Persistent organic pollutant levels in semi-domesticated reindeer (Rangifer tarandus tarandus L.), feed, lichen, blood, milk, placenta, foetus and calf

Science of the Total Environment 476–477 (2014) 125–135

Contents lists available at ScienceDirect

Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv

Persistent organic pollutant levels in semi-domesticated reindeer (Rangifer tarandus tarandus L.), feed, lichen, blood, milk, placenta, foetus and calf A. Holma-Suutari a,⁎, P. Ruokojärvi b, S. Laaksonen c, H. Kiviranta b, M. Nieminen d, M. Viluksela b, A. Hallikainen e a

Department of Biology, University of Oulu, P.O. Box 3000, 90014 Oulu, Finland Department of Environmental Health, National Institute for Health and Welfare, P.O. Box 95, 70701 Kuopio, Finland c University of Helsinki, P.O. Box 33, 00014 Helsinki, Finland d Reindeer Research Station, Finnish Game and Fisheries Research Institute, Toivoniementie 246, 99100 Kaamanen, Finland e Risk Assessment Research Unit, Finnish Food Safety Authority Evira, Mustialankatu 3, 00790 Helsinki, Finland b

H I G H L I G H T S • • • •

WHO-TEQs were higher in the reindeer calves than in the hinds. WHO-TEQs were lower in the foetuses than in their corresponding hinds. The reindeer placenta seems to function as a barrier of chlorinated substances. There is an effective transport of PBDEs through the reindeer placenta to foetus.

a r t i c l e

i n f o

Article history: Received 23 October 2013 Received in revised form 17 December 2013 Accepted 23 December 2013 Available online xxxx Keywords: POPs Reindeer Tissues Milk Foetus

a b s t r a c t A study concerning persistent organic pollutants in Finnish semi-domesticated reindeer was conducted in northern Finland. The aim of this study was to explore POP presence in different tissues of reindeer. In addition, it was studied how POPs are transported from food concentrates and lichen to reindeer hind tissues and further to the placenta, foetus, milk and calf. Concentrations of 17 polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs), 37 polychlorinated biphenyls (PCBs) (including 12 dioxin-like PCBs), and 15 polybrominated diphenyl ethers (PBDEs) were analysed. In most of the reindeer muscle tissue samples PCBs were clearly dominating compounds (on average 58% of the total WHO-TEQ). The total WHO-TEQ was higher in the muscle tissue of reindeer calves than in their corresponding hinds (on average 1.7 pg/g fat vs. 1.1 pg/g fat, respectively). The total WHO-TEQ concentrations were higher in the muscle and liver tissues of reindeer hinds than in their blood or placentas. The foetuses had clearly lower WHO-TEQ concentrations than their corresponding hinds. The contribution of WHOPCDD/F-TEQ to the total WHO-TEQ was somewhat higher in the liver than in the muscle tissue. The reindeer hind–calf pair, which had gone through the lichen diet, had on average higher WHO-PCDD/F- and PCB-TEQ concentrations in their tissues than the hind–calf-pair that had gone through the reindeer food concentrate diet. WHOPCB-TEQs in the reindeer foetuses were equal with the concentrations of placentas. The reindeer foetuses contained generally more PBDEs than their corresponding hinds and placentas. This may indicate effective transport of these compounds through the placenta of reindeer. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/Fs) and polychlorinated biphenyls (PCBs; including 12 dioxin-like PCBs) are widely known toxic organic contaminants included in the UNEP list of persistent organic pollutants (POPs) (UNEP, 2001). Polybrominated diphenyl ethers (PBDEs) have also been added to the list (UNEP, 2009). PCDDs/Fs, PCBs and PBDEs are lipophilic and ⁎ Corresponding author. Tel.: +358 40 546 2271. E-mail address: anniina.suutari@oulu.fi (A. Holma-Suutari). 0048-9697/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scitotenv.2013.12.109

indissoluble, which make them pose a threat to animals and humans when entering the food chains (European Commission, 2001; Ábalos et al., 2010; Rychen et al., in press). A level of POPs found in organisms is a net result of 1) feed, 2) uptake, 3) distribution, 4) metabolism, 5) excretion, and 6) stability. Several biological factors, like species differences in lipid distribution and lipid dynamics, physiological condition, age, sex, and reproductive status, may affect these functions. Thus, there may be interindividual differences between POP concentrations and congener patterns of compounds. Individual POP congeners differ from each other in their behaviour and fate. The structure and halogenation pattern of compounds

126

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

also affect their physicochemical and metabolic properties (AMAP, 2004; Mackay et al., 1992). A semi-domesticated reindeer (Rangifer tarandus tarandus L.) is a good pollution indicator for POPs because it uses natural pastures in addition to food concentrates. The fatty and energy rich milk of reindeer is the main food of calves for their neonatal life (Nieminen, 1987). The intestinal functions and lipid-metabolism of calves are similar to those in monogastric animals, until the microbial function of the rumen is on the level allowing a digestion of plant derived carbohydrates (Noble, 1981). A reindeer calf can therefore easily utilise incoming lipids. However, lipophilic contaminants may also be easily absorbed into the calf. When the fat sources contaminated by POPs are used for different metabolic processes of animals, contaminants achieve a new steady-state between the lipids in blood and tissues. This may result in transfer of compounds from the reindeer hind to its foetus (de March et al., 1998). Reindeer foetuses have been observed to have measurable concentrations of POPs, indicating placental transfer of these compounds. POPs have also been found from reindeer milk, reindeer calves, and adult reindeer (Ruokojärvi et al., 2007, 2011; Suutari et al., 2009, 2012). Due to the high fat content of reindeer milk, lactational transfer of lipophilic POPs may be significant. The effectiveness of placental transfer of POPs in reindeer and e.g. the relationship between the POP concentrations in the blood and placenta are not known. Reindeer products are generally used as foodstuffs in Scandinavia. In Finland the production of reindeer muscle meat is on average 2.7 million kg/year. The mean consumption of reindeer muscle meat in Finland is 0.5 kg/person/year (Finfood), but the amount may be much more among the reindeer herders. Reindeer liver is also used as food, but not so commonly than reindeer muscle meat. There are studies dealing with transfer of POPs from mother to offspring in mammal and avian species. Transfer of POPs has been noticed to be effective for instance in killer whales (Orcinus orca) (Krahn et al., 2009) and common bottlenose dolphin (Tursiops truncatus) (Yordy et al., 2010). It is observed that in blue tits (Cyanistes caeruleus) maternal transfer is selective for the more bioaccumulative and persistent congeners (Van den Steen et al., 2009). In a study with harp seals (Phoca groenlandica) it has been observed that the intensive offloading of pollutants via lactation constitutes a major but selective excretory route for reproductive female seals and also a significant route of exposure for pup seals (Frouin et al., 2012). In this study PCDDs/Fs, PCBs and PBDEs were analysed from the tissues of reindeer fed with food concentrates and lichen. The aim of this study was to study POPs in reindeer tissues (muscle, liver, blood, and placenta) and also consider the transfer of POPs from reindeer hind to foetus, milk and calf. Lipid contents of the samples were determined for comparison of the POP concentrations in the samples with different fat%. The results of this study give novel information about POP accumulation in the different parts of the body system of reindeer. 2. Materials and methods 2.1. Experimental protocol — captured reindeer From the beginning of April 2010 two pregnant reindeer hinds (age about 10 years) from the northern herd were captured and kept in the pounds over a period of 4.5 months in an experimental zoo of the University of Oulu, Finland. At first both of them were fed on the same diet; free hay, lichen (1.1–1.3 kg wet weight/day) and reindeer food concentrates (1.5 kg/animal/day). The hinds were individualised to hinds #1 and #2. About two weeks after calving, which occurred in the middle of May, the control milk samples were taken from both hinds, and the hind–calf-pairs were placed into separate pounds for the different diets: pair #1 was given 3.5 kg lichen/day and 750 g reindeer food concentrate/day and pair #2 was given green plants and 2 kg reindeer food concentrate/day, but no lichen.

