between the ingested plastics and seabird livers suggesting that while plastics do not contribute to the PCB concentrations, there may be some interactions between plastics and the chemicals that the birds are exposed to via ingested plastics.

Polycyclic aromatic hydrocarbon in urban soils of an Eastern European megalopolis: distribution, source identification and cancer risk evaluation

Abstract. This study explores qualitative and quantitative composition of 15 priority polycyclic aromatic hydrocarbons (PAHs) in urban soils of some parkland, residential and industrial areas of the large industrial centre of Saint Petersburg (Russian Federation) in Eastern Europe. The aim of the study was to test the hypothesis on the PAH loading differences among urban territories with different land use scenarios. Benzo(a)pyrene toxic equivalency factors (TEFs) were used to calculate BaPeq in order to evaluate carcinogenic risk of soil contamination with PAHs. Results of the study demonstrated that soils within residential and industrial areas are characterized by common loads of PAHs generally attributed to high traffic activity in the city. Considerable levels of soil contamination with PAHs were noted. Total PAH concentrations ranged from 0.33 to 8.10 mg kg−1. A larger portion of high-molecular-weight PAHs along with determined molecular ratios suggest the predominance of pyrogenic sources, mainly attributed to combustion of gasoline, diesel and oil. Petrogenic sources of PAHs have a significant portion and define the predominance of low-molecular-weight PAHs associated with petroleum, such as phenanthrene. Derived concentrations of seven carcinogenic PAHs as well as calculated BaPeq were multiple times higher than reported in a number of other studies. The obtained BaPeq concentrations of the sum of 15 PAHs ranged from 0.05 to 1.39 mg kg−1. A vast majority of examined samples showed concentrations above the safe value of 0.6 mg kg−1 (CCME, 2010). However, estimated incremental lifetime risks posed to the population through distinct routes of exposure were in an acceptable range. One-way ANOVA results showed significant differences in total PAHs and the sum of seven carcinogenic PAH concentrations as well as in levels of FLU, PHE, FLT, PYR, BaA, CHR, BbF, BaP and BPE among parkland, residential and industrial land uses, suggesting the influence of the land use factor.

Relative effective potencies of dioxin-like compounds in rodent and human lung cell models

Toxicity of dioxin-like compounds (DLCs), such as polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls, is largely mediated via aryl hydrocarbon receptor (AhR) activation. AhR-mediated gene expression can be tissue-specific; however, the inducibility of AhR in the lungs, a major target of DLCs, remains poorly characterized. In this study, we developed relative effective potencies (REPs) for a series of DLCs in both rodent (MLE-12, RLE-6TN) and human (A549, BEAS-2B) lung and bronchial epithelial cell models, using expression of both canonical (CYP1A1, CYP1B1) and less well characterized (TIPARP, AHRR, ALDH3A1) AhR target genes. The use of rat, murine and human cell lines allowed us to determine both species-specific differences in sensitivity of responses to DLCs in lung cellular models and deviations from established WHO toxic equivalency factor values (TEF) values. Finally, expression of selected AhR target genes was determined in vivo, using lung tissues of female rats exposed to a single oral dose of DLCs and compared with the obtained in vitro data. All cell models were highly sensitive to DLCs, with murine MLE-12 cells being the most sensitive and human A549 cells being the least sensitive. Interestingly, we observed that four AhR target genes were more sensitive than CYP1A1 in lung cell models (CYP1B1, AHRR, TIPARP and/or ALDH3A1). We found some deviations, with strikingly low REPs for polychlorinated biphenyls PCBs 105, 167, 169 and 189 in rat RLE-6TN cells-derived REPs for a series of 20 DLCs evaluated in this study, as compared with WHO TEF values. For other DLCs, including PCBs 126, 118 and 156, REPs were generally in good accordance with WHO TEF values. This conclusion was supported by in vivo data obtained in rat lung tissue. However, we found that human lung REPs for 2,3,4,7,8-pentachlorodibenzofuran and PCB 126 were much lower than the respective rat lung REPs. Furthermore, PCBs 118 and 156 were almost inactive in these human cells. Our observations may have consequences for risk assessment. Given the differences observed between rat and human data sets, development of human-specific REP/TEFs, and the use of CYP1B1, AHRR, TIPARP and/or ALDH3A1 mRNA inducibility as sensitive endpoints, are recommended for assessment of relative effective potencies of DLCs.

