PCDDs), Dibenzofurans Research Articles

Source identification of PCDD/Fs and PCBs in pine ( Cedrus deodara) needles: A case study in Dalian, China

Factor analysis model with nonnegative constraints (FA-NNC) and positive matrix factorization (PMF) were successful in source identification of polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in pine ( Cedrus deodara) needle samples collected from Dalian, China. The source profiles and source contributions derived from the two receptor models were comparable. The results suggested that the main sources of PCDD/Fs were various combustion processes (58–74%), pentachlorophenol contamination (15–17%), secondary aluminum smelters (9–12%), and traffic emissions (2–13%). As for PCBs, two sources were identified as PCB3 and PCB5, two typical Chinese technical PCB products. The overall source contributions of PCB3 are 72–80% and PCB5 20–28%, which is qualitatively consistent with the proportions of technical PCB products produced in China. This can be the first attempt to semi-quantitatively apportion PCDD/Fs and PCBs in vegetation samples using different receptor models.

TOXICITY EQUIVALENCY VALUES FOR POLYCHLORINATED BIPHENYL MIXTURES

For aquatic, avian, and mammalian species, dioxin equivalency values (TEQs) were computed for Aroclor, Clophen, Kanechlor, Chlorofen, Sovol, Delor, Phenoclor, and Chinese polychlorinated biphenyl (PCB) mixtures by using World Health Organization toxicity equivalency factors (TEFs) and compound-specific compositional data for PCBs, polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs) for the individual mixtures. The TEQs were similar across the different PCB product lines for mixtures of similar chlorine content. Depending on the PCB mixture, the polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) in the mixture contributed anywhere from 0 to 96% of the total TEQs, and the impact of PCDD/Fs was greatest for the fish TEQs. In comparison to the dioxin-like PCBs, few measurements have been performed for PCDD/Fs in the commercial PCB products.

Toxicity reference values for mink exposed to 2,3,7,8-tetrachlodibenzo- p-dioxin (TCDD) equivalents (TEQs)

Dietary and tissue residue-based toxicity reference values (TRVs) were derived for mink from the published results of studies in which mink were exposed to polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs), or related compounds. Because the primary mechanism of toxic action at the least concentration for these compounds is related to activation of the aryl hydrocarbon receptor (AhR), TRVs were described on the basis of 2,3,7,8-tetrachlorodibenzo- p-dioxin (TCDD) equivalents (TEQ). Each published study was critically reviewed for its usefulness in deriving a TRV based on the following criteria: (1) close relatedness of the test species to the wildlife receptor of concern (only mink studies were reviewed in this paper); (2) chronic duration of exposure which included sensitive life stages to evaluate potential developmental and reproductive effects; (3) measurement of ecologically relevant endpoints; (4) availability of congener-specific data to calculate TEQ concentrations; and (5) minimal impact of co-contaminants. Dietary TRVs for mink exposed to TEQ ranged from 12.1 to 56.6 ng TEQ/kg feed (wet weight) for the no observable adverse effect level (NOAEL) and from 50.4 to 242 ng TEQ/kg feed (wet weight) for the lowest observable adverse effect level (LOAEL). TRVs based on tissue residue concentrations ranged from 50.2 to 77.8 ng TEQ/kg liver (wet weight) for the no observable adverse effect concentration (NOAEC) and the value was 189 ng TEQ/kg liver (wet weight) for the lowest observable adverse effect concentration (LOAEC). Selection of a TRV should be based on studies of compounds that are most similar to those at a site of interest. In particular, it was determined that the effects of PCDFs could not be accurately predicted from the use of TEQ-based TRVs developed from studies of PCDDs or PCBs. Risk assessors should be aware that exceedance of these TRVs would not necessarily be expected to lead to ecologically relevant adverse effects because of the inherently conservative assumptions made in the TRV derivation process.

