I won't pass judgement on whether 410 micrograms/kg is an "unbelievable" amount, but I will just mention that it is 410 parts per billion, or less than 1 ppm.
The last cited article reports however that as much as 1,925 ppb have been found in some specific canned olives.
https://www.fda.gov/food/foodborneillnesscontaminants/chemic...
This whole data set is oddly fascinating.