heavy metals and pops in red king crab from the barents sea
TRANSCRIPT
Food Chemistry 167 (2015) 409–417
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Food Chemistry
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Heavy metals and POPs in red king crab from the Barents Sea
http://dx.doi.org/10.1016/j.foodchem.2014.07.0030308-8146/� 2014 Elsevier Ltd. All rights reserved.
⇑ Corresponding author. Tel.: +47 95 27 36 43; fax: +47 55 90 52 99.E-mail address: [email protected] (S. Valdersnes).
Kaare Julshamn a, Stig Valdersnes a,⇑, Arne Duinker a, Kjell Nedreaas b, Jan H. Sundet b, Amund Maage a
a National Institute of Nutrition and Seafood Research (NIFES), P.O. Box 2029 Nordnes, N-5817 Bergen, Norwayb Institute of Marine Research, P.O. Box 1870 Nordnes, N-5817 Bergen, Norway
a r t i c l e i n f o
Article history:Received 6 January 2014Received in revised form 29 May 2014Accepted 1 July 2014Available online 9 July 2014
Keywords:Heavy metalsPOPsDioxinsPCBPBDEPFASRed king crabParalithodes camtschaticusSeafood safety
a b s t r a c t
The aim of this paper is to evaluate the food safety of the red king crab from Norwegian waters and obtaininformation on possible geographical and gender differences. Samples of claw and leg meat of 185 redking crabs (Paralithodes camtschaticus), collected from 23 positions in the Barents Sea, were analysedfor dioxins, furans, non-ortho and mono-ortho PCBs, non dioxin-like PCBs, polybrominated diphenylethers, and perfluorinated alkyl substances and elements, such as arsenic, cadmium, mercury and lead.The concentrations of persistent organic pollutants and metals were low compared to maximum levelslaid down in European regulations. Hence, red king crab is a safe food. Significant differences in theconcentrations of metals among different areas, and between male and female crabs, were found. Positivecorrelations were found between carapace length and mercury, methylmercury and cadmium concentra-tions, and between fat and arsenic and inorganic arsenic concentrations.
� 2014 Elsevier Ltd. All rights reserved.
1. Introduction
Red king crab (Paralithodes camtschaticus) was deliberatelyintroduced to the Barents Sea by Russian scientists during the1960s. The aim was to establish a new and valuable fishingresource for the fishermen in the region (Orlov & Ivanov, 1978;Orlov & Karpevich, 1965). The red king crab stock has increasedheavily in the distribution area, and is now common in coastalareas of Norway west to about 25�E. In Russian waters, the crabhas a more off-shore distribution and is found as far east as theKoguljev Island and north to the Goose Bank (Pinchukov &Sundet, 2011). The total stock size in Norwegian waters is notpossible to calculate due to difficulties in sampling juvenile crabsrepresentatively. However, recent estimates of the legal size malestock indicate a stock size of about 2000 tons (Sundet, Hvingel, &Hjelset, 2012). This part of the stock is judged to constitute approx-imately 5–10% of the total stock. The stock index of legal males hasdecreased steadily since 2004, which is probably also the situationfor the total stock (Sundet et al., 2012). Female king crab hasbecome significantly less fecund in Norwegian waters during thelast 10–15 years (Hjelset, Nilssen, & Sundet, 2012). This, combinedwith a lower abundance has probably caused a 30% reduction in
the reproduction potential of the red king crab stock in Norwegianwaters (Hjelset, 2013). The crab larvae hatch and develop in thefjords and near coastal areas, and the larvae may be transportedconsiderable distances by currents (Pedersen, Nilssen, Jorgensen,& Slagstad, 2006). However, the main expansion of the crab isbelieved to be carried out by adult specimens moving westwardsalong the coast (Sundet, Kuzmin, Hjelset, & Nilsen, 2001).
Through the Grey Zone Agreement between the Soviet Unionand Norway in 1978, there was a general ban on crab fishing but,in 1994, Norwegian and Russian authorities agreed to start a lim-ited experimental fishery in each country’s national zone (Anon,2007). From 2002 on, Norway decided to change the managementto an ordinary quota regulated commercial fishery. At the sametime, they introduced a western and a northern border for an areawhere the red king crab should be managed as a fishing resource. Amore permanent management system for the red king crab inNorwegian waters was settled in 2008, which added severalprovisions. One decided that the crab was unwanted outside thequota-regulated area, and should be eradicated. In addition, trapsare the only legal fishing gear in the commercial crab fishery andthe minimum legal size for commercial catch is 130 mm carapacelength (CL), for both males and females. To limit the spread of thespecies, further westwards a non-regulated fishery was introducedwest of 26�E and north of 71�300N. This free fishery, in addition toorganised eradication fishery in this area, appears to be an effective
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means to limit further spread of the crab. Propagation westwardalong the coast has not changed much since 2009 (Sundet et al.,2012).
Adult red king crabs feed on most sessile benthic organismsavailable, but some species, such as polychaetes, mussels and echi-noderms, seem to be preferred (Sundet et al., 2001). In addition,the red king crab is a scavenger, feeding on most dead organismsavailable, such as dead fish, e.g. capelin and lumpsucker, in ourareas (Jewett & Feder, 1982; Sundet et al., 2001).
The Norwegian quota in 2012/2013 was set at 900 tons of malecrabs and 50 tons of female crabs. The red king crab is available ascooked and raw clusters, or live whole crabs from the fish landingfacilities. The major product is clusters which consist of legs, clawsand shoulders, and the meat return in a cluster is about 40% byweight. Norwegian products of red king crabs are exported tomany countries, such as South Korea, Japan and China, as well asa number of European countries (www.seafood.no, Retrieved 11November 2013).
No studies have previously been done to evaluate the foodsafety of red king crab (P. camtschaticus) in the Barents Sea. Thiscrab specie has gained increasing popularity as an exquisite deli-cacy in recent years and is often preferred over lobster. The aimof this paper is to determine the content of harmful substances,that may threaten food safety, in the red king crab from Norwegianwaters and to evaluate the data to gain more information on differ-ences between geographical areas and between male and femalecrabs, as well as possible correlations of metal contents withregard to physical properties of the crabs. Several countries haveintroduced maximum limits for different persistent organicpollutants (POPs) and metals, and in this paper we will comparethe levels found with current relevant legal limits found inEuropean legislation. Food safety in this context is related to theconcentration of undesirable substances, such as metals (alsomethylmercury and inorganic arsenic), dioxins (PCDDs), furans(PCDFs), dioxin-like PCBs (dl-PCBs), non-dioxin-like PCBs (ndl-PCBs, PCB6), polybrominated flame retardants (PBDEs) and perfluo-rinated alkyl substances (PFASs) in crabs of different sizes andgenders caught in the Barents Sea off the Norwegian coast. Typicalconcentrations of mercury in the Atlantic ocean are found tobe around 0.3 ng l�1, while the Barents Sea is in the range0.4–1.0 ng l�1 with even higher concentrations in arctic regionsfurther north (3 ng l�1) due to ice melting processes (Sagerup,Beyer, Evenset, Green, & Falk, 2013). The levels of POPs in theBarents Sea, however, are considerably lower and typically in thepg l�1 range (Sagerup et al., 2013). Previous investigations haveshown that considerable levels of cadmium may be found in thebrown meat of edible crab and currently there is a general adviceto avoid eating this (EC, 2011b).
