Recent survey and effects of cooking processes on levels of PCDDs,PCDFs and Co-PCBs in leafy vegetables in Japan

We report here the latest levels of polychlorinated dibenzo-p-dioxins/polychlorinated dibenzofurans (PCDD/Fs) and coplanar polychlorinated biphenyls (Co-PCBs) in leafy vegetables in Japan as well as the effect of cooking processes on the reduction of these contaminants. Three kinds of leafy vegetables (“komatsuna”, lettuce and spinach) from seven districts in Japan in 1998 were analyzed for the 2,3,7,8-chlorine substituted PCDD/Fs and three non-ortho-PCBs (#77, 126 and 169). The mean total TEQ levels (using the WHO-TEFs) in the komatsuna, lettuce and spinach were 0.094, 0.025 and 0.196 pg/g fresh weight, respectively. The TEQ levels are dominated by 2,3,7,8-TCDD, 1,2,3,7,8-PeCDD, 2,3,4,7,8-PeCDF and 3,3^′,4,4^′,5-PeCB in many of the samples. For one of these isomers, the 2,3,4,7,8-PeCDF TEQ levels showed good correlation with the total TEQ levels in the samples (r=0.957). This suggests that 2,3,4,7,8-PeCDF may be an indicator for dioxin contamination in the analysis of the leafy vegetables. Also, the effects of two cooking processes (washing and washing followed by boiling) on the dioxin levels in two types of spinach samples were investigated. On average, in both samples, the total concentrations of the PCDDs, PCDFs and Co-PCB were reduced to about 38%, 73% and 88% of the initial concentrations by washing, and to 21%, 35% and 61% of the initial concentrations by washing followed by boiling. The total TEQ levels were reduced to about 30% of the initial TEQ levels by washing followed by boiling. Significant reductions in the TEQ levels were observed in the cooked samples. Thus, the cooking processes may reduce the risk of dioxin intake from the leafy vegetables.     

杭州市环境空气中二噁英类物质检测与分析

为了解二噁英类物质(PCDD/Fs)在环境空气中污染现状及不同季节不同时段浓度、组成和存在形式等的变化情况,于夏、冬两季对杭州西湖区空气中PCDD/Fs进行了采样分析。结果表明,空气中PCDD/Fs毒性当量浓度与国内其他城市(北京、上海、广州)相近,夏、冬两季空气中PCDD/Fs质量浓度和毒性当量浓度分别为4.92 pg/m3、0.34 I-TEQ pg/m3和4.51 pg/m3、0.40 I-TEQ pg/m3,夏季PCDD/Fs毒性当量浓度略低于冬季;在分时段采样检测结果中,晚间空气中PCDD/Fs质量浓度和毒性当量浓度均高于白天空气中的PCDD/Fs浓度;夏季样品中TCDD/Fs、PeCDD/Fs主要以气相的形式存在,HpCDD/Fs、OCDD/F主要以颗粒相的形式存在,冬季样品中PCDD/Fs主要以颗粒相形式存在。     

Environmental release of dioxins from reservoir sources during beach nourishment programs

In late 1990s, USEPA/FDA made an important connection regarding the presence of elevated levels of dioxins (e.g., 1500 ng kg⁻¹ TEQ) in ball clays mined in Mississippi (USA) from a geological deposit dated to ∼40 million years (Mississippi Embayment) that stretches over several states (northern part of Mississippi to Kentucky) and levels of dioxins in selected animal food sources. Following a recent beach nourishment program along the mid-Atlantic coast of the US, a number of dark gray, blue tinted nuggets of varying sizes were found on beach strands and near the shoreline. Using the presence of these balls of clay (shape, color, and knowledge regarding their use in pottery) on the beach, together with our direct experience analyzing ball clays for dioxins, we made a possible association between these clays and elevated dioxins. Concerns regarding the potential of nourishment programs to cause severe damage to our beaches drove us to test the dioxin content of nourishment exposed clays. A number of the nuggets, along with freshly dredged and deposited sand (collected the morning after nourishment) with the same coloration, and others (sun-bleached), collected approximately 2 weeks after the completion of the nourishment efforts, were analyzed for the presence of PCDD/Fs, PCBs, and selected semi-volatile chlorinated organics. The clay PCDD/F WHO2005-TEQs (dry weight; ND = DL; EMPC = EMPC) ranged from 0.41 to 5.78 ng kg⁻¹ with an average of 2.64 ng kg⁻¹, whereas the sand sample’s TEQs ranged from 0.18 to 0.31 ng kg⁻¹ PCDD/F WHO-2005, with an average of 0.22 ng kg⁻¹. The average total tetra- through octachlorinated dibenzo-p-dioxin concentration was 2700 ng kg⁻¹ (with a maximum of 5800 ng kg⁻¹) for the clays and 8.5 ng kg⁻¹ (with a maximum of 16.8 ng kg⁻¹) for the sand samples. The congener 2,3,7,8-TCDD (TEF = 1) was detected in half of the clay samples (0.11-0.77 ng kg⁻¹). All of the clay and sand samples displayed an unambiguous and dominating 1,4,6,9-chlorination pattern across homolog groups. No other chlorinated aromatics were detected above background levels. The observations, along with the absence or an extremely low level of polychlorinated dibenzofurans, together with the mineralogical analysis, supports the conclusion that off-shore dredging activities are reaching reservoir sources containing dioxin-tainted, smectic/kaolinite clay minerals. Subsequent beach erosion provides additional environmental releases over time, as buried balls of clay from previous nourishment efforts become exposed.     

