I read that estuarine beluga in Canada had been found to be so noxious that their carcasses were classified as toxic waste for disposal. Tissue sampling of sperm whales around the world revealed quantities of cadmium that would kill living cells in a lab. (Cadmium, a compound found in paint and industrial manufacturing, and a by-product of burning fossil fuels, causes metal fume fever, fluid in the lungs, kidney disease and cancer in humans.) The most polluted animals on the face of the earth were thought to be American killer whales in Puget Sound, a place where the starfish had been observed actually melting. The data supported a highly improbable hypothesis, even given the levels of contaminants in the area: that the whales had been chewing batteries or drinking flame retardant to supplement their marine dinners.
Additional note, 14 Jan 2016: UK's last resident killer whales 'doomed to extinction'