Ion-Trap Tandem Mass Spectrometry for the Analysis of Polychlorinated Dibenzo-p-dioxins, Dibenzofurans, and Dioxin-like Polychlorinated Biphenyls in Food

This paper reports on the applicability of gas chromatography coupled to ion-trap tandem mass spectrometry (GC/ITMS/MS) for the analysis of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (dl-PCBs) in food. MS/MS parameters were selected to achieve the high sensitivity and selectivity required for food analysis. Good precision (RSD=5-18% for PCDD/Fs and 6-14% for dl-PCBs) and low limits of detection for PCDD/Fs (0.1-0.93 pg/g of fat) and dl-PCBs (0.1-0.89 pg/g of fat) were obtained. A comparative study of the congener-specific determination using both GC/ITMS/MS and GC-high resolution mass spectrometry (GC/HRMS) was performed by analyzing several matrices such as milk, fish oil, chicken, pork, fish, eggs, and a chicken compound feed, at low pg/g levels. The results using GC/ITMS/MS were in good agreement with those obtained by GC/HRMS. Consequently, GC/ITMS/MS is proposed for the analysis of PCDD/Fs and dl-PCBs in food and feed samples.

Evaluation of gas-particle partition of dioxins in flue gas II: Estimation of gas-particle partition of dioxins in dust-rich flue gas by parallel sampling with different conditions

For an accurate determination of the gas-particle partition of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like biphenyls (DLPCBs) in dust-rich flue gas, a parallel monitoring procedure with an isokinetic and a non-isokinetic train was used. For four flue gas samples, the two trains gave a significantly different weight of the collected fly ash particles despite the equal gas volume sampled. On the basis of the quantitative values of PCDD/F and DLPCB homologues and the weight of the collected particles, ratios of each homologue in the real flue gas samples in gaseous form were predicted using simultaneous equations. For the four flue gas samples examined, the predicted gaseous ratios were considerably higher that those calculated using a previously reported equation, suggesting that there are some properties which affect partitions of PCDD/Fs in flue gas besides their saturation vapor pressures and fly ash concentration. The partitions for higher temperature flue gases obtained by fractional determinations of each collection device were additionally different from those predicted by the parallel collection, indicating that conventional determination by fractional measurements is subjected to large errors in dust-rich flue gas due to severe adsorption of gaseous PCDD/Fs and DLPCBs onto particles collected on a low-temperature collection device.

Polychlorinated dibenzo- p-dioxins/dibenzofurans distributions in ash from different units in a municipal solid waste incinerator

This study determined the polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) contents in ash in the super heater (SH), economizer (EC), semi-dryer absorber (SDA), fabric filter (FF), fly ash pit (FAP) and bottom residue (BR) in a municipal solid waste incinerator (MSWI). A high-resolution gas chromatograph/high-resolution mass spectrometer (HRGC/HRMS) was utilized for analyzing 17 PCDD/F species. Experimental results showed that average PCDD/F contents in ash samples from the SH, EC, SDA, FF, FAP and BR were 0.102, 0.788, 0.210, 1.95, 2.04 and 0.0218 ng I-TEQ g −1, respectively. PCDD/F content was very low in the SH and BR due to high temperatures (around 461 °C in the SH and 914 °C in combustion chamber). Conversely, total PCDD/F content was significantly high in ash samples from the EC (around 340 °C), mainly because the temperature is within the favorable range of 250–400 °C for PCDD/F formation due to de nova reformation mechanisms. Although the SDA operated at 245 °C, the PCDD/F content decreased very significantly, mainly because the temperature was relatively low and because calcium carbonate was introduced into flue gases to dechlorinate and dilute chlorine-containing species. PCDD/Fs were captured by the active carbon in the FF. Furthermore, the duration that fly ash remained in the FF was longer than that for other incinerator units, and thus causing an increasing trend of PCDD/Fs level downstream (except the SDA). Total PCDD/Fs emission factors (μg tonnes-waste −1; μg I-TEQ tonnes-waste −1) in ash samples from different units were: SH (42.3; 0.846), EC (326; 6.12), SDA (58.1; 1.10), FF (1540; 61.3), FAP (2950; 107) and BR (537; 4.31). Most PCDD/Fs in ash were contributed by the FF (about 56%), and the generation of PCDD/Fs in ash was significant (about 35%) during the transfer process from different units to the FAP. A strong and positive correlation in a logarithmic form existed between PCDD/Fs and chlorine (Cl −1) contents in ash. In Taiwan, the government policy for incineration residues advocates their reuse as road sub-bases or secondary building materials provided that total PCDD/Fs content is below the legal limit (1 ng I-TEQ g −1). Thus, ash with total PCDD/Fs content below the legal limit, such as that from the SH, EC, SDA and BR, can be collected and transferred to the FAP and reused. Ash with total PCDD/Fs content exceeding the legal limit, such as that from the FF, should be collected separately and be treated properly before being disposal in a landfill.

