This observation comes as no big surprise (although linking it to increased cancer rates may be a bit of a stretch at this stage).
Many hazardous chemicals attach to small particles which trek through the air and later deposit virtually anywhere, including glaciers. When the glaciers melt, the compounds bound within can travel with the ice melt.
However, it is not a stretch to link flooding of hazardous waste storage sites to potential increases in cancer rates. Apparently a number of these sites were basically washed away by the recent flooding in Pakistan. That’s why it’s best to keep hazardous waste storage sites on high ground.