Dietary accumulation efficiencies and biotransformation of polybrominated diphenyl ethers in farmed Atlantic salmon (Salmo salar).

The consumer safety of farm-raised salmon could be improved by determining the transfer efficiency of hazardous pollutants from fish feed to the salmon. A controlled feeding trial for 30 weeks was carried out to investigate the transfer of polybrominated diphenyl ethers (PBDEs) in Atlantic salmon (Salmo salar). Using three feed concentrations, an average of 95% of the total PBDE content of feed accumulated in whole salmon. Skinned fillet accumulated 42-59% of the PBDE intake. Equal partitioning according to the lipid content of the tissue was demonstrated. The formation of less brominated PBDEs via preferential debromination from the meta-position was thought to explain the exceptional accumulation efficiencies of BDE 47, BDE 66, BDE 75, BDE 119 and BDE 183 that were either >100% or else increasing with the exposure dose. Monitoring of a larger number of PBDE congeners is recommended to verify the biotransformation routes. The PBDE concentration in salmon of different ages, fed on a known concentration of PBDEs in fish feed, could be predicted by using the accumulation efficiencies determined in this study.     

Identification of hydroxylated and methoxylated polybrominated diphenyl ethers in Baltic Sea salmon (Salmo salar) blood

Methoxylated and hydroxylated polybrominated diphenyl ethers (MeO-PBDEs and OH-PBDEs) have recently been reported to be present in wildlife from Northern Europe. The structures of a majority of these compounds have however been unknown. In the present study, nine OH-PBDEs and six MeO-PBDEs were identified in Baltic Sea salmon (Salmo salar) blood. All OH- and MeO-PBDEs identified were substituted with four or five bromines, and five of these had one chlorine substituent. Fourteen of the OH- and MeO-PBDEs have the methoxy or hydroxy group substituted in the ortho position to the diphenyl ether bond. Identification was done by comparison of relative retention times of authentic reference standards with compounds present in salmon plasma on two gas chromatographic columns of different polarities. The identification was supported by comparisons of full-scan mass spectrometric data: electron ionization (EI) and electron capture negative ionization (ECNI). Nine of the 15 OH- and MeO-PBDEs identified have not previously been reported to occur in the environment. The structures of several identified OH- and MeO-PBDEs support natural origin. However, at least one of the OH-PBDEs may be a hydroxylated metabolite of anthropogenic polybrominated diphenyl ether (PBDE).     

Exposure to polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (DL-PCBs) and polybrominated diphenyl ethers (PBDEs) through the consumption of prepared meals in Italy

Diet is a relevant source of exposure to environmental pollutants. Dietary intake of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), dioxin-like polychlorinated biphenyls (DL-PCBs) and polybrominated diphenyl ethers (PBDEs) by the Italian population was assessed through a duplicate diet study on prepared meals. Baby food composite representative of the diet of toddlers aged 9–12 months and school canteen servings from four towns in Italy representing the diet of children aged 4–9 years were collected on a 5-day basis. Similarly, 5-day lunches from an office canteen, 7-day lunches from a hotel-school, three fast food meals, and eight duplicate 1-day meals of individuals (one vegetarian) were selected to represent the diet of adults aged above 18 years. Servings from each diet were then pooled to form a composite and analysed. Dietary intake was estimated from the resulting contaminant levels in composites combined with age-related food consumption data from national survey. The mean upper bound (UB) intakes for cumulative PCDDs, PCDFs, and DL-PCBs were 0.67, 0.63–0.92, and 0.27–0.63 pg WHO₂₀₀₅-TE kg^?1 body weight (bw) day^?1 for toddlers, children and adults, respectively. BDE-47 (UB) ng kg^?1 bw day^?1 estimates were 2.75 in toddlers, 0.08–0.16 in children and 0.03–0.09 in adults. Similarly, for BDE-99 higher UB intakes (ng kg^?1 bw day^?1) resulted in toddlers (1.26), than those in children (0.06–0.08) and adults (0.03–0.10), respectively. The above estimates fall below the tolerable weekly intake (TWI) (14 WHO₂₀₀₅-TE kg^?1 bw day^?1) established by the European Union Scientific Committee on Food (SCF) for PCDD/Fs and DL-PCBs. The margin of exposure (MOE = 3) of toddlers to BDE-99 clearly indicates this age group as target for a risk-oriented approach. This study is proposed as a first cost-effective screening in PCDD, PCDF, DL-PCB and PBDE intake assessment, with a focus also on time trends.     