The milk samples were collected in June about six weeks from calving and at the end of August 2010, after which the hinds and their calves were slaughtered. 2.2. Experimental protocol — free-living reindeer Two randomly assigned pregnant reindeer hinds (age about 10 years) from the northern herd were slaughtered in the beginning of May 2010. These animals were fed with lichen and reindeer food concentrates according to normal herding practise. The hinds were individualised to hind #3 and hind #4. The unborn foetuses of these hinds were dissected out with the placentas for the sampling. They were individualised to foetus #3 and foetus #4. In addition, formerly in February 2008 slaughtered reindeer hind (individualised to hind #5) and its foetus (#5) were included in the study. That hind (age 11 years) was gathered from the more southern herd than the other reindeer in this study. However, the diet of that hind; hay, lichen and reindeer food concentrates, was the same. 2.3. Sampling The reindeer muscle samples of hinds #1–5 and their calves/foetuses were all taken in the same method: rump, shoulder and rib muscles were cut using a clean instrument and placed in polyethylene bags. The livers were taken from the hinds and calves/foetuses and placed in polyethylene bags. Blood from the jugular vein was sampled from the hinds #3 and #4 to the glass bottles. The placentas from the hinds #3 and #4 were taken and stored frozen until the preparation before the analyses. The inner lumps of uterine cones were separated for the analyses. The placenta of hind #5 was analysed as complete with uterus. The milk samples (30 ml) were taken from hinds #1 and #2 to the glass bottles after oxytocin injection (10 IU, i.m.). All the samples were stored at temperature of − 20 °C until the analyses. 2.4. Ethical considerations The tissue samples were collected from the reindeer which had been slaughtered for human consumption. Animals were slaughtered under the inspection of an official veterinarian according to the Finnish regulations on animal welfare (European Commission, 1993). 2.5. Chemical analysis The analysed PCDD/F congeners included 17 toxic 2378-substituted congeners (2378-TCDD, 12378-PeCDD, 123478-HxCDD, 123678HxCDD, 123789-HxCDD, 1234678-HpCDD, OCDD, 2378-TCDF, 12378PeCDF, 23478-PeCDF, 123478-HxCDF, 123678-HxCDF, 234678-HxCDF, 123789-HxCDF, 1234678-HpCDF, 1234789-HpCDF, OCDF). PCB congeners included 12 dioxin-like congeners (PCB-77, -81, -126, -169, -105, -114, -118, -123, -156, -157, -167, -189) and 25 other PCB congeners (PCB-18, -28/31, -33, -47, -49, -51, -52, -60, -66, -74, -99, -101, -110, -122, -128, -138, -141, -153, -170, -180, -183, -187, -194, -206, -209). PBDEs included 15 congeners (BDE-28, -47, -66, -71, -75, -77, -85, -99, -100, -119, -138, -153, -154, -183, -209). The chemical analyses were carried out at the Chemical Exposure Unit of the National Institute for Health and Welfare, which has been accredited according to the ISO 17025 standard by FINAS (testing laboratory TO77). The scope of accreditation includes PCDD/F, PCB and PBDE analyses from biological matrices. The laboratory also acts as a national reference laboratory (NRL) for analyses of PCDDs/Fs and PCBs in food and feed. After homogenisation, the solid tissue samples were freeze-dried and fat was extracted with ethanol–toluene mixture (15/85 v/v) using ASE apparatus (Accelerated solvent extractor, Dionex ASE 300). Blood samples were liquid–liquid extracted with a mixture of ethanol and

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135 Table 1 The lipid (fat) contents of the reindeer samples. Sample

Fat%

Hind, muscle (n = 5) Calf, muscle (n = 2) Foetus, muscle (n = 2) Foetus, complete (n = 1) Hind, liver (n = 5) Calf, liver (n = 2) Foetus, liver (n = 2) Placenta (n = 2) Placenta + uterus (n = 1) Hind, blood (n = 2) Milk 1 control Milk 1 early summer Milk 1 late summer Milk 2 control Milk 2 early summer Milk 2 late summer

2.9 4.0 2.2 2.1 4.5 5.4 1.8 3.2 1.6 0.2 12.0 16.7 10.5 10.3 12.9 19.6

diethyl ether–hexane (50/50 v/v). Saturated aqueous sodium hydroxide was used for separation of the organic and aquatic phases. The organic extract was then washed with ultrapure water and dried with sodium sulphate. After that the solvent was exchanged to hexane and the fat percentage was determined gravimetrically. 13 C-labelled PCDDs/PCDFs (altogether 16 standards) were used as internal standards to quantitate the amount of PCDDs/PCDFs. 13Clabelled PCB congeners (PCB 52, 80, 101, 105, 114, 118, 123, 128, 138, 153, 156, 157, 167, 170, 180, 189, 194 and 209), and 13C-labelled nonortho- (co-PCB) congeners (PCB 77, 81, 126 and 169) were used as internal standards for PCBs and co-planar PCBs. 13C-labelled PBDE standards (BDE28, 47, 77, 99, 100, 153, 183 and 209) were used for quantification of PBDEs. The recovery standards were added to all of the samples before their quantification. Recoveries of 60–120% were accepted for

127

analysis. In each batch of the samples, two blank samples (a reagent blank and a blank covering the whole procedure) and a control sample were analysed for each batch of meat, feed and blood samples. The laboratory has the pork meat and feed control samples provided from WP 4 of EU project difference as reference material for PCDDs/Fs, DL-PCBs, indicator-PCBs and PBDEs for meat and feed, respectively, and in addition an in-house serum control sample that was analysed for the batch of blood samples. The samples were defatted on an acidic multilayer silica column, purified and finally fractionated on alumina and activated carbon columns. The studied compounds were analysed with HRGC/HRMS (VG 70250SE) method, using a selected ion monitoring mode (SIM) with a resolution of 10,000. The status of instruments was assessed on a daily basis and the instruments were calibrated and serviced regularly. DB-Dioxin column (J&W Scientific, 60 m, ID 0.25 mm, 0.15 μm) was used for separation of PCDDs/Fs and PCBs, and J&W Scientific DB-5 MS column (60 m, ID 0.25 mm, 0.25 μm; for PBDE209 column length 5 m) was used for PBDEs. In addition to internal quality control, the laboratory participates in annual interlaboratory comparisons e.g. for food, feed and serum organised by Folkhelseinstitutet in Norway, EU-Central Reference Laboratory in Germany and Centre de Toxicologie in Canada (AMAP ring tests in human serum).

