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Polychlorinated naphthalenes (PCNs) in Irish foods: Occurrence and human dietary exposure
Chemosphere 85 (2011) 322–328
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Polychlorinated naphthalenes (PCNs) in Irish foods: Occurrence and human dietary exposure A.R. Fernandes a,⇑, C. Tlustos b, M. Rose a, F. Smith a, M. Carr a, S. Panton a a b
Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, UK Food Science and Standards Division, Food Safety Authority of Ireland, Dublin D1, Ireland
a r t i c l e
i n f o
Article history: Received 12 November 2010 Received in revised form 11 May 2011 Accepted 23 June 2011 Available online 23 July 2011 Keywords: TEQ Congener-specific Fish Dietary-intake HRMS Risk assessment
a b s t r a c t The concentrations of selected polychlorinated naphthalene (PCN) congeners (PCNs 52, 53, 66/67, 68, 69, 71/72, 73, 74 and 75) were determined in 100 commonly consumed foods, in the first study on occurrence of these contaminants in the Republic of Ireland. Congener selection was based on current knowledge on PCN occurrence and toxicology, and the availability of reliable reference standards. The determinations were carried out using validated analytical methodology based on 13C10 labelled internal standardisation and measurement by HRGC-HRMS. The results showed PCN occurrence in the majority of studied foods – milk, fish, dairy and meat products, eggs, animal fat, shellfish, offal, vegetables, cereal products, etc. ranging from 0.09 ng kg 1 whole weight for milk to 59.3 ng kg 1 whole weight for fish, for the sum of the measured PCNs. The most frequently detected congeners were PCNs 66/67, PCN 52, and PCN 73. The highest concentrations were observed in fish, which generally showed congener profiles that reflect some commercial mixtures. The data compares well with other recently reported data for Western Europe. The dioxin-like toxicity (PCN TEQ) associated with these concentrations is lower than that reported for chlorinated dioxins or PCBs in food from Ireland. The dietary exposure of the Irish adult population to PCNs was calculated following a probabilistic approach, using the full dataset of occurrence and current consumption data. The estimates of dietary intakes at approximately 0.14 pg TEQ kgbw 1 month 1 for adults on an average diet, reflects the relatively lower occurrence levels. Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved.
1. Introduction Polychlorinated naphthalenes (PCNs) comprise a sub-group of 75 congeners, some with recognised toxic, bio-accumulative and persistence properties. As an industrial chemical, commercial PCN mixtures (e.g. Halowaxes) were mass produced over much of the last century and were commonly used in electrical equipment due to their physical properties of hydrophobicity, high chemical and thermal stability, good weather resistance, good electrical insulating properties and low flammability. Apart from the environmental release associated with this commercial use, PCNs are also reported to be produced in small amounts as combustion products (Helm and Bidleman, 2003). The structural similarity of PCNs to the highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin molecule, indicates an aryl hydrocarbon (Ah) receptor-mediated mechanism of toxicity, and a number of toxic responses such as mortality, embryotoxicity, hepatotoxicity, immunotoxicity, dermal lesions, teratogenicity and carcinogenicity have been reported (Hanberg et al., 1990; ⇑ Corresponding author. Tel.: +44 (0)1904 462605. E-mail address: [email protected] (A.R. Fernandes).
Engwall et al., 1994; Blankenship et al., 1999, 2000; Villeneuve et al., 2000). In humans, severe skin reactions (chloracne) and liver disease have both been reported after occupational exposure to PCNs. Other symptoms found in workers include cirrhosis of the liver, irritation of the eyes, fatigue, headache, anaemia, haematuria, anorexia, and nausea. A European Food Safety Authority (EFSA) scientific colloquium on dioxins in 2004 concluded that compounds such as PCNs that exhibited dioxin-like toxicity should be considered for the Toxic Equivalency Factor (TEF) approach to defining toxicity (EFSA, 2004). This conclusion was shared by the expert panel reviewing the WHO TEF system in 2005 (Van den Berg et al., 2006). In common with other similar contaminants such as polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) and polychlorinated biphenyls (PCBs), the main pathway to human exposure is likely to be through dietary intake. However there is very little data on the presence of these contaminants in foods to support risk assessments arising from dietary exposure (Falandysz, 2003). Data on PCN occurrence levels in fish have been reported as part of environmental monitoring studies in some countries (Koistinen, 1990; Kannan et al., 2000; Hanari et al., 2004), which has demonstrated the bio-accumulation potential of the compounds.
0045-6535/$ - see front matter Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2011.06.093
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They have also been found to bio-accumulate in animals (Guruge et al., 2004) and have been detected in human milk (Noren and Meironyte, 2003). At present there is very little information on dietary exposure of humans to PCNs, but two surveys of foods have been carried out in Spain (Domingo et al., 2003; Marti-Cid et al., 2008) and recently a study on occurrence levels in food in the UK and the resulting human exposure, has been reported (Fernandes et al., 2010). A Spanish study (Domingo et al., 2003) showed that the highest concentrations were in fats and oils, cereals, fish, dairy products and meat. Foods that were subject to some measure of processing (oils and fats, cereals, dairy products, meat and meat products), and fish showed the highest levels. An exposure assessment based on the data indicated that children showed higher exposure (1.65 ng kgbw 1 d 1) than adults (0.54 ng kgbw 1 d 1). In the UK study, PCNs were detected in all the different food types analysed, with the highest levels and widest range of PCN congeners observed in fish, particularly in farmed and organically produced salmon. The concentrations observed in fish in general (average concentration 20 ng/kg) were approximately an order of magnitude greater than any of the other food types. A wide range of congeners was also observed in the eggs/poultry samples albeit at a relatively lower level, but for most meat/offal and dairy products, PCN 66/67 and PCN 73 were often the only congeners detected which maybe the result of selective bio-accumulation or metabolic processes. The Food Safety Authority of Ireland (FSAI) has conducted a number of studies over the last few years on the occurrence of environmental contaminants in food (Fernandes et al., 2009b; FSAI, 2004, 2007) These have included investigations on PCDD/ Fs, PCBs, brominated dioxins (PBDD/Fs) and a range of brominated flame retardants such as PBDEs, PBBs, HBCD, TBBPA, HBB, BTBPE and DBDPE. Apart from the recent incident of contaminated Irish feed (Tlustos, 2009), these studies have revealed food concentrations that are lower than the European average for some environmental contaminants such as PCDD/Fs and PCBs. However, there is no data available for PCNs. This study addresses the data gap and provides information on the occurrence of PCNs in commonly consumed Irish food products, and estimates of the resulting human exposure using a probabilistic modelling approach.
2. Experimental 2.1. Sampling and analysis The sampling plan for this study included commonly consumed foods of animal, marine and vegetable origin destined for retail use. A total of 100 composite samples were prepared after collection of individual sub-samples at the production or processing stage. These included 17 samples of marine and farmed fish and shellfish, 15 samples each of milk and eggs, 21 samples of carcass fat taken from beef cattle, pigs, lambs, chickens and ducks, 12 samples of liver (bovine, porcine, ovine, equine and avian) six dairy products, and 14 other miscellaneous foods. In the case of liver and carcass fat, the composites were prepared from between ten and 40 sub-samples, for the eggs, 24 sub-samples were used. The fish and shellfish composites were prepared from 40 to 100 sub-samples and the milk was taken from bulk tanks at dairies, reflecting the produce of the entire herd. Samples were collected during the period 2007–2008 and were stored frozen at 20 °C prior to analysis during 2008. These samples were not intended to be a comprehensive reflection of the Irish food market, but to enable a preliminary view to be formed of whether PCNs were present in the food supply. Further information on sampling has been reported elsewhere (Food Safety Authority of Ireland, 2010b).
The following compounds were analysed: PCN 52 PCN 53 PCN 66/67 PCN 68 PCN 69 PCN71/72 PCN 73 PCN 74 PCN 75
1,2,3,5,7-Pentacn 1,2,3,5,8-PentaCN 1,2,3,4,6,7-HexaCN/ 1,2,3,5,6,7-hexaCN 1,2,3,5,6,8-HexaCN 1,2,3,5,7,8-HexaCN 1,2,4,5,6,8-HexaCN/ 1,2,4,5,7,8-HexaCN 1,2,3,4,5,6,7-HeptaCN 1,2,3,4,5,6,8-HeptaCN Octachloro-CN
A full description of the reagents, reference standards and procedures used for the extraction and analysis has been reported earlier (Fernandes et al., 2010). In brief, samples were fortified with 13C-labelled analogues of target compounds and exhaustively extracted using mixed organic solvents. PCNs were chromatographically fractionated from potential interferants such as PCBs, using activated carbon. The extract was further purified using adsorption chromatography on alumina. Analytical measurement was carried out using high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC-HRMS). Additional control was provided by the inclusion of methods blanks and a reference material. 2.2. Method quality assurance The methodology used for the analysis was robustly validated prior to sample analysis and validation data, including method performance parameters have been reported (Fernandes et al., 2010). The extraction and purification stages were adapted from the ISO17025 accredited methodology used for the analysis of similar contaminants such as PCDD/Fs, PCBs, PBDEs, and PBDD/Fs. (Fernandes et al., 2004, 2008). This methodology has been peer-reviewed and has been used successfully over many years (Fernandes et al., 2006, 2009). It has recently been assessed by expert EU laboratories, and will shortly become part of the European standard (CEN) for dioxin analysis in feed and related matrices. Measurement was carried out by HRGC-HRMS which confers a high degree of measurement specificity as well as sensitivity. The method limits of detection (LODs) were computed from instrument sensitivity and levels detected in the method blanks. The LODs ranged typically from 0.01 ng kg 1 to 0.1 ng kg 1 on a whole weight basis for individual PCN congeners. The use of 13C10 labelled PCN congeners as internal standards allows a greater degree of control and precision, and replicate measurements on the same matrix have shown an average precision of <10%, as defined by the co-efficient of variation (Fernandes et al., 2010). The general analytical recovery rate (measured using 13C10 labelled PCNs) was typically of the order of 50–77% (average 63%) for the foods reported here (Recovery ranges for individual food types: fish 50–93%, shellfish 60–73%, milk 55–83%, eggs 51–72%, fats 56– 68%, other foods 51–94%). The accuracy of the measurement has been confirmed by the successful analysis of fortified food matrices, returning concentrations that were in good agreement with the fortified values. There are no available reference materials (RMs) specific to PCNs, but the use of CRM 350 (Griepink et al., 1988), which was found to contain appreciable amounts of PCNs has been reported in an earlier study (Fernandes et al., 2010). CRM 350 which is a mackerel oil, was analysed several times during the course of this work and the results showed good consistency and agreement with the established values (Fernandes et al., 2010) which typically range from 25 ng kg 1 to 200 ng kg 1. Measurement uncertainty was also estimated and for PCN concentrations around 1 ng kg 1, the uncertainty returned is 20%; for
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concentrations approaching, or at the (0.02 ng kg 1), the value can rise to 200%.
