Dioxins (PCDD/Fs) and PCBs in offal: occurrence and dietary exposure.

Offals are widely consumed in different cuisines, but information on the occurrence of dibenzo-p-dioxins, dibenzofurans (PCDD/Fs) and polychlorinated biphenyls (PCBs) in these foods is sparse. In the first structured investigation of its kind, this study reports levels of these contaminants in commonly consumed offals (n=173) such as lamb, ox, deer and pig's liver, kidneys, tongue and heart, and offal products such as pâté, haggis, tripe and black pudding. The results support literature observations on the preferential accumulation of contaminants in liver tissue, as the highest concentrations of PCDD/Fs were observed in liver, relative to the other organs (e.g. 8.4 ng WHO-TEQ kg(-1) lamb liver compared to 1.1 ng WHO-TEQ kg(-1) lamb kidney and 1.27 ng WHO-TEQ kg(-1) lamb heart). Offal products generally showed lower contaminant levels which may be a result of processing or dilution. For most samples, the main contribution to WHO-TEQ arose from PCDD/Fs rather than PCBs. Just under half of the lamb liver samples showed PCDD/F concentrations that exceeded the EU maximum limit of 6 ng kg(-1) fat weight (although deer liver which is not subject to the regulation, generally showed higher levels). Dietary exposure estimates indicate that the weekly consumption of up to two 100g portions of lamb, ox, calf or pig liver or one portion of deer liver would not breach the tolerable daily intake (TDI) level even when the rest of the diet was included. However, the consumption of more than one portion of deer liver per week may lead to the TDI being exceeded.

Polychlorinated naphthalenes (PCNs): congener specific analysis, occurrence in food, and dietary exposure in the UK.

Information on the occurrence of toxicologically significant polychlorinated naphthalenes (PCNs) in food, or on human exposure, is sparse. In this work, PCN congeners (PCNs 52, 53, 66/67, 68, 69, 71/72, 73, 74, and 75) were selected for analysis, based on the available literature on current occurrence and toxicology, and limited by the commercial availability of reference standards. The analytical methodology used cold solvent extraction of prehydrolyzed samples fortified with internal standards ((13)C(10) labeled PCNs), activated carbon and basic alumina purification, and measurement by HRGC-HRMS. The investigation showed PCN occurrence in all studied foods: meat, milk, fish, dairy and meat products, eggs, poultry, vegetables, fruits, etc. The most frequently detected congeners were PCN 52, PCNs 66/67, and PCN 73. The highest concentrations were observed in fish (maximum value of 37 ng/kg w.w. for the sum of the measured congeners). The dioxin-like toxicity (PCN TEQ) associated with these concentrations is 1-2 orders of magnitude lower than those reported for chlorinated dioxins or PCBs in food and, on the basis of dietary intakes estimated using very conservative assumptions regarding concentrations of these contaminants in the UK, the levels of PCNs alone in food do not suggest any toxicological concerns.

Brominated dioxins (PBDD/Fs) and PBDEs in marine shellfish in the UK.

The occurrence of brominated dioxins (PBDD/Fs) and polybrominated diphenyl ethers (PBDEs) was investigated in commonly consumed species of marine shellfish in the UK. Individual samples of Pacific oysters (Crassostrea gigas), native oysters (Ostrea edulis), mussels (Mytilus edulis), scallops (Pecten maximus), and cockles (Cerastoderma edule) were collected from different coastal regions between 2006 and 2007. Samples of a particular species from each site were composited and 60 samples were analysed. Polybrominated dibenzofurans (PBDFs) occurred more frequently and generally at a higher level than polybrominated dibenzodioxins (PBDDs), except for 237-TriBDD, which was the predominant PBDD/F congener in some species, notably oysters. This profile may reflect the environmental distribution of these compounds and the effects of removal mechanisms, such as degradation, selective uptake and metabolism. PBDEs were detected in all samples. The dominant congeners were BDEs 47, 49, 99 and 100 and, to a lesser extent, BDEs 66 and 154. The occurrence of BDE-209 was observed in most samples and appears to be species selective, with the highest values occurring almost exclusively in mussels and cockles. Among the species studied, oysters and mussels displayed relatively higher levels of both sets of contaminants; native oysters, in particular, showed elevated levels of 237-TriBDD (up to 14.5 ng/kg). In general, contaminant levels appeared to be consistent with the extent of local industrialisation with lower levels observed in more remote areas such as the north of Scotland. Polybrominated biphenyls (PBBs) were also measured, and PBBs 49, 52 and 77 were the most frequently detected, although levels were very low. Dietary intakes, estimated for PBDD/Fs, showed that 237-TriBDD from single portions of oysters constituted a high proportion of the total dietary intake of the congener but, otherwise, dietary intakes of PBDD/Fs from shellfish were relatively low.