Chemical-by-chemical and cumulative risk assessment of residential indoor exposure to semivolatile organic compounds in France

BackgroundThe toxic effects of environmental exposure to chemicals are increasingly being studied and confirmed, notably for semivolatile organic compounds (SVOCs). These are found in many products and housing materials, from which they are emitted to indoor air, settled dust and other surfaces. ObjectivesThe objective of this work is to assess the human health risk posed by residential indoor exposure to 32 SVOCs, assessed in previous nationwide studies. MethodsA chemical-by-chemical risk assessment, using a hazard quotient (HQ) or excess risk (ER) method, was supplemented by a cumulative risk assessment (CRA). For CRA, a hazard index (HI) method, as well as higher tier approaches using relative potency factors (RPFs) or toxic equivalency factors (TEFs) were used for the following endpoints: neurotoxicity, reproductive toxicity, genotoxicity and immunotoxicity. ResultsHQs were above 1 for 50% of French children from birth to 2 years for BDE 47, and for 5% of children for lindane and dibutyl phthalate (DBP). Corresponding hazards are reprotoxic for BDE 47 and DBP, and immunotoxic for lindane. The CRA approach provided additional information of reprotoxic risks (HI > 1) that may occur for 95% of children and for 5% of the offspring for pregnant women's exposure. The SVOCs contributing most to these risks were PCB 101 and 118, BDE 47, and DBP. The higher tier CRA approaches showed that exposure to dwellings' SVOC mixtures were of concern for 95% of children for neurotoxic compounds having effects linked with neuronal death. To a lesser extent, effects mediated by the aryl hydrocarbon receptor (AhR) or by a decrease in testosterone levels may concern 5% of children and adults. Lastly, unacceptable immunotoxic risk related to exposure to 8 indoor PCBs was also observed for 5% of children. ConclusionsIn view of uncertainties related to compounds' toxicity for humans, these results justify the implementation of preventive measures, as well as the production of more standardized and comprehensive toxicological data for some compounds.

Proportions of predominant Ergot alkaloids (Claviceps purpurea) detected in Western Canadian grains from 2014 to 2016

Ergot alkaloids, produced by the fungusClaviceps purpurea, are contaminants of cereal crops. Depending on various factors, the relative composition of individual ergot alkaloids can differ among samples. The objective was to determine if the percentage of individual ergot alkaloids were similar across different cereal grains (barley n=39, rye n=7, triticale n=9, wheat n=94) collected in Western Canada over different years. Ergocristine was the predominant alkaloid accounting for half of the total alkaloids in all grain types. This study documented that barley, rye, triticale and wheat collected across Western Canada had similar percentages of ergocornine (6±1%,P=0.201), ergocristine (48±2%,P=0.939), ergocryptine (17±2%,P=0.302) and ergosine (5±0.5%,P=0.239). There were differences between grain types for ergometrine (P=0.027) and ergotamine (P=0.011), which ranged between 6 to 13% and 11 to 24%, respectively, of the total alkaloid content in different cereals. Both barley and wheat alkaloid percentages were similar between 2015 and 2016; ergocornine (7±1%,P=0.969), ergocristine (47±2%,P=0.680), ergocryptine (18±2%,P=0.572), ergometrine (8±1%,P=0.080), ergosine (15±1%,P=0.119) and ergotamine (P=0.189). The ergocornine percentage was higher in wheat (P=0.017) as compared to barley for 2015/2016 samples. Ergometrine was higher in barley (P=0.002) as compared to wheat for 2015/2016 samples. While two of the alkaloid proportions varied statistically, overall proportions of the six ergot alkaloids were comparable among the four grain types collected across Western Canada. If proportions of ergot alkaloids are similar across a region, then it may be deemed acceptable to recommend a maximum total ergot alkaloid concentration for that region. However, areas that exhibit variation among the ergot alkaloid proportions, individual ergot alkaloid guidelines based on a toxic equivalence factor, may be more appropriate. In contrast, since major differences were not seen between years or grain type, from a producer perspective there may be limited biological/toxicological significance for individual alkaloid guidelines.

OCCURRENCE OF PAHs IN THE ATMOSPHERE AND INCENSE BURNING AREA IN HA NOI ASSOCIATED WITH HEALTH RISK ASSESSMENT

The presence of polycyclic aromatic hydrocarbon compounds (PAHs) was investigated through the particulate matter of samples air samples collected in the ambient air and the incense burning area in Ha Noi. The concentration of PAHs in the incense burning area was higher than that in the ambient air. The mixture of PAHs in both sites was predominantly composed of PAHs 4 and more than 4 aromatic rings. Benzo(a)pyrene, (BaP), regarded one of the most toxic PAHs, was found in all samples, with the concentrations higher than the maximum concentrations defined by several EU Countries. The health risk assessment was conducted using the toxic equivalent factor (TEF) that was obtained by comparing the toxicity of individual PAHs to BaP. Derma contact was the main routes of exposure in the studied area. The incremental lifetime cancer risk (ILCR) model was used to find the risk level for human. The ILCR was higher than 10-3, indicating high health risk to community. The incense burning activity increases the risk to exposure human.

