Reduction strategies for polycyclic aromatic hydrocarbons in processed foods

Polycyclic aromatic hydrocarbons (PAHs) are a large group of carcinogenic compounds. PAHs are ubiquitous in the environment and food, thus human beings may be exposed to PAHs through ingestion (water and food), inhalation (air and smoking), and skin contact in daily life. Dietary intake is the major source of exposure to PAHs in humans. Significant and harmful levels of PAHs can be generated during food processing and cooking. Although the formation of PAHs during processing is almost unavoidable, the levels can be diminished with reduction strategies. This review aims to provide comprehensive insights into the mechanisms underlying the formation of PAHs and factors influencing their formation in processed foods. The strategy for the reduction of PAHs including change in ingredients (i.e., reducing fat content), pretreatment conditions (i.e., reducing the pH), processing methods and parameters (i.e., reducing processing temperature and time), and packaging and storage conditions, are discussed. Potential novel strategies for PAH reduction are also identified and the feasibility is evaluated.     

高脂食品中多环芳烃研究

多环芳烃具有非极性强特点,易在脂质含量丰富食品中造成污染。该文对富脂肉类等高脂肪食品中多环芳烃来源、形成及污染现状、检测方法等进行概述,并对控制其中多环芳烃污染方法进行总结和讨论。     

Soil ecotoxicity of polycyclic aromatic hydrocarbons in relation to soil sorption,lipophilicity, and water solubility

A data set was generated aiming to predict the toxicity of PAHs to soil organisms. Toxicity data include the effects of 16 PAHs on the survival and reproduction of the soil-dwelling springtail Folsomia fimetaria. The results show that only PAHs with reported log Kow values < or = 5.2 (i.e., naphthalene, acenaphthene, acenaphthylene, anthracene, phenanthrene, fluorene, pyrene, and fluoranthene) significantly affected the survival or reproduction of the test organisms. Threshold values for the toxicity of the individual PAHs could be expressed as pore-water concentrations by the use of reported organic carbon-normalized soil-pore-water partitioning coefficients (Koc values). For the PAHs with a log Kow < or = 5.2, toxicity significantly increased with increasing lipophilicity of the substances (r2 = 0.67; p = 0.012; n = 8), suggesting a narcotic mode of toxic action for most substances. However, the position of anthracene in the regression plot indicated a more specific mode of toxic action than narcosis, and removing this data point yielded the following regression equation: log EC10 (micromol/L) = -0.97 log Kow + 4.0 (r2 = 0.80; p = 0.006; n = 7). Using this quantitative structure-activity relationship (QSAR) to calculate threshold values for the toxicity of the remaining nontoxic substances (benz[a]anthracene, chrysene, benzo[b]fluoranthene, benzo[k]fluoranthene, dibenz[a,h]anthracene, benzo[a]pyrene, perylene, and indeno[1,2,3-cd]pyrene), the absence of toxicity could, in most cases, be explained by a limited water solubility, indicating that these substances do act by narcosis as the mode of toxic action and that their toxicity is governed by concentrations in the pore-water. The results provide important input to future model predictions of the ecological risk posed by PAH contaminated sites.     

食品中多环芳烃的提取、纯化、以及检测方法的研究进展

对食品中多环芳烃(PAHs)的提取、纯化机理和检测方法进行了概述,侧重介绍了样品提取、纯化和分离过程中影响PAHs回收率的各种因素。     

Occurrence of polycyclic aromatic hydrocarbons and their hydroxylated metabolites in infant foods

Eleven polycyclic aromatic hydrocarbons (PAHs) have been analysed in commercial milk formulae and infant cereals. Two hydroxylated PAHs metabolites (1-OH-Pyr and 3-OH-B[a]P) and their conjugates were also analysed in milk samples. To determine the selected PAH metabolites, a simple, fast quantitative and economic method was developed. This method comprising ultrasound-assisted solvent extraction, enzymatic hydrolysis, solid-phase clean-up and detection by liquid chromatography with fluorescence detection (LC–FD) and liquid chromatography tandem mass spectrometry (LC–MS/MS) as confirmatory technique. The method was evaluated by constructing calibration curves, measurement of recovery, precision and the limits of detection. The purpose of this survey was to determine the selected analytes, to assess the exposure of babies and infants and to produce data for comparison with proposed limits that were being considered at the time of the survey. The results showed that not only no samples would have exceeded the limit for benzo[a]pyrene which is used as an indicator for the presence of PAHs, but also no hydroxy PAH metabolites have been detected.     