2.6. Data analysis The relationship between octanol/water partition coefficient (log Kow) values and bioaccumulation rates (sink/source — calculation) was assessed. Log Kow values were taken from Braekevelt et al. (2003) for PBDE congeners, from Wong et al. (2001) and Hardy (2001) for BDE209, from Hawker and Connell (1988) for PCB congeners, and from Mackay et al. (1991) for PCDD/F congeners.

Table 2 WHO-PCDD/F-TEQs and WHO-PCB-TEQs as pg/g wet weight (ww) and pg/g lipid weight (lw) concentrations calculated with upper bound TEFs 2005 and 1998. Sample

WHO-PCDD/F-TEQ (ww)

WHO-PCDD/F-TEQ (lw)

WHO-PCB-TEQ (ww)

WHO-PCB-TEQ (lw)

#1 hind muscle #2 hind muscle #3 hind muscle #4 hind muscle #5 hind muscle #1 calf muscle #2 calf muscle #3 foetus muscle #4 foetus muscle #5 foetus complete #1 hind liver #2 hind liver #3 hind liver #4 hind liver #5 hind liver #1 calf liver #2 calf liver #3 foetus liver #4 foetus liver #3 placenta #4 placenta #5 placenta & uterus #1 milk control #2 milk control #1 milk early summer #2 milk early summer #1 milk late summer #2 milk late summer Lichen Reindeer food #3 hind blood #4 hind blood

0.006 (0.007) 0.009 (0.01) 0.01 (0.01) 0.02 (0.02) 0.03 (0.03) 0.01 (0.02) 0.01 (0.01) 0.009 (0.01) 0.007 (0.007) 0.04 (0.04) 1.29 (1.72) 0.16 (0.21) 0.97 (1.24) 0.67 (0.87) 3.63 (4.97) 1.68 (2.18) 0.48 (0.62) 0.02 (0.02) 0.01 (0.01) 0.03 (0.04) 0.02 (0.02) 0.03 (0.04) – – – – – – 0.12 (0.14) 0.05 (0.05) – –

0.39 (0.45) 0.23 (0.25) 0.54 (0.6) 0.44 (0.48) 0.91 (1.11) 0.46 (0.55) 0.27 (0.3) 0.4 (0.46) 0.31 (0.34) 1.73 (2.1) 24.1 (32.2) 3.05 (3.99) 23.4 (30) 17.5 (22.9) 90.8 (124) 31.9 (41.4) 8.79 (11.3) 0.88 (1) 0.7 (0.79) 0.98 (1.12) 0.65 (0.74) 1.88 (2.26) 0.64 (0.74) 0.44 (0.52) 0.46 (0.54) 0.26 (0.3) 0.55 (0.63) 0.31 (0.34) 0.34a 1.05 (1.1) 2.39 (2.56) 4.9 (5.09)

0.006 (0.007) 0.01 (0.01) 0.02 (0.03) 0.02 (0.02) 0.03 (0.03) 0.06 (0.07) 0.04 (0.04) 0.01 (0.02) 0.006 (0.006) 0.02 (0.02) 1.33 (1.33) 0.19 (0.19) 1.16 (1.16) 0.68 (0.68) 1.65 (1.65) 2.64 (2.64) 0.88 (0.88) 0.01 (0.016) 0.005 (0.006) 0.04 (0.05) 0.02 (0.02) 0.02 (0.02) – – – – – – 0.05 (0.055) 0.004 (0.007) – –

0.41 (0.45) 0.26 (0.29) 0.97 (1.11) 0.53 (0.6) 1.04 (1.17) 1.9 (2.19) 0.76 (0.88) 0.65 (0.73) 0.27 (0.3) 1.04 (1.14) 24.8 (24.9) 3.66 (3.69) 28.1 (27.9) 17.8 (17.8) 41.1 (41.2) 50.1 (50.1) 16 (16) 0.72 (0.79) 0.3 (0.34) 1.31 (1.51) 0.58 (0.66) 1.09 (1.2) 0.94 (1.06) 0.69 (0.74) 0.96 (1.06) 0.38 (0.42) 1.17 (1.3) 0.28 (0.31) 0.13a 0.1 (0.16) 1.41 (1.71) 3.78 (3.62)

a

pg/g dry weight.

128

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

2.7. Reporting of the results The sums and congener specific concentrations of POPs in the reindeer tissues and milk are reported as wet weight or lipid weight based lower bound concentrations. WHO-PCDD/F- and WHO-PCB-TEQs are reported as lipid based upper bound concentrations (EU requirement) for the food safety purpose. The results of POPs in reindeer food concentrates and lichen are reported as wet weight, dry weight and/or lipid weight based concentrations, depending on the context. WHO-TEQ results are calculated with toxic equivalent factors (TEFs) 2005 (Van den Berg et al., 2006) and are also compared to the results calculated with TEFs 1998 (Van den Berg et al., 1998). 3. Results and discussion 3.1. Lipid contents The lipid (fat) contents of the reindeer tissue and milk samples are shown in Table 1. The reindeer calves had on average higher fat% in their muscle and liver than hinds. The foetuses' muscle and liver fat contents were lower than the fat contents in the calves and hinds. The blood fat% was very low. With the milk samples there were two different trends: in the milk sample of hind #1 (hind in lichen diet) the fat content increased from control (12%) to early summer (16.7%), but decreased again till late summer (10.5%). In the milk of hind #2 (hind in reindeer food concentrate diet) there was an increasing trend from control (10.3%) and early summer (12.9%) to late summer (19.6%) sampling. A decreasing trend of the fat content in the milk samples of hind #1 may indicate insufficient energy intake in the lichen diet. 3.2. WHO-TEQ concentrations and profiles in reindeer tissue and milk samples In Table 2 there are wet weight and/or lipid weight based WHOPCDD/F- and WHO-PCB-TEQ upper bound concentrations (calculated with WHO-TEQs 2005 and 1998) in the reindeer tissue and milk samples, and in reindeer food concentrate and lichen. In most of the reindeer muscle tissue samples PCBs dominated the total TEQ concentration. This is consistent with the earlier study (Suutari et al., 2009). However, some of the samples, like two placentas, livers of foetuses and liver of hind #5, had more PCDDs/Fs than PCBs. PCDDs/Fs were also the dominating compounds in the blood samples of hinds #3 and #4. However, as lower bound values, PCBs were also clearly the dominating compounds in the blood samples. There was a clear consistency in the concentrations of PCDDs/Fs and PCBs in the studied hind–calf-pairs (#1 and #2). The total WHOTEQs were higher in the muscle tissue of reindeer calves (on average 1.7 pg/g fat) than in the muscle tissue of hinds (1.1 pg/g fat). This is probably the consequence of effective intake and distribution of PCDDs/Fs, and especially dioxin-like PCBs in the calves after that the hinds had excreted and transferred the compounds into milk. We do not know if POPs originated from diet are more easily excreted in milk than POPs from the lipid reservoirs of reindeer hinds. There were deviating trends in WHO-PCB-TEQ concentrations between the milk #1 and #2; in the milk #2 PCBs decreased from control (0.69 pg/g fat) and early summer (0.38 pg/g fat) to late summer (0.28 pg/g fat), when in the milk #1 concentration increased (control 0.94, early summer 0.96, and late summer 1.17 pg/g fat). This may be the consequence of decreasing fat% (from early summer till late summer) in the milk of hind #1 and of the concentration effect of PCBs in milk with low fat content. On the other hand, decreasing PCB concentration in the milk #2 may be the result of dilution effect in milk with high fat%. WHO-PCDD/F-TEQs decreased first from control to early summer, but increased slightly in both late summer milk samples of #1 and #2. This may indicate increased exposure to PCDDs/Fs via diet during summer or excretion of PCDDs/Fs from body storages.