limit
of
detection
2.3. Intake assessment Food consumption data for the adult Irish population were taken from the North South Food Consumption Survey (NSFCS) conducted by the Irish Universities Nutrition Alliance (IUNA) (IUNA, 2001). The detailed food consumption database, which contains information from a 7-d dietary record for 958 subjects, age 18–64, was modified to suit contaminant intake calculations (recipes were used to convert meals into their respective ingredients). All consumption data were expressed on a per kilogram bodyweight (kg bw) basis calculated for each individual consumer (average bodyweight – 75 kg). The exposure of the Irish adult population to PCNs was calculated following a probabilistic approach, using the whole datasets of occurrence and consumption data, inputted into Crème probabilistic modelling software (Creme Food, 2005), for carcass fat, milk and dairy products, eggs, offal, fish and shellfish. 3. Results and discussion 3.1. Choice of PCN congeners and toxic equivalence factors The choice of congeners selected in this study was based principally on the toxicological characteristics of individual PCN congeners and the levels and patterns of occurrence. In practice however, the selection was limited by the availability of reliable reference standards. Thus the choice of congeners made in this study included mostly penta- to octa-chlorinated compounds, and generally those that are reported to show the highest toxicological effect e.g. PCN 66, 67, 68, 73, etc. In order to provide an indication of the dioxin-like toxicity arising from the presence of PCNs, the data has also been presented as toxic equivalents (TEQs), computed using Toxic Equivalency Factors (TEFs) taken from four studies (Hanberg et al., 1990; Engwall et al., 1994; Blankenship et al., 2000; Villeneuve et al., 2000; Behnisch et al., 2003). Where more than one TEF for the same congener has been reported, the highest value was used, together with the assumption that, where congeners co-eluted, the content comprised only the congener with the higher or only TEF. The debate on this approach to expressing toxicity-normalised exposure for dietary PCN content, which mirrors the approach used for PCDD/Fs and PCBs, is ongoing – on the one hand there is a reluctance to use this TEF approach for PCNs due to lack of information on persistence, and repeat dose toxicity studies (COT, 2009). However as observed elsewhere (Kannan et al., 2000; COT, 2009; Fernandes et al., 2010) relative potencies identified from in vitro studies provide an extremely conservative
approach to risk cumulative assessment for the dioxin-like toxicity of PCNs. Accordingly, given the qualifications that the TEFs currently proposed and used, would require confirmation as they have not been widely used, nor have they been adopted by regulatory bodies, the derived TEQ values are useful in that they provide an interim indication of the possible PCN-associated toxicity of the foods. These indicative TEQ values will of course be underestimates as they do not include all of the PCN congeners with proposed TEFs. 3.2. PCNs in food Concentration data for the 11 PCN congeners measured in the various food samples is given in Table 1. Additionally data for the sum of the PCNs and for PCN TEQ is also reported as upper-bound values, i.e. where congeners were not detected they were assumed to be present at the level of the limit of detection. All concentrations are expressed on a whole weight basis. In order to allow comparison with other food data, the fat content of the sample has also been included. All samples apart from rice, processed tomatoes and beans, showed the presence of PCNs, although the frequency of detection and relative abundance varied depending on the congener and the type of food. Fish showed a larger range of detected congeners as well as the most abundant occurrence. The moderately chlorinated congeners (penta-) dominated the profile, with abundance gradually declining as the degree of chlorination increased. A similar profile was observed for eggs, but for most animal fat (apart from poultry) and dairy products, the toxicologically more significant compounds – PCN 66/67 and PCN 73, were often the only congeners detected. This contrasting profile observed for tissue from higher order animal and milk/dairy products may be the result of selective bio-accumulation or metabolic processes (Fernandes et al., 2010). Only three popular species of fish were investigated – mackerel, salmon and trout, but of these the most oily fish, salmon (15% fat), showed the highest PCN levels – on average, an order of magnitude higher than trout (2.3% fat). These concentrations for farmed salmon are marginally higher than those observed for the UK (Fernandes et al., 2010), but in general, the average concentrations found in fish are similar for both studies. The observation for fish samples from Catalonia, Spain, are also similar, with the highest levels observed for salmon, although not directly comparable, because homologue totals were measured rather than individual congeners (Marti-Cid et al., 2008). However, an earlier study on PCNs in Catalonian food found significantly higher concentrations in oils and fats, and cereals relative to fish and shellfish (Domingo et al., 2003). On average, relatively high concentrations were also observed in the samples of animal fat which reflect PCN concentrations in meat, although the average here is influenced by two samples of avian (chicken) fat. The second of these, in particular is remarkable as it is a composite sample made up of 40 individual sub-samples.
Fig. 1. Relative distribution of sum-PCN and PCN-TEQ in food.
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A.R. Fernandes et al. / Chemosphere 85 (2011) 322–328 Table 1 Concentrations of PCN congeners in foods (ng kg
Fish
1
whole weight). Sum of 12 PCNs and TEQ are given as upper bound values.
ID
Sample Details
Fat%
PCN 52/ 60
PCN 53
15660 15662 15663 15670 15664 15667 15671 15672 15673 15701 15702 15703
Mackerel Mackerel Mackerel Mackerel Farmed salmon Farmed salmon Farmed salmon Farmed salmon Farmed salmon Trout Trout Trout
5.2 3.5 3.1 5.2 14.7 11 15.1 16.5 17.5 2.7 2.5 1.8
4.37 8.57 4.43 4.30 9.52 33.12 45.07 41.14 34.63 0.90 3.57 1.9
0.53 1.98 0.79 1.49 0.81 2.07 2.83 3.66 3.44 <0.32 1.58 0.46
PCN 66/ 67 0.18 0.73 0.19 0.17 0.86 3.37 4.84 4.18 3.33 0.13 0.35 0.26
PCN 68
PCN 69
PCN 71/ 72
PCN 73
PCN 74
PCN 75
Sum PCNs
PCN TEQa
<0.15 0.61 0.13 0.18 0.40 1.53 2.06 1.77 1.52 <0.13 0.43 0.15
<0.20 0.38 <0.18 <0.18 0.41 1.45 1.96 1.57 1.43 <0.18 0.54 0.16
<0.27 0.46 <0.24 0.3 0.39 1.62 1.77 1.3 1.23 <0.24 0.80 0.30
<0.03 <0.03 <0.03 <0.03 0.06 0.36 0.57 0.46 0.69 <0.03 0.10 0.10
<0.14 <0.12 <0.13 <0.13 <0.17 <0.15 <0.17 <0.17 <0.18 <0.13 0.08 0.04
<0.03 <0.02 <0.02 <0.02 <0.03 <0.03 <0.03 <0.03 0.03 0.02 <0.02 0.04
5.9 12.9 6.14 6.8 12.65 43.7 59.3 54.3 46.5 2.08 7.47 3.41
0.0018 0.0057 0.0017 0.0018 0.0058 0.0228 0.0321 0.0274 0.0236 0.0014 0.0042 0.0022
21.8
0.011
Average Shellfish
15661 15665 15666 15668 15669
Pacific Pacific Pacific Pacific Pacific
oysters oysters oysters oysters oysters
3.1 1.7 1.7 2.2 1.9
1.61 0.10 0.17 0.62 1.26
0.65 <0.01 0.04 0.25 0.47
<0.01 <0.01 <0.01 <0.01 <0.01
0.01 <0.01 <0.01 <0.01 0.01
0.02 <0.01 <0.01 <0.01 0.03
<0.01 <0.01 <0.01 <0.01 0.02
<0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01
Average Milk
14577 14579 14608 14609 14612 14615 14617 14620 14622 14625 14627 14628 14630 14632 14633