Exposure to heavy metals and PCDD/Fs by the population living in the vicinity of a hazardous waste landfill in Catalonia, Spain: Health risk assessment

Most fly ashes produced in municipal waste incinerators of Catalonia (Spain) are deposited in a hazardous waste landfill (HWL) placed in Castellolí (Barcelona). This facility means a concern for the population living nearby. In response to this, we performed a probabilistic study focused on assessing human health risks derived from environmental exposure to heavy metals and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) around the HWL. Concentrations of various metals and PCDD/Fs were determined in soil and air samples collected at the HWL, and in 4 locations around it. Health risks were evaluated according to the distance from the sampling locations to the HWL (near and far-sites). In general terms, metal and PCCD/F levels were relatively low in air and soil samples. However, concentrations of PCDD/Fs, as well as those of some metals, were found to be relatively higher in the HWL and Castellolí (the nearest village) samples than in those collected far away, resulting in a slight increase of exposure to those pollutants. Anyhow, the current concentrations of metals and PCDD/Fs suggest that it is highly unlikely that there are any additional non-carcinogenic and carcinogenic risks for the population living near the HWL.     

逆燃式医废焚烧炉烟气实测及灰渣分析

概述了我国目前医疗废物焚烧处置中的主要炉型，着重介绍了LFX-20型逆燃式焚烧炉焚烧处置医疗废物的实际运行工况。通过对医疗废物焚烧烟气进行检测，各项常规指标均低于国标限值，同时对医疗废物焚烧后产生烟气中二恶英和灰渣的检测结果进行了分析，并给出分析结论。     

Changes in Chlorinated Organic Pollutants and Heavy Metal Content of Sediments during Pyrolysis (7 pp)

Background There has been an increasing concern about the treatment and disposal of contaminated sediment from dredged river, harbor or estuary due to the accumulated toxic organics such as dioxins and inorganics particularly heavy metals like Cr, Pb, Zn, Cu, Hg and Cd. However, considering the huge amount of materials and financial costs involved, any candidate technology must ultimately result to reusable residual by-products. This can only be made possible if the toxic pollutants are removed or stabilized in the raw sediment and then fed back into the materials cycle. Currently, we are developing a pyrolysis process for the commercial-scale cleanup of dioxins and heavy metal-contaminated river sediment to yield reusable char for various economical applications. In this connection, this paper describes our preliminary investigation into the extent of dioxins and heavy metal volatilization from actual contaminated sediment. The stabilization of certain metallic species particularly Cr ions was studied. Methods Laboratory scale pyrolysis experiments were conducted using a special horizontal lab-scale pyrolyzer. Sediment samples from Shanghai Suzhou Creek and Tagonoura Harbor were pyrolyzed in the reactor under nitrogen gas at 800°C and different retention times of 30, 60 and 90 min. A constant heating rate of 10°C min-1 was employed. The pyrolysis gas was first allowed to pass through a cold trap to condense the tar. Uncondensed gases were then channeled through a column containing an adsorbent (XAD-2 Resin) for dioxins. Heavy metal concentrations in the initial and final sediment residues were analyzed by ICP (Nippon Jarrel-Ash) following their acid and alkali (for Cr6+) digestion. Dioxins content of the pyrolysis char, tar, and exhaust gases in the dioxin adsorbent were also determined. For comparative purpose, thermal treatment under air flow was conducted. Results The data for the removal of heavy metals from Suzhou Creek sediment showed very significant reductions in Pb, Zn and Cr6+ content of the sediment at this condition. Percentage removals were 42.4%, 60.8% and 42.2%, respectively. The disappearance of Cr6+ was due to reduction reactions rather than volatilization since the total Cr content remained almost unchanged. Other heavy metals such as Cu, Fe and Ni showed very minimal reductions. Nonetheless, Toxicity Characteristics Leaching Procedure (TCLP) tests confirmed that these residual heavy metals were rather stable in the pyrolysis char. Reduction of toxic Cr6+ at 42.2% has also been achieved by pyrolysis (with N2) as opposed to the more than 580 % increase in Cr6+ observed during thermal oxidation (with air). Discussion Pyrolysis also remove toxic organics particularly dioxins from the sediment. For the total dioxins, removal percentage of 99.9999% was achieved even at the lowest retention time of 30 min. Almost all polychlorinated dibenzo-p-dioxine (PCDDs) and polychlorinated dibenzo-furans (PCDFs) were removed at any retention time. The TEQs detected from the solid residues were mainly contributed by dioxin-like PCBs, yet these were present in relatively trace quantities. At the shortest retention time of 30 min, only 0.000085 pg-TEQ g-1 of polychlorinated biphenyls (PCBs) was detected in the pyrolysis char. Furthermore, the residual PCBs have very low toxicity ratings and none of the highly toxic PCBs, which were initially present in the sediment such as 3,3',4,4',5-PeCB and 3,3',4,4'5,5'-HxCB, were detected in the char. Results further confirmed that most of the dioxins that were removed were transferred to the gas phase so that volatilization may be considered as the main mechanism for their removal. Conclusion Some heavy metals particularly Pb and Zn can be volatilized under N2 pyrolysis at 800oC. Pyrolysis also prevented the formation of more toxic Cr6+ ions and at the same time resulted to its reduction by around 42.2% contrast to the 580% increase during thermal oxidation. PCDDs and PCDFs have been removed and were not formed in the solid products over the retention time range of 30-90 min at 800°C. Dioxin-like PCBs mostly remained and a retention time of 30 min was found sufficient for its maximum removal. Recommendations and Perspective . With the above results, a temperature of 800oC at a retention time of 30 min is sufficient for the removal of total dioxins and some heavy metals by volatilization. It is however necessary to destroy the dioxins as well as recover heavy metals in the gas phase. Stability of remaining heavy metals in the char also needs to be confirmed by leaching tests. These are the major concerns, which we are currently evaluating to establish the feasibility of our proposed large scale pyrolysis system for sediment treatment.     

