The researchers examined eggs from among other bird species Osprey.
For almost ten years there has högflourerande toxic substance PFOS has been banned in the EU, but the levels of the substance in rovfågelägg has not fallen.
40 percent of the eggs they collected contained levels of PFOS above the level of previous confirmation is harmful to other species.
The researchers are not surprised by the results.
They do not break down, says Ylva Lind, curator at the Museum of Natural History, to Vetenskapsradion.
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