In the hind–foetus-pairs (#3 and #4) it was seen that the total TEQs were lower in the muscle of foetuses (on average 0.8 pg/g fat) and liver (on average 1.3 pg/g fat) than in their corresponding hinds. This may indicate probably the effective barrier of placentas to toxic compounds (PCDDs/Fs and DL-PCBs). In addition, the total TEQs were higher in the muscle and liver tissues of hinds #3 and #4 than in their blood. The results of this study showed that WHO-PCDD/F-TEQ concentrations of placenta are not in equilibrium with blood concentrations of hinds since the placentas of hinds #3 and #4 had higher concentrations of PCDDs/Fs than blood (calculated as lower bound concentrations). However, WHO-PCB-TEQs were higher in the blood samples of hinds #3 and #4 than in their placentas, respectively. This may indicate the more accurate binding sites for PCDDs/Fs than DL-PCBs in the placenta. The hind–foetus-pair #5 deviated from the pairs #3 and #4, when the total TEQ was higher in the foetus (analysed as complete body) than in the hind muscle, although the sampled foetus was younger (about 100 days) than the foetuses #3 and #4 (about 200 days). This may indicate some effective POP collector tissue in that individual foetus, or POP concentrations in the foetus #5 just reflect the high concentration in the hind #5. However, WHO-TEQs in the placenta of hind #5 were similarly higher than in the hind muscle, like it was in the pairs #3 and #4. However, the total body WHO-TEQ concentration (muscle + liver) of hind #5 was clearly higher than the placenta's WHO-TEQ concentration. Considering the liver samples (Table 2) of the hind–calf- and hind– foetus-pairs, it was seen, like with the muscle tissue samples, that the calves (#1 and #2) had higher WHO-PCDD/F-TEQs and WHO-PCBTEQs than their corresponding hinds, but foetuses (#3 and #4) had lower WHO-TEQs than hinds. The undeveloped liver functions (low CYP1A2 concentration in foetus liver) of foetuses are probably a reason for low contaminant burdens in their livers, whereas in the calves the production of CYP1A2 in the liver has already started and they are thus able to bind PCDDs/Fs and dioxin-like PCBs. The proportions of WHO-PCB-TEQs from the total TEQs were generally somewhat higher in the liver samples of reindeer calves, like it was in their muscle tissue, also, which is an opposite result observed in the earlier study (Suutari et al., 2012). This may indicate different kinds of exposure to contaminants (more PCBs in this study than in earlier study). Table 3 The sum concentrations of PCDDs/Fs, PCBs and PBDEs in the reindeer samples. Sample

PCDD/F pg/g fat

PCB ng/g fat

PBDE ng/g fat

Calf #1 muscle Calf #1 liver Hind #1 muscle Hind #1 liver Calf #2 muscle Calf #2 liver Hind #2 muscle Hind #2 liver Foetus #3 muscle Foetus #3 liver Hind #3 muscle Hind #3 liver Hind #3 placenta Foetus #4 muscle Foetus #4 liver Hind #4 muscle Hind #4 liver Hind #4 placenta Foetus #5 complete Hind #5 muscle Hind #5 liver Hind #5 placenta Milk #1 control Milk #2 control Milk #1 early summer Milk #2 early summer Milk #1 late summer Milk #2 late summer

2.3 250 0.8 151 1.0 103 0.3 37 0.56 1.6 1.5 148 3 0.55 0.7 1.0 90 2.6 4.1 3.3 462 5.7 2.3 1.7 1.8 0.5 1.8 0.2

14 15 3.7 8.9 4.9 8.4 2.4 3.7 5.1 5.3 9.0 9.3 11 2.2 4.1 4.0 6.0 4.5 5.1 6.7 9.6 6.2 5.3 2.4 5.6 1.9 7.0 1.9

2.7 0.5 3.9 0.4 0.5 0.3 1.9 0.3 2.9 0.7 3.8 0.5 0.5 6.4 1.2 2.1 0.6 1.3 23 2.0 4.1 3.4 0.14 0.04 0.15 0.22 0.18 0.03

