Transfer of PCDDs and PCDFs into the edible parts of farmed rainbow trout, Oncorhynchus mykiss (Walbaum), via feed

This study was carried out to quantify the transfer of polychlorinated dibenzo‐p‐dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) from commercial fish feed into the edible part of rainbow trout (Oncorhynchus mykiss, Walbaum) under normal rearing conditions. Trout were fed with high‐energy feed for salmon (fat content 26–30%) over a period of 19 months. The average weight of the fish increased from 10 g to more than 2092 g, reaching a size of up to 51‐cm length (Tl). Considerable amounts of PCDDs and PCDFs were transferred from the fish feed into the tissue of the trout. Dioxin concentrations increased during the time of feeding from 0.054 up to 0.914 ng WHO‐PCDD/F‐TEQs kg^?1 wet weight and from 4.991 to 15.815 ng WHO‐PCDD/F‐TEQs kg^?1 fat. A correlation was found between the dioxin concentration of the feed and the resulting concentration in the fat of the muscle tissue. The data allow the establishment of transfer rates from a high‐energy diet to farmed rainbow trout.     

二噁英污染事件初步文献调查

对国际上的二噁英污染事件以及国内少量污染源和污染程度的研究报道进行了初步文献调查。自20世纪60年代以来,人类就有意或无意地造成了二噁英的"事故性污染",其实质是人类大量合成二噁英类或含二噁英的物质,以及工业、医药和生活垃圾的堆积、焚烧产生二噁英的结果。20世纪90年代和21世纪初,二噁英污染事件报道频度增加了很多,多为直接针对食品的污染。说明人们对二噁英污染的关注和认识有了很大提高。二噁英污染报道主要集中在欧美等发达国家,这虽不能说明西方发达国家污染较为严重,但可以表明发达国家较为重视二噁英污染,并已率先开展了研究和检测监控。通过初步文献调查,对二噁英污染事件进行了汇总分析。     

Influence of terrestrial lipid and protein sources and activated carbon‐treated fish oil on levels of persistent organic pollutants and fatty acids in the flesh of Atlantic salmon

Reductions in flesh contaminant concentrations were evaluated in a 36‐week feeding trial examining several dietary techniques. Atlantic salmon were fed one of seven dietary treatments for 24 weeks. These diets included a fishmeal, fish oil control diet, an industry control diet, three diets that examined a 75% replacement level of anchovy oil (AO) with flaxseed oil, canola oil and poultry fat, and two diets formulated to be low in contaminants formulated with canola oil, activated carbon‐treated anchovy oil and canola protein concentrate or soy protein concentrate. Following this initial 24‐week feeding interval, a 12‐week finishing diet was utilized to restore the levels of omega‐3 highly unsaturated fatty acids (n‐3 HUFAs). The salmon had marked reductions in their flesh concentrations of total polychlorinated biphenyls (PCBs), dioxin‐like PCBs and total toxic equivalents by the end of the grow‐out phase, but also exhibited significant depressions in their flesh concentrations of n‐3 HUFAs relative to 100AO‐fed fish. The 12‐week finishing diet period was effective in partially re‐instating omega‐3 levels to those present in the flesh lipids of fish fed 100AO while concurrently maintaining lower flesh contaminant concentrations.     

Reducing the levels of dioxins and dioxin-like PCBs in farmed Atlantic salmon by substitution of fish oil with vegetable oil in the feed

Atlantic salmon were fed extruded diets based on either 100% fish oil (FO) or 100% vegetable oil blend (VO) substitution for 22 months. A total of seven distinct feeding periods were studied that incorporated higher levels of dietary oil inclusion, and larger pellet size as fish size increased. Whole fish levels of polychlorinated dibenzo‐p‐dioxins and dibenzofurans (PCDD/F) and dioxin‐like PCBs (DLPCB) were analysed at the beginning and end of each of the seven feeding periods. The PCDD/F and DLPCB concentrations in the FO diets increased from 2.43 to 4.74 ng WHO‐TEQ kg^?1 (TEQ, toxic equivalents), while VO diets decreased from 1.07 to 0.33 WHO‐TEQ kg^?1 as oil inclusion increased. Partial least square regression analyses identified feed concentration, growth rate and feed utilization, but not variations in lipid content, as factors significantly affecting fish PCDD/F and DLPCB levels. Accumulation efficiencies for DLPCB (740 ± 90 g kg^?1) were significantly (P < 0.01) higher than for PCDD/F (430 ± 60 g kg^?1), explaining the increasing dominance of DLPCB levels over PCDD/F levels in whole fish (DLPCB : PCDD/F ratio of 2.4 ± 0.1 for both VO and FO fed fish) compared with feed (DLPCB : PCDD/F ratio of 1.5 and 0.34 for FO and VO feed respectively). Vegetable oil substitution significantly reduced the level of PCDD/F and DLPCB (eightfold and twelve‐fold, respectively) in the fillet of a 2 kg salmon, but, also negatively affected beneficial health components such as fillet n‐3/n‐6 fatty acid ratio.     

