Risk assessment of PCDD/Fs levels in human tissues related to major food items based on chemical analyses and micro-EROD assay

Nine groups of food items (freshwater fish, marine fish, pork, chicken, chicken eggs, leafy, non-leafy vegetables, rice and flour) and three types of human samples (human milk, maternal serum and cord serum) were collected for the analysis of PCDD/Fs. Results of chemical analysis revealed PCDD/Fs concentrations (pg g^− 1 fat) in the following ascending order: pork (0.289 pg g^− 1 fat), grass carp (Ctenopharyngodon idellus) (freshwater fish) (0.407), golden thread (Nemipterus virgatus) (marine fish) (0.511), chicken (0.529), mandarin fish (Siniperca kneri) (marine fish) (0.535), chicken egg (0.552), and snubnose pompano (Trachinotus blochii) (marine fish) (1.219). The results of micro-EROD assay showed relatively higher PCDD/Fs levels in fish (2.65 pg g^− 1 fat) when compared with pork (0.47), eggs (0.33), chicken (0.13), flour (0.07), vegetables (0.05 pg g^− 1 wet wt) and rice (0.05). The estimated average daily intake of PCDD/Fs of 3.51 pg EROD-TEQ/kg bw/day was within the range of WHO Tolerable Daily Intake (1–4 pg WHO-TEQ/kg bw/day) and was higher than the Provisional Tolerable Daily Intake (PMTL) (70 pg for dioxins and dioxin-like PCBs) recommended by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) [Joint FAO/WHO Expert Committee on Food Additives (JECFA), Summary and conclusions of the fifty-seventh meeting, JECFA, 2001.]. Nevertheless, the current findings were significantly lower than the TDI (14 pg WHO-TEQ/kg/bw/day) recommended by the Scientific Committee on Food of the Europe Commission [European Scientific Committee on Food (EU SCF), Opinions on the SCF on the risk assessment of dioxins and dioxin-like PCBs in food, 2000.]. However, it should be noted that micro-EROD assay overestimates the PCDD/Fs levels by 2 to 7 folds which may also amplify the PCDD/Fs levels accordingly. Although the levels of PCDD/Fs obtained from micro-EROD assay were much higher than those obtained by chemical analysis by 2 to 7 folds, it provides a cost-effective and rapid screening of dioxin levels in food and human samples.     

Polybrominated diphenyl ethers in food and associated human daily intake assessment considering bioaccessibility measured by simulated gastrointestinal digestion

The concentrations of PBDEs in 299 vegetable and animal-based food samples of 31 species, collected in Shanghai, China, and the bioaccessibility of PBDEs in part of the samples were determined. The PBDE concentrations ranged from 0 to 1245.4 pg g⁻¹ with animal-based food containing more PBDEs than vegetables. The bioaccessibility of PBDEs, determined by a method simulating human gastrointestinal digestion process, were from 2.6% to 39.9% in vegetables, and from 5.2% to 105.3% in animal-based food. For animal-based food, good correlations were observed between the bioaccessibility of PBDEs and the fat content, thus the fat content in animal-based food was able to be used to estimate the bioaccessibility of PBDEs. The total daily intake of PBDEs via ingestion of vegetables and animal-based food for an average Shanghai resident was estimated as 13 235.7 and 13 668.0 pg d⁻¹, respectively, but the amounts available for human absorption were reduced to 2674.4 and 4316.6 pg d⁻¹ after the PBDE bioaccessibility was considered. Finally, the contributions of different food groups to the total daily intake of PBDEs were evaluated. The results revealed that, when not considering the bioaccessibility of PBDEs, vegetables were the leading contributor (49.2%), followed by fish (34.0%). However, the sequence was reversed after the PBDE bioaccessibility was taken into account. The results indicated that human exposure to PBDEs via food ingestion might have been significantly overestimated and the exposure assessment could be misleading if the bioaccessibility of PBDEs was not considered.     

Alterations in Carbohydrate Metabolism in Selected Tissues of Crab,Oziotelphusa Senex Senex (Fabricius) Under Fenvalerate-Induced Stress

Changes in carbohydrate metabolism in hepatopancreas and muscle of the crab, Oziotelphusa senex senex exposed to a sublethal concentration (0.2 ppm) of fenvalerate, a pyrethroid insecticide, were studied. the glycogen and total carbohydrate levels decreased significantly in the tissues of crab exposed to fenvalerate. an increase in phosphorylase ‘a’ and decrease in aldolase activity levels suggested increased glycogenolysis, and decreased glycolysis during fenvalerate toxicity. Krebs cycle enzymes such as NAD-isocitrate dehydrogenase, succinate dehydrogenase and malate dehydrogenase were decreased, suggesting reduced mitochondrial oxidative metabolism. Glucose-6-phosphate dehydrogenase activity was increased significantly, indicating enhanced oxidation of glucose through the hexose monophosphate shunt pathway. Lactate dehydrogenase activity was elevated indicating the development of anaerobic conditions at tissue level in the stressed crab. Cytochrome C oxidase and Mg2+ ATPase activity levels were also decreased, indicating the impaired energy synthesis and prevalence of energy crisis. These results suggest that fenvalerate has a profound effect on the glucose metabolism of crab.     