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

In the livers of foetuses #3 and #4, WHO-PCDD/F-TEQs were dominating. This may indicate the more efficient transport of dioxins than PCBs to undeveloped liver. However, in the liver of adult hind #5 WHO-PCDD/F-TEQ was also clearly dominating from the total TEQ. Generally in the livers of hinds WHO-PCDD/F-TEQs and WHO-PCB-TEQs were equal. Complete analysed foetus #5 had also more WHO-PCDD/ F-TEQ than WHO-PCB-TEQ. It may be a consequence of the sampling procedure: the hind #5 and foetus #5 were sampled earlier and from different locations than other samples. There may be a stronger exposure to PCDDs/Fs than PCBs in that area from which they were sampled. 3.3. Sum concentrations of PCDDs/Fs, PCBs and PBDEs The sum concentrations (Table 3) were parallel with the results calculated with WHO-TEQs. Considering the reindeer muscle and liver samples it was seen that calves #1 and #2 had higher PCDD/F sum concentrations than their hinds. The foetuses #3 and #4 had lower concentrations of PCDDs/Fs in their muscle and liver than their hinds. A similar trend was seen with WHO-PCDD/F-TEQs between the hinds and calves/ foetuses. The placentas of hinds #3 and #4 contained higher PCDD/F sums (about 5 times higher than PCDD/F sum in the muscle of foetuses) than the corresponding foetuses, that may indicate effective barrier to PCDD/F transport from hind to foetus, at least in the specific cases. The hind #5 had the highest PCDD/F sum of all hinds, and this also reflected as higher PCDD/F sum in its placenta & uterus and, in this case, in the foetus. It is worth to notice that complete analysed foetus #5 had higher PCDD/F sum than what was found from its hind muscle. However, the liver of hind #5 contained clearly the highest sum of PCDD/F, so the total body burden was bigger in that hind. Interestingly the percentage of PCDD/F sum in foetus #5 (GD 100) was smaller than in foetuses #3 and #4 (GD 200), respectively. A comparison to stillborn reindeer calves (Suutari et al., 2012) indicates that they have even higher PCDD/F concentrations than foetuses (calculated as total body burden of stillborn calves i.e. the muscle and brown adipose tissue concentrations). Both calves #1 and #2 had higher PCDD/F sums in their livers than what were found from the livers of their hinds. However, the foetuses #3 and #4 had very much lower (over 100 folded) levels of PCDDs/Fs in their liver than their hinds. This observation may mean that a liver activity in relation to accumulation of toxic contaminants increases significantly, or start to work, after birth and during the first living months of reindeer calves.

129

The PCB sum was lower in the placenta samples than in the milk samples. However, the sum of PCBs was about three fold higher in the placenta #3 than in the placenta #4 and the placenta & uterus #5. In the milk #1 PCBs increased from control to early summer and late summer. In the milk #2 PCBs increased from control to early summer and then stayed constant till late summer. The reindeer calves #1 and #2 had lower PBDE levels in their muscle than their corresponding hinds. The PBDE sum was clearly highest in the foetus #5. The foetus #5 had clearly more PBDEs than the corresponding placenta & uterus, and also higher level than the muscle and liver of hind #5. The other foetuses also contained generally more PBDEs than their corresponding placentas. This may indicate effective transport of PBDEs through the reindeer placenta. There have been studies which demonstrate that PBDEs accumulate within the human foetal compartment at a very early stage in gestation (Doucet et al., 2009). The PBDE sums in the reindeer hinds' #3 and #4 were quite low; lower than in the placenta and muscle of hind #3, but equal with muscle of the hind #4. In addition, PBDE concentration of the hind #4 placenta was lower than in the blood sample. The lower PBDE sums in the foetuses #3 and #4 than the foetus #5 may indicate stronger exposure to PBDEs in the more southern region, from where the foetus #5 was sampled. In addition, PBDEs in the liver of hind #5 (the southern sampling area) were higher than in the livers of hinds #3 and #4 (the northern sampling area). However, the PBDE sums in foetus #4 muscle and liver were also higher than in its corresponding hind. The lower fat contents of foetuses' muscle and liver may also affect the concentrations detected in their tissues. In the reindeer liver samples the highest PBDE sum concentration was detected in the hind #5. In that sample a proportion of BDE-209 was as high as 96%. It is worth to notice that the PBDE sum concentrations were generally lower in the reindeer liver samples than in other samples, including the muscle samples of foetuses. An exception was the hind #5, whose liver contained more PBDEs than the corresponding muscle sample. An effective transport of PBDEs to reindeer muscle has been supposed in earlier study, too (Suutari et al., 2011). The PBDE sums in the reindeer milk samples increased both in hinds #1 and #2 from control to early summer. In the hind #1 increasing trend continued till late summer, but in the hind #2 a level of PBDE decreased till late summer sampling. This indicates an effective excretion of PBDEs via milk in reindeer. In the milk #2 the fat content increased from early to late summer, which may affect (by dilution effect) the PBDE levels detected in the milk samples.

a)

b) 7

0.04

6.5 0.035

6 5.5

0.03

5 4.5

0.025

4 0.02

3.5 OCDD

0.015 23478PeCDF

0.01

3 2.5 2 1.5

0.005

1 0.5

0

0

Fig. 1. The most abundant PCDD/F congeners (pg/g wet weight) in the reindeer a) muscle and b) liver samples.

OCDD 23478PeCDF 123478HxCDF

130

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

3.4. PCDD/F congeners

3.5. PCB congeners

The congener profiles in the reindeer muscle and liver were partly different (Fig. 1). The most dominating PCDD/F congeners in the reindeer muscle were OCDD and 23478-PeCDF. In the liver samples the corresponding congeners were OCDD, 23478-PeCDF, 123478HxCDF and 1234678-HpCDF. PCDD/F profile differences between the muscle and liver tissues have been found in the earlier studies, too; the main PCDD/F congeners in the muscle have been OCDD and 23478-PeCDF, and in the liver OCDD, 23478-PeCDF and 123478HxCDF (Suutari et al., 2012). Quantitatively the liver had more WHOPCDD/F-TEQs than the muscle tissue. 23478-PeCDF levels were highest in the hind–foetus-pair #5: especially in the muscle of foetus #5 (0.04 pg/g wet weight) and the liver of hind #5 (6.6 pg/g ww). The reindeer calf #1 liver also contained quite a number of 23478-PeCDF (2.5 pg/g ww), and also 1234678HpCDF (2.1 pg/g ww). 23478-PeCDF's contribution to WHO-TEQ was relatively high. The muscle sample of calf #1 had also quite a higher level of 23478-PeCDF, and milk and lichen as well. Considering reindeer milk the most conspicuous PCDD/F congeners were 23478-PeCDF, 123678-HxCDD, and 123478-HxCDF. Especially these congeners were well representative in both control milk samples (#1 and #2), and also in the summer milk sample #1. In the milk of reindeer hind #2 the part of congeners stayed under LOQ during the lactation period, while in the milk of hind #1 the congener pattern remained very stable. This may be the result of different diets of these hinds (hind #1 in lichen diet, hind #2 in reindeer food concentrate diet). In addition, the fat content in the milk of hind #2 increased from early to late summer that may result in a dilution of PCDD/F congeners in milk. In the placenta samples the most important PCDD/F congeners were 123678-HxCDD, 2378-TCDF and 23478-PeCDF. It was interesting that OCDD concentrations in the milk samples were very low; however, in the reindeer muscle and liver samples OCDD was found. In the earlier study (Suutari et al., 2012) OCDD was found to exist in reindeer milk (0.6 pg/g fat) in late summer even if its concentration was under the LOQ in summer milk. This indicates the exposure peak to OCDD, which has observed to be one of the major congeners in deposition in northern Finland (Kiviranta, 2005).

