Frank Riget

Publications (12)27.96 Total impact

• Source

  Available from: Henning S Pedersen

  Article: Human accumulation of mercury in Greenland.

  Poul Johansen, Gert Mulvad, Henning Sloth Pedersen, Jens C Hansen, Frank Riget
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  ABSTRACT: In the Arctic, the traditional diet exposes its people to a high intake of mercury especially from marine mammals. To determine whether the mercury is accumulated in humans, we analyzed autopsy samples of liver, kidney and spleen from adult ethnic Greenlanders who died between 1990 and 1994 from a wide range of causes, natural and violent. Liver, kidney and spleen samples from between 33 and 71 case subjects were analyzed for total mercury and methylmercury, and liver samples also for selenium. Metal levels in men and women did not differ and were not related to age except in one case, i.e. for total mercury in liver, where a significant declining concentration with age was observed. The highest total mercury levels were found in kidney followed by liver and spleen. Methylmercury followed the same pattern, but levels were much lower, constituting only 19% of the total mercury concentration in liver and spleen and as little as 3% in kidney. In liver selenium was found in surplus to mercury on a molar basis. Mercury concentrations in the liver and kidneys of Greenlanders were elevated compared to levels in the general population in Japan, Korea and several European countries, except in the Faroe Islands where mercury levels were 2-3 times higher. This is in accordance with the expected exposure of mercury in the diet.
  Science of The Total Environment 06/2007; 377(2-3):173-8. · 3.29 Impact Factor
• Article: Accumulation of cadmium in livers and kidneys in Greenlanders.

  Poul Johansen, Gert Mulvad, Henning Sloth Pedersen, Jens C Hansen, Frank Riget
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  ABSTRACT: In the Arctic, the traditional diet exposes its people to a very high intake of cadmium because it is highly concentrated in the liver and kidneys of commonly eaten marine mammals. In one study in Greenland, the cadmium intake was estimated to 182 microg/day/person in the fall and 346 in the spring. To determine whether the cadmium is accumulated in humans, we analyzed autopsy samples of liver and kidneys from 95 ethnic Greenlanders (aged 19-89) who died from a wide range of causes. The cadmium concentration in liver (overall mean 1.97 microg/g wet wt) appeared to be unrelated to any particular age group, whereas the concentrations in the kidneys peaked in Greenlanders between 40 and 50 years of age (peak concentration 22.3 microg/g wet wt). Despite the high cadmium levels in the typical Greenlander diet, we found that the cadmium concentrations in livers and kidneys were comparable to those reported from Denmark, Sweden, Australia and Great Britain. Furthermore, even though the mean cadmium intake from the diet was estimated to be 13-25 times higher in Greenlanders than in Danes, we found similar cadmium levels in the kidneys of both. Seal livers and kidneys are the main source of cadmium in the diet of Greenlanders, but these tissues are not eaten in Denmark. Thus, our results suggest that the accumulation of cadmium from Greenlander's marine diet is very low.
  Science of The Total Environment 01/2007; 372(1):58-63. · 3.29 Impact Factor
• Article: Lead shot from hunting as a source of lead in human blood.

  Poul Johansen, Henning Sloth Pedersen, Gert Asmund, Frank Riget
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  ABSTRACT: This study investigates the relationship between the intake of birds hunted with lead shot and the lead concentration in human blood. Fifty adult men from Nuuk, Greenland took part in the study. From September 2003 to June 2004 they regularly gave blood samples and recorded how many birds they ate. We found a clear relationship between the number of bird meals and blood lead and also a clear seasonal variation. The concentration was highest in mid-winter when bird consumption is at its highest. Blood lead was low (15 microg/L, mean concentration) among the participants reporting not eating birds. Among those reporting to eat birds regularly, blood lead was significantly higher, up to 128 microg/L (mean concentration). Concentrations depended on the frequency of bird meals: the more the bird meals, the higher the resulting blood lead. This clear relationship points to lead shot as the dominating lead source to people in Greenland.
  Environmental Pollution 08/2006; 142(1):93-7. · 3.75 Impact Factor
• Article: Circumpolar pattern of mercury and cadmium in ringed seals.