2. Materials and methods
2.1. Sampling
Samples of red king crabs were taken during the routine crabsurveys carried out by the Institute of Marine Research (IMR), fromboth IMR’s reference fleet and from selected fishermen in the per-iod from April 24 to November 2 2012. Most of the samples weretaken in September. In total, 185 red king crabs were sampled at23 different positions off the coast of northern Norway from68�480N 30�480E to 71�050N and 24�230E (Fig. 1). The crabs werecaught at a depth varying from 64 to 366 m. One claw and oneleg were taken from each individual crab at each position, put intoa plastic bag and frozen at �20 �C immediately. The samples werepacked in polystyrene boxes and shipped to the laboratory by mail.In addition to information about the catch position and fishing
depth, the weight and the carapace length (CL) and sex, wererecorded.
2.2. Sample preparation
At the laboratory, the samples were coded and registered in thelaboratory information management system (LIMS). For each crab,the data on CL and weight were recorded. The claw and the legwere thawed and then cooked individually. The meats of the clawand leg from each crab (i.e., at least 100 g) were dissected, pooled,and weighed prior to freeze-drying. The dry matter was calculated(g 100 g�1) by weighing the samples before and after the freeze-drying. The dry matter was then ground to a fine powder, homog-enised, and kept dry prior to analysis. Each sample was dividedinto two parts, one for the determination of dioxins, furans,dl-PCBs, PBDEs, and PFASs, and the other part for the determina-tion of the elements and the lipid contents. All analyses werecarried out on individual crabs, using methods accredited in accor-dance with ISO-EN 17025 by the Norwegian Accreditation body.
2.3. Element determination (As, Hg, Cd, and Pb)
For the determination of elements by inductively coupledplasma mass spectrometry (ICP-MS), subsamples were subjectedto microwave-assisted wet digestion, using concentrated nitricacid and hydrogen peroxide in an Ethos Pro microwave system(Julshamn, Thorlacius, & Lea, 2000). The digests were diluted withdeionised water and external calibration curves were constructedfor determining total mercury (Hg), arsenic (As), cadmium (Cd),and lead (Pb). Rhodium was used as an internal standard in orderto correct for instrumental drift. Gold was added in order to stabi-lise Hg (Julshamn et al., 2007). The method has been adopted as aNordic Committee on Food Analysis (NMKL) method (NMKL, 2007),as well as a European Normalisation Organisation (CEN) method,EN 15763:2009 (CEN, 2009).
The trueness values of the Hg, As, Cd, and Pb determinationswere evaluated by analysis of the CRM TORT-2 (lobster hepatopan-creas). The obtained values (mean ± 95% uncertainty) were0.29 ± 0.04 mg Hg kg�1, 24.1 ± 1.6 mg As kg�1, 27.6 ± 1.6 mg Cdkg�1, and 0.33 ± 0.04 mg Pb kg�1. The results agreed well with thecertified values for TORT-2 (0.27 ± 0.06 mg Hg kg�1, 21.6 ± 1.8 mgAs kg�1, 26.7 ± 0.6 mg Cd kg�1, and 0.35 ± 0.13 mg Pb kg�1. Thepresent method has been tested in several proficiency tests (PT)and the results from two PTs are given elsewhere (Julshamn,Duinker, Nilssen, et al., 2013). The limit of detection (LOD) isexpressed as three times the standard deviation (sd) of the meanresult of a large number of blanks (N P 20). The limit of quantifica-tion (LOQ) is expressed as two times the LOD (6 sds). The LOQs forthe elements were estimated as 0.005 mg Hg kg�1, 0.01 mg As kg�1,0.005 mg Cd kg�1, and 0.03 mg Pb kg�1 dry weight.
The precision (i.e., internal reproducibility), measured as resid-ual standard deviation (RSDr [%]), was calculated to be 6–10% forthese elements in cod muscle in the present study (N = 30). Themeasurement uncertainties estimated for Hg, As, Cd, and Pb werebased on the internal reproducibility, taken from the control chart,and the results achieved from PTs. The following results for mea-surement uncertainty, as a percentage, were obtained: Hg (20%),As (12%), Cd (12%), and Pb (14%).
2.4. Lipid determination
Fat content of the samples was determined gravimetrically,using isopropanol in ethyl acetate (NS, 1994). The method for fatdetermination has been used in PTs since 1998, with an averageaccuracy of 98% (Julshamn, Duinker, Nilssen, et al., 2013).
Fig. 1. Map showing the 23 positions where red king crabs were sampled.
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2.5. Determination of PCDD/Fs, dl-PCBs, ndl-PCBs, and PBDEs
The concentrations of dioxins and furans (PCDD/Fs) andnon-ortho PCBs were determined by using high-resolution gaschromatography/high-resolution mass spectrometry (HRGC/HRMS); mono-ortho PCBs and ndl-PCBs (PCB6) were determinedby GC triple-quad MS (GC–MS/MS), and polybrominated diphenylether congeners (PBDE7) were determined by GC-NCI-MS (negativechemical ionising) following sample extraction and clean-up. Themethods are published elsewhere (Julshamn, Duinker, Berntssen,et al., 2013; USEPA, 1994, 1999) and only a brief outline is givenhere. The same method of sample clean-up and extraction wasused for all POPs determined in this study.
Homogenised samples were mixed with hydromatrix andinternal standards were added for dioxins, furans, PCBs, and PBDEs.The extraction was carried out by means of hexane in anAccelerated Solvent Extractor-300 (ASE) or by pressurised liquidextraction (PLE). The fat was broken down on-line with acidic silicagel. The extract was further purified chromatographically, usingPowerPrep (FMS Inc.) over three columns packed with multilayersilica, basic aluminium, and carbon, respectively, and was elutedwith different solvents. Two fractions were collected: fraction 1contained PBDEs, ndl-PCBs, and mono-ortho PCBs, and fraction 2contained PCDD/Fs and non-ortho PCBs.
The quantification of PCDD/Fs and non-ortho PCBs was doneusing an internal standard, a five-point calibration curve, and theratio RF. Mono-ortho PCBs, ndl-PCBs, and PBDEs were quantified,using internal standards and a five-point external calibrationcurve, except for ndl-PCB where a one-point calibration curvewas used.