1.11
Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk
3.8 5.1 3.9 4 4.1 3.6 3.6 4 2.6 4.4 3.9 3.7 4.1 4 3.7
<0.03 <0.03 <0.03 <0.03 <0.04 0.08 <0.05 <0.06 <0.03 <0.04 0.03 0.01 0.03 0.02 0.02
<0.03 <0.03 <0.03 <0.03 <0.04 0.03 <0.04 <0.05 <0.03 <0.04 <0.01 <0.01 0.01 0.01 0.01
0.03 0.03 0.03 0.02 0.04 0.03 0.02 0.02 0.02 0.02 0.03 0.01 0.02 0.04 0.03
<0.01 <0.01 <0.01 <0.01 <0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.04 <0.04 <0.03 <0.03 <0.05 0.02 <0.05 <0.06 <0.03 <0.04 0.01 0.01 0.01 0.04 0.01
<0.03 <0.03 <0.03 <0.03 <0.04 <0.01 <0.04 <0.05 <0.03 <0.04 <0.01 <0.01 <0.01 <0.01 <0.01
<0.06 <0.07 <0.06 <0.06 <0.08 <0.01 <0.09 <0.11 <0.06 <0.08 <0.01 <0.01 <0.01 <0.01 <0.01
Average Eggs
14634 14635 14636 14637 14638 14639 14640 14641 14646 14648 14649 14650 14651 14652 14653
Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid
egg egg egg egg egg egg egg egg egg egg egg egg egg egg egg
14931 14932 14958 14960 14964 14933 14934 14959 14961 14962 14977 14978
sample sample sample sample sample sample sample sample sample sample sample sample sample sample sample
1 2 3 4 5 6 7 8 13 15 16 17 18 19 20
9.7 11 10.2 10.2 9.5 10.3 11.2 10 10.2 10.1 10.8 10.1 9.5 8.8 10.2
0.43 1.47 0.11 0.14 0.24 0.22 0.13 0.24 0.27 0.43 0.23 0.32 0.29 0.31 0.33
0.06 0.12 0.02 0.04 0.09 0.06 <0.02 0.03 0.09 0.09 0.05 0.11 0.08 0.09 0.07
0.09 0.11 0.02 0.03 0.03 0.03 0.03 0.08 0.03 0.06 0.03 0.05 0.03 0.06 0.04
0.06 0.11 0.02 0.02 0.03 0.02 0.01 0.04 0.03 0.03 0.02 0.04 0.03 0.04 0.03
0.10 0.26 0.02 0.02 0.04 0.03 0.02 0.05 0.04 0.05 0.02 0.06 0.04 0.04 0.04
0.04 0.08 <0.01 <0.01 0.03 0.02 <0.01 0.03 0.02 0.04 0.01 0.03 0.02 0.02 0.02
0.05 0.05 <0.01 0.02 0.02 <0.01 <0.01 0.04 <0.01 0.02 <0.01 0.02 <0.01 0.03 <0.01
0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02
Bovine liver Avian liver Avian liver Bovine liver Avian liver Ovine liver Porcine liver Porcine liver Equine liver Equine liver Ovine liver Ovine liver
16326 16327
Butter Irish creamery butter
0.85 2.22 0.23 0.3 0.5 0.42 0.26 0.54 0.52 0.75 0.4 0.66 0.53 0.62 0.57 0.62
3.3 4.8 5.1 3.8 5.1 4.9 4.2 3.7 4.7 3.8 7 4.3
<0.09 0.43 0.15 <0.08 <0.08 0.07 0.11 <0.07 <0.07 0.08 0.08 0.18
<0.02 0.05 0.05 <0.02 <0.02 0.06 0.09 0.03 0.02 0.04 0.06 0.24
0.08 0.03 0.02 0.09 0.01 0.69 0.08 0.11 0.38 0.29 0.9 1.96
<0.01 0.03 0.02 <0.01 <0.01 0.01 0.01 <0.01 <0.01 0.02 0.02 0.01
<0.02 <0.01 <0.02 <0.02 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.02 <0.02
<0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.03 0.03 0.01
0.03 0.02 0.03 0.05 0.01 0.42 <0.02 <0.01 0.04 0.03 0.58 1.8
<0.01 <0.01 <0.01 <0.01 <0.01 0.02 <0.01 <0.01 <0.01 <0.01 0.01 0.03
<0.02 <0.02 <0.02 <0.02 <0.02 0.05 <0.02 <0.01 <0.02 <0.02 <0.02 <0.01
Average Dairy
0.25 0.26 0.24 0.23 0.32 0.21 0.32 0.38 0.23 0.29 0.13 0.09 0.12 0.16 0.12 0.22
Average Liver
2.34 0.18 0.28 0.94 1.83
0.29 0.61 0.33 0.31 0.18 1.34 0.37 0.28 0.57 0.53 1.72 4.26 0.90
81 80.9
<0.66 <0.60
<0.10 <0.09
0.16 0.58
<0.06 <0.06
<0.09 <0.10
<0.06 <0.06
<0.05 0.31
<0.04 <0.03
<0.09 <0.08
1.31 1.91
0.0002 0.0001 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0003 0.0002 0.0004 0.0002 0.0003 0.0003 0.0002 0.0003 0.0002 0.0001 0.0002 0.0003 0.0002 0.0003 0.0009 0.0015 0.0002 0.0003 0.0004 0.0003 0.0002 0.0007 0.0003 0.0005 0.0003 0.0005 0.0003 0.0005 0.0004 0.0005 0.0005 0.0003 0.0003 0.0006 0.0001 0.0041 0.0005 0.0005 0.0017 0.0013 0.0055 0.0135 0.002 0.0012 0.0037
(continued on next page)
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Table 1 (continued) ID
Sample Details
Fat%
PCN 52/ 60
16328 16329
Irish creamery butter Irish creamery butter salted Irish unsalted butter Red cheddar
81.6 81.8
<0.45 <0.47
0.14 0.13
83 27.1
<0.48 <0.17
<0.10 <0.03
16330 16318
PCN 53
PCN 66/ 67
PCN 68
PCN 69
PCN 71/ 72
1.42 0.59
0.08 <0.07
<0.09 <0.09
<0.05 <0.05
0.61 0.26
<0.07 <0.02
<0.09 <0.03
<0.05 <0.01
PCN 73
PCN 74
PCN 75
0.73 0.33
<0.07 <0.07
<0.10 <0.10
3.13 1.9
0.0084 0.0038
0.35 0.12
<0.08 <0.01
<0.10 <0.03
1.93 0.68
0.0039 0.0015
Average Fat
14928 14935 14940 14946 14949 14966 14970 14971 14974 14975 14929 14930 14936 14943 14945 14950 14952 14955 14956 14957 14963
Bovine fat Avian fat (duck) Bovine fat Bovine fat Bovine fat Avian fat Avian fat Avian fat (duck) Avian fat Bovine fat Ovine fat Porcine fat Avian fat Porcine fat Ovine fat Ovine fat Ovine fat Ovine fat Porcine fat Porcine fat Porcine fat
84.8 91 81.8 75.8 77.9 67 86 92.7 85.9 87.3 86.2 74.6 85.2 77.2 84.2 84.5 93.7 88.9 71 67.6 64.8
0.5 1.15 0.47 0.48 0.62 6.38 <0.88 1.4 1.91 0.59 <0.42 <0.43 8.6 <0.68 <0.66 <0.69 <0.69 <0.44 <0.42 <0.42 <0.95
0.17 1.17 0.12 <0.11 0.15 1.54 0.29 0.93 0.68 0.12 <0.45 <0.46 1.44 <0.10 <0.10 <0.10 0.13 <0.47 <0.45 <0.44 <0.14
0.95 0.17 1.02 1.04 1.08 0.98 0.42 0.26 0.36 1.05 1.63 0.32 0.89 0.45 1.51 1.73 2.26 2.1 0.29 0.26 0.24
0.05 0.27 <0.05 <0.05 <0.05 0.69 0.26 0.37 0.25 <0.05 <0.06 <0.06 0.64 <0.06 <0.06 <0.06 <0.06 <0.06 <0.06 <0.06 <0.08
<0.09 0.23 <0.08 <0.09 <0.09 0.6 0.17 0.28 0.27 <0.08 <0.10 <0.10 0.75 <0.09 <0.09 <0.09 <0.09 <0.10 <0.10 <0.10 <0.13
<0.05 0.22 <0.05 <0.05 <0.05 0.29 0.16 0.27 0.14 <0.05 <0.12 <0.12 0.53 <0.06 <0.06 <0.06 0.08 <0.12 <0.12 <0.12 <0.09
0.29 0.3 0.34 0.28 0.34 0.73 0.45 0.4 0.26 0.26 0.56 <0.08 0.41 <0.06 0.34 0.59 0.71 0.46 <0.08 <0.08 <0.08
<0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.06 <0.05 <0.05 <0.05 <0.07 <0.07 0.06 <0.04 <0.04 <0.05 <0.05 <0.07 <0.07 <0.07 <0.06
<0.09 <0.08 <0.08 <0.09 <0.09 <0.09 <0.12 <0.08 <0.09 <0.09 <0.10 <0.11 <0.09 <0.09 <0.09 <0.10 <0.10 <0.11 <0.10 <0.10 <0.13
Average Other foods
Sum PCNs
PCN TEQa
1.81
0.0037
2.24 3.64 2.26 2.24 2.52 11.35 2.81 4.04 4.01 2.34 3.51 1.75 13.41 1.63 2.95 3.47 4.17 3.93 1.69 1.65 1.9
0.0050 0.0029 0.0055 0.0054 0.0057 0.0095 0.0042 0.0039 0.0035 0.0053 0.0086 0.0019 0.0084 0.0024 0.0075 0.0091 0.0116 0.0102 0.0018 0.0017 0.0017
3.69
0.0055
16310
Mushrooms composite
0.3
0.45
1.2
<0.01
0.01
0.02
0.04
<0.01
<0.01
<0.01
1.76
0.0002
16311
Vine tomatoes composite Bread composite Cabbage composite Ham composite Potatoes Rooster potatoes Cornflakes composite Oats composite Sausages Baked beans composite Sweetcorn composite Tomato puree composite Basmati rice
0.2
0.03
0.09
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
0.01
0.19
0.0001
2.2 0.2 2.5 0.1 0.2 1 6.8 35.4 0.3 2 0.7
<0.19 0.53 <0.05 <0.07 <0.08 <0.31 <0.30 <0.14 <0.06 0.07 <0.08
0.09 2.09 0.01 0.02 0.03 0.23 0.05 <0.13 <0.06 <0.06 <0.08
<0.02 0.01 0.01 <0.01 <0.01 <0.04 <0.04 0.14 <0.01 0.01 <0.01
<0.02 0.03 <0.01 <0.01 <0.01 <0.03 <0.03 <0.01 <0.01 0.01 <0.01
<0.03 0.05 <0.01 <0.01 <0.01 <0.05 <0.05 <0.03 <0.01 <0.01 <0.02
<0.02 0.1 <0.01 <0.01 <0.01 <0.03 <0.03 <0.02 <0.01 <0.01 <0.01
0.02 <0.01 <0.01 <0.01 <0.01 <0.02 <0.02 0.03 <0.01 0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.02 <0.01 <0.01 <0.01 <0.01
<0.02 <0.01 <0.01 <0.01 <0.01 <0.04 <0.04 <0.03 <0.01 <0.01 <0.02
0.42 2.84 0.13 0.16 0.18 0.77 0.58 0.54 0.19 0.2 0.25
0.0003 0.0003 0.0001 0.0001 0.0001 0.0004 0.0004 0.0007 0.0001 0.0001 0.0001
1.4
<0.13
<0.02
<0.02
<0.01
<0.02
<0.01
<0.01
<0.01
<0.02
16314 16319 16322 16331 16332 16355 16353 16346 16350 16351 16352 16354
Average
0.25 0.60
0.0002 0.0002
PCN 52-0.000025, PCN 53-0.0000018, PCN 66/67-0.004, PCN 68-0.0028, PCN 69-0.002, PCN 71/72-0.00009, PCN 73-0.0031, PCN 74-0.0000041, PCN 75-0.00001. a PCN TEQ is given in ng TEQ Kg 1 whole weight and is calculated using TEF values taken from Behnisch et al. (2003), Blakenship et al. (2000), Hanberg et al. (1990), and Villeneuve et al. (2000).
