A Dutch company specializing in water treatment and air purification systems has a page on its website devoted to the 10 worst environmental disasters. There are actually two lists: one for natural disasters and one for anthropogenic disasters. The criteria used to determine each disaster's rank included total death toll, the number of injuries, lasting damage and media exposure.
The list of natural disasters comprises earthquakes, epidemics, floods, tornadoes and, it would seem, the rest of the 10 plagues of Egypt. The histories are both tragic and fascinating.
The list of anthropogenic disasters -- that is, the disasters that have come about as a result of human activity -- is both tragic and appalling. Bhopal is first, Chernobyl second. Scan down to the sixth entry, and you see Love Canal.