Alwyn Fernandes

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.

Survey of background levels of PCDDs & PCDFs in UK soils

Abstract Soil samples collected at points on a 50 km grid covering England, Wales and lowland Scotland have been analysed for PCDDs and PCDFs. Mean concentrations for a reduced data set were in the range 6.6 ng kg −1 for PCDD to 191 ng kg −1 for OCDD and from 23 ng kg −1 for PCDF to 41 ng kg −1 for HxCDF. These levels provide an indication of the background concentrations of PCDDs and PCDFs in British soils.

Levels and sources of PCDDs and PCDFs in urban British soils.

Soil samples from five British cities have been analysed for PCDDs and PCDFs. Mean concentrations for PCDD and PCDF congeners were: TCDD, 65 ng Kg−2; PeCDD, 69 ng Kg−1; HxCDD, 154 ng Kg−1; HpCDD, 817 ng Kg−1; OCDD, 9980 ng Kg−1; TCDF, 232 ng Kg−1; PeCDF, 189 ng Kg−1; HpCDF, 156 ng Kg−1; HpCDF, 152 ng Kg−1; and OCDF, 196 ng Kg−1. The mean levels for urban samples are significantly higher (p < 0.001) than rural and semi-urban samples previously reported. Principal component analysis of isomer distributions for urban samples and those of known origin indicate that combustion processes are the principal source of PCDDs and PCDFs in these soils.

Determination of brominated flame retardants in food by LC–MS/MS: diastereoisomer-specific hexabromocyclododecane and tetrabromobisphenol A

The levels of the brominated flame retardants (BFRs) hexabromocyclododecane (α, β and γHBCD diastereoisomers) and tetrabromobisphenol A (TBBPA) have been determined in two studies using LC–MS/MS. The methodology developed was validated in-house and used to analyse UK 2004 Total Diet Study (TDS) samples and shellfish (oysters, mussels and scallops) collected from Scotland. HBCD was detected in most samples; in both studies the αHBCD diastereoisomer was generally the most abundant as opposed to the γ diastereoisomer that tends to dominate in environmental samples and manufactured products. It is reported that selective metabolism or biotransformation of the β and γ diastereoisomers may be taking place. TBBPA was not detected in any samples above the limit of detection, which was as low as 0.05 µg kg–1. This may be because TBBPA, unlike HBCD, is chemically bound to the polymer matrix during manufacture and not readily leached. The UK Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment (COT) concluded that the concentrations of HBCD and TBBPA detected in the TDS study did not raise toxicological concerns and, as levels in the shellfish samples were in a similar concentration range, it was concluded that exposure to the BFRs measured is not significant when compared to exposure from the rest of the diet.

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.

Background levels of polychlorinated biphenyls in British soils

Rural and urban soils from a 50 km grid covering England, Wales and lowland Scotland have been analysed for total polychlorinated biphenyl content and for selected single PCB isomers. These data extend an earlier study17 on background PCB levels in Southern England. PCDD and PCDF concentrations in these samples have been previously reported. In the present study the levels of total PCB ranged from 1.7 to 1199 μg kg−1. Statistical analysis of the data revealed the presence of a distinct sub-group comprising 93% of the samples with a mean total PCB concentration of 9.5 μg kg−1. These results are consistent with other published data2,3 for PCB background levels. Analysis of selected PCB isomer levels was conducted on a sub-group of the survey samples by high resolution gas chromatography/mass spectrometry in the selected ion monitoring mode. Levels of 0.48 to 22.77 μg−1 for the sums of these isomers were observed for background soils.

Domestic coal combustion as a source of PCDDs and PCDFs in the British environment

Abstract Samples of coal soot from UK domestic coal fires have been analysed for PCDDs and PCDFs together with samples of fly ash from UK MSWIs. The results indicate that both domestic coal combustion and household waste incineration are major sources of PCDDs and PCDFs. The significance of coal combustion is further implicated by the analysis of a historical UK soil (1927) which pre-dates recognised sources like large-scale waste incineration and widespread manufacture of organochlorine compounds but not the use of coal for domestic heating.

Investigation into the Occurrence in Food of Veterinary Medicines, Pharmaceuticals, and Chemicals Used in Personal Care Products

Human exposure to emerging contaminants by indirect routes is of increasing interest. This study assessed the contamination of food by chemicals used in human pharmaceuticals (HPs), veterinary medicines (VMs), and personal care products (PCPs). A prioritization study was undertaken to identify the chemicals and food-producing scenarios most likely to result in contamination of food. Around 400 samples of mushrooms, vegetables, aquaculture products, and animal tissues were collected from sites in the United Kingdom, along with aquaculture products imported from Southeast Asia. A number of multianalyte methods were developed and validated for the analysis of the prioritized compounds in these samples. The analysis of all sample-method combinations required approximately 18000 determinations. Around 325 individual residues, including parabens, musk compounds, and antibiotics, were detected in 118 individual samples, but mostly at low nanograms per gram concentrations. Results suggest that the limited contamination of target chemicals occurred in the realistic food-producing scenarios investigated.