The most dominating DL-PCB congeners in the reindeer muscle samples were PCB-126, -77, -118, -105 and -156. PCB-126 concentration was overwhelmingly highest in the reindeer liver (on average 9.4 pg/g ww). PCB-126 is the most toxic congener of dioxin-like PCBs having a TEF-value of 0.1. Its proportionally high level in the liver tissue may indicate liver function as a main organ in intoxication process. Hence, a high concentration of the most toxic compound is seen when adherence on dioxin-receptor is effective. Of indicator PCB congeners the most dominating ones in the reindeer muscle and liver were PCB138, -153, and -180 (Fig. 2). In the reindeer milk samples the most conspicuous DL-PCB congener was PCB-126. It was also a dominating compound in the placenta samples. Other abundant DL-PCB congeners were PCB-118, -105 and -156. In the reindeer milk, and also in the placentas, PCB-153, -138, -170, and -180 were the most dominating of other PCBs. Interestingly, PCB99 existed in higher levels in the hind #1 milk than in the other samples, and it remained stable during the whole lactation period from control (0.03 ng/g ww) to late summer (0.03 ng/g ww) sampling. 3.6. PBDE congeners The most important PBDE congeners in reindeer muscle samples were BDE-209, -153, -99, and -47 (Fig. 3). The set was similar in the liver samples and also in the placentas. The proportion of BDE-209 was clearly highest in all samples; in the muscle samples it was over 90% of the sum of PBDEs, and also in the liver and placenta samples its share was 58% and 77%, respectively. In the reindeer milk samples generally the most important PBDE congeners were BDE-47, -99, and -153 reflecting the profile of analysed reindeer tissues. Some differences were also found between the milk samples; for instance BDE-47 was more abundant in the milk samples of hind #1 than in the milk samples of hind #2. A proportion of BDE-209 was generally minor in the milk samples except in the #2 milk sample (early summer), when its share of the total sum was 81% (concentration 0.18 ng/g fat). This indicates quite strong exposure of the hind #2 to BDE-209 in the experimental zoo in

0.14

a)

0.3

b)

0.12 0.25

PCB138 PCB153

0.1

PCB170

0.2

PCB180

0.08 0.15 0.06 0.1 0.04

0.05 0.02

0

0 1 hind 1 calf 2 hind 2 calf 3 hind 3 foetus 4 hind 4 foetus 5 hind muscle muscle muscle muscle muscle muscle muscle muscle muscle

1 hind 1 calf 2 hind 2 calf 3 hind 3 4 hind 4 5 hind liver liver liver liver liver foetus liver foetus liver liver liver

Fig. 2. The most important non-dioxin-like PCB congeners (ng/g wet weight) in the a) reindeer muscle and b) reindeer liver samples.

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

0.2

131

BDE209 25

0.18

20

0.16

15 10

0.14

5

0.12

0

0.1 0.08 0.06 BDE47

0.04 BDE99

0.02

BDE153

0 1 Hind, muscle

2 Hind, muscle

3 Hind, muscle

4 Hind, muscle

5 Hind, muscle

1 Calf, muscle

2 Calf, muscle

3 Foetus, 4 Foetus, 5 Foetus, muscle muscle complete

Fig. 3. The most abundant PBDE congeners (ng/g fat) in the reindeer muscle samples.

early summer, because the BDE-209 in the control milk of hind #2 was zero. Considering the hind #2 diet (reindeer food concentrates), it was observed that it contained 94% (10.7 ng/g fat) of BDE-209 from the total PBDE sum. The PBDE sum in lichen was 1.4 ng/g dry weight. The reindeer calf #1 (lichen diet) had higher BDE-209 concentration in its muscle (2.4 ng/g fat) and liver (0.16 ng/g fat) than the calf #2 (0.4 ng/g fat in muscle, 0.11 ng/g fat in liver), so the figure is not so simple.

3.7. Transfer ratios and log Kows A comparison of the transfer ratios from hind to calf and foetus and log Kows is shown in Figs. 4, 5 and 6. In the hind–calf transition of PCDDs/Fs it was noticed that the lowest bioaccumulation factors (BAFs) were seen in 2378-TCDF and 12378-PeCDF, and these congeners had also quite low log Kow values. The congeners with the highest BAFs were hexa-, hepta- and octachlorinated congeners with log Kow values

a)

8 7 6 5 4 3 2 1 0

log Kow

BAF

b) 8 7 6 5 4 3 2 1 0

log Kow

BAF

Fig. 4. Comparison of log Kows and the transfer ratios of PCDDs/Fs in a) hind to calf and b) hind to foetus.

132

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

a) 9 8 7 6 5 4 3 2 1 0

log Kow

BAF

log Kow

BAF

b) 9 8 7 6 5 4 3 2 1 0

Fig. 5. Comparison of log Kows and the transfer ratios of PCBs in a) hind to calf and b) hind to foetus.

of 7 (Fig. 4a). In the hind–foetus transition of PCDDs/Fs a negative correlation between the BAFs and log Kow values was observed. Thus, there is no bioaccumulation of PCDDs/Fs from the hinds to the foetuses, but bioaccumulation occurs from the hinds to the calves (Fig. 4b). In the hind–calf transition of PCBs it was noticed that there is a positive correlation between the BAFs and log Kows. A clear bioaccumulation was seen in dioxin-like PCB congeners PCB-126 and PCB-169. From other PCBs there were some clearly bioaccumulating congeners; PCB-105, -118, -141, -153, -156, -167, -170, -180, and -194. These congeners began to accumulate when log Kow exceeded a value of 6.

However, PCB-209, of which log Kow value is the highest, did not accumulate from hind to calf (Fig. 5a). In the hind–foetus transition of PCBs there is a clear negative correlation between BAFs and log Kow values (Fig. 5b). In the hind–calf transition of PBDEs a clear bioaccumulation of congener BDE-153 is seen. However, BDE-209 did not bioaccumulate despite its high log Kow value (Fig. 6a). Comparing the hind–calf and hind–foetus transitions a totally different figure came out. With the hind–foetus transition there was a strong negative correlation between BAFs and log Kow values. BDE-28 with the lowest log

a) 11 10 9 8 7 6 5 4 3 2 1 0 BDE28

BDE47

BDE99 log Kow

BDE100 BAF

BDE153

BDE209

BDE28

BDE47

BDE99 log Kow

BDE100

BDE153

BDE209

b) 11 10 9 8 7 6 5 4 3 2 1 0 BAF

Fig. 6. Comparison of log Kows and the transfer ratios of PBDEs in a) hind to calf and b) hind to foetus.

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

133

0.60 0.55 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 0.10 0.05 0.00

Lichen

Food concentrate

Fig. 7. PBDE congener concentrations (ng/g wet weight) in lichen and reindeer food concentrates.

Kow bioaccumulated to foetus. BDE-209 also bioaccumulated which is an opposite result than with the hind–calf examination. However, BDE-153 did not bioaccumulate as it did in the hind–calf transition (Fig. 6b).

low. However, BDE-209 levels were high in both matrixes, especially in lichen (Fig. 7).