Pesticide residues intake of French adults under increased consumption of fresh fruits and vegetables – A theoretical study

The increase of fresh vegetable and fruit (FVF) intake could contribute to the prevention of obesity and several major pathologies and thus represents a major public health goal in industrial countries. Nutritional recommendations for increased consumption of FVF could lead to ingestion of unwanted amounts of pesticides. This study was undertaken to evaluate theoretical exposure of French adults to pesticide residues under increasing amounts of FVF intake. Balanced menus with 200 – 400 – 600 – 800 and 1200 g FVF/day were established. Amounts of active substances brought by every FVF vector, at the maximum residue level (MRL) were summed up to determine the intake for each active substance. Values were compared to the Acceptable Daily Intake (ADI) to point out any potential over exposure. A maximalistic approach was adopted and no reducing factor due to processing was taken into account. It was found that under minimal recommended consumption of fruit and vegetables (400 g/d), no active substance reached the ADI, but 18 vs 144 were over 10% of the ADI. Raising FVF to 600 g/d increased the number of active substances over 10 % of the ADI to 24, but again in no case was the ADI exceeded. Doubling the intake to 800 g/d gives values over the ADI for 2 active substances only (cyhexatin and thirame). It was concluded that the increase in fruit and vegetables up to 800 g per day should not expose adults over the ADIs for a majority of authorized pesticides. In this regard, residues levels of ten active substances in fruit and vegetables should deserve particular attention.     

果蔬罐头生产废水治理工程设计研究

采用接触氧化-SBR工艺对果蔬罐头生产废水进行治理,其工艺抗冲击负荷能力强,抗污泥膨胀性能较好,对水质水量变化的适应性强。本文对该公司废水来源及水质、废水处理工艺流程及其特点、主要构筑物及其设备参数、工程运行效果做出了详细的分析和讲解。试验研究表明,工艺运行稳定、出水水质较好,能够满足《污水综合排放标准》(GB 8978-1996)中的一级排放要求。     

Heavy Metal Concentrations in Water, Sediments and Body Tissues of Red Worm (Tubifex spp.) Collected from Natural Habitats in Mumbai, India

Live feeds, especially Tubifex spp., which are collected from a wide variety of polluted habitats, are used by aquarium fish keepers in India. These habitats receive domestic sewage and industrial wastes from nearby residential and industrial areas. Reports of morbidity and mortality from aquarium fish culturists in and around Mumbai led to the present investigations on the ecology of these habitats with a view to assess the water quality, presence of heavy metals in the environment and their bioaccumulation in Tubifex worms, and to examine whether these habitats could be exploited to meet the demand of the industry. Six natural red worm (Tubifex spp.) collection centres in Mumbai and Thane districts of Maharashtra state in India constituting a major source of live Tubifex supply to aquarium fish industry were evaluated for pollution, heavy metal concentration in water, sediments and in the body tissues of Tubifex. Data revealed the presence of heavy metals in water and sediments at collection sites and bioaccumulation of cadmium, iron, lead, zinc and copper in body tissues of Tubifex worms. Cadmium ranged from 2.38 to 7.21 mg/kg, iron 671.9 to 5738 mg/kg, lead 14.95 to 33.49 mg/kg, zinc 60.20 to 166.60 mg/kg and copper 29.38 to 108.90 mg/kg of dry Tubifex worms. The study suggests that all the six collection sites are polluted and the red worms contaminated with heavy metals and hence, unfit for use in aquaria or feeding any variety of fish or crustaceans in the hatcheries.     