Ovine fat showed comparable levels to some of the avian fat, and this is also reflected in the samples of ovine liver which showed the (relatively) highest levels. The distribution of PCNs as average values for each of the food groups studied (on a whole weight basis) is illustrated in Fig. 1. The detection of PCNs in these samples of food from Ireland – often seen as experiencing lower levels of environmental pollution because of its geography and the prevailing wind direction – demonstrates the persistence and ubiquity of these largely legacy pollutants. As observed for the congener profiles in the UK (Fernandes et al., 2010), samples of fish, eggs and vegetables still reflect profiles of environmental media (Nakano et al., 2000) and some commercial mixtures (Kannan et al., 2000), several years after the widespread use of these chemicals ceased. The calculated PCN TEQ values associated with the reported concentrations, range from 0.0001 ng kg 1 TEQ mainly for vegetable based foods and some shellfish to 0.03 ng kg 1 TEQ for fish
(whole weight basis, Table 1). In general, there is correlation (r = 0.91) between the calculated TEQ values and the sum of the measured PCNs which for some matrices is very strong (r = 0.99 for fish). This high level of correlation is unsurprising given that the congener selection was partly based on toxicity and supports the rationale used for the selection of congeners. For the samples analysed in this work, it is clear that PCN TEQ is considerably lower than for similar samples from Ireland analysed for PCB and PCDD/F TEQ. For example, the average PCN TEQ 0.02 ng kg 1, for salmon is more than an order of magnitude lower, compared to other dioxin-like compounds (average – 0.54 ng kg 1 PCDD/F TEQ and 1.61 ng kg 1 PCB-TEQ for fish) in similar foods. (Food Safety Authority of Ireland, 2007). Although this data for PCDD/Fs and PCBs is derived from samples that were taken earlier and levels are likely to have fallen since (Fernandes et al., 2004), the observation is in line with other literature reports. The observation on the relatively lower contribution of PCNs to dioxin-like TEQ has been
A.R. Fernandes et al. / Chemosphere 85 (2011) 322–328
made before, for environmental matrices (Nakano et al., 2000) with a reported TEQ contribution ratio of 2:10:85 for PCN:PCB:PCDD/F, but also for foods (Fernandes et al., 2010) where a similar, order of magnitude difference in contribution to TEQ was reported (e.g. average – 0.01 ng kg 1 TEQ for fish compared to average – 0.27 ng kg 1 PCDD/F TEQ and 0.9 ng kg 1 PCB-TEQ). It must be noted however, that all of the PCN congeners with proposed TEF values have not been included in these calculations, so the PCN contribution may well be marginally greater. 3.3. Dietary intakes The exposure to PCDD/F and PCB TEQ (upperbound) of the adult population consuming an average diet is estimated at 12 pg TEQ kgbw 1 month 1 (Food Safety Authority of Ireland, 2010) based on the consumption of food of animal origin. The estimated additional contribution to this exposure of PCN TEQ arising from consumption of food of animal origin was calculated at approximately 0.14 pg TEQ kgbw 1 month 1 (upperbound). Dairy products and fish including shellfish were the major contributors to exposure, each contributing 37% to the total exposure, meat and meat products contributed 23% and eggs 3%. Similar findings were recently reported for PBDEs, where fish was also found to be the major contributor followed by dairy products and meat (Trudel et al., 2010). These findings can be attributed to the higher contaminant concentration in fish tissue and the larger average consumption of dairy and meat products compared to fish (dairy on a weight basis around 18 times more than fish; meat products about seven times more than fish). Due to the very limited number of studies in the literature and the different methodologies used in these studies (different foodgroups, individual congeners versus homologue groups), it is difficult to make direct comparison to the findings of this study. Fernandes et al., 2010 illustrated a worst case intake scenario for the UK population based on the assumption that all solid food consumed (1.5 kg d 1 for adults, 1 kg d 1 for young children) contained 0.02 ng TEQ kg 1 (the highest result obtained in the study; same congeners as this study), resulting in an estimated exposure of 0.39 pg TEQ kgbw 1 d 1 for adults and 0.98 pg TEQ kgbw 1 d 1 for children, respectively. Marti-Cid et al., 2008 reported a total dietary intake of 7.25 ng/d (0.1 ng kg/bw) (sum tetra- to octachloro PCN homologues rather than individual congeners) for a standard adult man (70 kg) based on a comprehensive market basket survey. In this study, the estimated increase in dioxin-like TEQ exposure from dietary PCNs is relatively marginal and suggests that exposure to PCNs is of low concern. However, it is important to note as observed earlier, that all PCN congeners with TEF values have not been included in the current estimates, and that the TEFs currently proposed would require confirmatory studies which would allow harmonization of the values and a consensus on their use. 4. Conclusions This study demonstrates the universal presence of PCNs in Irish foods and provides baseline information on the concentrations found. Whilst there is variation in occurrence depending on individual congeners of these contaminants and the types of food studied, the widespread detection in a relatively cleaner environment (Ireland generally shows food contamination levels that are below the European average for environmental contaminants such as dioxins and PCBs except following specific contamination incidents) underlines the ubiquity of these contaminants. The profile of PCN congener occurrence in some foods (e.g. some vegetable based foods, fish, etc., where metabolic or other degradation pathways are unlikely to be significant) bears a good
327
resemblance to some commercial mixtures, and despite other sources such as incineration being reported, the legacy of past commercial usage still appears to strongly influence the background pattern of occurrence. The estimated contribution to dioxin-like toxicity associated with the PCN occurrence levels reported in this work is relatively marginal and although based on a limited study, contributes to the opinion that the levels of PCNs in the Irish produce studied, do not raise concern for human health. The general lack of data on PCNs in food does not support any discussion on trends. The gradual decline in food levels observed for other similar contaminants such as PCBs may be extrapolated to PCNs, but this would need to be confirmed empirically. Overall, the lack of information concerning PCN toxicity and dietary exposure warrants further attention to this group of contaminants. Acknowledgement The authors are grateful to the Food Safety Authority of Ireland for funding this work. References Behnisch, P.A., Hosoe, K., Sakai, S., 2003. Brominated dioxin-like compounds: in vitro assessment in comparison to classical dioxin-like compounds and other polyaromatic compounds. Environ. Int. 29, 861–877. Blankenship, A., Kannan, K., Villalobos, S., Villeneuve, D., Falandysz, J., Imagawa, T., Jakobsson, E., Giesy, J.P., 1999. Relative potencies of Halowax mixtures and individual polychlorinated naphthalenes (PCNs) to induce Ah receptormediated responses in the rat hepatoma H4IIE-luc cell bioassay. Organohalogen Compd. 42, 217–220. Blankenship, A., Kannan, K., Villalobos, S., Villeneuve, D., Falandysz, J., Imagawa, T., Jakobsson, E., Giesy, J.P., 2000. Relative potencies of Halowax mixtures and individual polychlorinated naphthalenes (PCNs) to induce Ah receptormediated responses in the rat hepatoma H4IIE-Luc cell bioassay. Environ. Sci. Technol. 34 (15), 3153–3158. Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, 2009. Polychlorinated Naphthalenes in Food.. Creme Food. CREMe Software Ltd., 2005–2008. . Domingo, J., Falco, G., Llobet, J., Casas, C., Teixido, A., Muller, L., 2003. PCNs in foods: estimated dietary intake by the population of Catalonia, Spain. Environ. Sci. Technol. 37 (11), 2332–2335. Engwall, M., Brundstrom, B., Jakobsson, E., 1994. Ethoxyresorufin O-deethylase (EROD) and arylhydrocarbon hydroxylase (AHH) – inducing potency and lethality of chlorinated naphthalenes in chicken (Gallus domesticus) and eider duck (Somateria mollissima) embryos. Arch. Toxicol. 68, 37–42. European Food Safety Authority, 2004. The EFSA’s 1st Scientific Colloquium Report – Dioxins. Methodologies and Principles for Setting Tolerable Intake Levels for Dioxins, Furans and Dioxin-like PCBs, European Food Safety Agency, Parma, Italy. Falandysz, J., 2003. Chloronaphthalenes as food chain contaminants: a review. Food Addit. Contam. 20, 995–1014. Fernandes, A., White, S., DSilva, K., Rose, M., 2004. Simultaneous Determination of PCDDs, PCDFs, PCBs and PBDEs in Food. Talanta 63, 1147–1155. Fernandes, A., Rose, M., White, S., Mortimer, D., Gem, M., 2006. Dioxins and polychlorinated biphenyls in fish oil dietary supplements: occurrence and human exposure in the UK. Food Addit. Contam. 23, 939–947. Fernandes, A., Dicks, P., Mortimer, D., Gem, M., Smith, F., White, S., Rose, M., 2008. Brominated and chlorinated dioxins and brominated flame retardants in scottish shellfish: methodology, occurrence and human dietary exposure. Mol. Nutr. Food Res. 52 (2), 238–249. Fernandes, A., Mortimer, D., Dicks, P., Gem, M., Smith, F., Rose, M., 2009. Brominated dioxins (PBDD/Fs), PBBs and PBDEs in Marine Shellfish in the UK. Food Addit. Contam. 26 (6), 918–927. Fernandes, A., Tlustos, C., Smith, F., Carr, M., Petch, R., Rose, M., 2009B. Polybrominated diphenylethers and brominated dioxins in Irish food of animal origin. Food Addit. Contam. 2 (1), 86–94. Fernandes, A., Mortimer, D., Gem, M., Smith, F., Rose, M., Panton, S., Carr, M., 2010. Polychlorinated Naphthalenes (PCNs): congener specific analysis, occurrence in food and dietary exposure in the UK. Environ. Sci. Technol. 44, 3533–3538. Food safety Authority of Ireland, 2004. Investigation into Levels of Dioxins, Furans, PCBs and PBDEs in Irish Food 2004. . Food Safety Authority of Ireland, 2007. Investigation into Levels of Dioxins, Furans, Polychlorinated Biphenyls and Brominated Flame Retardants in Fishery Produce in Ireland. . Food Safety Authority of Ireland, 2010a. Investigation into Levels of Chlorinated and Brominated Organic Pollutants in Carcass Fat, Offal, Eggs and Milk Produced in Ireland. Chemical Monitoring and Surveillance Series. .