我国二恶英和多氯联苯的研究现状及对策分析

为了解二恶英(PCDD/Fs)和多氯联苯(PCBs)在中国的研究水平、研究能力和驱动力,本文对有关研究论文的数量、题材、内容、资助来源和研究机构进行了系统调查和分析。调查发现,国内相关研究尚处在起步阶段,研究的方向和重点还需要进一步调整,研究能力有限,研究机构间合作交流不充分。针对这些问题,提出了相应的对策建议。     

垃圾焚烧设施的二噁(口英)类监测方法研究

在欧洲、美国和日本等国家的二噁■类测定方法的基础上,结合我国垃圾组成及其焚烧设施的实际情况,提出可行的废 物焚烧设施二噁■类监测方法,并对该方法进行了实验室内的实验室间的验证实验。与日本环境创造研究所同类二噁■类实验室 对比,分析结果达到了日本环境厅规定的实验室间分析精度要求。     

Bioaccumulation and trophic transfer of dioxins in marine copepods and fish

Despite the great concerns about dioxins in the marine environments, the biokinetics and bioaccumulation of these compounds in marine organisms remains little known. Using radioactive tracers the aqueous uptake, dietary assimilation efficiency, and elimination of dioxins were measured in marine phytoplankton, copepods and seabream. The calculated uptake rate constant of dioxins decreased with increasing trophic levels, whereas the dietary assimilation efficiency (AE) was 28.5-57.6% in the copepods and 36.6-70.2% in the fish. The dietary AE was highly dependent on the food concentrations and food type. The elimination rate constant of dioxin in the copepods varied with different exposure pathways as well as food concentration and food type. Biokinetic calculation showed that dietary accumulation was the predominant pathway for dioxin accumulation in marine copepods and fish. Aqueous uptake can be an important pathway only when the bioconcentration of dioxins in the phytoplankton was low.     

A mixture of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), and non-ortho polychlorinated biphenyls (PCBs) changed the lipid content of pregnant Long Evans rats

Pregnant Long Evans rats received 1.0 μg/kg of dioxin toxic equivalents (TEQ) by oral gavage on the 15th gestational day (GD 15), using a dosing mixture that contained two polychlorinated dioxins, four polychlorinated furans and three non-ortho polychlorinated biphenyls (PCBs). Rats were sacrificed on GD 16, GD 21 and postnatal day 4 (PND 4). The lipid content of fetus, pup, placenta and maternal liver, serum and adipose tissue were determined. Treated GD 16 and GD 21 fetuses had identical lipid content to the control group, yet the lipid content of treated pups on PND 4 was 32% higher than that of the control group. On the other hand, the lipid content of placenta, liver, and serum from the treated dams was 44–50%, 24%, and 38% lower than that of the control group, respectively. Thus, a low-dose mixture of dioxin-like compounds can cause changes in lipid content. The lipid content of offspring was not affected until they were exposed via lactation.