Seasonal and geographical variations in levels of polychlorinated biphenyls (PCB) and polybrominated diphenyl ethers (PBDE) in Polish butter fat used as an indicator of environmental contamination

The aim of this study was to evaluate the seasonal variation/geographical distribution of environmental concentration of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) across Poland using butter fat as an indicator of the contaminants. The average concentration of six indicator PCBs determined in the studied samples was 1500?pg?g^–1 fat. The average concentration of 12 dioxin-like PCBs expressed as lower-bound dioxin-equivalent toxicity was 0.684 pg TEQ g^?1 fat. The average total concentration of 14 investigated PBDE congeners was 105?pg?g^?1 fat. Statistically significant concentration differences between summer and winter samples were found. The results of this study indicate also a significant geographical diversification of butter contamination reflecting regional differences in environmental contamination. The seasonal variation of PBDE profiles evidences transformation of PBDE within the environment.     

Tissue distribution and elimination of deoxynivalenol and ochratoxin A in dietary-exposed Atlantic salmon (Salmo salar)

ABSTRACT

Post-smolt Atlantic salmon (Salmo salar) were fed standard feed with added 2 or 6 mg kg^–1 pure deoxynivalenol (DON), 0.8 or 2.4 mg kg^–1 pure ochratoxin A (OTA), or no added toxins for up to 8 weeks. The experiments were performed in duplicate tanks with 25 fish each per diet group, and the feed was given for three 2-h periods per day. After 3, 6 and 8 weeks, 10 fish from each diet group were sampled. In the following hours after the last feeding at 8 weeks, toxin elimination was studied by sampling three fish per diet group at five time points. Analysis of DON and OTA in fish tissues and plasma was conducted by liquid chromatography-mass spectrometry and high-pressure liquid chromatography with fluorescence detection, respectively. DON was distributed to the liver, kidney, plasma, muscle, skin and brain, and the concentrations in liver and muscle increased significantly from 3 to 8 weeks of exposure to the high-DON diet. After the last feeding at 8 weeks, DON concentration in liver reached a maximum at 1 h and decreased thereafter with a half-life (t_1/2) of 6.2 h. DON concentration in muscle reached a maximum at 6 h and was then eliminated with a t_1/2 = 16.5 h. OTA was mainly found in liver and kidney, and the concentration in liver decreased significantly from 3 to 8 weeks in the high-OTA group. OTA was eliminated faster than DON from various tissues. By using Norwegian food consumption data and kinetic findings in this study, we predicted the human exposure to DON and OTA from fish products through carryover from the feed. Following a comparison with tolerable daily intakes, we found the risk to human health from the consumption of salmon-fed diets containing maximum recommended levels of these toxins to be negligible.     

Elevated levels of urinary 8-hydroxy-2'-deoxyguanosine in male electrical and electronic equipment dismantling workers exposed to high concentrations of polychlorinated dibenzo-p-dioxins and dibenzofurans, polybrominated diphenyl ethers, and polychlorinated biphenyls

