Pollutants in Arctic foxes
Last updated 8 December 2022
In Svalbard, the Arctic fox (Vulpes lagopus) is a top predator and carrion eater feeding on the terrestrial and marine food chains. The Arctic fox is exposed to high levels of pollutants. Monitoring of Arctic foxes in Svalbard shows a significant decline in organic pollutants that are regulated internationally, while mercury shows a rising trend.
What is being monitored?
Organic pollutants, perfluorinated compounds and mercury liver in Arctic fox from Svalbard
The figure shows levels of polychlorinated biphenyls (sum of PCB-153, -118, -138 and -180), dichlorodiphenyldichloroethylene (DDE) and oxychlordane measured in the livers of young Arctic foxes from Svalbard in the period 1991 to 2018.
The PCB levels in Arctic foxes from Svalbard were stable and high in the 1990s. Since the end of the 1990s, the values have fallen by an average of 11% per year. As with PCBs, the levels of DDE and oxychlordane have also declined (8-11% per year on average) from the late 1990s.
(Cite these data: Norwegian Polar Institute (2022). Lipid weight of PCB, DDE and oxychlordane in Arctic fox liver. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/influence/pollution/pollutants-arctic-fox.html)
The figure shows levels of hexachlorobenzene (HCB) and β-HCH (beta-hexachlorocyclohexane) and the brominated flame retardant BDE-47 measured in the livers of young Arctic foxes from Svalbard in the period 1997-2018.
HCB levels show an average downward trend of 4% per year, while β-HCH fell 7% per year between 1997 and 2018. The levels of BDE-47 show an average downward trend of 12% per year. As with PCBs, there are also large interannual variations for these pollutants.
(Cite these data: Norwegian Polar Institute (2022). Lipid weight of HCB, β-HCH and PBDE-47 in Arctic fox liver. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/influence/pollution/pollutants-arctic-fox.html)
The figure shows levels of the perfluorinated compounds PFOS (perfluorooctanesulfonate) and sum of long-chain perfluorinated carboxylic acids (PFCA) measured in the livers of young Arctic foxes from Svalbard in the period 1997-2020. The annual decline for PFOS is 9%. PFCA levels shows an annual decline of 2% per year.
(Cite these data: Norwegian Polar Institute (2022). PFOS and PFCA in Arctic fox liver, wet weight. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/influence/pollution/pollutants-arctic-fox.html)
The figure shows levels of mercury measured in the livers of young Arctic foxes from Svalbard in the period 1997 to 2014. Levels of mercury show an average increasing non-significant trend. As with the organic pollutants, mercury also varies from year to year.
(Cite these data: Norwegian Polar Institute (2022). Mercury (Hg) in Arctic fox liver, wet weight. Environmental monitoring of Svalbard and Jan Mayen (MOSJ). URL: http://www.mosj.no/en/influence/pollution/pollutants-arctic-fox.html)
Details on these data
|Last updated||8 December 2022|
|Update interval||At least every second year.|
|Next update||September 2025|
|Commissioning organization||Norwegian Ministry of Climate and Environment|
|Executive organization||Norwegian Polar Institute|
|Contact persons||Heli Routti|
The Norwegian Polar Institute collects samples from Arctic foxes caught in Svalbard between 1 November and 15 March.
Tissue samples are taken from the liver and muscle for analyses of pollutants and trophic location and carbon source (measurement of stable isotopes). For the time series collected after 1997, individual liver samples have been taken from males and females that are 1–2 years old and have the same variation in condition.
For the time series collected before 1997, liver samples of Arctic foxes were taken in the period November to March.
Analyses of pollutants
For analyses of brominated and chlorinated fat-soluble pollutants, fat is extracted from liver tissue in accordance with methods described by Andersen et al. 2015. Pollutants in fat extracts are separated and quantified using gas chromatography, as described by Andersen et al. 2015. Analyses of perfluorinated compounds in liver are described by Aas et al. 2014 and Routti et al. 2017.
For the time series collected before 1997, the methods used are as described in Wang-Andersen et al. 1993.
