Biological Products+ 11
Tissue Extracts+ 6
Venoms+ 6
Waste Products+ 6
Radioactive Pollutants+ 5
Colloids+ 4
Particulate Matter+ 4
Fossil Fuels+ 3
Tars+ 2
Soil+ 1
Acid RainAmbergrisBiofuelsFreund's AdjuvantLigninManurePhytochemicalsVehicle Emissions