The range of LOQ was 0.02–0.10 pg/g ww for PCDD/Fs,0.07–1.5 pg/g ww for non-ortho PCBs, and 0.6–166 pg/g ww formono-ortho PCBs. Toxic equivalency factors (TEFs) have beenestablished for the seven congeners of PCDD, 10 congeners of PCDF,four congeners of non-ortho PCBs, and eight congeners of mono-ortho PCBs for human risk assessment (Van den Berg et al.,2006). The concentrations are expressed in the present work asWorld Health Organisation (WHO) toxic equivalents (TEQs), usingWHO-2005-TEF. Non-quantified individual congeners were set atthe LOQ (upper-bound LOQ). Recovery values were calculated asdescribed in the USEPA (USEPA, 1994) and were found to bebetween 78% and 110%. Concentrations are expressed as ng
upper-bound WHO-2005-TEQ kg�1 ww, according to EuropeanUnion (EU) legislation (EC., 2011a). The method has been testedin several PTs with good results (Julshamn, Duinker, Berntssen,et al., 2013).
PCB6 is defined as the sum of the six ndl-PCB congeners (i.e.,PCB-28, -52, -101, -138, -153, and -180). The LOQ in liver and mus-cle for the sum of ndl-PCBs was estimated as 0.3 ng/g ww and theLOQ for each of the congeners varied between 0.06 and0.15 lg kg�1 ww. Measurement uncertainty was estimated as20% for the ndl-PCB congeners. The ndl-PCB method was testedin a PT on cod liver oil with good results. (Julshamn, Duinker,Berntssen, et al., 2013).
The PBDE congeners (PBDE-28, -47, -66, -99, -100, -119, -138,-153, -154, and -183) were determined. The method quantifies 10different congeners of PBDEs, including seven congeners that addup to a ‘standard sum PBDE7’ (i.e., the sum of PBDE-28, -47, -99,-100, -153, -154, and -183). The LOQ for this matrix was estimatedto be 0.005 ng g�1 ww for the congeners PBDE-28, -100, -153, and-154 and 0.010 ng g�1 ww for the congeners PBDE-47, -99, and-183. The measurement uncertainties were highly related to theconcentrations of the congeners. The measurement uncertaintyclose to LOQ was estimated to be 45% for the PBDE congeners.The trueness of the PBDE method was tested in a PT on cod liveroil with good results (Julshamn, Duinker, Berntssen, et al., 2013).
2.6. Determination of PFAS
The method for PFAS determination was based on previouslypublished work (Berger & Haukas, 2005; Gledhilll et al., 2006;Jenkins, Ellor, Twohig, Worrall, & Kearney, 2006; Young & VanTran, 2006) Determinations were carried out by weighing the sam-ple in a polypropylene tube (PP) and adding mass-labelled internalstandards. The PFAS was extracted using methanol and ultrasound.After centrifugation, the supernatant was decanted into a syringefitted with a 0.45 lm nylon filter. The filtered supernatant wasdiluted with milliQ water and purified on ASPEC, using Oasis WAXSPE columns, followed by ultracentrifugation through a YM-3 filter.The purified extract was then analysed by LC–MS/MS and the PFASquantified by a calibration curve of 5–7 points, using internal stan-dards and analyte-specific RRF. LOQ is analyte-dependent and typ-ically varies from 0.3 to 1.5 lg kg�1 ww. The method participatesregularly in PTs with good results for analytes above LOQ.
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2.7. Determination of methylmercury
Methylmercury was determined by using isotope dilutionGC-ICP-MS (Valdersnes, Maage, Fliegel, & Julshamn, 2012). Briefly,0.2 g of the freeze-dried sample was weighed, followed by additionof an appropriate amount of 201HgMe-enriched internal standard.The sample was dissolved by mixing with TMAH overnight on arotator. The solubilised sample was pH-adjusted by adding concen-trated nitric acid and sodium acetate/acetic acid buffer, followedby derivatisation by sodium tetraethyl borate and extractioninto hexane. The hexane phase was removed and analysed byGC-ICP-MS and the methylmercury content determined using theisotope dilution equation. The method participates regularly inPTs from different organisations with good results (Z-scores from�0.36 to 1.66 over the past four years).
Table 1Sampling localities (see Fig. 1), number of crabs sampled at each site (N), sampling
2.8. Statistical analysis
The 23 stations were grouped into four geographical areas: ‘‘A:Havøysund’’ comprised of stations 1–5, ‘‘B: Laksefjorden’’, includ-ing stations 6–9; ‘‘C: Tanafjorden’’, comprised of stations 10–19;‘‘D: Varangerfjorden’’, including stations 20–23. One way analysisof variance (ANOVA) was used to assess differences in continuousmeasurements (e.g. metals, metal species and physiologicalparameters) across geographical areas and between male andfemale crabs. Analysis of covariance (ANCOVA) was used toinvestigate effects of categorical and continuous variables simulta-neously. Where significant differences were found with ANOVA/ANCOVA, a post hoc Bonferroni correction with p = 0.05 wasapplied in pair-wise comparison of groups. Correlations wereinvestigated by using regression analysis and scatter plots. In orderto conform to the assumptions of normality in regression analysisand ANOVA/ANCOVA, the variables cadmium, mercury, methyl-mercury and inorganic arsenic were log-transformed, due to highskewness (1.4–4.0) and kurtosis (2.5–18.0). Concentrations ofarsenic were used without any modification (skewness 0.8 andkurtosis 0.16). Weight was omitted from ANCOVA in the final sta-tistical evaluation of each metal and metal species since weightwas highly correlated with CL, which was included. POPs werenot investigated statistically due to the limited number of areasand samples investigated and the low levels found in the samplesin this study. Statistical analyses were carried out with STATISTICA12 version 12.0.1133.2 from StatSoft Inc.
depth, and width and weight of the red king crab. (N.D. = not determined).