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Food Safety Authority of Ireland, 2010b. Investigation into Levels of Polychlorinated Naphthalenes (PCNs) in Carcass Fat, Offal, Fish, Eggs, Milk and Processed Products.. Griepink, B., Wells, D.E., Ferreira, M.F., 1988. The Certification of the Contents (mass fraction) of chlorobiphenyls (IUPAC Nos 28, 52, 101, 118, 138, 153 and 180) in Two Fish Oils: Cod-liver Oil CRM No. 349; Mackerel Oil CRM No. 350. Report EUR11520EN, CEE, Community Bureau of Reference. Guruge, K.S., Seike, M., Yamanaka, N., Miyazaki, S., 2004. Accumulation of PCNs in domestic animal related samples. J. Environ. Monit. 6, 753–757. Hanari, N., Kannan, K., Horii, Y., Taniyasu, S., Yamashita, N., Jude, D., Berg, M., 2004. PCNs and PCBs in benthic organisms of a great lakes food chain. Arch. Environ. Contam. Toxicol. 47, 84–93. Hanberg, A., Waern, F., Asplund, L., Haglund, E., Safe, S., 1990. Swedish dioxin survey: determination of 2,3,7,8-TCDD toxic equivalent factors for some polychlorinated biphenyls and naphthalenes using biological tests. Chemosphere 20, 1161–1164. Helm, P.A., Bidleman, T.F., 2003. Current combustion-related sources contribute to polychlorinated naphthalene and dioxin-like polychlorinated biphenyl levels and profiles in air in Toronto, Canada. Environ. Sci. Technol. 37, 1075. IUNA, 2001. North/South Ireland Food Consumption Survey: Food and Nutrient Intakes, Anthropometry, Attitudinal Data & Physical Activity Patterns. Food Safety Promotion Board, Abbey Court, Lower Abbey Street, Dublin. Kannan, K., Yamashita, N., Imagawa, T., Decoen, W., Khim, J., Day, R., Summer, C., Giesy, J., 2000. PCNs and PCBs in fishes from Michigan waters including the Great Lakes. Environ. Sci. Technol. 34, 566–572.
Koistinen, J., 1990. Residues of planar polychloroaromatic compounds in Baltic fish and seal. Chemosphere 20, 1043–1048. Marti-Cid, R., Llobet, J., Castell, V., Domingo, J., 2008. Human exposure to PCNs and PCDEs from foods in Catalonia, Spain: temporal trends. Environ. Sci. Technol. 42, 4195–4201. Nakano, T., Matsumura, C., Fujimori, K., 2000. Isomer specific analysis of PCNs in environmental sample. Organohalogen Compd. 47, 178–181. Noren, K., Meironyte, D., 2003. Certain organochlorine and organobromine contaminants on Swedish human milk in perspective of the past 20–30 years. Chemosphere 40, 1111–1123. Tlustos, C., 2009. The dioxin contamination incident in Ireland 2008. Organohalogen Compd. 71, 1155. Trudel, D., Tlustos, C., Von Goetz, N., Scheringer, M., Hungerbuehler, K., 2010. PBDE exposure from food in Ireland: optimising data exploitation in probabilistic exposure modelling. J. Exposure Sci. Environ. Epidemiol. 59, 1–11. Van den Berg, M., Birnbaum, L.S., Denison, M., De Vito, M., Farland, W., Feeley, M., Fiedler, H., Hakansson, H., Hanberg, A., Haws, L., Rose, M., Safe, S., Schrenk, D., Tohyama, C., Tritscher, A., Tuomisto, J., Tysklind, M., Walker, N., Peterson, R.E., 2006. The 2005 world health organization re-evaluation of human and mammalian toxic equivalency factors for dioxins and dioxin-like compounds. Toxicol. Sci. 93, 223–241. Villeneuve, D.L., Khim, J.S., Kannan, K., Falandysz, J., Blankenship, A.L., Nikiforov, V., Giesy, J.P., 2000. Relative potencies of individual polychlorinated naphthalenes to induce dioxin-like response in fish and mammalian in vitro bioassays. Arch. Environ. Contam. Toxicol. 39 (3), 273–281.
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Polychlorinated naphthalenes (PCNs) in Irish foods: Occurrence and human dietary exposure A.R. Fernandes a,⇑, C. Tlustos b, M. Rose a, F. Smith a, M. Carr a, S. Panton a a b
Food and Environment Research Agency, Sand Hutton, York YO41 1LZ, UK Food Science and Standards Division, Food Safety Authority of Ireland, Dublin D1, Ireland
a r t i c l e
i n f o
Article history: Received 12 November 2010 Received in revised form 11 May 2011 Accepted 23 June 2011 Available online 23 July 2011 Keywords: TEQ Congener-specific Fish Dietary-intake HRMS Risk assessment
a b s t r a c t The concentrations of selected polychlorinated naphthalene (PCN) congeners (PCNs 52, 53, 66/67, 68, 69, 71/72, 73, 74 and 75) were determined in 100 commonly consumed foods, in the first study on occurrence of these contaminants in the Republic of Ireland. Congener selection was based on current knowledge on PCN occurrence and toxicology, and the availability of reliable reference standards. The determinations were carried out using validated analytical methodology based on 13C10 labelled internal standardisation and measurement by HRGC-HRMS. The results showed PCN occurrence in the majority of studied foods – milk, fish, dairy and meat products, eggs, animal fat, shellfish, offal, vegetables, cereal products, etc. ranging from 0.09 ng kg 1 whole weight for milk to 59.3 ng kg 1 whole weight for fish, for the sum of the measured PCNs. The most frequently detected congeners were PCNs 66/67, PCN 52, and PCN 73. The highest concentrations were observed in fish, which generally showed congener profiles that reflect some commercial mixtures. The data compares well with other recently reported data for Western Europe. The dioxin-like toxicity (PCN TEQ) associated with these concentrations is lower than that reported for chlorinated dioxins or PCBs in food from Ireland. The dietary exposure of the Irish adult population to PCNs was calculated following a probabilistic approach, using the full dataset of occurrence and current consumption data. The estimates of dietary intakes at approximately 0.14 pg TEQ kgbw 1 month 1 for adults on an average diet, reflects the relatively lower occurrence levels. Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved.
1. Introduction Polychlorinated naphthalenes (PCNs) comprise a sub-group of 75 congeners, some with recognised toxic, bio-accumulative and persistence properties. As an industrial chemical, commercial PCN mixtures (e.g. Halowaxes) were mass produced over much of the last century and were commonly used in electrical equipment due to their physical properties of hydrophobicity, high chemical and thermal stability, good weather resistance, good electrical insulating properties and low flammability. Apart from the environmental release associated with this commercial use, PCNs are also reported to be produced in small amounts as combustion products (Helm and Bidleman, 2003). The structural similarity of PCNs to the highly toxic 2,3,7,8-tetrachlorodibenzo-p-dioxin molecule, indicates an aryl hydrocarbon (Ah) receptor-mediated mechanism of toxicity, and a number of toxic responses such as mortality, embryotoxicity, hepatotoxicity, immunotoxicity, dermal lesions, teratogenicity and carcinogenicity have been reported (Hanberg et al., 1990; ⇑ Corresponding author. Tel.: +44 (0)1904 462605. E-mail address: [email protected] (A.R. Fernandes).
Engwall et al., 1994; Blankenship et al., 1999, 2000; Villeneuve et al., 2000). In humans, severe skin reactions (chloracne) and liver disease have both been reported after occupational exposure to PCNs. Other symptoms found in workers include cirrhosis of the liver, irritation of the eyes, fatigue, headache, anaemia, haematuria, anorexia, and nausea. A European Food Safety Authority (EFSA) scientific colloquium on dioxins in 2004 concluded that compounds such as PCNs that exhibited dioxin-like toxicity should be considered for the Toxic Equivalency Factor (TEF) approach to defining toxicity (EFSA, 2004). This conclusion was shared by the expert panel reviewing the WHO TEF system in 2005 (Van den Berg et al., 2006). In common with other similar contaminants such as polychlorinated dibenzo-p-dioxins and dibenzo-furans (PCDD/Fs) and polychlorinated biphenyls (PCBs), the main pathway to human exposure is likely to be through dietary intake. However there is very little data on the presence of these contaminants in foods to support risk assessments arising from dietary exposure (Falandysz, 2003). Data on PCN occurrence levels in fish have been reported as part of environmental monitoring studies in some countries (Koistinen, 1990; Kannan et al., 2000; Hanari et al., 2004), which has demonstrated the bio-accumulation potential of the compounds.
0045-6535/$ - see front matter Crown Copyright Ó 2011 Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.chemosphere.2011.06.093
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They have also been found to bio-accumulate in animals (Guruge et al., 2004) and have been detected in human milk (Noren and Meironyte, 2003). At present there is very little information on dietary exposure of humans to PCNs, but two surveys of foods have been carried out in Spain (Domingo et al., 2003; Marti-Cid et al., 2008) and recently a study on occurrence levels in food in the UK and the resulting human exposure, has been reported (Fernandes et al., 2010). A Spanish study (Domingo et al., 2003) showed that the highest concentrations were in fats and oils, cereals, fish, dairy products and meat. Foods that were subject to some measure of processing (oils and fats, cereals, dairy products, meat and meat products), and fish showed the highest levels. An exposure assessment based on the data indicated that children showed higher exposure (1.65 ng kgbw 1 d 1) than adults (0.54 ng kgbw 1 d 1). In the UK study, PCNs were detected in all the different food types analysed, with the highest levels and widest range of PCN congeners observed in fish, particularly in farmed and organically produced salmon. The concentrations observed in fish in general (average concentration 20 ng/kg) were approximately an order of magnitude greater than any of the other food types. A wide range of congeners was also observed in the eggs/poultry samples albeit at a relatively lower level, but for most meat/offal and dairy products, PCN 66/67 and PCN 73 were often the only congeners detected which maybe the result of selective bio-accumulation or metabolic processes. The Food Safety Authority of Ireland (FSAI) has conducted a number of studies over the last few years on the occurrence of environmental contaminants in food (Fernandes et al., 2009b; FSAI, 2004, 2007) These have included investigations on PCDD/ Fs, PCBs, brominated dioxins (PBDD/Fs) and a range of brominated flame retardants such as PBDEs, PBBs, HBCD, TBBPA, HBB, BTBPE and DBDPE. Apart from the recent incident of contaminated Irish feed (Tlustos, 2009), these studies have revealed food concentrations that are lower than the European average for some environmental contaminants such as PCDD/Fs and PCBs. However, there is no data available for PCNs. This study addresses the data gap and provides information on the occurrence of PCNs in commonly consumed Irish food products, and estimates of the resulting human exposure using a probabilistic modelling approach.
2. Experimental 2.1. Sampling and analysis The sampling plan for this study included commonly consumed foods of animal, marine and vegetable origin destined for retail use. A total of 100 composite samples were prepared after collection of individual sub-samples at the production or processing stage. These included 17 samples of marine and farmed fish and shellfish, 15 samples each of milk and eggs, 21 samples of carcass fat taken from beef cattle, pigs, lambs, chickens and ducks, 12 samples of liver (bovine, porcine, ovine, equine and avian) six dairy products, and 14 other miscellaneous foods. In the case of liver and carcass fat, the composites were prepared from between ten and 40 sub-samples, for the eggs, 24 sub-samples were used. The fish and shellfish composites were prepared from 40 to 100 sub-samples and the milk was taken from bulk tanks at dairies, reflecting the produce of the entire herd. Samples were collected during the period 2007–2008 and were stored frozen at 20 °C prior to analysis during 2008. These samples were not intended to be a comprehensive reflection of the Irish food market, but to enable a preliminary view to be formed of whether PCNs were present in the food supply. Further information on sampling has been reported elsewhere (Food Safety Authority of Ireland, 2010b).