Wood washing: Influence on gaseous and particulate emissions during wood combustion in a domestic pellet stove

Nowadays, the use of biomass increasingly replaces the fossil fuels for the domestic heating production. In order to reduce pollutant emissions from biomass combustion, wood was washed at room temperature in order to represent natural rain leaching before burning in a recent pellet stove (2010s) of nominal output of 6.3 kW. Raw and washed woods were combusted for three different types of wood (oak, beech and fir) and the study focused on their particulate and gaseous emissions (Total Suspended Particles (TSP), Particulate Matter with diameter below 2.5 μm (PM2.5), carbon monoxide (CO), nitrogen oxides (NOx) and Total Volatile Organic Compounds (TVOC)). Polycyclic Aromatic Hydrocarbons (PAH), aldehydes and wood tracers as phenols compounds were also measured. In addition, considering the toxic equivalent factor, the human health impact of adsorbed and gaseous PAH is considerably reduced (96%) in the case of washed fir combustion. Emission factors of CO and TSP for washed wood combustion also show a decrease up to 50% depending on the type of wood used. Furthermore, phenolic compounds, Benzene, Toluene, Ethylbenzene, Xylenes and Trimethylbenzene (BTEXT) emissions can also be reduced by the washing of biomass. Washed oak combustion leads to a clear decrease by 60% of the total of BTEXT. In the case of phenols emissions, phenol shows a significant decrease by 91% during the combustion of washed fir wood.

HUMAN HEALTH HAZARD OF POLYCYCLIC AROMATIC HYDROCARBON IN ROAD DUST IN HA NOI METROPOLIS

This study investigates PAHs content in road dust of Hanoi metropolis, Vietnam. The samples were colected from the roads around city and analyzed by gas chromatography mass spectrometry (GC/MS). The total PAHs mass concentration ranges from 33.88 μg/kg to 5588,16 μg/kg, with the mean of 356,24 μg/kg in which HMW accounted up 70 % and LMW made up 30 %. The toxic equivalence factors (TEFs), mutagenic potency equivalent factors (MEFs) and the incremental lifetime cancer risk (ILCR) methodologies were applied to evaluate human exposure to carcinogenic PAHs sources. Carcinogenic equivalents (BaP-TEQ) and mutagenic equivalents (BaP-MEQ) were calculated from the potency relative to BaP (TEF) and BaP (MEF). The value of BaP-TEQ for 8 PAHs varied from 1.13 μg/kg to 195.23 μg/kg with mean of 24.34 μg/kg, while the value of BaP-MEQ ranged 1.45 μg/kg to 123.15 μg/kg with mean of 19.96 μg/kg. Basing on ILCRs model, the total cancer risk for children and adults was up to 1.6×10-5 and 3.9×10-5, posing a moderate potential cancer risk, respectively.

Measurement of particulate polycyclic aromatic hydrocarbon emissions from gasoline light-duty passenger vehicles

Abstract Tackling vehicle emissions is one important task for governmental stakeholders to develop cleaner cities. Gasoline-fueled light-duty passenger vehicles (LDPVs) are intensively used in populous urban areas to meet passenger transportation demand. However, gasoline vehicle emissions raise the health risk due to the proximity of exposure to gasoline exhaust. To better understand the genotoxicity of gasoline emissions, this study is focused on their emissions of particulate polycyclic aromatic hydrocarbons (p-PAHs). We combined dynamometer testing, filter sampling and offline chemical analysis to measure p-PAH emissions from five in-use gasoline LDPVs. The results indicate that the emission factors of tested vehicles under the Worldwide Harmonized Light Vehicles Test Cycle (WLTC) decrease significantly with emission standard, from 11.27 μg km−1 for one China 3 LDPV to below 6 μg km−1 for the other newer LDPVs (China 4 and 5). Different from the mass distribution of p-PAH species for diesel vehicles, medium-and high-molecular-weight PAHs (e.g., 4, 5, and 6-ring species) are considerably identified from the gasoline particle samples. These medium and high-weight PAHs, such as benzo [a]pyrene (BaP) and dibenzo [ah]anthracene (DaA), in general have much greater toxic equivalency factors than low-molecular-weight PAHs. Furthermore, this study also reports that engine type and driving cycle conditions would have discernible impacts on p-PAH emissions. The gasoline direct injection (GDI) engine-equipped LDPVs would increase p-PAH emissions compared with the counterparts using port-fuel injection (PFI) engines. Cold start and transient driving conditions could also result in increased p-PAH emissions, while high-speed driving conditions tend to reduce the p-PAH content in total particles. The significant health impacts caused by p-PAH emissions from gasoline LDPVs should be concerned, and more effective measures should be taken to eliminate gasoline particle emissions.