Loc. No. Number (N) Depth (m) Width (cm) Weight (kg)
1 4 202 16 ± 2 (14–18) 2.1 ± 0.9 (1.4–3.0)2 10 168 14 ± 2 (11–19) 1.6 ± 0.7 (0.7–3.4)3 2 213 12 ± 3 (10–15) 1.1 ± 0.8 (0.5–1.7)4 10 221 15 ± 2 (13–18) 1.7 ± 0.5 (1.3–2.5)5 5 217 15 ± 2 (13–18) 1. 8 ± 0.7 (1.4–3.1)6 4 175 11 ± 1 (10–13) 1.2 ± 0.5 (0.8–2.0)7 6 181 14 ± 2 (12–17) 2.4 ± 1.1 (1.3–4.1)8 11 163 13 ± 2 (9–14) 1.8 ± 0.7 (0.7–2.7)9 10 81 13 ± 2 (10–16) 1.8 ± 0.8 (0.7–3.6)
10 10 154 13 ± 2 (11–17) 1.8 ± 0.9 (1.0–4.1)11 9 246 14 ± 2 (11–16) N.D.12 10 307 13 ± 2 (11–16) N.D.13 8 299 14 ± 2 (12–16) N.D.14 9 227 14 ± 2 (13–18) N.D.15 10 299 13 ± 2 (11–15) N.D.16 7 227 13 ± 3 (10–16) N.D.17 10 366 14 ± 2 (10–16) 1.5 ± 0.6 (0.5–2.1)18 10 335 14 ± 2 (12–16) 1.6 ± 0.4 (1.0–2.2)19 10 366 14 ± 2 (11–16) 1.5 ± 0.4 (0.7–2.0)20 10 155 13 ± 2 (11–15) 1.7 ± 0.8 (1.0–3.0)21 10 156 12 ± 2 (9–16) 1.6 ± 0.9 (0.5–3.2)22 3 64 14 ± 1 (13–15) 1.7 ± 0.3 (1.5–1.9)23 7 176 13 ± 2 (10–15) 1.0 ± 1.1 (0.2–3.2)Total 185 (64–366) 14 ± 2 (9–19) 1.7 ± 0.7 (0.2–4.1)
3. Results and discussion
3.1. Physical parameters
Of the 185 samples collected, there were 110 male crabs, 74female crabs and one crab of unknown sex (60% males). There were12 males and 19 females from area A (38% males), 20 males and 11females from area B (64% males), 66 males and 37 females from areaC (64% males) and 12 males, 7 females and 1 crab of unknown sexfrom area D (63% males). Difference test revealed that there was asignificant difference in the proportion of male crabs between areaA and area B (p = 0.01) and between A and C (p = 0.01), but notbetween areas A and D probably due to the limited number of crabs(valid N = 19) in the latter group. CL was determined in 184 of the185 king crabs and varied between 85 mm and 193 mm, with amean ± sd of 135 ± 20 mm. ANOVA revealed a significant differencein CL between the areas. Post-hoc test revealed that crabs from areaA were significantly longer (p < 0.005) than those from other areasand that CLs of the crabs were not significantly different among theremaining areas. Male crabs were significantly larger than femalecrabs when looking at the whole dataset (p < 0.001) and this was
also true for areas A (p < 0.001) and C (p = 0.002) separately. Weightwas determined in 131 samples and ranged from 186 to 4120 g,with a mean weight of 1658 g and a standard deviation of 744 g.In contrast to CL, ANOVA demonstrated that there were no signifi-cant differences in weight across areas. But, just as for CL, malecrabs were significantly heavier than female crabs (p < 0.001) whenlooking at the whole dataset and this was also true for areas A(p < 0.001) and B (p = 0.03) separately. There was a significant posi-tive correlation between CL and weight of the crabs when looking atthe whole dataset (p < 0.001), as well as for each area (p < 0.001–0.01). Scatter plots revealed that many samples from areas B, Cand D appeared to be relatively heavier than were crabs from areaA for crabs of similar CL. Depth of sampling was recorded for all 23sampling positions and ranged from 64 m for position 22 in area Dto 366 m for position 17 in area C. Fat percentage was determined in151 samples, of which none samples were from area D. Fat contentranged from 0.7% to 2.1% with a mean of 1.4% and a standard devi-ation of 0.3. The crabs from area B had a significantly (p < 0.001)higher fat content than had crabs from area C, but there was no dif-ference between A and B or between A and C. There was, further, nodifference in fat content between male and female crabs withrespect to the complete dataset or when considering each area byitself (Table 1).
3.2. The elements
3.2.1. GeneralAn overview of the results for the determination of the ele-
ments present in samples of claw and leg meat from 185 individualcrabs are shown in Table 2. The concentrations of lead were verylow, less than the LOQ of 0.01 mg kg�1 ww for all samples, andhence well below the EU’s maximum value for lead of 0.5 mg kg�1
ww for crab meat. In the following, more detailed presentationsand discussion of the results are given for arsenic, mercury, andcadmium which, in addition to lead, are often the elements ofgreatest concern for seafood safety and the environment.
3.2.2. Arsenic and inorganic arsenicThe concentrations of total arsenic in the meat of red king crab
from the fjords and coastal area of the county of Finnmark varied
Table 2Contents of mercury, arsenic, inorganic arsenic, cadmium, and lead (mg/kg wet weight) in claw and leg bone meat of King crab sampled at 23 different positions (see Fig. 1) in theBarents Sea in 2012. (N.D. = not determined).
Position Mercury (mg/kg ww) Arsenic (mg/kg ww) Inorganic As (lg/kg ww) (N = 100) Cadmium (mg/kg ww) Lead (mg/kg ww)
1 0.046 ± 0.014 (0.03–0.06) 15 ± 3 (12–17) 25 ± 6 (19–30) 0.080 ± 0.054 (0.035–0.150) <0.012 0.038 ± 0.013 (0.02–0.05) 13 ± 4 (7–20) 31 ± 23 (9–90) 0.042 ± 0.021 (0.009–0.075) <0.013 0.051 ± 0.030 (0.03–0.07) 21 ± 1 (20–22) 33 ± 39 (5–60) 0.160 ± 0.150 (0.05–0.26) <0.014 0.038 ± 0.011 (0.02–0.05) 17 ± 4 (11–21) 14 ± 10 (6–40) 0.060 ± 0.048 (0.013–0.17) <0.015 0.055 ± 0.026 (0.03–0.09) 17 ± 3 (13–20) 17 ± 12 (4–30) 0.130 ± 0.080 (0.03–0.21) <0.016 0.029 ± 0.004 (0.023–0.034) 13 ± 7 (5–22) 21 ± 7 (16–30) 0.007 ± 0.003 (0.004–0.010) <0.017 0.036 ± 0.011 (0.03–0.05) 11 ± 3 (7–15) N.D. 0.008 ± 0.002 (0.005–0.011) <0.018 0.033 ± 0.010 (0.02–0.05) 8 ± 1 (6–10) N.D. 0.005 ± 0.003 (0.002–0.013) <0.019 0.036 ± 0.013 (0.02–0.06) 7 ± 2 (4–10) N.D. 0.006 ± 0.003 (0.003–0.013) <0.01