  Frank Riget, Derek Muir, Michael Kwan, Tatiana Savinova, Madeleine Nyman, Victoria Woshner, Todd O'Hara
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  ABSTRACT: Mercury (Hg) and cadmium (Cd) concentrations in ringed seal liver and kidney were compared from 11 locations across the Arctic, from Alaska, Canada, Greenland, Svalbard to the White Sea. Adult and sub adult seals were evaluated separately to account for age accumulations of Hg and Cd. Only recently (1995-2001) collected samples were included to minimize influence of changes over time. The Hg and Cd concentrations in ringed seal liver and kidney differed significantly among the studied locations. The Hg concentrations in liver of ringed seals was highest in the western Canadian Arctic locations, while Cd in liver was highest in the eastern Canadian and West Greenland locations. In general, Hg and Cd concentrations in liver and kidney were significantly higher in adult ringed seals than in sub adults and the circumpolar patterns were most pronounced in adult ringed seals. The Hg and Cd concentrations in kidney of ringed seals in general supported the geographical pattern found in livers although the coverage was more limited. The most likely explanation for the observed circumpolar pattern appears mainly to be related to natural geological differences in mineral (Hg and Cd) among regions.
  Science of The Total Environment 01/2006; 351-352:312-22. · 3.29 Impact Factor
• Article: Levels and temporal trends of PCDD/PCDFs and non-ortho PCBs in ringed seals from East Greenland.

  Frank Riget, Jørgen Vikelsøe, Rune Dietz
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  ABSTRACT: The levels and temporal trend of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) and non-ortho substituted PCBs (c-PCBs, i.e. CB77, CB126 and CB169) were determined in ringed seal blubber from central East Greenland collected in 1986, 1994, 1999 and 2003, respectively. Since 1986 the concentrations of PCDDs, PCDFs and c-PCBs all show a decreasing trend. The annual decreases were estimated to 5.2% and 5.3% for pg/g WHO-TEQ ww of PCDD/Fs and c-PCB, respectively. The annual median concentrations of PCDDs ranged from 5.4 to 24.4 pg/g WHO-TEQ ww and those of PCDFs from 2.5 to 5.1 pg/g WHO-TEQ ww. Compared to PCDD/Fs concentrations in ringed seals from other Arctic areas the levels of PCDD/Fs found in 1986 were the highest recorded. The annual median concentrations of c-PCBs decreased 24.2 to 9.1 pg/g WHO-TEQ ww. The levels of c-PCBs observed in 1986 are similar to levels found in ringed seals from Svalbard in 1990 and from eastern Hudson Bay in 1989-1992. The dominant and most TEQ-contributing PCDD congener was 1,2,3,7,8-PeCDD. CB126 was the dominating and most TEQ-contributing c-PCB congener. The concentrations of PCDDs, PCDFs and c-PCBs were highly significantly inter-correlated. Principal component analysis of the PCDD/PCDF congeners and c-PCBs was performed to analyse the pattern of compounds during time.
  Marine Pollution Bulletin 01/2006; 50(12):1523-9. · 2.50 Impact Factor
• Article: Chlorobenzenes, chlorinated pesticides, coplanar chlorobiphenyls and other organochlorine compounds in Greenland biota.

  Katrin Vorkamp, Frank Riget, Marianne Glasius, Maria Pécseli, Michel Lebeuf, Derek Muir
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  ABSTRACT: This paper summarises the levels and composition of chlorobenzenes, chlorinated pesticides, coplanar polychlorinated biphenyls (PCBs) and the chlorinated compounds octachlorostyrene (OCS), hexachlorocyclobutadiene (HCBD) and pentachloro-anisole (PCA) in biota from the terrestrial, freshwater and marine environment of Greenland. The data were obtained during the second phase of the Arctic Monitoring and Assessment Programme (AMAP). Of the chlorobenzenes, hexachlorobenzene was the main constituent detected in almost all samples. The chlorobenzenes accumulate in the marine food web in a similar manner to the better-studied persistent organic pollutants, with maximum concentrations in beluga, minke whale and narwhal. However, concentrations in ringed seals and kittiwakes were lower than in marine fish, contradicting biomagnification. Of the organochlorine pesticides, the drin pesticides (aldrin, endrin, dieldrin) and heptachlor had increasing concentrations along the food chain, whilst biomagnification was less pronounced for endosulfan, methoxychlor and mirex. Endosulfan and methoxychlor are pesticides still in use and considered less persistent than other organochlorine pesticides. Their occurrence in Arctic biota is of particular concern, also given the high acute toxicity of endosulfan to fish. Chlorobenzene and pesticide concentrations tended to be lower in the Greenland samples than in the same animals from the Canadian Arctic, whilst their concentrations were similar to samples from Svalbard and Iceland. However, temporal trends might overlap the geographical differences. Coplanar chlorobiphenyls (CBs) were found in all samples analysed, with the maximum concentrations found in marine mammals such as beluga and narwhal. Biota from the terrestrial environment appeared to be less contaminated. The main contributor on a TEQ basis was CB126. OCS, HCBD and PCA were detected in biota from Greenland, although at very low concentrations. OCS seems to have the widest occurrence and the highest potential for biomagnification of the three compounds analysed.
  Science of The Total Environment 10/2004; 331(1-3):157-75. · 3.29 Impact Factor
• Article: Human exposure to contaminants in the traditional Greenland diet.