Contamination of Russian Baltic fish by polychlorinated dibenzo- p-dioxins, dibenzofurans and dioxin-like biphenyls

Nineteen species of fish products caught and produced in the Russian economic zone of the Baltic region in 2002–2005 were analyzed for polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like biphenyls (WHO-PCBs). Freshwater fish had significantly lower PCDD/PCDFs levels than most saltwater fish, except cod's fillet for which TEQ was comparable. In some cases pollutant levels of sea fish tissues essentially exceeded current regulatory values. Concentration of WHO PCDD/F-TEQ ranged from 0.06 to 0.57 pg/g f.w. for freshwater fish, and from 0.16 to 17.83 pg/g f.w. for sea fish. The special concern is caused by the high concentration of dioxin-like PCBs, whose contribution to the WHO-TEQ PCDD/F,PCB considerably exceeded that of PCDDs and PCDFs. Concentration of WHO PCB-TEQ ranged from 2.56 to 124.40 pg/g f.w. Profiles of PCDD/Fs congeners in fish were rather similar: in our opinion, the most probable sources of pollution were chlorine bleaching and outflow of PCBs. There is no real reason to assume that fish contamination was affected by the fungicide Ky-5 or similar chlorophenols mixtures. Relative contributions of each dioxin-like PCBs congener to total TEQ in fish tissue are presented in Fig. 2. Profiles of dioxin-like PCBs in general are close to Aroclor 1254, though in some cases there are essential differences.

Ecotoxicological characterization of photoelectrocatalytic process for degradation of pentachlorophenol on titania nanotubes electrode

Luminescence bioassay using Vibrio fischeri and in vitro ethoxyresorufin- O-deethylase (EROD) induction bioassay using H4-IIE rat hepatoma cell were employed to test toxicity changes during the photoelectrocatalysis process for the degradation of pentachlorophenol (PCP) on TiO 2 nanotubes electrode. Acute toxicity of the reaction solution reduced by 83% after 120 min of irradiation. Bioassay-derived 2,3,7,8-TCDD equivalents (TEQ bio) increased from 0.72 to 6.72 ng l −1 during the former reaction stage, decreasing rapidly to 1.25 ng l −1 during the latter reaction stage. HRGC/HRMS analysis detected polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) congeners in the reaction mixtures. TEQ bio and chemical-derived 2,3,7,8-TCDD equivalents (TEQ cal) were about of the same order of magnitude. Both results illustrated the formation of dioxins and their removal by photoelectrocatalysis. Moreover, photoelectrocatalysis showed a significant priority over direct photolysis and photocatalysis depending on the reaction conditions, not only for PCP removal but also for reduction in toxicity.

Polychlorinated Dibenzo-p-dioxins, Dibenzofurans and Dioxinlike Biphenyls in Sediments from the Suzhou Creek, China

Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and biphenyls (PCBs) were detected in sediments from Suzhou Creek with mean concentrations of 478.1, 245.1, and 4727.6 pg/g dw, respectively. WHO-TEQ concentrations of PCDD/Fs in sediments ranged from 2.90 to 13.96 pg/g dw, while TEQ concentrations of PCBs varied from 0.27 to 1.41 pg/g dw. OCDD or HpCDD were the dominant congeners but PeCDF or HpCDD was the major contributor to PCDD/Fs-TEQ in all the sites. For dioxinlike biphenyls, PCB 118 was the major congener while PCB-TEQ was attributable to PCB 126 in all the samples.

Polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls in fish from the Netherlands: concentrations, profiles and comparison with DR CALUX® bioassay results

Fish from Dutch markets were analysed for concentrations of polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (DL-PCBs) and compared with the new European maximum residue levels (MRLs), set in 2006. In a first study on 11 different fish and shellfish from various locations, concentrations of PCDD/Fs were nearly all below the MRL for PCDD/Fs [4 pg toxic equivalents (TEQ) per gram wet weight (ww)] and nearly all below 8 pg total TEQ/g ww, the new MRL for the sum of PCDD/Fs and DL-PCBs. Some samples exceeded the total TEQ MRL, such as anchovy, tuna and sea bass. Furthermore, 20 (out of 39) wild eel samples exceeded the specific MRL for eel (12 pg total TEQ/g ww), as the study revealed PCDD/F TEQ levels of 0.2-7.9 pg TEQ/g ww and total TEQ values of 0.9 to 52 pg/g ww. TEQ levels in farmed and imported eel were lower and complied with the MRLs. Smoking eel, a popular tradition in the Netherlands, only had marginal effects on PCDD/F and DL-PCB concentrations. Owing to volatilization, concentrations of lower-chlorinated PCBs were reduced to below the limit of quantification after smoking. DL-PCBs contributed 61-97% to the total TEQ in all eel samples. This also holds for other fish and shellfish (except shrimps): DL-PCB contributed (on average) from 53 (herring) to 83% (tuna) to the total TEQ. Principal-component analysis revealed distinctive congener profiles for PCDD/Fs and non-ortho PCBs for mussels, pikeperch, herring and various Mediterranean fish. The application of new TCDD toxic equivalency factors (TEFs) set by the World Health Organization in 2006 (to replace the 1997 TEFs) resulted in lower TEQ values, mainly owing to a decreased mono-ortho PCB contribution. This decrease is most pronounced for eel, owing to the relative high mono-ortho PCB concentrations in eel. Consequently, a larger number of samples would comply with the MRLs when the new TEFs are applied. The DR CALUX(R) assay may be used for screening total TEQ levels in eel, in combination with gas chromatography-high resolution mass spectrometry confirmation of suspected samples. An almost 1:1 correlation was found when the 1997 TEFs were applied, but, surprisingly, a 1.4-fold overestimation occurred with application of the 2006 TEFs.

Occurrence of polychlorinated dibenzo-p-dioxins, dibenzofurans and biphenyls pollution in sediments from the Haihe River and Dagu Drainage River in Tianjin City, China

The pollution status of polychlorinated dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in the sediments of Haihe River, which is the most polluted among the seven largest basins in China, Dagu Drainage River flowing through a chemical industry zone, and two other rivers flowing into Bohai Sea in Tianjin City, China were investigated. The concentrations of PCDD/Fs and PCBs in the sediments from the mainstream of Haihe River were 1.3-26pgI-TEQg(-1) dry weight (dw) and 0.07-0.54pgTEQg(-1)dw, respectively. Heavy PCDD/Fs and PCBs pollution, with 1264pgI-TEQg(-1)dw and 21pgTEQg(-1)dw, was found in sediment from Dagu Drainage River. The congener profiles of PCDD/Fs indicated that the principal contamination source was the production of pentachlorophenol (PCP) or PCP-Na in this area. The correlation between PCDD/Fs or PCBs and total organic matter (TOM) showed that PCDD/Fs or PCBs were independent on TOM.

Levels and trends of organochlorines and brominated flame retardants in Ivory Gull eggs from the Canadian Arctic, 1976 to 2004