生鲜乳中二[口恶]英毒性作用及其机理

二[口恶]英是一类氯代含氧三环芳烃类持久性有机污染物,因为其特有的化学和物理特性,很容易在食物链中积累。二[口恶]英包含多氯二苯并对二[口恶]英(PCDDs)和多氯二苯并呋喃(PCDFs)两大类,其中2,3,7,8-四氯二苯并对二[口恶]英(TCDD)是毒性最强的一种。本文主要就生鲜乳中PCDDs和PCDFs的含量、来源及其中TCDD的毒性作用及其机理进行概述,为相关研究提供一定参考。     

Bioaccumulation of POPs from contaminated sediment to lamprey<Emphasis Type="Italic">(lampetra fluviatilis l.</Emphasis>) larva

Background  Adult sea lampreys, a delicate food species catch from Baltic Sea rivers, migrate from sea and spawn to sediments of still river water areas. Their larva live there four years before return to sea. The few published studies of toxicity of the sediment contaminants to the lamprey larva, however, do not include chlorinated persistent organic pollutants (POPs), thus far. Kymijoki River in southeast Finland is known for high polychlorinated POP contamination which has been measured to accumulate in several bottom fauna and fish species. Goal of the Study  To obtain the first screening results of the bioaccumulation power of POPs from sediment to lamprey larva during their life stage in the contaminated sediment. The accumulated dioxin-type of toxic load (TEQ) was also studied as a possible human hazard. Methods  Surface sediment and lamprey larva were sampled from four localities of the lower Kymijoki River and analysed for MeO-PBDEs, PBDEs, PCBs, PCDDs, PCDEs, PCDFs, and PCDTs by solvent extraction, column clean up and GC/MS procedures. The larva were sorted to seven composites according to locality and (for one place) size of the specimens (to classes of small, medium and large individuals). From the analysis results, TEQ values for composites and the bioaccumulation factors from dry sediment to fresh larva (BSAF), from dry sediment to larva lipid (BSAFlw) and from sediment organic carbon to larva lipid (BSAFoc) were calculated. Results and Discussion  TEQ load was highest (about 500 pg g^-1 ww) in large larva composite due to high bioaccumulation of PCB 118, 1,2,3,4,7,8-hexachlorodibenzo-p-dioxin (D66) and toxic penta- to octa-CDFs. A high positive significant correlation was found between weight and length of larva. Instead, lipid content had no significant correlations with weight and length of larva. Larva lipid or sediment organic carbon did not correlate significantly with any of the calculated BSAF, BSAFlw and BSAFoc values. Therefore, statistical comparisons between substance properties and bioaccumulation rate were possible for BSAF alone. These comparisons indicated a slightly significant increase of PCBs, but very significant decrease of PCDF bioaccumulation from sediment to larva by increase of the number of chlorine atoms (NCI) in the molecule. This property of highly chlorinated PCDFs indicates, as found earlier for local fish, a kinetic control of bioaccumulation by slow release from sediment back to water and the food chain. Recommendation and Outlook  The results obtained point out that bioaccumulation of POPs in lamprey larva is a possible source of toxic hazard to human food consumption and to development of lamprey species. Therefore, both larva and adult lampreys should be studied further for significance of their POP contamination compared with other experiences on impact of POPs to human and wildlife.     

Evaluation of cold‐pressed flaxseed oil as an alternative dietary lipid source for juvenile sablefish (Anoplopoma fimbria)

This study was undertaken to determine the suitability of using cold‐pressed flaxseed oil (FO) as a major source of lipid in place of anchovy oil (AO) in the diet of juvenile sablefish (Anoplopoma fimbria), a relatively new marine species to aquaculture. Sablefish were fed one of four diets twice daily to satiation for 15 weeks. The test diets were identical in composition, except for the source of supplemental lipid which was either 100% AO (100AO), or increasing replacement of AO with FO i.e., 75AO:25FO, 50AO:50 FO or 25AO:75FO. Sablefish growth parameters, whole body and fillet proximate constituent concentrations and apparent digestibility coefficients were uninfluenced by diet treatment. There were also no adverse effects of the diet treatments on fish health, as determined from analysis of various haematological and innate immunological parameters. Terminal fillet fatty acid compositions generally reflected the dietary fatty acid compositions, while flesh contaminant concentration decreased with increasing dietary flaxseed oil content. Results indicated that FO may comprise up to 75% of the supplemental lipid in a grower diet for sablefish, while still providing humans with a rich dietary source of highly unsaturated fatty acids.     

Dietary uptake of dioxins (PCDD/PCDFs) and dioxin-like PCBs in Atlantic salmon (Salmo salar)

Atlantic salmon (Salmo salar) were fed graded levels of dioxins (polychlorinated dibenzo‐p‐dioxins and polychlorinated dibenzofurans) and dioxin‐like polychlorinated biphenyls (DLPCBs) in their diets for 7 months. The dioxin and DLPCB concentrations in both fillet and whole body of salmon increased with increasing dietary exposure. DLPCBs transferred more efficiently from the feed to edible flesh of salmon than dioxins, and contributed a higher proportion to the total toxic equivalents (TEQ). At the end of the trial, the maximum concentrations of dioxins in fillet and whole fish were 1.9 and 2.3 pg WHO‐TEQ g^?1 fresh weight, respectively. Hence with this feeding period even with the most contaminated feed (4.9 pg WHO‐TEQ g^?1 dw) the dioxin concentrations in salmon did not exceed the maximum level set by the European Commission [4 pg WHO‐TEQ g^?1 (EC 2375/2001)]. The inclusion of DLPCBs in this study provides valuable information for forthcoming risk assessments and the future establishment of maximum limits for these compounds in feed and fish.