The baleen whales (sifters) may be most at risk as they indiscriminately take in huge quantities of water, and filter it as they push the water out through the sieve (baleen), leaving the food and such in their mouths. They have relatively small esophagi for such large animals, so stuff could get stuck there or further down their gut. The toothed whales tend to have larger esophagi since they swallow their prey whole and swallowing an entire seal or giant squid takes some space.
Plastic and garbage islands all over the world. I'm a bit of a tree hugger when it comes to what we are doing to the earth.