The ivory gull (Pagophila eburnea) is a circumpolar marine bird which has recently been listed as an endangered species in Canada. To determine whether contaminants may be playing a role in the population decline of this species, ivory gull eggs collected in 1976, 1987 and 2004 from Seymour Island in the Canadian Arctic were analyzed for organochlorines, polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and non-ortho PCBs. This study also provides the first account of polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and polybrominated biphenyls (PBBs) in ivory gulls. The most quantitatively abundant legacy organochlorines found in the ivory gull eggs were p,p'-DDE, SigmaPCB and oxychlordane. Concentrations of the organochlorines analyzed either decreased or showed little change between 1976 and 2004. Concentrations of SigmaPCDD in ivory gull eggs were greater than SigmaPCDF, and the non-ortho PCBs (primarily PCB-126) contributed the largest fraction to the total TEQ value in all years sampled. Concentrations of PCDDs, PCDFs and SigmaTEQ decreased from 1976 to 2004. In contrast, concentrations of the PBDEs steadily increased between 1976 and 2004 driven primarily by increases in BDE-47. Although concentrations of the persistent chlorinated compounds (i.e. organochlorine pesticides, PCBs, PCDDs, PCDFs) reported in this study were below published toxicological threshold values for eggs of wild birds, we cannot rule out the possibility of synergistic/additive, sublethal effects. Very few studies have been carried out to evaluate the exposure-effect relationship of the persistent brominated compounds in avian species. Given the scarcity of information on toxicity threshold levels for PBBs and PBDEs in avian species, coupled with the trend toward increasing concentrations in ivory gulls, continued monitoring and further toxicological studies of these compounds are warranted.

The 2005 World Health Organization re-evaluation of TEFs for dioxins and dioxin-like compounds — What are the consequences for German human background levels?

In 2005 the World Health Organization (WHO) re-evaluated toxicity equivalency factors (TEFs) for dioxins and dioxin-like compounds. WHO 2005 toxicity equivalent (TEq) levels were calculated based on our data on German background levels of polychlorinated dibenzo- p-dioxins (PCDD), dibenzofurans (PCDF) and polychlorinated biphenyls (PCB) in human blood and milk of the Duisburg birth cohort study. Levels of WHO 2005 TEq (PCDD/F+PCB) were in the range of 3.77–63.6 pg/g lipid base ( n=226, median: 19.38, arithmetic mean: 20.86) for blood, or 2.62–59.2 pg/g lipid base ( n=176, median: 19.78, arithmetic mean: 20.57) for milk, respectively. Compared to WHO 1998 TEq values WHO 2005 TEq levels were about 25% lower in both matrices. The shares of PCB (31% blood, 43% milk), especially of mono-ortho-substituted PCB (4% blood and milk), on total WHO 2005 TEq has become lower. If similar congener patterns can be assumed for certain matrices, appropriate multiplication factors can be used to convert TEq values of other TEF models sufficiently to WHO 2005 TEq values.

Polychlorinated dibenzo-p-dioxins/furans and polychlorinated biphenyls in fresh fishes from Qiantangjiang River, China

Muscles of two species of fish collected in Qiangtangjiang River were analyzed for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). Average concentrations of total PCDD/Fs in Crucian carp and White Amur bream were 1.14-7.88 pg g(-1)ww and 1.02-8.18 pg g(-1)ww respectively. Corresponding values for PCBs were 469.36-10972 pg g(-1)ww and 364.79-4948.0 pg g(-1)ww. Average total WHO-TEQ of Crucian carp and White Amur bream from five areas ranged from 0.25 to 2.33 pg g(-1)ww and 0.30 to 1.70 pg g(-1)ww. The contamination level was compared with other studies and risk assessment was discussed.

Intermolecular interactions governing the partition between particulate and gas phases for typical organic pollutants

The partition coefficients between particulate and gas phases (K p) for organic pollutants are of great importance to characterize the behavior of organic pollutants in atmosphere, and are basic data needed by ecological risk assessment. Partial least squares (PLS) regression with 16 theoretical molecular structural descriptors was used to develop polyparameter linear free energy relationship (LFER) model for K p of 18 aliphatic hydrocarbons, 21 polycyclic aromatic hydrocarbons (PAHs), 16 polychlorinated biphenyls (PCBs) and 13 polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs). The obtained model has a good predictive ability and robustness, which can be used for estimating K p of chemicals with similar structures. Intermolecular dispersive interactions play a leading role in governing K p, followed by charge-transfer interactions and hindrance effects of molecular size. The respective models developed for different group compounds imply that the action mechanism is similar, and dipole-dipole and dipole-induced dipole interactions play a minor role in governing K p of n-alkanes, PCBs and PCDD/Fs.