10 0.038 ± 0.010 (0.02–0.05) 12 ± 5 (5–20) 19 ± 12 (7–40) 0.008 ± 0.004 (0.003–0.018) <0.0111 0.081 ± 0.034 (0.03–0.14) 9 ± 4 (4–16) N.D. 0.020 ± 0.026 (0.003–0.088) <0.0112 0.046 ± 0.019 (0.02–0.08) 9 ± 3 (5–14) N.D. 0.007 ± 0.003 (0.005–0.014) <0.0113 0.039 ± 0.019 (0.03–0.09) 8 ± 4 (3–13) N.D. 0.007 ± 0.003 (0.005–0.015) <0.0114 0.042 ± 0.020 (0.02–0.08) 6 ± 2 (4–9) N.D. 0.010 ± 0.006 (0.004–0.019) <0.0115 0.030 ± 0.011 (0.02–0.05) 8 ± 4 (3–17) N.D. 0.007 ± 0.004 (0.003–0.014) <0.0116 0.035 ± 0.008 (0.03–0.05) 7 ± 3 (5–14) N.D. 0.008 ± 0.003 (0.005–0.015) <0.0117 0.036 ± 0.024 (0.02–0.09) 10 ± 3 (5–14) 23 ± 13 (11–40) 0.013 ± 0.004 (0.008–0.018) <0.0118 0.035 ± 0.010 (0.02–0.05) 12 ± 4 (7–19) 22 ± 16 (6–50) 0.011 ± 0.005 (0.007–0.021) <0.0119 0.032 ± 0.011 (0.02–0.05) 11 ± 3 (7–18) 20 ± 20 (3–60) 0.011 ± 0.005 (0.005–0.021) <0.0120 0.051 ± 0.025 (0.03–0.11) 8 ± 2 (5–10) 31 ± 22 (10–80) 0.014 ± 0.010 (0.006–0.038) <0.0121 0.025 ± 0.010 (0.01–0.05) 10 ± 6 (4–25) 33 ± 22 (6–70) 0.015 ± 0.011 (0.004–0.036) <0.0122 0.049 ± 0.015 (0.04–0.07) 10 ± 3 (7–13) 17 ± 12 (6–30) 0.032 ± 0.035 (0.008–0.072) <0.0123 0.026 ± 0.017 (0.002–0.06) 8 ± 4 (1–12) 11 ± 6 (5–20) 0.005 ± 0.002 (0.001–0.007) <0.01
Total 0.040 ± 0.020 (0.002–0.14) 10 ± 5 (1–25) 23 ± 17 (3–90) 0.021 ± 0.036 (0.001–0.26) <0.01
K. Julshamn et al. / Food Chemistry 167 (2015) 409–417 413
from 1.0 to 25 mg kg�1 ww, with an overall mean ± sd of10 ± 5 mg kg�1 ww (Table 2). The mean concentration of arsenicin red king crab was, however, highest at positions in the far west(Table 2). Jewett and Naidu (2000) have reported levels of totalarsenic in 67 red king crabs caught near the coast of Norton Sound,north-eastern Bering Sea, Arctic Alaska, ranging from 7.85 to25.5 mg kg�1 dry weight, which gave an average of 14.2 mg kg�1
dry weight. The concentration based on ww was estimated to be2.8 mg kg�1, with a dry matter content of 20 g 100 g�1. This levelis only one fourth of that found in the present study. The arseniccontent of red king crab is, however, somewhat lower than thatfound in edible crabs (Cancer pagurus) caught along the Norwegiancoast in 2011 (Julshamn, Nilsen, Valdersnes, & Frantzen, 2012). Thearsenic content in edible crabs was found to vary from 4 to50 mg kg�1 ww, with a mean of 19 mg kg�1 ww. ANOVA, withthe arsenic content as the dependent variable and area as categor-ical predictor, showed a significant (p < 0.001) difference in arseniccontent across areas. Post-hoc tests revealed that area A had ahigher arsenic content than had the rest of the areas (p < 0.001).The remaining areas did not show any significant differences withregard to arsenic content in the crabs. ANOVA, with the arseniccontent as the dependent variable and sex as categorical predictor,showed significantly (p < 0.001) higher arsenic in female crabsthan in male crabs when looking at the whole dataset. Only in areaC did female crabs have a significantly (p = 0.002) higher arseniccontent compared to male when looking at each area separately.There was no significant correlation between CL and arsenic con-tent when considering the complete dataset without any adjust-ments. When investigating each area by itself, only crabs fromarea D showed a significant (p = 0.003) decreasing trend of arsenicwith increasing CL of the crabs. CL of the crabs was also signifi-cantly associated (p = 0.009) with arsenic content for the completedataset when adjusting for area in ANCOVA, but not when adjust-ing for sex. A significant positive correlation between arsenic andfat content of the crabs was found when looking at the completedataset (p = 0.02). Looking at each area by itself, area B showed asignificant (p = 0.04) but weak negative correlation betweenarsenic and fat whereas area C showed a significant positivecorrelation (p < 0.001) and no correlation was found for area A.
Adjusting for either area or sex, fat was still significantly(p < 0.03) associated with arsenic when looking at the whole data-set. No significant correlation between arsenic and weight of thecrabs was found when looking at the complete dataset or wheninvestigating each position by itself. Taking into account CL, area,sex and fat in ANCOVA, area, sex and fat were significantly associ-ated with arsenic content (p < 0.003).
The concentration of inorganic arsenic in red king crab rangedfrom 1 to 90 lg kg�1 ww, with a mean ± sd of 23 ± 17 lg kg�1
ww. The results showed no correlation between the concentrationsof total arsenic and inorganic arsenic in the meat of claw and leg ofred king crab meat, as has been reported in blue mussel (Sloth &Julshamn, 2008). At present, no maximum limit is set by the EUfor total As or inorganic As in any seafood product. ANOVA withthe inorganic arsenic content as the dependent variable, and areaas categorical predictor, showed no difference in inorganic arseniccontent across areas. ANOVA, with the inorganic arsenic content asthe dependent variable and sex as categorical predictor, showedsignificantly (p = 0.04) higher inorganic arsenic in female crabsthan in male crabs when looking at the whole dataset. Area-specific analysis revealed that female crabs from both areas B(p = 0.04) and C (p = 0.01) had significantly higher inorganic arseniccontent than had male. There was no significant linear correlationbetween crab CL and inorganic arsenic content when consideringthe complete dataset. In area-specific analyses, only area C showeda significant (p = 0.03) negative linear correlation. CL was not sig-nificantly associated with inorganic arsenic when adjusting foreither area or sex in ANCOVA for the complete dataset. A signifi-cant (p = 0.004) positive linear correlation between inorganicarsenic and fat was found when examining the whole dataset.When considering each area individually, area A also displayed asignificant (p = 0.003) positive correlation but there was no corre-lation in area C. Areas B and D did not contain any samples forwhich both inorganic arsenic and fat were determined. Whenadjusting for either area or sex in the dataset, fat was still signifi-cantly (p < 0.004) correlated with arsenic. No significant linear cor-relations between inorganic arsenic and weight of the crabs werefound when looking at the complete dataset or when looking ateach area. This was also true when adjusting for either area or
414 K. Julshamn et al. / Food Chemistry 167 (2015) 409–417
sex in ANCOVA. Taking into account CL, area, sex and fat inANCOVA, only fat was significantly associated with inorganicarsenic content (p = 0.003).
Fig. 3. Difference in log cadmium content (mg/kg ww) between male (1) andfemale (0) red king crabs.