食品中多环芳烃及卤代多环芳烃的研究进展

综述了多环芳烃及卤代多环芳烃的性质、毒性及国内外食品中的污染情况和研究现状,并对目前的分析测定方法进行了介绍,希望为我国开展食品领域内多环芳烃和卤代多环芳烃的研究提供参考。     

Determination of polycyclic aromatic hydrocarbons in water and water-based alcoholic beverages

This paper proposes a simple HPLC method for the determination of polycyclic aromatic hydrocarbons (PAHs) in water, wine and beer. Samples were purified by PAH collection in solid-phase extraction (SPE) and analysed by reversed-phase HPLC (Supelcosil LC-PAH column from Supelco). For the beer sample, recoveries amounted to 28% for naphthalene and varied from 57% to 103% for the other PAHs; results are quantitative starting from fluoranthene (FI, the seventh component eluted). Almost all the beer and wine samples showed the presence of benzo(b)fluoranthene (BbF), benzo(k)fiuoranthene (BkF), benzo(a)pyrene (BaP), benz(ghi)perylene (BghiP) and indeno(1,2,3-cd)pyrene (IP), and in some cases there were traces of FI, benzo(a)anthracene (BaA) and dibenz(ah) anthracene (DBahA). Total contents of PAHs ranged from trace amounts to 0.72 ppb. Traces of BbF, BkF, BaP, BghiP and IP were also found in the wine samples.     

Cyclodextrin enhanced biodegradation of polycyclic aromatic hydrocarbons and phenols in contaminated soil slurries

This work aimed to evaluate the relative contribution of soil catabolic activity, contaminant bioaccessibility, and nutrient levels on the biodegradation of field-aged polycyclic aromatic hydrocarbons and phenolic compounds in three municipal gas plant site soils. Extents of biodegradation achieved, in 6 week-long soil slurry assays, under the following conditions were compared: (i) with inoculation of catabolically active PAH and phenol-degrading microorganisms, (ii) with and without hydroxypropyl-beta-cyclodextrin supplementation (HPCD; 100 g L(-1)), and finally (iii) with the provision of additional inorganic nutrients in combination with HPCD. Results indicated no significant (p < 0.05) differences between biodegradation endpoints attained in treatments inoculated with catabolically active microorganisms as compared with the uninoculated control. Amendments with HPCD significantly (p < 0.05) lowered biodegradation endpoints for most PAHs and phenolic compounds. Only in one soil did the combination of HPCD and nutrients consistently achieve better bioremediation endpoints with respect to the HPCD-only treatments. Thus, for most compounds, biodegradation was not limited by the catabolic activity of the indigenous microorganisms but rather by processes resulting in limited availability of contaminants to degraders. It is therefore suggested that the bioremediation of PAH and phenol impacted soils could be enhanced through HPCD amendments. In addition, the biodegradability of in situ and spiked (deuterated analogues) PAHs following 120 days aging of the soils suggested that this contact time was not sufficient to obtain similar partitions to that observed for field-aged contaminants; with the spiked compounds being significantly (p < 0.05) more available for biodegradation.     

Long-term fate of polychlorinated biphenyls and polycyclic aromatic hydrocarbons in an agricultural soil

Laboratory studies are useful for understanding the behavior of persistent organic pollutants (POPs) in soil, although such investigations do not always relate directly to field conditions. Outdoor lysimeter studies may be used to overcome this problem. This work aimed to investigate the behavior of two polycyclic aromatic hydrocarbons (PAHs) (fluoranthene and benzo[a]pyrene) and two polychlorinated biphenyls (PCBs; congeners 28 and 52) in soil, using lysimeters established in 1990 atthe Agrosphere Institute (Forschungszentrum Julich GmbH, Germany). The two PAHs were in one lysimeter, and the PCBs were in a second lysimeter. Afurther aim of the study was to determine soil half-lives for each of the contaminants. The overall decline in PAH concentrations was considerably greater than forthe PCBs over the 152 month study. The PCBs exhibited greater chemical extractability than the PAHs and were demonstrated to have migrated through the soil column to a greater extent than the PAHs. Loss of PCBs from surface soil was not considered to have been congener specific for the two PCB congeners in this study. The two PAHs varied in their extents of total loss and movement through the soil column. Soil half-lives were determined as 10.9 y for [12C]PCB 28, 11.2 yr for [12C]PCB 52, 2.7 yr for benzoqpyrene, and 32 d (phase 1) to 38 yr (phase 2) for fluoranthene. These are shown to disagree with some previous estimates of POP half-lives in soil, suggesting that previous studies underestimated persistence by 10-fold or more.     