The historical record of PCB and PCDD/F deposition at Greifensee, a lake of the Swiss plateau, between 1848 and 1999

Dated sediment cores provide an excellent way to investigate the historical input of persistent organic pollutants into the environment and to identify possible sources of pollution. The vertical distribution of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/F) and polychlorinated biphenyls (PCB) was investigated in a sediment core from Greifensee to elucidate the historical trends of PCDD/F and PCB inputs between 1848 and 1999. Concentrations of PCB and PCDD/F increased by more than one order of magnitude between 1930 and 1960. PCB and PCDD/F concentrations were 5700 ng/kg dry weight (dw) and 160 ng/kg dw, respectively, in sediments originating from the late 1930s and reached a maximum of 130,000 ng/kg dw and 2400 ng/kg dw, respectively, in the early 1960s. From 1960 on, concentrations decreased to the 1930s level by the mid 1980s. A remarkable shift in the PCDD/F pattern was observed after the early 1940s. Before 1940, the PCDD/F pattern was PCDF dominated (ratio of PCDD to PCDF=0.41+/-0.11), while the PCDD started to be the major species after the early 1940s (ratio of PCDD to PCDF=1.46+/-0.38). The temporal trends of PCB and PCDD/F correlate surprisingly well with each other. This might be due to the coincidence of two factors. The introduction of PCB on the market in the 1930s resulted in emissions due to the widespread use of these industrial chemicals. In the same time period, waste incineration became an increasingly popular way to get rid of garbage, boosting the PCDD/F emissions significantly. The rapid decline of PCDD/F and PCB concentrations in the sediment starting in the early 1960s reflects the result of better emission control techniques in thermal processes and the improvement of waste water treatment in the catchment of Greifensee.

Partial Removal of PCDD/Fs, Coplanar PCBs, and PCBs from Municipal Solid Waste Incineration Fly Ash by a Column Flotation Process

Municipal solid waste incineration (MSWI) fly ash has recently attracted much attention because of its large quantity and enrichment of high toxic combustion generating organohalogen contaminants such as polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), coplanar polychlorinated biphenyls (coplanar PCBs), and polychlorinated biphenyls (PCBs). Since the organohalogen contaminants in MSWI fly ash are known to be enriched in the unburnt carbon (UC) fraction, the organohalogen contaminants can therefore be removed by the removal of UC. In this research, we used a modified column flotation technique to remove the organic contaminants from MSWI fly ash. UC was removed for 27.7% under the flotation condition without chemical flotation aids. The removal efficiencies of UC, PCDD/Fs, coplanar PCBs, and PCBs are further improved by adding flotation aids during the flotation process. UC was removed for 49.0% by adding a collector assistant with a HLB value of 13.5 and a concentration in the kerosene of 3% during the flotation process. In addition,the UC removal efficiencies are increased with the decrease of the diameter of the micropores in the gas spargers. By optimizing the flotation condition, 41.9% total PCDD/Fs, 40.8% coplanar PCBs, and 44.1% PCBs with 64.0% UC have been successfully removed from MSWI fly ash. The total toxic equivalent (TEQ) of the fly ash was decreased from 6.2 ng/g to 4.2 ng/g in the residue.

Selective pressurized liquid extraction of polychlorinated dibenzo- p-dioxins, dibenzofurans and dioxin-like polychlorinated biphenyls from food and feed samples