To investigate the occupational exposure levels to polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs), polybrominated diphenyl ethers (PBDEs), and polychlorinated biphenyls (PCBs), indoor dust (n = 3) in workshops and hair samples from male workers (n = 64) were collected at two electrical and electronic equipmentwaste (E-waste) dismantling factories located in the LQ area in east China in July 11--13, 2006. Pre- and postworkshift urines (64 of each) were also collected from the workers to study oxidative damage to DNA using 8-hydroxy-2'-deoxyguanosine (8-OHdG) as a biomarker. The concentrations of PCDD/Fs, PCDD/F-WHO-TEQs, PBDEs, PCBs and PCB-WHO-TEQs were (50.0 +/- 8.1) x 10(3), 724.1 +/- 249.6, (27.5 +/- 5.8) x 10(6), (1.6 +/- 0.4) x 10(9), (26.2 +/- 3.0) x 10(3) pg/g dry weight (dw) in dust, and (2.6 +/- 0.6) x 10(3),42.4 +/- 9.3, (870.8 +/- 205.4) x 10(3), (1.6 +/- 0.2) x 10(6), 41.5 +/- 5.5 pg/g dw in hair, respectively. The homologue and congener profiles in the samples demonstrated that high concentrations of PCDD/Fs, PBDEs, and PCBs were originated from open burning of E-waste. The 8-OHdG levels were detected at 6.40 +/- 1.64 micromol/mol creatinine in preworkshift urines. However, the levels significantly increased to 24.55 +/- 5.96 micromol/mol creatinine in postworkshift urines (p < 0.05). Then, it is concluded that there is a high cancer risk originated from oxidative stress indicated by the elevated 8-OHdG levels in the E-waste dismantling workers exposed to high concentrations of PCDD/Fs, PBDEs, and PCBs.     

Organoleptic characterization and PAH content of salmon (Salmo salar) fillets smoked according to four industrial smoking techniques

Four industrial processes for smoking food were studied through their effects on the organoleptic properties of smoked salmon and on the occurrence of 20 polycyclic aromatic hydrocarbons (PAHs) known as being contaminants of smoking processes. The contamination by PAHs of the food might be measured by their corresponding toxic equivalent quantity (TEQ) expressed in µg kg^?1. The results show a significant correlation between the smoking process parameters, the odour of the smoked fish and the presence of PAHs. Smouldering, thermostated plates and friction smoking processes allow smoked fish with very close odorant characteristics to be obtained. However, differences of pyrolysis temperature (between 380 and 500 °C) causes significant differences of PAHs concentration even if the contents are under the legal threshold concerning benzo(a)pyrene (5 µg kg^?1). Smoked fish obtained by liquid smoke vaporisation presented the lowest level of PAHs but benzo(a)pyrene concentration is nevertheless important. The odours brought by the liquid smoke process are more ‘cold smoke’ and ‘vegetal/green’ than the other techniques, which are smokier and fishier. Copyright © 2007 Society of Chemical Industry     

Development and application of a simplified clean-up procedure for the determination of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in horse fat by gas chromatography-tandem mass spectrometry (GC-MS/MS)

A simplified clean-up procedure was developed in combination with gas chromatography-tandem mass spectrometry (GC-MS/MS) for the determination of polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in adipose tissue. Clean-up was performed by the successive application of a Mega Bond Elut® silica column and a Bond Elut® PCB column. Validation of the method was conducted according to European Union Commission Decision 2002/657/EC. In order to evaluate the applicability of the method, 44 horse fat samples were analysed. The total PCB concentration (sum of PCBs 28, 52, 101, 118, 138, 153 and 180) ranged from 5.35 to 140 ng g^-1 lipid weight. The total PBDE concentration (sum of BDEs 28, 47, 99, 100, 153, 154 and 183) ranged from below the decision limit to 6.34 ng g^-1 lipid weight.     