食品中多环芳烃的研究进展

简述了近年来关于食品中多环芳烃的形成机理、分析方法及控制措施的研究进展,以期为解决食品中多环芳烃的污染问题提供依据。     

Calibration and field verification of semipermeable membrane devices for measuring polycyclic aromatic hydrocarbons in water

The use of semipermeable membrane devices (SPMDs) has become common in environmental sampling of nonpolar organic contaminants, yet few data exist for the uptake or sampling rates of polycyclic aromatic hydrocarbons (PAH). Two separate laboratory calibration experiments were conducted to determine the sampling rates of 28 individual PAH and 19 homologues. PAH with a log Kow > 4.5 remained in the linear uptake phase for 30 days, but PAH with a log Kow < 4.5 began to approach steady state within 15 days. Sampling rates, corrected for dissolved organic carbon, ranged from 2.11 to 6.06 L d(-1). Shear flow across the membrane had no statistically significant effect on rates over the range of 0.01-0.50 cm s(-1). Field verification of these sampling rates yielded agreement within about a factor of 2 for most PAH and a factor of 4 for all PAH. The worst agreement was for the most hydrophobic PAH, where partitioning into dissolved and particulate organic carbon pools are more important and less certain. These SPMD sampling rate data will allow quantitative estimations of freely dissolved concentrations of 47 compounds that are commonly used for PAH and petroleum product source identification and allocation.     

Factors affecting elimination of polycyclic aromatic hydrocarbons from smoked meat foods and liquid smoke flavorings

This review deals with effects of environmental and physicochemical factors affecting polyaromatic hydrocarbon (PAH) elimination from smoked meat products and liquid smoke flavoring (LSF). In the introductory part, some essential information are aimed at principles of food smoking and PAH formation during smoke generation as a result of incomplete wood combustion. Also, an application of alternative technology for food aromatization using LSF is briefly mentioned. Similarly, latest European legislation, biological effects, and analytical aspects of PAHs are mentioned concisely. The main part is devoted to physicochemical factors affecting the PAH content in smoked meat products, such as light, additional cooking, and packaging, which are able to decrease considerably PAH content in some meat products. The most important effect on PAH concentration decrease in LSF has low-density polyethylene (LDPE) package due to sorption processes on a surface of the plastic with subsequent diffusion into the plastic bulk. A less effective material is polyethylene terephthalate (PET), when only a surface adsorption process comes into account. Moreover, this process is affected also by other compounds presented in liquid media able to compete for the adsorption center on the PET surface.     

Removal of polycyclic aromatic hydrocarbons from water by migration into polyethylene

Water was spiked with three polycyclic aromatic hydrocarbons (PAHs) and filled into a steel diffusion chamber. Low-density polyethylene sheet combined of five polyethylene foils was used as a partition in the chamber. Depth of PAHs migration into the sheet was followed for 143 h, using high performance liquid chromatography with selective fluorimetric detection after extraction of PAHs from the foils peeled off. On the basis of the results obtained, the process of PAHs migration into PE was characterised as a one-dimensional diffusion into polyethylene bulk. The diffusion coefficients were calculated for individual compounds using the second Fick law. It was concluded that PAHs are primarily adsorbed on the polyethylene surface with subsequent migration into bulk polymer. Transportation of PAHs through the bulk can be described satisfactorily by Fickian laws of diffusion and is consistent with the theory of the depth adsorption of PAHs in polyethylene.     

Emission of polycyclic aromatic hydrocarbons in China

Emission of 16 polycyclic aromatic hydrocarbons (PAHs) listed as U.S. Environmental Protection Agency (U.S. EPA) priority pollutants from major sources in China were compiled. Geographical distribution and temporal change of the PAH emission, as well as emission profiles, are discussed. It was estimated that the total PAH emission in China was 25,300 tons in 2003. The emission profile featured a relatively higher portion of high molecular weight (HMW) species with carcinogenic potential due to large contributions of domestic coal and coking industry. Among various sources, biomass burning, domestic coal combustion, and coking industry contributed 60%, 20%, and 16% of the total emission, respectively. Total emission, emission density, emission intensity, and emission per capita showed geographical variations. In general, the southeastern provinces were characterized by higher emission density, while those in western and northern China featured higher emission intensity and population-normalized emission. Although energy consumption in China went up continuously during the past two decades, annual emission of PAHs fluctuated depending on the amount of domestic coal consumption, coke production, and the efficiency of energy utilization.     

Removal of polycyclic aromatic hydrocarbons from contaminated soil by aqueous DNA solution

An aqueous DNA solution was applied for the extraction of polycyclic aromatic hydrocarbons (PAHs) from a spiked soil. Solubilities of 0.56, 11.78, and 11.24 mg L(-1) for anthracene, phenanthrene, and pyrene, respectively, were achieved after 1 day equilibration in 1% DNA. Using a spiked soil that contained 72 mg kg(-1) anthracene, 102 mg kg(-1) phenanthrene, and 99 mg kg(-1) pyrene, extractions of close to 88, 78, and 94%, respectively, were attained with 5% DNA at a 1:50 soil/extractant ratio. Maximum PAH dissolution occurred after 4-6 h. Comparative tests showed the main advantage of DNA over methyl-beta- and gamma-cyclodextrins and Tween 80 for pyrene removal. An ionic strength of 0.1 M NaCl was found necessary for maximum PAH dissolution and extraction. The performance of hexane regenerated DNA also remained stable after three stages of recycling. These results show the huge potential of DNA as an aqueous washing agent for PAH-contaminated soil.     