3.9. WHO-TEQs in reindeer diet — reflection to reindeer tissue concentrations 3.8. PCDDs/Fs, PCBs and PBDEs in reindeer food concentrate and lichen When comparing WHO-PCDD/F- and WHO-PCB-TEQ concentrations in reindeer food concentrate and lichen it can be noticed that both wet weight based levels of WHO-PCDD/F-TEQs and WHO-PCB-TEQs are higher in lichen than in reindeer food concentrate (Table 2). The contributions of WHO-PCDD/F-TEQs to the total TEQs are bigger in both matrixes (on average 78% of total mass). This may indicate effective adherence of PCDDs/Fs in carbohydrates; the main organic component and the most important energy source of reindeer, in food concentrate and lichen. However, generally it is known that POPs are lipid soluble and lipophilic chemicals. The most important PCDD/F congeners in lichen were OCDD, 1234678-HpCDD, 1234678-HpCDF and OCDF. In reindeer food concentrates the most dominating congener was OCDD. Of dioxin-like PCBs the most dominating congeners in lichen and reindeer food concentrates were PCB-77, -118, and -105. The most important non-dioxin-like PCB congeners in lichen were PCB-28/31, -138 and -153, when the most dominating congeners in reindeer food concentrates were PCB-28/31, -52, -101, -138 and -153. PBDE concentrations in lichen and reindeer food concentrates were generally very

It is seen that the reindeer hind–calf pair #1 which had gone through the lichen diet had on average higher total WHO-TEQ concentrations than the pair #2 in the reindeer food concentrate diet (Fig. 8). When comparing WHO-PCDD/F-TEQs in the reindeer food concentrate and in the reindeer muscle tissue, it was seen that concentration in the food concentrate was higher. However, when considering the reindeer liver, there can be seen bioaccumulation of PCDDs/Fs from the reindeer food concentrate to the liver. WHO-PCB-TEQs accumulated from the reindeer food concentrate to the reindeer liver, and deviating from PCDDs/Fs, also into the muscle. WHO-PCDD/F-TEQs and WHO-PCBTEQs accumulated from lichen (dry weight) to the liver and muscle (lipid weight) of the reindeer calf #1 and the hind #1. WHO-PCDD/F-TEQ concentration in the reindeer milk was lower than in the food concentrate. WHO-PCB-TEQ did accumulate from the reindeer food concentrate to the milk. This may be the result of the rumen's ability to produce fatty acids, containing DL-PCBs, and transport them to the blood circulation and finally to excretive route of lactation. The overall consequence is higher WHO-PCB-TEQ levels in the reindeer calf muscle and liver than corresponding concentrations in the reindeer hind tissues. WHO-PCDD/F-TEQs in the muscles of calves

9 8 7 6 5 4 3 2 1 0

WHO-PCB-TEQ

WHO-PCDD/FTEQ

Fig. 8. WHO-PCDD/F-TEQs and WHO-PCB-TEQs in the reindeer samples (pg/g fat) and in lichen and reindeer food concentrate (pg/g wet weight).

134

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135

#1 and #2 did not deviate from their hinds: it was especially DL-PCBs, which made the differences between the calves and their hinds. However, there were higher WHO-PCDD/F-TEQs in the liver of calves than in their corresponding livers of hinds. WHO-PCDD/F- and WHO-PCB-TEQ results in the reindeer–calf pair #1 (lichen diet) show that compounds accumulate effectively from lichen to the reindeer hind liver tissue, and also to milk, which results as high WHO-PCDD/F-TEQ and WHO-PCB-TEQ concentrations in the calf muscle and liver tissues. Bioaccumulation of WHO-PCDD/F- and WHO-PCB-TEQs from lichen to the reindeer hind muscle is not so effective than to the liver. This may be the result of effectiveness in lichen digestion from the rumen in adult reindeer. The overall observation was that WHO-PCDD/F- and WHO-PCB-TEQs were accumulated in the reindeer calves in both diets, but especially that was seen in the lichen-diet. However, the control milk samples showed that the reindeer hind #1 was originally exposed more to PCDDs/Fs and PCBs than the hind #2. It remained open if there are some other routes than food (like atmospheric deposition or water supply) for PCDDs/Fs and PCBs getting to the reindeer food chain, but this is less probable. 4. Conclusions The concentrations of 17 PCDDs/Fs, 37 PCBs (including 12 dioxinlike PCBs), and 15 PBDEs were analysed in the reindeer muscle and liver tissues, milk and reindeer food concentrates and lichen. In the reindeer muscle samples PCBs were dominating compounds. The total WHO-TEQs were higher in the reindeer calves than in the reindeer hinds. The total WHO-TEQs were lower in the foetuses than in their corresponding hinds. The reindeer hind–calf pair #1 in the lichen diet had higher total WHO-TEQ concentrations than the pair #2 in the reindeer food concentrate diet. However, the control milk samples showed that the hind #1 had already higher WHO-PCDD/F-PCB-TEQ in its body before the diet treatment. Considering the toxic equivalents, WHO-TEQs of PCDDs/Fs and PCBs showed equal concentrations in the foetuses and placentas. The PCDD/F congener profiles in the reindeer muscle and liver differed slightly from each other. The most abundant PCDD/F congeners in the muscle were OCDD and 23478-PeCDF. In the liver samples the most abundant congeners were OCDD, 23478-PeCDF and 123478-HxCDF. The most dominating DL-PCB congeners in the reindeer muscle and liver samples were PCB-126, -77, -118, -105 and -156. The most dominating other PCB congeners were PCB-138, -153, -170 and -180. The most important PBDE congeners in the reindeer muscle, liver and placenta samples were BDE-209, -153, -99, and -47. In the reindeer milk samples generally the most important PBDE congeners were BDE47, -99, and -153. The reindeer foetuses contained generally more PBDEs than their corresponding hinds and placentas. PCDDs/Fs, PCBs and PBDEs accumulated effectively from the food concentrates and lichen, although in quite low concentrations, to the reindeer hind. Our findings suggest that PCDDs/Fs and even better DL-PCBs are transferred efficiently into the calves via lactation. For PCDDs/Fs and PCBs lactational transfer is much more important than placental transfer. Placenta seems to function as a barrier of these substances, especially for PCDDs/Fs and DL-PCBs. However, there is an effective transport of PBDEs through the reindeer placenta to foetus. In order to better understand transfer of PCDDs/Fs, DL-PCBs and differences between them and PBDEs more data about the stability, accumulation and metabolism of these substances in different organs is needed. For instance more information is required about the levels of P450 (CYP) 1A2 that may have low binding affinity to dioxin-like compounds in the reindeer foetus liver. Competing interests The authors declare that they have no competing interests.