Influence of chloride and metals on silver bioavailability to Atlantic salmon (Salmo salar) and Rainbow trout (Oncorhynchus mykiss) yolk-sac fry

The effects of differing water chloride concentrations (0-10 mM) or competing metals [Cu(II), Cd(II), Zn(II), Pb(II), Co(II) (1-10,000 nM)] on Ag(I) uptake in yolk-sac fry of two salmonid species, the Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), were studied. None of the metals tested were strong competitors of Atlantic salmon yolk-sac fry whole body Ag(I) influx. Inhibition of Ag(I) influx was only seen with a 100-fold excess of Cu(II) or Cd(II) or a 1000-fold excess of Pb(II) or Co(II). At these concentrations, the degree of competition appears to be directly proportional to the conditional stability constant of the competing metal to the gill (metal-gill log K). The range of [Cl-] allowed an assessment of Ag+, AgCl(aq), and AgCl2- bioavailability. The pattern of Ag(I) uptake was similar for each fish species. At <1 mM Cl-, where the [Ag+] dominates, the Ag(I) accumulation rate was constant. Above 1 mM Cl-, where the [AgCl(aq)] is dominant and the [AgCl2-] increases, there was a decline in Ag(I) uptake rate. However, even when very little Ag+ was present (i.e., at 10 mM Cl-) Ag(I) accumulated, albeit at a lower rate. This was suggestive of passive influx by AgCl(aq) and indicated little or no entry of negatively charged silver chloride complexes. The decline in Ag(I) uptake above 1 mM Cl- demonstrated that, if Ag(I) was present as both Ag+ and AgCl(aq), salmonid Ag(I) accumulation was dominated by Ag+ uptake. Therefore, the order of bioavailability of the Ag(I) species was determined as Ag+ > AgCl(aq) > AgCl2-.     

The quality of cold-smoked Atlantic salmon (Salmo salar) as affected by salting method, time and temperature

The effects of temperature (4 and 10–12 °C) and time (6, 12 and 24 h) on colorimetric parameters (Commission International de l'Eclairage (CIE) L*a*b*), carotenoid concentration, salt content and yield were investigated in brine (saturated or 50% saturation) and dry salted fillets of cold‐smoked Atlantic salmon (Salmo salar). Lightness (L*), yellowness (b*), hue (H_ab) and chroma (C*) values were lower at 10 than 4 °C (P < 0.01), whereas redness (a*) was unaffected. L* increased (P < 0.05) and a*, b*, H_ab and C* values dropped when salting time was increased (P < 0.001). Astaxanthin concentration of brine‐salted fillets decreased with increasing salting time (P < 0.05), but was unaffected by salting temperature. Increasing salting time affected colour negatively. The salt content of dry salted fillets increased with temperature and salting time. The process yield was unaffected by temperature and decreased with salting time. In conclusion, the cold smoking process is more important for variation in quality parameters than the salting process.     

Butter as an indicator of regional persistent organic pollutant contamination: further development of the approach using polychlorinated dioxins and furans (PCDD/Fs), and dioxin-like polychlorinated biphenyls (PCBs)

The potential for use of butter as a widely available, relatively uniform lipid-rich matrix for the determination of spatial distributions of persistent organic pollutants has already been demonstrated. The present study determines the contributions to toxicity equivalence (TEQ) from polychlorinated dioxins and furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) using butter samples from 24 countries world wide. Concentrations of PCDD/Fs and dioxin-like PCBs ranged from 0.07 to 5.69 pg ΣWHO-TEQ g -1 lipid. For most samples, PCDD/F TEQ fell within ranges reported for European dairy products over the last decade (0.3-2 pg g -1 lipid I-TEQ), though a single sample from Spain was a notable exception. Other than this sample, the highest values were recorded for samples from the Netherlands and Italy, with those from India, China and Tunisia also being relatively high. The contribution from non- ortho -PCBs was particularly significant in samples from Germany, Austria, Italy, the Czech Republic, Tunisia, India and Argentina. Although overall TEQs were generally highest in European and Mediterranean butters, elevated levels were also apparent in industrializing regions of Asia (India, China) and Latin America (Argentina). More detailed regional studies would be necessary to identify likely dioxin and PCB sources in each case. Nevertheless, this study supports the utility of butter as a monitoring matrix that may be especially applicable in regions for which monitoring programmes are currently lacking.     

Modelling of the feed-to-fillet transfer of ethoxyquin and one of its main metabolites,ethoxyquin dimer,to the fillet of farmed Atlantic salmon (Salmon salar L.)