Brominated and chlorinated dioxins, PCBs and brominated flame retardants in Scottish shellfish: methodology, occurrence and human dietary exposure.

The most commonly consumed shellfish species produced in Scotland - mussels, oysters and scallops - were investigated for the occurrence of a range of brominated and chlorinated contaminants in order to establish current levels and estimate human dietary exposure. Flesh from individual sub-samples was representatively pooled and 35 composites were analysed for brominated and chlorinated dioxins (PBDD/Fs, PCDD/Fs), brominated and chlorinated biphenyls (PBBs, PCBs), polybrominated diphenyl ethers (PBDEs), hexabromocyclododecanes (HBCDs) and tetrabromobisphenol A (TBBPA). The analytical methodology used (13)C(12) labelled surrogates of the target compounds, with GC coupled to (usually) high resolution MS, and LC-MS/MS for HBCD and TBBPA analysis. Positive identifications were made in the majority of samples for most analytes with the exception of TBBPA and most PBDD congeners measured. None of the levels detected for PCDD/F and PCB were above the maximum permitted levels specified in European Union regulations. The levels of brominated furans predominated over brominated dioxins, reflecting the environmental distribution and source emission profiles of these contaminants, and relatively high levels of the tri-brominated congeners were observed. Levels of the flame retardant chemicals reflected current and legacy use, with appreciable concentrations of PBDEs and HBCDs (predominantly alpha-HBCD) but far lower levels of PBBs. TBBPA was not detected in any of the species. In general, mussels and oysters displayed relatively higher levels of contamination than scallops, although the gonad tissue of the latter showed significant levels of brominated dioxins. The estimated adult dietary intakes of PCDD/Fs and PCBs arising from the consumption of a typical portion of these foods in combination with an otherwise average UK diet were in the range 0.5-0.6 pg World Health Organisation (WHO)-toxic equivalent (TEQ)(2005)/kg bodyweight per day. These estimated dietary intakes are well within the Tolerable Daily Intake for dioxins and dioxin-like PCBs of 2 pg WHO-TEQ(2005)/kg bodyweight/day endorsed by the independent expert Committee on Toxicology of Chemicals in Food, Consumer Products and the Environment. The corresponding intakes for sumPBDEs and sumHBCDs were 5.6-6.1 and 5.9-7.9 ng/kg bodyweight/day respectively.

Dioxins and polychlorinated biphenyls (PCDD/Fs and PCBs) in food from farms close to foot and mouth disease animal pyres.

To control the outbreak of foot and mouth disease, which occurred in the UK in early 2001, a large number of farm animals were slaughtered. Where it was not possible to render or landfill the carcasses, they were destroyed by burning on open pyres, with wood, coal and other materials. Uncontrolled combustion such as this is known to produce small quantities of dioxins and an investigation was made into whether, as a result of the burning, there was an elevation in the concentrations of these compounds in food produced in the areas close to the pyres. With few exceptions, concentrations of PCDD/Fs and PCBs were within the expected ranges as predicted by reference data. No accumulation over time was evident from a repeat milk sampling exercise. Where elevated concentrations of PCDD/Fs and PCBs were found in chickens and eggs, they were in samples not destined for the food chain. Elevated levels in some samples of milk from Dumfries and Galloway were not found in earlier or later samples and may have been found as a result of a temporary feeding regime. Elevated concentrations in lamb from Carmarthenshire were from very young animals which would not have entered the food chain. There was no evidence of any significant increase in dietary exposure to PCDD/Fs and PCBs as a result of the FMD pyres.