Acknowledgements The Finnish Food Safety Authority Evira, Finnish Cultural Foundation and University of Oulu are acknowledged for funding of the study. The staffs of Unit of Chemical Exposure in THL and Finnish Food Safety Authority Evira are thanked for their technical assistance. References Ábalos M, Parera J, Rivera J, Abad E. PCDD/F and DL-PCB levels in meat from broilers and rabbits fed with fish-oil enriched feeds. Chemosphere 2010;78:175–84. AMAP. AMAP assessment 2002: persistent organic pollutants in the Arctic. Oslo, Norway: Arctic Monitoring and Assessment Programme (AMAP); 2004 [xvi + 310 pp.]. Braekevelt E, Tittlemier SA, Tomy GT. Direct measurement of octanol–water partition coefficients of some environmentally relevant brominated diphenyl ether congeners. Chemosphere 2003;51:563–7. de March BGE, de Wit CA, Muir DCG, Braune BM, Gregor DJ, Norstrom RJ, et al. Persistent organic pollutants. AMAP assessment report 1998. Arctic pollution issues, chapter 6. Oslo, Norway: Arctic Monitoring and Assessment Programme; 1998. p. 183–372. Doucet J, Tague B, Arnold DL, Cooke GM, Hayward S, Goodyer CG. Persistent organic pollutant residues in human fetal liver and placenta from Greater Montreal, Quebec: a longitudinal study from 1998 through 2006. Environ Health Perspect 2009;117: 605–10. European Commission. COUNCIL DIRECTIVE 93/119/EC of 22 December 1993 on the protection of animals at the time of slaughter or killing; 1993. European Commission. Communication from the Commission to the Council, the European Parliament and the Economic and Social Committee. Community strategy for dioxins, furans and polychlorinated biphenyls. (2001/C 322/02). (COM (2001) 593 final); 2001. Finfoodhttp://www.finfood.fi. Frouin H, Lebeuf M, Hammill M, Fournier M. Transfer of PBDEs and chlorinated POPs from mother to pup during lactation in harp seals Phoca groenlandica. Sci Total Environ 2012;417–418:98–107. Hardy ML. The toxicology of the three commercial polybrominated diphenyl oxide (ether) flame retardants. Chemosphere 2001;46:757–77. Hawker D, Connell DW. Octanol–water partition coefficients of polychlorinated biphenyl congeners. Environ Sci Technol 1988;22:382–7. Kiviranta H. Exposure and human PCDD/F and PCB body burden in Finland (PhD thesis)National Public Health Institute, Department of Environmental Health; 2005. Krahn MM, Hanson MB, Schorr GS, Emmons CK, Burrows DG, Bolton JL, et al. Effects of age, sex and reproductive status on persistent organic pollutants concentrations in “Southern Resident” killer whales. Mar Pollut Bull 2009;58:1522–9. Mackay D, Shiu WY, Ma KC. Illustrated handbook of physical–chemical properties and environmental fate for organic chemicals. Monoaromatic hydrocarbons, chlorobenzenes and PCBs, vol. I. Boca Raton, FL: Lewis Publishers; 1991 [697 pp.]. Mackay D, Shiu WY, Ma KC. Illustrated handbook of physical–chemical properties and environmental fate for organic chemicals. Polynuclear aromatic hydrocarbons, polychlorinated dioxins and dibenzofurans, vol. II. Boca Raton, FL: Lewis Publishers; 1992 [597 pp.]. Nieminen M. Poronmaito-liian vahvaa imeväisten ravinnoksi? Poromies 1987;54:18–25. Noble RC. Essential fatty acids in the ruminant. In: Wiseman J, editor. Fats in animal nutrition. London: Butterworths; 1981. p. 185–200. Ruokojärvi P, Laaksonen S, Suutari A, Kiviranta H, Vartiainen T. Levels of PCDD/Fs and PCBs in reindeer — first results of the Finnish study on POPs in reindeer food chain. Organohalogen Compd 2007;69:2319–22. Ruokojärvi P, Suutari A, Hallikainen A, Laaksonen S, Nieminen M, Kiviranta H. Distribution of PCDD/Fs, PCBs and PBDEs in semidomesticated reindeer (Rangifer tarandus tarandus L.) meat and liver. Organohalogen Compd 2011;73:1321–4. Rychen G, Jurjanz S, Fournier A, Toussaint H, Feidt C. Exposure of ruminants to persistent organic pollutants and potential of decontamination. Environ Sci Pollut Res Int 2014. http://dx.doi.org/10.1007/s11356-013-1882-8. [In press]. Suutari A, Ruokojärvi P, Kiviranta H, Hallikainen A, Laaksonen S. Polychlorinated dibenzo-p-dioxins and polychlorinated biphenyls in reindeer (Rangifer tarandus tarandus) and moose (Alces alces) meat in Finland. Chemosphere 2009;75:617–22. Suutari A, Ruokojärvi P, Kiviranta H, Verta M, Korhonen M, Nieminen M, et al. Polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) in Finnish semi-domesticated reindeer (Rangifer tarandus tarandus). Environ Int 2011;37: 335–41. Suutari A, Hallikainen A, Ruokojärvi P, Kiviranta H, Nieminen M, Laaksonen S. Persistent organic pollutants in Finnish reindeer (Rangifer tarandus tarandus L.) and moose (Alces alces). Acta Vet Scand 2012;54(Suppl. 1):S11. UNEPFinal act of the conference of Plenipotentiaries on the Stockholm convention on persistent organic pollutants; 2001. [Geneva, Switzerland]. UNEP. C.N. 524; 2009 [TREATIES-4. (Depositary Notification)]. Van den Berg M, Birnbaum L, Denison M, De Vito M, Farland W, Feeley M, et al. Human and mammalian toxic equivalency factors for dioxins and dioxin like compounds: the WHO 2005 re-evaluation. Organohalogen Compd 2006;68: 834–5.

A. Holma-Suutari et al. / Science of the Total Environment 476–477 (2014) 125–135 Van den Steen E, Jaspers VLB, Covaci A, Neels H, Eens M, Pinxten R. Maternal transfer of organochlorines and brominated flame retardants in blue tits (Cyanistes caeruleus). Environ Int 2009;35:69–75. Van der Berg M, Birnbaum L, Bosveld ATC, Brunström B, Cook P, Feeley M, et al. Toxic Equivalency Factors (TEFs) for PCBs, PCDDs PCDFs for humans and wildlife. Environ Health Pespect 1998;106:12.

135

Wong A, Lei YD, Alaee M, Wania F. Vapor pressures of polybrominated diphenyl ethers. J Chem Eng Data 2001;46:239–42. Yordy JE, Wells RS, Balmer BC, Schwacke LH, Rowles TK, Kucklick JR. Life history as a source of variation for persistent organic pollutant (POP) patterns in a community of common bottlenose dolphins (Tursiops truncatus) resident to Sarasota Bay, FL. Sci Total Environ 2010;408:2163–72.