The laboratories are quality-assured and accredited. The work is carried out in accordance with AMAP’s guidelines for sampling and analysis. Tissue samples are processed by persons with experience from ecotoxicological studies, in part to avoid contaminating the samples. The analysis is quality-assured in accordance with the methods described in the accreditation. Only super-clean equipment is used in the laboratory to avoid contaminating the sample. Blank and standard reference samples are analysed. The laboratory participates regularly in international ring tests.
The Norwegian Polar Institute has all metadata in its possession.
Reference level and action level
Since polychlorinated biphenyls (PCBs), chlorinated pesticides, brominated flame retardants and perfluorinated compounds are anthropogenic pollutants and are not found naturally, the reference value for an unaffected state will be zero. Mercury is a natural element, but more than 90% of the mercury observed in Arctic fauna today is the result of human activity.
Status and trend
Levels of PCBs and chlordanes were higher in Arctic foxes in Svalbard compared to Arctic foxes in Canada and Alaska. In contrast, levels of mercury and hexachlorocyclohexane (HCH) were higher in Arctic foxes in North America and Iceland compared to Svalbard. No geographical trend was found for dichlorodiphenyldichloroethylene (DDE) and hexachlorobenzene (HCB) in Arctic foxes. The geographical trends for organic pollutants in Arctic foxes correspond to the trends found in polar bears and seals.
Levels of PCBs and chlorinated pesticides in Arctic foxes from Svalbard are similar to those found in polar bears, while levels of perfluorinated compounds and mercury are significantly lower.
Levels of polychlorinated biphenyls (PCBs), chlorinated pesticides and polybrominated diphenyl ethers (BDE) in Arctic foxes show an average decline from the late 1990s to 2018. Comparison with previous studies shows that PCB levels measured in the liver of Arctic foxes from Svalbard remained stable and high from 1973–74 until the end of the 1990s.
Levels of perfluorooctaxosulfonate (PFOS) in Arctic foxes also declined from the late 1990s. The decline of the sum of long-chain perfluorinated carboxylic acids (PFCA) in the period 1997-2020 has been somewhat slower than the decline of PFOS.
It is important to note that, although an average, statistically significant, decline in levels of several pollutants in Arctic foxes has been measured from the 1990s until now, the levels vary between years.
It is important to be aware that different analytical methods have been used for the samples analysed before and after 1997, and that there is no information on the age and body condition of Arctic foxes in the earlier studies.
Results of analyses of mercury in Arctic foxes from Svalbard showed an average increasing, but not significant, time trend in the period 1997-2013.
Effect of climate-related change on diet and access to food
In studies published in the period 2015-2019, time trends of pollutants in Arctic foxes from Svalbard have been investigated in relation to climate-related changes in diet and food availability.
The studies showed that the concentration of all pollutants was higher in Arctic foxes with a marine diet, such as seabirds, their eggs and seal carcasses, compared to Arctic foxes with preferentially terrestrial diets such as reindeer carcasses. The studies also showed that increased access to reindeer carcasses, which often occurs in winters with heavy rain on snow, results in lower concentrations of HCB, PFCA and mercury in Arctic foxes. Furthermore, it was found that the concentration of β-HCH, PFOS and mercury in Arctic foxes from Svalbard increased with increasing sea ice cover in the fjords, which resulted in increased access to marine prey.
When changes in eating habits and food availability between years were included in the statistical analyses of time trends in Arctic foxes, the models showed that changes in eating habits and food availability had from moderate to no effect in the measured trends. This means that time trends in pollutant levels in Arctic foxes are mainly related to emission patterns and levels in the environment in general, and variation in diet is less important in time trends of pollutants. However, the mercury levels adjusted for eating habits and food availability rose faster (7% per year) than the measured levels (3.5% per year).
The main reason for the decline in levels of most of the so-called legacy organic pollutants in Arctic foxes is that their manufacture and use are regulated nationally and internationally.
Efforts to regulate PCBs and chlorinated herbicides began at the end of the 1970s and the international ban on the substances under the Stockholm Convention came into force in 2004. The main sources of releases of these substances have therefore stopped.
The reason they are still found in the environment is because they are stable, and can recirculate and be concentrated up the food chain.