Selective pressurized liquid extraction (PLE) of polychlorinated dibenzo- p-dioxins/dibenzofurans (PCDD/Fs) and dioxin-like polychlorinated biphenyls (dl-PCBs) from various food and feed samples was performed with a selective PLE method previously developed for bulk PCBs. The method utilizes sulfuric acid impregnated silica inside the extraction cell to oxidize coextracted fat. Extractions were performed at 100 °C with n-heptane for 5 min in two cycles. Data obtained by selective PLE combined with gas chromatography/high-resolution mass spectrometry (GC-HRMS) were compared to concentrations derived from reference laboratories applying conventional sample preparation and GC-HRMS. Experiments performed on spiked vegetable oil, naturally contaminated crude fish oil and oil containing compound feed samples showed good results for these relatively simple matrices. The accuracy was generally ±20% as compared to spiked levels or to values obtained by the reference laboratories. The precision, measured as the relative standard deviation (RSD) for 2,3,7,8-tetrachlorodibenzo- p-dioxin toxic equivalency values (TEQs), was below 10% in all cases. The method was also tested on naturally contaminated herring tissue, chicken tissue, pork tissue and sepiolitic clay, which all caused some trouble. It was observed that sufficient amounts of sodium sulfate should be used for dehydration of tissue samples and additionally, the cells should not be packed too dense in order to avoid suppressed extraction efficiency. Once this was attended to, satisfactory data could be obtained, except for sepiolithic clay. This study demonstrates that selective PLE can be applied with success to a number of food and feed matrices in analysis of PCDD/Fs and dl-PCBs. Since the fat removal step is on-line, the selective PLE method will reduce time and solvent consumption for sample preparation as compared to traditional clean-up.

Concentrations of PCDD/PCDFs and PCBs in fish and seafood from the Catalan (Spain) market: Estimated human intake

The concentrations of polychlorinated dibenzo- p-dioxins (PCDDs), dibenzofurans (PCDFs) and biphenyls (PCBs) in samples from 14 fish and seafood species widely consumed by the population of Catalonia, Spain, were measured. These samples were randomly purchased independently of their geographical origin. The intake of PCDD/Fs and PCBs through consumption of these species was also estimated for various age and sex groups of this population. The highest and lowest levels of PCDD/Fs and dioxin-like PCBs (DL-PCBs) were found in red mullet and shrimp, respectively. For a standard adult man (70 kg body weight), the intake of PCDD/Fs plus DL-PCBs through consumption of fish and other seafood was estimated to be 38.0 pg WHO-TEQ/day. Tuna, hake, and sardine were the species with the highest contribution to this intake. The results of this study indicate that, in general terms, the dietary habits of the population of Catalonia (Spain) regarding fish and seafood consumption do not contribute remarkably to increase PCDD/F and DL-PCB intake.

The use of the DR CALUX® bioassay and indicator polychlorinated biphenyls for screening of elevated levels of dioxins and dioxin‐like polychlorinated biphenyls in eel

The DR CALUX bioassay is a very suitable screening method for dioxins and dioxin-like-PCBs in feed and food. This was, e. g. demonstrated in a survey in the Netherlands to control the dioxin levels in eel. The DR CALUX assay, but also indicator polychlorinated biphenyls (PCB) were evaluated as a screening method. Based on the limit for polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/F) [at that time 8 pg toxic equivalents (TEQ)/g eel], and the relation between PCDD/F and dioxin-like-PCB, a decision limit of 30 pg TEQ/g eel was used for screening of 153 field samples. Suspected samples (21) and part of the higher contaminated negative samples (35) were analyzed by GC/MS for dioxins, non-ortho, mono-ortho and indicator PCB, revealing 13 samples exceeding the action limit of 30 pg TEQ/g eel. Only one sample slightly exceeded the dioxin level of 8 pg TEQ/g eel. The relatively low sensitivity for mono-ortho PCB was overcome by the use of reference samples, as shown by the correlation of 0.93 between GC/MS and CALUX determined total TEQ levels. The present data show that the DR CALUX assay can be used for screening of total TEQ levels in eel. The use for dioxins only requires a safe, and therefore relatively low, decision limit. The indicator PCB also showed a good correlation with total TEQ levels, mainly due to the large contribution of the mono-ortho PCB at higher concentrations. The relation with dioxins was very poor and as such indicator PCB seem less suitable than the DR CALUX assay for screening for dioxins only. The present study clearly shows that part of the wild eel samples contains high total TEQ levels and will exceed the future European Union limit of 12 pg TEQ/g eel for dioxins and dioxin-like PCB. Especially at high TEQ levels, dioxin-like PCB contribute most to the total TEQ. In practice, wild eel presents only a minor part of the eel consumed.