The following compounds were analysed: PCN 52 PCN 53 PCN 66/67 PCN 68 PCN 69 PCN71/72 PCN 73 PCN 74 PCN 75
1,2,3,5,7-Pentacn 1,2,3,5,8-PentaCN 1,2,3,4,6,7-HexaCN/ 1,2,3,5,6,7-hexaCN 1,2,3,5,6,8-HexaCN 1,2,3,5,7,8-HexaCN 1,2,4,5,6,8-HexaCN/ 1,2,4,5,7,8-HexaCN 1,2,3,4,5,6,7-HeptaCN 1,2,3,4,5,6,8-HeptaCN Octachloro-CN
A full description of the reagents, reference standards and procedures used for the extraction and analysis has been reported earlier (Fernandes et al., 2010). In brief, samples were fortified with 13C-labelled analogues of target compounds and exhaustively extracted using mixed organic solvents. PCNs were chromatographically fractionated from potential interferants such as PCBs, using activated carbon. The extract was further purified using adsorption chromatography on alumina. Analytical measurement was carried out using high resolution gas chromatography coupled to high resolution mass spectrometry (HRGC-HRMS). Additional control was provided by the inclusion of methods blanks and a reference material. 2.2. Method quality assurance The methodology used for the analysis was robustly validated prior to sample analysis and validation data, including method performance parameters have been reported (Fernandes et al., 2010). The extraction and purification stages were adapted from the ISO17025 accredited methodology used for the analysis of similar contaminants such as PCDD/Fs, PCBs, PBDEs, and PBDD/Fs. (Fernandes et al., 2004, 2008). This methodology has been peer-reviewed and has been used successfully over many years (Fernandes et al., 2006, 2009). It has recently been assessed by expert EU laboratories, and will shortly become part of the European standard (CEN) for dioxin analysis in feed and related matrices. Measurement was carried out by HRGC-HRMS which confers a high degree of measurement specificity as well as sensitivity. The method limits of detection (LODs) were computed from instrument sensitivity and levels detected in the method blanks. The LODs ranged typically from 0.01 ng kg 1 to 0.1 ng kg 1 on a whole weight basis for individual PCN congeners. The use of 13C10 labelled PCN congeners as internal standards allows a greater degree of control and precision, and replicate measurements on the same matrix have shown an average precision of <10%, as defined by the co-efficient of variation (Fernandes et al., 2010). The general analytical recovery rate (measured using 13C10 labelled PCNs) was typically of the order of 50–77% (average 63%) for the foods reported here (Recovery ranges for individual food types: fish 50–93%, shellfish 60–73%, milk 55–83%, eggs 51–72%, fats 56– 68%, other foods 51–94%). The accuracy of the measurement has been confirmed by the successful analysis of fortified food matrices, returning concentrations that were in good agreement with the fortified values. There are no available reference materials (RMs) specific to PCNs, but the use of CRM 350 (Griepink et al., 1988), which was found to contain appreciable amounts of PCNs has been reported in an earlier study (Fernandes et al., 2010). CRM 350 which is a mackerel oil, was analysed several times during the course of this work and the results showed good consistency and agreement with the established values (Fernandes et al., 2010) which typically range from 25 ng kg 1 to 200 ng kg 1. Measurement uncertainty was also estimated and for PCN concentrations around 1 ng kg 1, the uncertainty returned is 20%; for
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A.R. Fernandes et al. / Chemosphere 85 (2011) 322–328
concentrations approaching, or at the (0.02 ng kg 1), the value can rise to 200%.
limit
of
detection
2.3. Intake assessment Food consumption data for the adult Irish population were taken from the North South Food Consumption Survey (NSFCS) conducted by the Irish Universities Nutrition Alliance (IUNA) (IUNA, 2001). The detailed food consumption database, which contains information from a 7-d dietary record for 958 subjects, age 18–64, was modified to suit contaminant intake calculations (recipes were used to convert meals into their respective ingredients). All consumption data were expressed on a per kilogram bodyweight (kg bw) basis calculated for each individual consumer (average bodyweight – 75 kg). The exposure of the Irish adult population to PCNs was calculated following a probabilistic approach, using the whole datasets of occurrence and consumption data, inputted into Crème probabilistic modelling software (Creme Food, 2005), for carcass fat, milk and dairy products, eggs, offal, fish and shellfish. 3. Results and discussion 3.1. Choice of PCN congeners and toxic equivalence factors The choice of congeners selected in this study was based principally on the toxicological characteristics of individual PCN congeners and the levels and patterns of occurrence. In practice however, the selection was limited by the availability of reliable reference standards. Thus the choice of congeners made in this study included mostly penta- to octa-chlorinated compounds, and generally those that are reported to show the highest toxicological effect e.g. PCN 66, 67, 68, 73, etc. In order to provide an indication of the dioxin-like toxicity arising from the presence of PCNs, the data has also been presented as toxic equivalents (TEQs), computed using Toxic Equivalency Factors (TEFs) taken from four studies (Hanberg et al., 1990; Engwall et al., 1994; Blankenship et al., 2000; Villeneuve et al., 2000; Behnisch et al., 2003). Where more than one TEF for the same congener has been reported, the highest value was used, together with the assumption that, where congeners co-eluted, the content comprised only the congener with the higher or only TEF. The debate on this approach to expressing toxicity-normalised exposure for dietary PCN content, which mirrors the approach used for PCDD/Fs and PCBs, is ongoing – on the one hand there is a reluctance to use this TEF approach for PCNs due to lack of information on persistence, and repeat dose toxicity studies (COT, 2009). However as observed elsewhere (Kannan et al., 2000; COT, 2009; Fernandes et al., 2010) relative potencies identified from in vitro studies provide an extremely conservative
approach to risk cumulative assessment for the dioxin-like toxicity of PCNs. Accordingly, given the qualifications that the TEFs currently proposed and used, would require confirmation as they have not been widely used, nor have they been adopted by regulatory bodies, the derived TEQ values are useful in that they provide an interim indication of the possible PCN-associated toxicity of the foods. These indicative TEQ values will of course be underestimates as they do not include all of the PCN congeners with proposed TEFs. 3.2. PCNs in food Concentration data for the 11 PCN congeners measured in the various food samples is given in Table 1. Additionally data for the sum of the PCNs and for PCN TEQ is also reported as upper-bound values, i.e. where congeners were not detected they were assumed to be present at the level of the limit of detection. All concentrations are expressed on a whole weight basis. In order to allow comparison with other food data, the fat content of the sample has also been included. All samples apart from rice, processed tomatoes and beans, showed the presence of PCNs, although the frequency of detection and relative abundance varied depending on the congener and the type of food. Fish showed a larger range of detected congeners as well as the most abundant occurrence. The moderately chlorinated congeners (penta-) dominated the profile, with abundance gradually declining as the degree of chlorination increased. A similar profile was observed for eggs, but for most animal fat (apart from poultry) and dairy products, the toxicologically more significant compounds – PCN 66/67 and PCN 73, were often the only congeners detected. This contrasting profile observed for tissue from higher order animal and milk/dairy products may be the result of selective bio-accumulation or metabolic processes (Fernandes et al., 2010). Only three popular species of fish were investigated – mackerel, salmon and trout, but of these the most oily fish, salmon (15% fat), showed the highest PCN levels – on average, an order of magnitude higher than trout (2.3% fat). These concentrations for farmed salmon are marginally higher than those observed for the UK (Fernandes et al., 2010), but in general, the average concentrations found in fish are similar for both studies. The observation for fish samples from Catalonia, Spain, are also similar, with the highest levels observed for salmon, although not directly comparable, because homologue totals were measured rather than individual congeners (Marti-Cid et al., 2008). However, an earlier study on PCNs in Catalonian food found significantly higher concentrations in oils and fats, and cereals relative to fish and shellfish (Domingo et al., 2003). On average, relatively high concentrations were also observed in the samples of animal fat which reflect PCN concentrations in meat, although the average here is influenced by two samples of avian (chicken) fat. The second of these, in particular is remarkable as it is a composite sample made up of 40 individual sub-samples.
Fig. 1. Relative distribution of sum-PCN and PCN-TEQ in food.
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A.R. Fernandes et al. / Chemosphere 85 (2011) 322–328 Table 1 Concentrations of PCN congeners in foods (ng kg
Fish
1
whole weight). Sum of 12 PCNs and TEQ are given as upper bound values.