  Poul Johansen, Derek Muir, Gert Asmund, Frank Riget
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  ABSTRACT: The traditional diet is a significant source of contaminants to people in Greenland, although contaminant levels vary widely among species and tissue from very low in many to very high in a few. Our study has included cadmium, mercury, selenium, polychlorinated biphenyls (PCB), dichlorophenyltrichloroethane (DDT), chlordane, hexachlorocyclohexanes (HCH), chlorobenzenes, dieldrin and toxaphene in the major species and tissues consumed by Greenlanders. In general, the levels of these are very low in terrestrial species and in muscle of many marine species. High organochlorines concentrations are typically found in blubber of marine mammals and high metal levels in liver and kidney of seals and whales. In this study, the mean intakes of cadmium, chlordanes and toxaphene significantly exceed 'acceptable/tolerable intakes' (ADI/TDI) by a factor between 2.5 and 6. Mean intakes of mercury, PCB and dieldrin also exceed ADI/TDI by up to approximately 50%. However as these figures are mean intakes and as variation in both food intake and contaminant levels is large, the variation of contaminant intake among individuals is also large, and some individuals will be exposed to significantly higher intakes. The mean intakes of DDT, HCH and chlorobenzenes are well below the ADI/TDI values, and it seems unlikely that the TDI for these contaminants normally is exceeded in the Greenland population. The evaluation of contaminant intake in this study points to seal muscle, seal liver, seal kidney, seal blubber and whale blubber as the dominant contributors of contaminants in the traditional diet. Levels in liver from Greenland halibut, snow crab, king eider, kittiwake, beluga and narwhal and kidney of beluga and narwhal are also high but were, with the exception of toxaphene in Greenland halibut liver, not important sources in this study, because they were eaten in low quantities. A way to minimize contaminant intake would be to avoid or limit the consumption of diet items with high contaminant levels. If we assume a traditional diet composition in this study without fish liver, bird liver, seal liver, seal kidney, seal blubber, whale liver, whale kidney and whale blubber, the intake of all contaminants would be below the TDIs for these. This will result in a reduction of the intake of the amount of traditional food of only 24-25%, and it is not likely that this changed diet will result in deficiency of minerals, vitamins or other nutritional compounds.
  Science of The Total Environment 10/2004; 331(1-3):189-206. · 3.29 Impact Factor
• Article: Polybrominated diphenyl ethers and organochlorine compounds in biota from the marine environment of East Greenland.

  Katrin Vorkamp, Jan H Christensen, Frank Riget
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  ABSTRACT: Ten black guillemot eggs, 19 ringed seals, 20 shorthorn sculpins and 20 Arctic chars were collected around Ittoqqortoormiit (Scoresbysund, Central East Greenland) in summer 2001 and analysed for 11 brominated diphenyl ether congeners (BDEs) and organochlorine compounds. Congeners BDE85 and BDE183 were not detected in any sample. SigmaBDE was highest in black guillemot eggs, with a median value of 80 ng/g lipid weight. This was approximately three times higher than that found for black guillemot eggs from West Greenland, thus supporting the spatial trend observed for organochlorines in Greenland. The median SigmaBDE concentration in ringed seal blubber was 36 ng/g lipid weight. This was clearly higher than SigmaBDE concentrations in ringed seal from the Canadian Arctic, but slightly lower than those found in ringed seals from Svalbard collected in 1981 and approximately 10 times lower than levels in seals from the Baltic Sea. Adult ringed seals had significantly higher SigmaBDE concentrations than animals less than 5 years old. Shorthorn sculpin liver and Arctic char muscle had similar concentrations of SigmaBDE, both with a median value of 7-10 ng/g lipid weight. The levels in shorthorn sculpin were similar to those reported from a previous study in Southwest Greenland. SigmaBDE levels correlated with PCB, DDT and chlordane-concentrations in the same samples, indicating similar mechanisms of uptake, bioaccumulation and biomagnification. The summed chlorobiphenyl concentrations in the same samples exceeded the SigmaBDE concentrations by a factor of approximately 15-30. The BDE congener patterns in black guillemot eggs and ringed seals were investigated using compound ratios and multivariate data analysis. The intraspecies variance was relatively small for black guillemot eggs and larger for ringed seals. Ringed seals had higher relative levels of the lower BDE congeners, e.g. BDE28 and BDE47 than black guillemots. The reasons for these different accumulation patterns are largely unknown and may reflect species-related differences in pollutant exposure, bioavailablity and metabolism.
  Science of The Total Environment 10/2004; 331(1-3):143-55. · 3.29 Impact Factor
• Article: Recent temporal trend monitoring of mercury in Arctic biota--how powerful are the existing data sets?