3.2.3. CadmiumThe concentrations of cadmium in the samples varied from
0.001 to 0.26 mg kg�1 ww (Table 2), with a mean ± sd of0.021 ± 0.036 mg kg�1 ww. No individual red king crab assessedin the present study showed a cadmium concentration in meatexceeding 0.5 mg kg�1 ww, which is the maximum acceptablelevel set by the EU and Norway for cadmium in the meat of crabsintended for human consumption (EC, 2006). The highest meancadmium values from individual positions were found for positionsin the far west, positions 3 and 5 in area A, with a mean ± sd of0.16 ± 0.15 and 0.13 ± 0.08 mg kg�1 ww, respectively. Jewett andNaidu (2000) reported that the average cadmium value in the mus-cle of red king crab varied from 0.19 to 0.25 mg kg�1 dry weight,with an average of 0.23 mg kg�1 dry weight (N = 67). With a drymatter content of 20 g 100 g�1, this gave a mean cadmium concen-tration, based on ww, of 0.05 mg kg�1 ww. This is quite similar tothe values reported in the present study. In comparison, a previousstudy showed that cadmium concentrations in the claw meat ofthe edible crab caught off the coast of Norway varied from 0.004to 3.7 mg kg�1 ww, with a mean of 0.25 mg kg�1 ww, and withthe highest concentration in samples from the north (Julshamnet al., 2012). Edible crab does not live as far north as Finnmark.ANOVA, with the log-transformed cadmium content as the depen-dent variable and area as categorical predictor, showed a signifi-cant (p < 0.001) difference between areas. Post-hoc tests revealeda significantly (p < 0.001) higher cadmium content in area A thanin the rest of the areas and also that area B was significantly(p = 0.006) lower in cadmium content than was area C, but thatthere was no difference between area D and area B or area D andarea C (Fig. 2). ANOVA, with the log-transformed cadmium contentas the dependent variable and sex as categorical predictor, showeda significantly (p < 0.001) higher cadmium content in female thanin male crabs when looking at the whole dataset (Fig. 3). Thiswas also true in area-specific analysis for areas B (p = 0.03), C(p = 0.007) and D (p = 0.03) but not A. There was a significant(p < 0.001) positive linear correlation between CL and cadmiumcontent when considering the complete dataset but no significantcorrelations were found when looking at each area isolated orwhen adjusting for area in ANCOVA. This is probably due the factthat crabs from area A are longer and have more cadmium
Fig. 2. Difference in log cadmium content (mg/kg ww) in red king crabs fromdifferent areas. Different letters above the bars denote significant differences andthe whiskers define the 95% confidence intervals.
compared to the other areas, producing a correlation betweencadmium and CL which is actually due to the differences in thesetwo variables between the areas. Adjusting for sex in ANCOVA,CL was still significant (p < 0.001). No significant linear correlationbetween cadmium and fat content in the crabs were found whenlooking at the complete dataset or when adjusting for either areaor gender. Looking at each area, only area B displayed a weakly sig-nificant (p = 0.047 negative linear correlation between cadmiumand fat. No significant linear correlations between cadmium andweight of the crabs were found when looking at the complete data-set. When grouping on area, only area D showed a significant(p = 0.04) positive linear correlation between weight and cadmiumcontent. Adjusting for area in ANCOVA, weight was no longer sig-nificant, but weight was still significant (p = 0.005) after adjustingfor sex. Taking into account CL, area, sex and fat in ANCOVA, CL,area and sex were all found to be significantly associated with cad-mium content (p < 0.02).
3.2.4. Mercury and methylmercuryThe mean mercury content in all samples was 0.04 mg kg�1 ww,
with the concentration ranging from 0.002 to 0.14 mg kg�1 ww.None of the samples had levels of mercury that exceeded the EU’smaximum level for mercury in the meat of red king crab of0.5 mg kg�1 ww. The mean values of mercury in crab meat fromthe individual sites ranged from 0.03 to 0.08 mg kg�1 ww. Thelocality with the highest mercury content (0.08 mg kg�1 ww) wasposition 11 in area C. Data reported by Jewett and Naidu (2000)showed mercury levels of 0.056 mg kg�1 dry weight or0.011 mg kg�1 ww. Their results are somewhat lower than ours.The mercury content in the claw meat of the edible crab (C. pagurus)showed a slightly higher content, with a mean of 0.095 mg kg�1
ww, and a range varying from 0.021 to 0.40 mg kg�1 ww(Julshamn et al., 2012). None of the samples of claw meat of the edi-ble crab showed mercury levels exceeding the EU’s maximum levelof 0.5 mg kg�1 ww. It seems likely that the absorption and metabo-lism of mercury are different for the two crab species. ANOVA, withthe log-transformed mercury content as the dependent variableand area as categorical predictor, showed a significant (p < 0.001)difference across areas. Post-hoc tests revealed a significantly highermercury content in area A (p = 0.002) than in area D. Area C was alsosignificantly (p < 0.001) higher in mercury than area D. Area B wasnot different from any of the other areas. ANOVA, with the log-transformed mercury content as the dependent variable and sexas categorical predictor showed no significant difference in
K. Julshamn et al. / Food Chemistry 167 (2015) 409–417 415
mercury content between female and male crabs when looking atthe whole dataset. Only for area C did female crabs have a signifi-cantly (p = 0.008) higher mercury content than in male. There wasa significant (p < 0.001) positive linear correlation between crabCL and mercury content when considering the complete dataset.Significant positive correlations were also found for the areas A(p = 0.01) and C (p = 0.002) and also for the complete dataset whenadjusting for either area or sex in ANCOVA. No significant linear cor-relation was found between mercury and fat when considering thewhole dataset, when looking at each area separately or whenadjusting for either area or sex. Significant (p < 0.001) positive cor-relations between mercury and weight of the crabs were foundwhen looking at the complete dataset. All areas, except for B, alsoshowed significant positive correlations between weight and mer-cury content (A; p = 0.005, C; p = 0.002 and D; p = 0.01). Weightwas still significant when adjusting for either area or sex inANCOVA. Taking into account CL, area, sex and fat in ANCOVA, bothCL and sex were significantly associated with mercury content(p < 0.001).
Methylmercury concentration in red king crab ranged from0.017 to 0.140 mg kg�1 ww, with a mean ± sd of 0.050 ±0.024 mg kg�1 ww. In total, 51 samples were determined, amongwhich 31 were from area A and 20 from area C. The percent meth-ylmercury in the samples ranged from 100% to 182%, with amean ± sd of 126 ± 16%, showing that the mercury is indeed storedas methylmercury, as expected. The more than 100% methylmer-cury content is an effect of the combined measurement uncertain-ties of the two methods at the levels measured. There was a highlinear correlation (p < 0.001) between the concentrations of totalmercury and methylmercury in the meats of claw and leg of redking crab, as has been reported previously in meat of other marinespecies with a high percentage of methylmercury relative to thetotal mercury (Julshamn, Duinker, Nilssen, et al., 2013). At present,no maximum limit is set by the EU for methylmercury specificallyin any seafood product. ANOVA, with the log-transformed methyl-mercury content as the dependent variable and area as categoricalpredictor, showed a significantly (p = 0.02) higher methylmercurycontent in area A than in area C. ANOVA, with the log-transformedmethylmercury content as the dependent variable and sex as cat-egorical predictor, showed no significant difference in methylmer-cury content between female and male crabs when looking at thewhole dataset. Looking at areas A and C separately, female crabsfrom area C had significantly (p = 0.03) more methylmercury thanhad male crabs. There was a significant (p < 0.001) positive correla-tion between crab CL and methylmercury content when consider-ing the complete dataset and also for both areas A (p = 0.002) and C(p = 0.05) separately. CL was still significant after ANCOVA withadjustment for either area or sex. Looking at the whole dataset,each area by itself or when adjusting for either area or sex, no sig-nificant linear correlation was found between methylmercury andfat content. Significant (p < 0.001) positive correlations betweenmethylmercury and weight of the crabs were found when lookingat the complete dataset. Both areas A (p < 0.001) and B (p = 0.03)showed significant linear correlation as well. Taking into accountCL, area, sex and fat in ANCOVA, only CL was significantly associ-ated with methylmercury (p < 0.001).