The manufacture and use of newer pollutants such as BDE-47 and PFOS have been restricted in the last 15 years. Tetra-BDE, penta-BDE, hexa-BDE, hepta-BDE and PFOS were included in the Stockholm Convention in 2009, while deca-BDE was included in 2017. It has been proposed to include long-chain perfluorinated carboxylic acids in the Stockholm Convention and production has declined in many countries, but many PFCA precursors are not currently regulated.
Global mercury emissions have been stable over the past 30 years. In 2017, the global Minamata Convention on Mercury, designed to reduce mercury emissions, was signed.
Temporal trends of pollutants in apex predators are not only influenced by discharge patterns and regulations, but also by variations in the presence of various prey, which, in turn, are influenced by rapid changes in the climate in the Arctic. As recently shown above, climate-related changes in Arctic foxes’ diet and access to prey may affect pollutant levels in Arctic foxes from Svalbard to some extent.
In addition, changes in physical factors, such as increased precipitation and reduced sea ice cover, can lead to increased deposition of specific pollutants from air to soil and sea, and increased evaporation from sea to air. Melting sea ice will contain pollutants that can be absorbed into the food chain.
PCBs and chlorinated herbicides (particularly oxychlordane) make up the greater part of the pollutant burden in Arctic foxes. The levels in Arctic foxes are still high, and comparable with those in polar bears. In common with many other arctic animals, Arctic foxes have seasonal variations in their body condition. As summer approaches, they burn the body fat they have in winter as a natural adaptation from winter to summer conditions, and may repeatedly through the winter also lose body weight when they find insufficient food and must fall back on their fat reserves.
Periods of hunger and consumption of body fat are natural for the Arctic fox, but the process may be critical because pollutants stored in fatty tissue are released into the blood stream when the fat is consumed. The pollutants will then be available to be taken up in vital organs like the liver and brain.
The Arctic fox also has high levels of PCB metabolites. This is because the Arctic fox is very efficient at converting PCBs to more water-soluble variants. The purpose of such conversion processes is to convert contaminants into other compounds that are more easily dissolved in water, and can hence be excreted from the body. But, in the process, metabolites of PCBs are also produced, which remain in the body, and these compounds are actually more toxic than the original ones.
Very little is known about the effects the high levels of pollutants might have on, for example, a nursing fox and her cubs, or a fox that fails to find food and must fall back on its fat reserves in winter. The effects of pollutants on Arctic foxes have been experimentally studied in studies feeding whale blubber to farmed foxes and sled dogs in Greenland. In the exposed foxes and dogs, pollutant burdens correspond to comparable or lower levels than we see in Arctic foxes from Svalbard today. These studies found changes in levels of testosterone, vitamin A, vitamin E and thyroid hormone, and in kidney tissue, thyroid tissue and liver weight in the exposed animals compared to the control group. At the same time, no significant differences in liver tissue, bone mineral density and sperm quality were observed. It is therefore likely that the pollutant levels have negative effects on the health of Arctic foxes.
Comparing levels of mercury in Arctic foxes to threshold limits for effects in mink indicates that the health of Arctic foxes from Svalbard is not affected by mercury.
About the monitoring
The Arctic fox is uppermost in the food chain in Svalbard, both on land and in the marine ecosystem, thus putting it at risk of taking up pollutants. High levels of POPs have been found in several sets of samples, initially from 1973–74, most recently in 2012–13. In particular, high levels of oxychlordane and highly chlorinated PCBs, including PCB-153 and PCB-180, were found.
Mapping of pollutants in Arctic foxes in Alaska, Canada and Norway has shown that Arctic foxes from Svalbard have the highest levels of pollutants. Negative effects of exposure to pollutants have been demonstrated in controlled studies on farmed foxes, where the foxes were exposed to similar pollutant burdens, or lower levels, than we see in Arctic foxes in Svalbard today. This is worrying for the Arctic fox population in Svalbard, and further monitoring is therefore necessary.
The overall pollutant burden on Arctic foxes may also be affected by climate change, which further reinforces the importance of monitoring levels of pollutants in Arctic foxes.
Places and areas
Relations to other monitoring
International environmental agreements
Voluntary international cooperation
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