ID
Sample Details
Fat%
PCN 52/ 60
PCN 53
15660 15662 15663 15670 15664 15667 15671 15672 15673 15701 15702 15703
Mackerel Mackerel Mackerel Mackerel Farmed salmon Farmed salmon Farmed salmon Farmed salmon Farmed salmon Trout Trout Trout
5.2 3.5 3.1 5.2 14.7 11 15.1 16.5 17.5 2.7 2.5 1.8
4.37 8.57 4.43 4.30 9.52 33.12 45.07 41.14 34.63 0.90 3.57 1.9
0.53 1.98 0.79 1.49 0.81 2.07 2.83 3.66 3.44 <0.32 1.58 0.46
PCN 66/ 67 0.18 0.73 0.19 0.17 0.86 3.37 4.84 4.18 3.33 0.13 0.35 0.26
PCN 68
PCN 69
PCN 71/ 72
PCN 73
PCN 74
PCN 75
Sum PCNs
PCN TEQa
<0.15 0.61 0.13 0.18 0.40 1.53 2.06 1.77 1.52 <0.13 0.43 0.15
<0.20 0.38 <0.18 <0.18 0.41 1.45 1.96 1.57 1.43 <0.18 0.54 0.16
<0.27 0.46 <0.24 0.3 0.39 1.62 1.77 1.3 1.23 <0.24 0.80 0.30
<0.03 <0.03 <0.03 <0.03 0.06 0.36 0.57 0.46 0.69 <0.03 0.10 0.10
<0.14 <0.12 <0.13 <0.13 <0.17 <0.15 <0.17 <0.17 <0.18 <0.13 0.08 0.04
<0.03 <0.02 <0.02 <0.02 <0.03 <0.03 <0.03 <0.03 0.03 0.02 <0.02 0.04
5.9 12.9 6.14 6.8 12.65 43.7 59.3 54.3 46.5 2.08 7.47 3.41
0.0018 0.0057 0.0017 0.0018 0.0058 0.0228 0.0321 0.0274 0.0236 0.0014 0.0042 0.0022
21.8
0.011
Average Shellfish
15661 15665 15666 15668 15669
Pacific Pacific Pacific Pacific Pacific
oysters oysters oysters oysters oysters
3.1 1.7 1.7 2.2 1.9
1.61 0.10 0.17 0.62 1.26
0.65 <0.01 0.04 0.25 0.47
<0.01 <0.01 <0.01 <0.01 <0.01
0.01 <0.01 <0.01 <0.01 0.01
0.02 <0.01 <0.01 <0.01 0.03
<0.01 <0.01 <0.01 <0.01 0.02
<0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01
Average Milk
14577 14579 14608 14609 14612 14615 14617 14620 14622 14625 14627 14628 14630 14632 14633
1.11
Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk Milk
3.8 5.1 3.9 4 4.1 3.6 3.6 4 2.6 4.4 3.9 3.7 4.1 4 3.7
<0.03 <0.03 <0.03 <0.03 <0.04 0.08 <0.05 <0.06 <0.03 <0.04 0.03 0.01 0.03 0.02 0.02
<0.03 <0.03 <0.03 <0.03 <0.04 0.03 <0.04 <0.05 <0.03 <0.04 <0.01 <0.01 0.01 0.01 0.01
0.03 0.03 0.03 0.02 0.04 0.03 0.02 0.02 0.02 0.02 0.03 0.01 0.02 0.04 0.03
<0.01 <0.01 <0.01 <0.01 <0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.04 <0.04 <0.03 <0.03 <0.05 0.02 <0.05 <0.06 <0.03 <0.04 0.01 0.01 0.01 0.04 0.01
<0.03 <0.03 <0.03 <0.03 <0.04 <0.01 <0.04 <0.05 <0.03 <0.04 <0.01 <0.01 <0.01 <0.01 <0.01
<0.06 <0.07 <0.06 <0.06 <0.08 <0.01 <0.09 <0.11 <0.06 <0.08 <0.01 <0.01 <0.01 <0.01 <0.01
Average Eggs
14634 14635 14636 14637 14638 14639 14640 14641 14646 14648 14649 14650 14651 14652 14653
Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid Liquid
egg egg egg egg egg egg egg egg egg egg egg egg egg egg egg
14931 14932 14958 14960 14964 14933 14934 14959 14961 14962 14977 14978
sample sample sample sample sample sample sample sample sample sample sample sample sample sample sample
1 2 3 4 5 6 7 8 13 15 16 17 18 19 20
9.7 11 10.2 10.2 9.5 10.3 11.2 10 10.2 10.1 10.8 10.1 9.5 8.8 10.2
0.43 1.47 0.11 0.14 0.24 0.22 0.13 0.24 0.27 0.43 0.23 0.32 0.29 0.31 0.33
0.06 0.12 0.02 0.04 0.09 0.06 <0.02 0.03 0.09 0.09 0.05 0.11 0.08 0.09 0.07
0.09 0.11 0.02 0.03 0.03 0.03 0.03 0.08 0.03 0.06 0.03 0.05 0.03 0.06 0.04
0.06 0.11 0.02 0.02 0.03 0.02 0.01 0.04 0.03 0.03 0.02 0.04 0.03 0.04 0.03
0.10 0.26 0.02 0.02 0.04 0.03 0.02 0.05 0.04 0.05 0.02 0.06 0.04 0.04 0.04
0.04 0.08 <0.01 <0.01 0.03 0.02 <0.01 0.03 0.02 0.04 0.01 0.03 0.02 0.02 0.02
0.05 0.05 <0.01 0.02 0.02 <0.01 <0.01 0.04 <0.01 0.02 <0.01 0.02 <0.01 0.03 <0.01
0.01 0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02
Bovine liver Avian liver Avian liver Bovine liver Avian liver Ovine liver Porcine liver Porcine liver Equine liver Equine liver Ovine liver Ovine liver
16326 16327
Butter Irish creamery butter
0.85 2.22 0.23 0.3 0.5 0.42 0.26 0.54 0.52 0.75 0.4 0.66 0.53 0.62 0.57 0.62
3.3 4.8 5.1 3.8 5.1 4.9 4.2 3.7 4.7 3.8 7 4.3
<0.09 0.43 0.15 <0.08 <0.08 0.07 0.11 <0.07 <0.07 0.08 0.08 0.18
<0.02 0.05 0.05 <0.02 <0.02 0.06 0.09 0.03 0.02 0.04 0.06 0.24
0.08 0.03 0.02 0.09 0.01 0.69 0.08 0.11 0.38 0.29 0.9 1.96
<0.01 0.03 0.02 <0.01 <0.01 0.01 0.01 <0.01 <0.01 0.02 0.02 0.01
<0.02 <0.01 <0.02 <0.02 <0.01 <0.01 <0.02 <0.01 <0.01 <0.01 <0.02 <0.02
<0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 <0.01 0.03 0.03 0.01
0.03 0.02 0.03 0.05 0.01 0.42 <0.02 <0.01 0.04 0.03 0.58 1.8
<0.01 <0.01 <0.01 <0.01 <0.01 0.02 <0.01 <0.01 <0.01 <0.01 0.01 0.03
<0.02 <0.02 <0.02 <0.02 <0.02 0.05 <0.02 <0.01 <0.02 <0.02 <0.02 <0.01
Average Dairy
0.25 0.26 0.24 0.23 0.32 0.21 0.32 0.38 0.23 0.29 0.13 0.09 0.12 0.16 0.12 0.22
Average Liver
2.34 0.18 0.28 0.94 1.83
0.29 0.61 0.33 0.31 0.18 1.34 0.37 0.28 0.57 0.53 1.72 4.26 0.90
81 80.9
<0.66 <0.60
<0.10 <0.09
0.16 0.58
<0.06 <0.06
<0.09 <0.10
<0.06 <0.06
<0.05 0.31
<0.04 <0.03
<0.09 <0.08
1.31 1.91
0.0002 0.0001 0.0001 0.0001 0.0002 0.0002 0.0003 0.0003 0.0003 0.0002 0.0004 0.0002 0.0003 0.0003 0.0002 0.0003 0.0002 0.0001 0.0002 0.0003 0.0002 0.0003 0.0009 0.0015 0.0002 0.0003 0.0004 0.0003 0.0002 0.0007 0.0003 0.0005 0.0003 0.0005 0.0003 0.0005 0.0004 0.0005 0.0005 0.0003 0.0003 0.0006 0.0001 0.0041 0.0005 0.0005 0.0017 0.0013 0.0055 0.0135 0.002 0.0012 0.0037
(continued on next page)
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Table 1 (continued) ID
Sample Details
Fat%
PCN 52/ 60
16328 16329
Irish creamery butter Irish creamery butter salted Irish unsalted butter Red cheddar
81.6 81.8
<0.45 <0.47
0.14 0.13
83 27.1
<0.48 <0.17
<0.10 <0.03
16330 16318
PCN 53
PCN 66/ 67
PCN 68
PCN 69
PCN 71/ 72
1.42 0.59
0.08 <0.07
<0.09 <0.09
<0.05 <0.05
0.61 0.26
<0.07 <0.02
<0.09 <0.03
<0.05 <0.01
PCN 73
PCN 74
PCN 75
0.73 0.33
<0.07 <0.07
<0.10 <0.10
3.13 1.9
0.0084 0.0038
0.35 0.12
<0.08 <0.01
<0.10 <0.03
1.93 0.68
0.0039 0.0015
Average Fat
14928 14935 14940 14946 14949 14966 14970 14971 14974 14975 14929 14930 14936 14943 14945 14950 14952 14955 14956 14957 14963
Bovine fat Avian fat (duck) Bovine fat Bovine fat Bovine fat Avian fat Avian fat Avian fat (duck) Avian fat Bovine fat Ovine fat Porcine fat Avian fat Porcine fat Ovine fat Ovine fat Ovine fat Ovine fat Porcine fat Porcine fat Porcine fat
84.8 91 81.8 75.8 77.9 67 86 92.7 85.9 87.3 86.2 74.6 85.2 77.2 84.2 84.5 93.7 88.9 71 67.6 64.8
0.5 1.15 0.47 0.48 0.62 6.38 <0.88 1.4 1.91 0.59 <0.42 <0.43 8.6 <0.68 <0.66 <0.69 <0.69 <0.44 <0.42 <0.42 <0.95
0.17 1.17 0.12 <0.11 0.15 1.54 0.29 0.93 0.68 0.12 <0.45 <0.46 1.44 <0.10 <0.10 <0.10 0.13 <0.47 <0.45 <0.44 <0.14
0.95 0.17 1.02 1.04 1.08 0.98 0.42 0.26 0.36 1.05 1.63 0.32 0.89 0.45 1.51 1.73 2.26 2.1 0.29 0.26 0.24
0.05 0.27 <0.05 <0.05 <0.05 0.69 0.26 0.37 0.25 <0.05 <0.06 <0.06 0.64 <0.06 <0.06 <0.06 <0.06 <0.06 <0.06 <0.06 <0.08
<0.09 0.23 <0.08 <0.09 <0.09 0.6 0.17 0.28 0.27 <0.08 <0.10 <0.10 0.75 <0.09 <0.09 <0.09 <0.09 <0.10 <0.10 <0.10 <0.13
<0.05 0.22 <0.05 <0.05 <0.05 0.29 0.16 0.27 0.14 <0.05 <0.12 <0.12 0.53 <0.06 <0.06 <0.06 0.08 <0.12 <0.12 <0.12 <0.09
0.29 0.3 0.34 0.28 0.34 0.73 0.45 0.4 0.26 0.26 0.56 <0.08 0.41 <0.06 0.34 0.59 0.71 0.46 <0.08 <0.08 <0.08
<0.05 <0.05 <0.05 <0.05 <0.05 <0.05 <0.06 <0.05 <0.05 <0.05 <0.07 <0.07 0.06 <0.04 <0.04 <0.05 <0.05 <0.07 <0.07 <0.07 <0.06
<0.09 <0.08 <0.08 <0.09 <0.09 <0.09 <0.12 <0.08 <0.09 <0.09 <0.10 <0.11 <0.09 <0.09 <0.09 <0.10 <0.10 <0.11 <0.10 <0.10 <0.13
Average Other foods
Sum PCNs
PCN TEQa
1.81
0.0037
2.24 3.64 2.26 2.24 2.52 11.35 2.81 4.04 4.01 2.34 3.51 1.75 13.41 1.63 2.95 3.47 4.17 3.93 1.69 1.65 1.9
0.0050 0.0029 0.0055 0.0054 0.0057 0.0095 0.0042 0.0039 0.0035 0.0053 0.0086 0.0019 0.0084 0.0024 0.0075 0.0091 0.0116 0.0102 0.0018 0.0017 0.0017
3.69
0.0055
16310
Mushrooms composite
0.3
0.45
1.2
<0.01
0.01
0.02
0.04
<0.01
<0.01
<0.01
1.76
0.0002
16311
Vine tomatoes composite Bread composite Cabbage composite Ham composite Potatoes Rooster potatoes Cornflakes composite Oats composite Sausages Baked beans composite Sweetcorn composite Tomato puree composite Basmati rice
0.2
0.03
0.09
<0.01
<0.01
<0.01
<0.01
<0.01
<0.01
0.01
0.19
0.0001
2.2 0.2 2.5 0.1 0.2 1 6.8 35.4 0.3 2 0.7
<0.19 0.53 <0.05 <0.07 <0.08 <0.31 <0.30 <0.14 <0.06 0.07 <0.08
0.09 2.09 0.01 0.02 0.03 0.23 0.05 <0.13 <0.06 <0.06 <0.08
<0.02 0.01 0.01 <0.01 <0.01 <0.04 <0.04 0.14 <0.01 0.01 <0.01
<0.02 0.03 <0.01 <0.01 <0.01 <0.03 <0.03 <0.01 <0.01 0.01 <0.01
<0.03 0.05 <0.01 <0.01 <0.01 <0.05 <0.05 <0.03 <0.01 <0.01 <0.02
<0.02 0.1 <0.01 <0.01 <0.01 <0.03 <0.03 <0.02 <0.01 <0.01 <0.01
0.02 <0.01 <0.01 <0.01 <0.01 <0.02 <0.02 0.03 <0.01 0.01 <0.01
<0.01 <0.01 <0.01 <0.01 <0.01 <0.02 <0.02 <0.01 <0.01 <0.01 <0.01
<0.02 <0.01 <0.01 <0.01 <0.01 <0.04 <0.04 <0.03 <0.01 <0.01 <0.02
0.42 2.84 0.13 0.16 0.18 0.77 0.58 0.54 0.19 0.2 0.25
0.0003 0.0003 0.0001 0.0001 0.0001 0.0004 0.0004 0.0007 0.0001 0.0001 0.0001
1.4
<0.13
<0.02
<0.02
<0.01