3.2.5. Summary of elementsAll elements and species, except for inorganic arsenic, were
higher in area A than in the other areas. This could, in part, bedue to the higher number of female crabs collected in area A thanin the rest of the areas but, also, other factors, e.g. local elevatedlevels of metals in the Havøysund region, or differences in dietsbetween this area and the other areas, could be important. Arsenic,inorganic arsenic and cadmium were higher in female crabs than inmale crabs. This could, in part, be due to the dilution of elements
through the increased growth of male crabs compared to femalecrabs, since male crabs were found to be significantly longer andheavier (Karimi, Fisher, & Folt, 2010). However, gender-specific dif-ferences in the disposition and toxicity of metals could also play arole and this has previously been demonstrated in humans (Vahter,Akesson, Liden, Ceccatelli, & Berglund, 2007). Total mercury washighly correlated with methylmercury and our results show thatmercury is indeed stored as methylmercury in red king crab. Formercury and methylmercury, only area C had higher levels infemale crabs than in male. Mercury and methylmercury demon-strated positive linear correlation with both CL and weight, butcadmium was only positively correlated with CL. No correlationbetween total arsenic and inorganic arsenic was found. Neverthe-less, both arsenic and inorganic arsenic displayed linear correlationwith fat. Area, sex and fat were found to be significantly associatedwith arsenic, but only fat was significantly related to inorganicarsenic. CL, area and sex were significantly associated with cad-mium. Mercury was significantly associated with CL and sex but,for methylmercury, only the CL of the crabs was significantlyrelated. This difference between mercury and methylmercuryprobably arises because the limited number of samples determinedfor methylmercury is not sufficient to reveal the significance ofgender. Since the bioaccumulation depends on the uptake, storageand metabolism of the specific element, differences in storage ofmercury (as methylmercury) and of cadmium and arsenic are tobe expected.
3.3. Dioxins/furans, dl-PCBs, PBDEs
3.3.1. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinateddibenzofurans (PCDFs), dl-PCBs (non-ortho and mono-ortho PCBs)
Table 3 shows the concentrations of sum PCDDs, sum PCDFs,sum-non-ortho PCBs, mono-ortho PCBs, sum PCDD/Fs, and sumPCDD/Fs and dl-PCBs in the claw and legs meat of 44 red king crabsfrom six positions in addition to the overall mean for these sub-stances. The concentration of the sum of PCDDs and PCDFs(PCDD/Fs) in the claw and leg meat of 44 individual red king crabsranged from 0.05 to 0.36 ng TEQ kg�1 ww, with a mean ± sd of0.10 ± 0.05 ng TEQ kg�1 ww. All samples analysed showed valuesfar below the EU’s maximum level of 3.5 ng TEQ kg�1 ww forsum PCDD/Fs in crab meat (EC, 2011a). The concentration of thesum of PCDD/Fs and dl-PCBs varied from 0.07 to 0.38 ng TEQkg�1 ww, with a mean ± sd of 0.14 ± 0.05 ng TEQ kg�1 ww, andnone of the samples had a content of sum PCDD/Fs and dl-PCBshigher than the EU’s maximum level of 6.5 ng TEQ kg�1 ww. Asfar as we know, there are no published data on POPs in red kingcrab meat. In lean fish muscle, however, Julshamn, Duinker,Berntssen, et al. (2013) have found a similar concentration ofPCDD/Fs in the muscle of northeast arctic cod caught in the BarentsSea, which ranged from 0.026 to 0.13 ng TEQ kg�1 ww, with amean ± sd of 0.045 ± 0.026 ng TEQ kg�1 ww, and the concentra-tions of the sum of PCDD/Fs and dl-PCB ranged from 0.048 to0.14 ng TEQ kg�1 ww, with a mean ± sd of 0.076 ± 0.032 ng TEQkg�1 ww. For the TEQ concentrations of the PCDD/Fs, 2378-TCDFwas the only quantifiable congener out of the 17 congeners forPCDD/Fs. Of the non-ortho PCBs, PCB-77 and PCB-126 were theonly quantifiable congeners, where PCB-126 contributed to 98%of the sum of non-ortho PCBs. Of the mono-ortho PCBs, PCB-118was the dominating congener, with 54% of the sum of mono-orthoPCBs. Here, it must be noted that all TEQ values were based onupper-bound LOQ, which meant that all values less than the LOQwere set to be equal to it. The congener profile of PCDD/Fs in north-east arctic cod is quite different from what we have found for redking crab (Julshamn, Duinker, Berntssen, et al., 2013). The studyreported that 12378-PeCDD, 2378-TCDD, and 12378-PeCDF werethe dominating congeners and not 2378-TCDF, as was found in
Tabl
e3
Cont
ents
ofdi
oxin
s(P
CDD
),fu
rans
(PCD
F),n
on-o
rtho
PCBs
,and
mon
o-or
tho
PCBs
,as
wel
las
sum
PCD
D/F
san
dsu
mPC
DD
/Fs
and
dl-P
CBs
(ng
WH
O-T
EQ/k
gw
etw
eigh
t,us
ing
TEF,
2005
;up
per-
boun
dLO
Q)
and
ND
L-PC
Bsan
dPB
DE 7
(lg/
kgw
etw
eigh
t)in
claw
and
leg
bone
mea
tof
red
king
crab
sam
pled
atsi
xdi
ffer
ent
posi
tion
sin
the
Bare
nts
Sea
(Fig
.1)
in20
12.
Posi
tion
PCD
DPC
DF
Sum
PCD
D/F
sN
on-o
rth
oPC
Bs
Mon
o-or
tho
PCB
sSu
mdl
-PC
BsSu
mPC
DD
/Fs
+dl
-PC
Bs
Sum
ND
L-PC
Bs
Sum
PBD
E 7
60.
09±
0.02
(0.0
6–0.
11)
0.02
±0.
01(0
.02–
0.03
)0.
12±
0.02
(0.0
8–0.
13)
0.03
±0.
01(0
.02–
0.04
)0.
003
±0.
001
(0.0
02–0
.003
)0.
03±
0.01
(0.0
2–0.
