In extreme cases, rivers, lakes and wells have been known to ignite. For example, in 1969, the Cuyahoga River in Cleveland, Ohio ignited. Runoff from land, municipal, and industrial wastes. Spills and operational discharge from land drilling leak and flow to the sea. There are many forms of natural 'Oil Pollution', once such for is when eroding rocks release oil into the sea.
Toxic waste is the most harmful form of pollution to marine creatures and humans alike.
Toxic wastes arrive from the leakage of landfills, dumps, mines and farms. Sewage and industrial wastes introduce chemical pollutants such as PCB, DDT, and Sevin. Radioactive wastes, reactor leaks, natural radioactivity, and radioactive particles which originate from the Atmospheric Testing Program from explosions of nuclear weapons are dispersed in water all over the world. The effect of these radioactive particles is currently being researched. All of these factors allow seafood to have a chance of being hazardous to human health.