Effects of a chemical company fire on the occurrence of polycyclic aromatic hydrocarbons in plant foods

On Friday, September 1, 2006, the facilities of a chemicals distributor in the Spanish town of Caldas de Reis, were almost completely destroyed as a result of a fire. Comprehensive liquid chromatography-fluorescence detection (LC-FD) analyses were performed on plant foods to determine the toxic impact of this kind of accident on population. PAHs from a polluted atmosphere are generally transferred to plants by particle-phase deposition on the waxy leaf cuticle or by uptake in the gas phase through stomata. PAH levels in all samples were not alarming (total PAHs were below 4.240 ng/g) and the PAH profiles were similar, with the exception of peppers, in all vegetal materials (5-to-4 rings ratio of 1–2), suggesting the similarity in source type (the fire). PAH concentrations in plants were related to their surface exposed to air, indicating that the contribution of soil/water PAHs to plants (aerial part) accumulation was insignificant.     

Desorption kinetics for field-aged polycyclic aromatic hydrocarbons from sediments

This study considers desorption kinetics for 12 field-aged polycyclic aromatic hydrocarbons (PAHs) desorbing from size- and density-fractionated sediments collected from two locations in the New York/New Jersey Harbor Estuary. Desorption kinetics for PAHs with a log octanol-water partition coefficient greater than 6 were well-described by a one-domain diffusion model that assumes that PAHs are initially uniformly distributed throughout spherical sediment aggregates. PAH hydrophobicity and sediment specific surface area were the parameters most strongly correlated with the magnitude of the observed diffusivity for the one-domain model. For less hydrophobic PAHs, a two-domain desorption model was used also, and the results suggest that a substantial fraction of these field-aged PAHs desorb via a relatively fast macro-mesopore diffusion mechanism. The model-predicted fraction of PAHs in the fast-diffusion regime by compound and sediment was highly correlated with the measured percent PAH desorption in 24 h. The fast-domain diffusivity was 100 times greater than the slow-domain diffusivity, was correlated with both PAH properties and sediment physical and chemical properties, and could be estimated by readily obtainable physical and chemical parameters. In contrast, the slow-domain diffusivity was not significantly correlated with PAH properties. Our results suggest that macro-mesopore diffusion may control mass transport of less-hydrophobic PAHs in estuarine sediments.     

New method for testing phototoxicity of polycyclic aromatic hydrocarbons

Polycyclic aromatic hydrocarbons (PAHs), widespread environmental pollutants, were recently reported to show photomutagenesis. As contaminants in the environment are usually exposed to sunlight, a way to evaluate the phototoxic characteristics of pollutants is required. We have previously found that phosphorylation of histone H2AX (gamma-H2AX), which accompanied the induction of DNA double strand breaks (DSBs), was significantly induced by low concentrations of benzo[a]pyrene (10(-9)-10(-7) M) and UVA (0.6 J/cm2) in CHO-K1 cells. Higher concentrations have been required for the detection of DSBs. The aim of the present study is to investigate the applicability of gamma-H2AX in a new phototoxicity assay of PAHs. The human keratinocytes, HaCaT, were treated with four model PAHs (naphthalene, phenanthrene, pyrene, and benzo[a]pyrene, 10(-11)-10(-7) M) and/or UVA (5 J/cm2), and the induction of gamma-H2AX was assessed. Furthermore, DSBs were directly detected using a biased sinusoidal field gel electrophoresis, and the cell viability was examined as a general assay of phototoxicity. The induction of gamma-H2AX was detected in the presence of all the PAHs except naphthalene at concentrations of 10(-9)-10(-7) M, whereas neither DSBs nor cell death could be detected at those concentrations, and higher concentrations were required for the detection. Naphthalene showed no phototoxicity in any of the three different assays. These findings suggest that histone H2AX is a potential moleculartargetfor detecting the phototoxicity of PAHs more sensitively than the detection of cell viability and DSBs.     

食用油中多环芳烃的研究进展

多环芳烃(PAHs)是指2个或2个以上苯环以稠环形式相连的一类化合物,具有基因毒性和致癌性.对食用油中PAHs的来源、检测方法及控制和脱除方法进行了详尽的阐述,并指出PAHs前处理方法和控制、脱除方法是未来的研究方向.