05)
0.15
±0.
03(0
.11–
0.18
)0.
34±
0.16
(0.2
0–0.
57)
0.00
4(0
a)–0
.007
)
170.
07±
0.02
(0.0
4–0.
09)
0.02
±0.
01(0
.02–
0.04
)0.
09±
0.02
(0.0
6–0.
13)
0.04
±0.
02(0
.02–
0.09
)0.
003
±0.
002
(0.0
02–0
.003
)0.
04±
0.02
(0.0
2–0.
10)
0.14
±0.
03(0
.09–
0.18
)0.
25±
0.12
(0.1
6–0.
55)
0.00
9±
0.00
6(0
.005
–0.0
20)
180.
17±
0.13
(0.0
6–0.
32)
0.03
±0.
01(0
.02–
0.04
)0.
20±
0.14
(0.0
8–0.
35)
0.05
±0.
02(0
.02–
0.06
)0.
004
±0.
002
(0.0
02–0
.006
)0.
05±
0.02
(0.0
2–0.
07)
0.25
±0.
12(0
.14–
0.38
)0.
32±
0.10
(0.2
1–0.
38)
0.01
5±
0.00
9(0
.005
–0.0
20)
200.
07±
0.02
(0.0
3–0.
09)
0.02
±0.
01(0
.01–
0.03
)0.
09±
0.02
(0.0
5–0.
12)
0.04
±0.
02(0
.01–
0.06
)0.
004
±0.
002
(0.0
03–0
.009
)0.
05±
0.02
(0.0
2–0.
07)
0.13
±0.
02(0
.11–
0.18
)0.
26±
0.14
(0.1
4–0.
61)
0.00
3(0
a)–0
.010
)
220.
09±
0.02
(0.0
7–0.
10)
0.03
±0.
01(0
.02–
0.04
)0.
11±
0.02
(0.1
0–0.
13)
0.04
±0.
02(0
.02–
0.06
)0.
004
±0.
001
(0.0
03–0
.004
)0.
04±
0.02
(0.0
3–0.
07)
0.16
±0.
01(0
.15–
0.17
)0.
21±
0.01
(0.2
0–0.
23)
0.00
6(0
a)–0
.010
)
230.
06±
0.01
(0.0
5–0.
08)
0.02
±0.
01(0
.01–
0.03
)0.
08±
0.02
(0.0
6–0.
11)
0.03
±0.
02(0
.01–
0.05
)0.
003
±0.
001
(0.0
02–0
.004
)0.
03±
0.02
(0.0
1–0.
06)
0.10
±0.
02(0
.07–
0.13
)0.
17±
0.10
(0.0
8–0.
35)
0.00
7(0
a)–0
.010
)
Tota
l0.
08±
0.05
(0.0
3–0.
32)
0.02
±0.
01(0
.01–
0.04
)0.
10±
0.05
(0.0
5–0.
36)
0.04
±0.
02(0
.01–
0.09
)0.
004
±0.
002
(0.0
02–0
.009
)0.
04±
0.02
(0.0
1–0.
10)
0.14
±0.
05(0
.07–
0.38
)0.
25±
0.12
(0.0
8–0.
61)
0.00
5(0
–0.0
20)
EUm
axim
um
leve
l3.
56.
575
a)Lo
wer
bou
nd
LOQ
isu
sed
for
PBD
E.0
mea
ns
that
con
cen
trat
ion
sof
all
con
gen
ers
are
less
than
LOQ
.
416 K. Julshamn et al. / Food Chemistry 167 (2015) 409–417
the present study. However, the dominating congeners for non-ortho and mono-ortho PCBs were almost the same as found forred king crab.
3.3.2. ndl-PCBs (PCB6)The concentrations of ndl-PCB in the claw and legs meat of the
44 red king crabs analysed were low and ranged from 0.08 to0.61 lg kg�1 ww, with a mean ± sd of 0.25 ± 0.12 lg kg�1 ww(Table 3). In comparison, the concentration of sum ndl-PCB in themuscle of northeast arctic cod ranged from 0.6 to 1.3 lg kg�1 ww(Julshamn, Duinker, Berntssen, et al., 2013). In the present paper,all congeners were quantifiable in all samples, except PCB-180.The dominating congeners of ndl-PCB in the meat of red king crabwere PCB-153 and PCB-138, with a proportion of PCB-55 and 34%of the sum ndl-PCB (data not shown). The same dominating cong-eners were also found in the muscle of northeast arctic cod(Julshamn, Duinker, Berntssen, et al., 2013). The concentration ofthe sum of ndl-PCB in the meat of red king crab was well belowthe maximum level of 75 lg kg�1 ww set by the EU for humanconsumption. The meat of red king crab had low lipid contentand, in such samples, low levels of lipid-soluble compounds, suchas ndl-PCB, are expected (www.nifes.no/seafooddata, Retrieved 8November 2013).
3.3.3. PBDE7
The concentration of the sum of PBDE7 in the claw and leg bonemeats of red king crab was very low. The only congener with con-centrations higher than the LOQ was PBDE-47, with a mean of0.005 lg kg�1 ww. The lower-bound LOQ was used for concentra-tions lower than the LOQ; thus, concentrations lower than the LOQwere set to zero. Similarly low levels were found in the muscle ofnortheast arctic cod (Julshamn, Duinker, Berntssen, et al., 2013).
3.4. Perfluorinated alkyl substances (PFAS)
PFOSA was the only PFAS found in quantifiable amounts in twoindividual samples of red king crab, one from position 20 and onefrom position 23, both with a content of 1.6 lg kg�1 ww.
4. Conclusions
This first study on the Red king crab (P. camtschaticus) from theBarents Sea has demonstrated that this crab specie is a safe food.The concentrations of persistent organic pollutants and metalswere low compared to maximum levels laid down in Europeanregulations. Statistical evaluation of the data revealed that allelements and element species except for inorganic arsenic werehigher in area A than in the other areas. Mercury and methylmer-cury showed positive linear correlation with both CL and weight,but cadmium was only positively correlated with CL. Gender differ-ences were found for the metals arsenic, inorganic arsenic andcadmium which were higher in female crabs than in male crabs.We hypothesise that this difference could be due to the dilutionof elements through the increased growth of male crabs comparedto female crabs, since male crabs were found to be significantlylonger and heavier and/or by the gender-specific differences inthe disposition and toxicity of metals (Karimi et al., 2010; Vahteret al., 2007). This work will aid in the understanding of the red kingcrab, although more work is needed to reveal the reasons for thegeographical and gender differences found in this study.
Acknowledgements
The authors would like to thank the Norwegian Food SafetyAuthority for funding this work. Annette Bjordal and co-workers
K. Julshamn et al. / Food Chemistry 167 (2015) 409–417 417
and Marita Kristoffersen and co-workers are acknowledged fortheir skilful technical assistance, and we would also like to thankthe personnel of the Institute of Marine Research who sampledthe red king crab.
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