<0.02
<0.01
<0.01
<0.01
<0.02
16314 16319 16322 16331 16332 16355 16353 16346 16350 16351 16352 16354
Average
0.25 0.60
0.0002 0.0002
PCN 52-0.000025, PCN 53-0.0000018, PCN 66/67-0.004, PCN 68-0.0028, PCN 69-0.002, PCN 71/72-0.00009, PCN 73-0.0031, PCN 74-0.0000041, PCN 75-0.00001. a PCN TEQ is given in ng TEQ Kg 1 whole weight and is calculated using TEF values taken from Behnisch et al. (2003), Blakenship et al. (2000), Hanberg et al. (1990), and Villeneuve et al. (2000).
Ovine fat showed comparable levels to some of the avian fat, and this is also reflected in the samples of ovine liver which showed the (relatively) highest levels. The distribution of PCNs as average values for each of the food groups studied (on a whole weight basis) is illustrated in Fig. 1. The detection of PCNs in these samples of food from Ireland – often seen as experiencing lower levels of environmental pollution because of its geography and the prevailing wind direction – demonstrates the persistence and ubiquity of these largely legacy pollutants. As observed for the congener profiles in the UK (Fernandes et al., 2010), samples of fish, eggs and vegetables still reflect profiles of environmental media (Nakano et al., 2000) and some commercial mixtures (Kannan et al., 2000), several years after the widespread use of these chemicals ceased. The calculated PCN TEQ values associated with the reported concentrations, range from 0.0001 ng kg 1 TEQ mainly for vegetable based foods and some shellfish to 0.03 ng kg 1 TEQ for fish
(whole weight basis, Table 1). In general, there is correlation (r = 0.91) between the calculated TEQ values and the sum of the measured PCNs which for some matrices is very strong (r = 0.99 for fish). This high level of correlation is unsurprising given that the congener selection was partly based on toxicity and supports the rationale used for the selection of congeners. For the samples analysed in this work, it is clear that PCN TEQ is considerably lower than for similar samples from Ireland analysed for PCB and PCDD/F TEQ. For example, the average PCN TEQ 0.02 ng kg 1, for salmon is more than an order of magnitude lower, compared to other dioxin-like compounds (average – 0.54 ng kg 1 PCDD/F TEQ and 1.61 ng kg 1 PCB-TEQ for fish) in similar foods. (Food Safety Authority of Ireland, 2007). Although this data for PCDD/Fs and PCBs is derived from samples that were taken earlier and levels are likely to have fallen since (Fernandes et al., 2004), the observation is in line with other literature reports. The observation on the relatively lower contribution of PCNs to dioxin-like TEQ has been
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made before, for environmental matrices (Nakano et al., 2000) with a reported TEQ contribution ratio of 2:10:85 for PCN:PCB:PCDD/F, but also for foods (Fernandes et al., 2010) where a similar, order of magnitude difference in contribution to TEQ was reported (e.g. average – 0.01 ng kg 1 TEQ for fish compared to average – 0.27 ng kg 1 PCDD/F TEQ and 0.9 ng kg 1 PCB-TEQ). It must be noted however, that all of the PCN congeners with proposed TEF values have not been included in these calculations, so the PCN contribution may well be marginally greater. 3.3. Dietary intakes The exposure to PCDD/F and PCB TEQ (upperbound) of the adult population consuming an average diet is estimated at 12 pg TEQ kgbw 1 month 1 (Food Safety Authority of Ireland, 2010) based on the consumption of food of animal origin. The estimated additional contribution to this exposure of PCN TEQ arising from consumption of food of animal origin was calculated at approximately 0.14 pg TEQ kgbw 1 month 1 (upperbound). Dairy products and fish including shellfish were the major contributors to exposure, each contributing 37% to the total exposure, meat and meat products contributed 23% and eggs 3%. Similar findings were recently reported for PBDEs, where fish was also found to be the major contributor followed by dairy products and meat (Trudel et al., 2010). These findings can be attributed to the higher contaminant concentration in fish tissue and the larger average consumption of dairy and meat products compared to fish (dairy on a weight basis around 18 times more than fish; meat products about seven times more than fish). Due to the very limited number of studies in the literature and the different methodologies used in these studies (different foodgroups, individual congeners versus homologue groups), it is difficult to make direct comparison to the findings of this study. Fernandes et al., 2010 illustrated a worst case intake scenario for the UK population based on the assumption that all solid food consumed (1.5 kg d 1 for adults, 1 kg d 1 for young children) contained 0.02 ng TEQ kg 1 (the highest result obtained in the study; same congeners as this study), resulting in an estimated exposure of 0.39 pg TEQ kgbw 1 d 1 for adults and 0.98 pg TEQ kgbw 1 d 1 for children, respectively. Marti-Cid et al., 2008 reported a total dietary intake of 7.25 ng/d (0.1 ng kg/bw) (sum tetra- to octachloro PCN homologues rather than individual congeners) for a standard adult man (70 kg) based on a comprehensive market basket survey. In this study, the estimated increase in dioxin-like TEQ exposure from dietary PCNs is relatively marginal and suggests that exposure to PCNs is of low concern. However, it is important to note as observed earlier, that all PCN congeners with TEF values have not been included in the current estimates, and that the TEFs currently proposed would require confirmatory studies which would allow harmonization of the values and a consensus on their use. 4. Conclusions This study demonstrates the universal presence of PCNs in Irish foods and provides baseline information on the concentrations found. Whilst there is variation in occurrence depending on individual congeners of these contaminants and the types of food studied, the widespread detection in a relatively cleaner environment (Ireland generally shows food contamination levels that are below the European average for environmental contaminants such as dioxins and PCBs except following specific contamination incidents) underlines the ubiquity of these contaminants. The profile of PCN congener occurrence in some foods (e.g. some vegetable based foods, fish, etc., where metabolic or other degradation pathways are unlikely to be significant) bears a good
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resemblance to some commercial mixtures, and despite other sources such as incineration being reported, the legacy of past commercial usage still appears to strongly influence the background pattern of occurrence. The estimated contribution to dioxin-like toxicity associated with the PCN occurrence levels reported in this work is relatively marginal and although based on a limited study, contributes to the opinion that the levels of PCNs in the Irish produce studied, do not raise concern for human health. The general lack of data on PCNs in food does not support any discussion on trends. The gradual decline in food levels observed for other similar contaminants such as PCBs may be extrapolated to PCNs, but this would need to be confirmed empirically. Overall, the lack of information concerning PCN toxicity and dietary exposure warrants further attention to this group of contaminants. Acknowledgement The authors are grateful to the Food Safety Authority of Ireland for funding this work. References Behnisch, P.A., Hosoe, K., Sakai, S., 2003. Brominated dioxin-like compounds: in vitro assessment in comparison to classical dioxin-like compounds and other polyaromatic compounds. Environ. Int. 29, 861–877. Blankenship, A., Kannan, K., Villalobos, S., Villeneuve, D., Falandysz, J., Imagawa, T., Jakobsson, E., Giesy, J.P., 1999. Relative potencies of Halowax mixtures and individual polychlorinated naphthalenes (PCNs) to induce Ah receptormediated responses in the rat hepatoma H4IIE-luc cell bioassay. Organohalogen Compd. 42, 217–220. Blankenship, A., Kannan, K., Villalobos, S., Villeneuve, D., Falandysz, J., Imagawa, T., Jakobsson, E., Giesy, J.P., 2000. Relative potencies of Halowax mixtures and individual polychlorinated naphthalenes (PCNs) to induce Ah receptormediated responses in the rat hepatoma H4IIE-Luc cell bioassay. Environ. Sci. Technol. 34 (15), 3153–3158. Committee on Toxicity of Chemicals in Food, Consumer Products and the Environment, 2009. Polychlorinated Naphthalenes in Food.
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