ABSTRACT

Ethoxyquin (EQ) is an antioxidant supplemented to feed ingredients, mainly fish meal, which is currently under re-evaluation for use in the food production chain. EQ is partly metabolized into several metabolites of which the ethoxyquin dimer (EQDM) accumulates most in the farmed fish fillet. In this study, the feed-to-fillet transfer of dietary EQ and EQDM in Atlantic salmon fillet was investigated, and a physiologically based pharmacokinetic (PBPK-) two-compartmental model was developed, based on experimental determined EQ and EQDM uptake, metabolism, and elimination kinetics. The model was verified with an external data-set and used to simulate the long term (>1.5 years) EQ and EQDM feed-to fillet transfer in Atlantic salmon under realistic farming conditions such as the seasonal fluctuations in feed intake, growth, and fillet fat deposition. The model predictions showed that initial EQDM levels in juvenile fish are the driving factor in final levels found in food-producing animals, while for EQ the levels in feed, and seasonal variations were the driving factor for food EQ levels.     

Effects of dietary alpha-tocopheryl acetate on lipid oxidation and alpha-tocopherol content of novel omega-3-enhanced farmed rainbow trout (Oncorhynchus mykiss) fillets

A trout diet was supplemented with 0, 8.5, or 15 g/100 g of flaxseed oil (FO). To prevent lipid oxidation of fillets, FO-supplemented diets were also enhanced with 0, 400, and 900 mg/kg of alpha-tocopheryl acetate (α-TA). Total fat, moisture content, lipid oxidation, fatty acid profile, and α-tocopherol content of fillets were determined following fish harvest on days 0, 30, 60, 90, and 120. FO supplementation resulted in increased (P<0.05) concentration of omega-3 fatty acid (ω3 FA) in fillets, mainly due almost two-fold increase (P<0.05) of α-linolenic acid, while docosahexaenoic and eicopentaenoic acids slightly decreased (P<0.05). Regardless of supplementing trout diets with FO or α-TA, no (P>0.05) difference of the total fat in fillets was measured. The highest (P<0.05) α-tocopherol content in fillets was determined when supplementing trout with 900 mg/kg of α-TA at day 120. The effect of retarding lipid oxidation in fillets was recorded after supplementing trout with α-TA for 60 days. Our results indicate that regardless of FO level in trout diet, 900 mg/kg of α-TA can prevent lipid deterioration of fillets. However, to achieve more pronounced antioxidant effect in the ω-3-enhanced trout fillets, a synergetic effect of antioxidants and anaerobic packaging with α-TA supplementation should be investigated.     

Analysis of incurred crystal violet in Atlantic salmon (Salmo salar L.): comparison between the analysis of crystal violet as an individual parent and leucocrystal violet and as total crystal violet after oxidation with 2,3-dichloro-5,6-dicyanobenzoquinone

Due to on-going concern about the occurrence of triphenylmethane dye residues in fish destined for human consumption, a depletion study of crystal violet in salmon was carried out. Atlantic salmon less than 12 months old were exposed to crystal violet in fresh water at 15°C and subsequently sampled at 1, 7, 14, 28, 63 and 91 days after exposure. The salmon were then analysed by two analytical methods. In the first method, 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ) was used to oxidise leucocrystal violet to its parent form. Total parent crystal violet was then analysed by LC-MS/MS. In the second method, crystal violet and leucocrystal violet were analysed individually by LC-MS/MS without oxidation. Both methods gave comparable results for total crystal violet concentrations, with a correlation of r ^2?=?0.69. Statistical treatment for 88 incurred salmon samples showed no significant difference between the two sets of results with t?=?1.68 and t _crit?=?1.99. Up to 98% of crystal violet was metabolised to its leuco form in the salmon after 1 day of exposure and could be detected at significant concentrations (approximately 20?µg?kg^–1) 91 days after exposure. The depletion data also suggest that crystal violet has a half-life of approximately 15–16 days in salmon.