Benzo(a)Pyrene Equivalency and Source Identification of Priority Polycyclic Aromatic Hydrocarbons in Surface Sediments from Yamuna River

ABSTRACTIdentification of polycyclic aromatic hydrocarbons (PAHs) sources in the environmental compartments is crucial, but there is a need for appropriate management and remediation plan in the environment. PAHs can provide useful information, because they have been utilized for source apportionment. In this study, priority 16 PAHs were determined in sediments from Yamuna River in Delhi for the assessment of their possible sources. Among 16 PAHs, the dominant compounds were fluoranthene, chrysene, fluorine, and pyrene, and their sum accounted for more than 96% of the total 16 priority PAHs. The concentrations of ∑16PAHs at locations between upstream and downstream were not showing any considerable spatial gradient. The concentration of seven probable carcinogenic PAHs ranged 236–6230 µg kg−1 with the mean value of 1897 ± 1740 µg kg−1, and accounted for 40% of the ∑16PAHs. Benzo(a)pyrene toxic equivalent factors (TEFs) used for the quantification of relative toxicity potential of priority PAHs in terms of BaP toxicity equivalency (BaPTEQ) were presented. Homolog profiles demonstrated the dominance of two-, three-, and four-ring PAHs. Composition profile and selected concentration ratios of PAHs were used as diagnostic tools for the identification of possible emission sources of PAHs. The study suggested the pyrogenic activities of petroleum, coal, and biomass combustions as a major source of PAH contamination in the river. However, marginally petrogenic sources from automobile workshops and accidental spillage cannot be ruled out. The observed levels of total PAHs and their toxicity equivalency in sediments were more or less comparable with similar studies carried out worldwide.

Analysis and toxicity of 59 PAH in petrogenic and pyrogenic environmental samples including dibenzopyrenes, 7H-benzo[c]fluorene, 5-methylchrysene and 1-methylpyrene

In this study 59 PAH were analyzed in samples of petrogenic and pyrogenic sources as well as mixed environmental matrices. Among the analytes, PAH of molecular weights from 128 Da to 302 Da in alkylated and in native form were included. Results show that non-EPA PAH make up 69.3–95.1% of the overall toxic equivalents (TEQ) as based on the toxic equivalent factors (TEF) of 24 PAH. Particularly 7H-benzo[c]fluorene, dibenzopyrene isomers and alkylated PAH (in particular 5-methylchrysene and 1-methylpyrene) turned out to have a huge impact on the toxicity and must not be neglected in future risk assessment. In detail, dibenzopyrenes have a high impact on toxicity predominantly in pyrogenic materials (21% to 84%; mean: 59%) whereas 7H-benzo[c]fluorene dominates toxicity of petrogenic materials (up to 80%; mean: 26%). However, in the studied mixed environmental samples the toxic impact of both groups together is as high as about 80%. Many non-EPA PAH are not considered in risk assessment and amongst them there are some very toxic ones. This needs to be carefully evaluated in future studies.

Distribution, sources, and toxicity assessment of polycyclic aromatic hydrocarbons in surface soils of a heavy industrial city, Liuzhou, China.

As a heavy industrial city, Liuzhou has been facing a serious pollution problem. It is necessary to take steps to control and prevent environmental pollution wherever possible. Surface soil samples were collected from four communities in Liuzhou City, to determine the concentrations, distributions, sources, and toxicity potential of polycyclic aromatic hydrocarbons (PAHs) present. The mean concentrations of total PAHs in the surface soil are 756.43ng/g for the heavy industrial area, 605.06ng/g for the industrial area, 481.24ng/g for the commercial-cum-residential area, and 49.93ng/g for the rural area. Both the isomer ratio and principal component analyses for the PAHs prove that these pollutants originate mainly from coal, diesel, gasoline, and natural gas combustion. The pollution hierarchies and toxic equivalency factor of BaP prove that the city is subject to heavy pollution caused by industry, transportation, and daily human activities.