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Lead is a toxic heavy metal, and there is no level of exposure that is known to be without harmful effects.
Lead has been removed from products such as petrol and paint, and the levels of lead in humans and the environment have generally dropped drastically over the past 40 years.
– The lead levels in the blood of Scandinavian brown bears, however, have not followed this trend, Boris Fuchs writes to inn.no.
Fuchs has been part of a large research project that has taken and analysed blood samples from a record number of bears during the period from 2010 to 2020.
The researchers have taken blood samples from both male and female bears, and not least their cubs. The average level of lead in the blood of the bears studied was 97 micrograms per litre.
To put these figures in context, the negative consequences of having lead in the body begin at 12 micrograms per litre of blood in humans.
- Read more about this project in this article on forskning.no: Alle bjørnene var fulle av bly
Boris Fuchs has also investigated where the lead in the bears' blood comes from. There are primarily two sources.
Emissions of lead from earlier times, including from lead-containing petrol, are transported through the air and spread into the environment through rain. The second main source is lead-containing ammunition used in hunting.
– After many hundreds of years of using lead, there is a lot of it in the landscape, including in blueberries or other foods that bears eat, says Fuchs.
In his PhD dissertation, the lead levels in the blood of bears and other wildlife, as well as the lead levels in the bears' food, were used to map out lead exposure and lead sources.
Boris completed his PhD in the Applied Ecology and Biotechnology doctoral programme. His dissertation is titled 'Lead exposure in Scandinavian brown bears (Ursus arctos)'.
The PhD project is funded by the Norwegian Environment Agency, Inland Norway University of Applied Sciences, the Scandinavian Bear Project, the Norwegian Institute for Nature Research (NINA), and the Swedish Environmental Protection Agency.
Her finner du mer informasjon om disputasen til Boris Fuchs 5. juni 2024.
Here you can find more information about Boris Fuchs' defence on June 5, 2024.
Main findings in the doctoral work:
- Scandinavian brown bears are highly exposed to lead.
- In lactating female bears, milk lead levels were positively correlated with blood lead levels.
- Blood lead levels of suckling cubs were positively correlated with their mothers blood lead levels and dependent cubs are exposed to lead in milk from birth to weaning.
- Environmental lead, mainly from ant nest material, and lead from spent hunting ammunition in gut piles or carcasses are the most likely sources of lead exposure.
Contact information:
- boris.fuchs@inn.no
- Phone
- +47 62 43 08 16