  Anders Bignert, Frank Riget, Birgit Braune, Peter Outridge, Simon Wilson
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  ABSTRACT: The goal of this paper is to describe and discuss statistical power with respect to mercury in Arctic biota, using data gathered during the past two or three decades, mostly under the auspices of AMAP Phases I and II. It will describe the current levels of power of existing data sets to detect temporal trends of Hg concentrations. If the desired power is fixed to an appropriate magnitude, the minimum size of a detectable trend within a specified time period or the number of years that is required to detect a certain trend could be estimated provided that the random between-year variation for the current time-series is known. These various measures of performance of the AMAP mercury time-series, derived from the power analysis, are discussed in some detail. The number of years required to detect a certain trend at a particular power at a specific Type I error rate (alpha) is compared with the actual number of years available when the AMAP Phase II assessment was carried out. In general the investigated time-series were too short to possess an acceptable statistical power. The effect of varying the Type-I error rate, the slope of a trend and the desired power is investigated to rank the importance of the various components regulating the statistical power. The consequence of sampling less frequently than once a year is considerable loss of power.
  Journal of Environmental Monitoring 05/2004; 6(4):351-5. · 1.99 Impact Factor
• Article: Circumpolar Trends of PCBs and Organochlorine Pesticides in the Arctic Marine Environment Inferred from Levels in Ringed Seals

  Derek Muir, Frank Riget, Marianne Cleemann, Janneche Skaare, Lars Kleivane, Haruhiko Nakata, Rune Dietz, Torbjørn Severinsen, Shinsuke Tanabe
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  ABSTRACT: Geographical trends in levels of ΣPCB10 (sum of 10 major congeners), hexachlorocyclohexanes (HCH), ΣDDT (sum of DDT-related compounds), and other persistent organochlorines (OCs) in ringed seal blubber were examined at 13 sampling locations in the Arctic over 175 deg longitude from northern Canada to the South Kara Sea (Yenisey Gulf) in Russia. Concentrations of OCs were adjusted, using analysis of covariance, for effects of the covariates, sex, age, and blubber thickness. Adjusted mean concentrations of ΣPCB10 and ΣDDT were significantly higher in the samples from the Yenisey Gulf in the Russian Arctic, Svalbard, and East Greenland than in west Greenland or the Canadian Arctic. ΣPCB10 and ΣDDT in Yenisey Gulf samples were 8× and 6× higher, respectively, than the average in levels from four Canadian locations. ΣPCB10 and ΣDDT means declined significantly with increasing westerly longitude (r 2 = 0.75 and 0.73, respectively). ΣHCH levels for sites in the Canadian Arctic were significantly higher than those from west Greenland (Qeqertarsuaq), east Greenland (Ittoqqortoormiit), and Svalbard and increased significantly from east to west. The geographical trend ΣHCH is in general agreement with observed trends of HCH in seawater where higher levels have been found in the Canadian Arctic. Higher proportions of more recalcitrant hexa- and pentachloro-PCB congeners were observed in seal blubber samples in the European/Russian Arctic. The continued use of PCBs in electrical equipment and other applications in Russia is a likely source of the more highly chlorinated congeners.
  05/2000;
• Article: Zinc, cadmium, mercury and selenium in Greenland fish

  Frank Riget, Rune Dietz, Poul Johansen
  Meddelelser om Grønland, Bioscience. 01/1997; 48:29.
• Article: Baseline levels and natural variability of elements in three seaweed species from West Greenland

  Frank Riget, Poul Johansen, Gert Asmund
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  ABSTRACT: Element levels in three seaweed species (Fucus vesiculosus, F. distichus and Ascophyllum nodosum) from different sampling sites in a West Greenland fjord system were determined during a three year period. The elements studied were Cd, Cu, Pb, Zn, Na, Ca, Sc, Cr, Fe, Co, As, Br, Rb, Sr, Cs and Ce. The variability of element concentrations showed a complicated pattern. Differences between both species and localities were found for most elements. Species differences were found to depend on the locality. In most cases where differences between seaweed species were found, concentrations were lower in A. nodosum than in F. vesiculosus which in turn were lower than in F. distichus. At the outer part of the fjord system concentrations of Na, Br and Cd were considerably higher than in the inner part while concentrations of Ca, Fe, Co, Ce, Sr, Sc and Cu were lower. Pb and Zn concentrations show no consistent geographical pattern. The results from a principal component analysis were difficult to interpret. The possible underlying factors controlling the variability of element concentrations are poorly understood. The influence of seawater on the fjord system and variations in run-off from rivers may account for a significant part of the variability seen for many elements. The concentrations of most of the elements, especially the heavy metals, were relatively low compared to other areas in Europe and North America.
  Marine Pollution Bulletin.