锌冶炼区菜地土壤和蔬菜重金属污染状况及风险评价

对黔西北地区某典型锌冶炼区菜地土壤和主要蔬菜进行取样调查,测定了土壤和蔬菜可食用部分Pb、Cd、Zn、Cu、As、Ni 6种重金属的含量,采用单项污染指数和综合污染指数法评价了土壤和蔬菜中重金属的污染状况,并分别采用潜在生态风险指数（RI）和目标危险系数法（THQ）评价了菜地土壤重金属污染的潜在生态风险和蔬菜中重金属对成人和青少年儿童的健康风险.结果表明,该区域菜地土壤已受到重金属的重度污染,且以Cd对综合指数的贡献最大,土壤Cd存在极强生态风险,研究区处于轻微、中等、强和很强的生态风险程度的采样点比例分别为2.0%、14.3%、35.7%和48.0%;在所采集的蔬菜样本中,土豆处于重度污染水平,芸豆处于中度污染水平;复合重金属健康风险指数评价结果表明,食用研究区域蔬菜对成人和青少年儿童健康产生负面影响的可能性很大.     

Distribution of PAHs in tissues of wetland plants and the surrounding sediments in the Chongming wetland, Shanghai, China

Polycyclic aromatic hydrocarbons (PAHs) concentrations were determined in sediments and three types of wetland plants collected from the intertidal flats in the Chongming wetland. The concentration of total PAHs in sediments ranged from 38.7 to 136.2 ng g⁻¹. Surface sediment concentrations were higher in regions with plant cover than in bare regions. Rhizome-layer sediments (56.8-102.4 ng g⁻¹) contained less PAHs than surface sediments (0-5 cm). Concentrations of PAHs in plant tissues ranged from 51.9 to 181.2 ng g⁻¹, with highest concentrations in the leaves of Scirpus. Most of the PAHs in the leaves and other plant tissues were low molecular weight compounds (LMW, 2-4 rings), and a similar distribution pattern of PAHs in different types of plants was also observed. Source analysis indicated that plants and sediments both came from pyrogenic sources, but plants had additional petroleum contamination. The low ratio of benzo[a]anthracene over chrysene suggests that the wetland PAHs came mainly from long-distance atmospheric transportation. Significant bioaccumulation of PAHs from the sediments into plants was not observed for high molecular weight PAHs (HMW, 5-6 rings) in Chongming wetland. The small RCFs (root concentration factor from sediments) for HMW PAHs and large RCFs for LMW PAHs suggested that roots accumulated LMW PAHs selectively from sediments in Chongming wetland.     

盆栽条件下常见蔬菜对污染土壤中铀的吸收

通过盆栽实验,研究了胡萝卜、生菜、马铃薯、豌豆4种蔬菜在人工铀污染土壤中的种植情况。结果表明蔬菜吸收铀的能力不同,相同条件下的4种蔬菜可食用部位中铀含量大小顺序为:土豆>生菜叶>胡萝卜>豌豆;平均铀含量分别为:0.26,0.25,0.11,0.09 mg/kg,且均为低铀富集作物。加入铀溶液的土壤所种植的蔬菜样品中铀含量相比对照组土壤均有所升高,但其铀含量未超过国家标准限值,处于安全水平。     

蔬菜水果中的新烟碱类农药残留量与人群摄食暴露健康风险评价

新烟碱类农药是目前被广泛用于农业中的一类作用独特、高效广谱的内吸性杀虫剂,它们在蔬菜水果中的残留对人体健康构成威胁。本研究目的是查明北京市场上蔬菜水果中不同新烟碱类农药的残留量,并对人群摄食暴露健康风险进行评估。从北京市场上采集49种蔬菜和24种水果,采用Qu ECh ERS–高效液相色谱串联质谱(HPLC-MS/MS)法测定蔬菜水果中9种新烟碱类农药的含量。利用测得数据和中国居民膳食结构调查资料,采用蒙特卡罗模拟方法计算了不同年龄段人群的日均经口摄入暴露量的概率分布,并采用商值法计算了新烟碱类农药的非致癌风险。结果显示新烟碱类农药普遍存在于北京市场上的蔬菜水果中。49种蔬菜样品中检出7种新烟碱类农药,其中吡虫啉、啶虫脒和噻虫嗪检出率均达100%,噻虫胺、烯啶虫胺、噻虫啉和呋虫胺的检出率分别为47%、14%、10%和4%。24种水果样品中检出5种新烟碱类农药,其中吡虫啉和啶虫脒的检出率均达100%,噻虫嗪、噻虫胺和噻虫啉的检出率分别为54%、13%和4%。不同新烟碱类农药在蔬菜水果中的含量范围为0.01 ng·g~(-1)~126 ng·g~(-1),均未超过我国食品安全国家标准或美国联邦管理条例中的限量值。小部分(约3%)人群因摄食蔬菜水果暴露于新烟碱类农药的非致癌风险商值大于0.1。新烟碱类农药在蔬菜水果中普遍存在,对人体健康有潜在的风险。