Polychlorinated biphenyls are Germany H. Schmidt and G. Schultz in 1881 was the first synthesis. United States in 1929, the first production, the mid-60, polychlorinated biphenyl production reached a peak in the world, an annual output of about 100,000 tons. It is estimated that world PCB production and application of well over 1 million tons, which has 1/4 to 1/3 into the human environment, hazards.
Polychlorinated biphenyl is insoluble in water but soluble in fats and organic solvents, and extremely difficult to break down, allowing rich sets in the fat of organisms. 1968 Japan was famous due to PCB contaminated rice bran oil-pollution disease: "oil". After 1973 all started to reduce or cease production. Basic structure of the PCB for: 10 hydrogen atoms on the biphenyl ring, according to the different number of hydrogen atoms are replaced by chlorine atoms, forming a chloride, dichloride ... ... Ten chloride, each of them has several isomers. Chlorides in theory there are 3 isomers, dichloride has 12, c chloride 21. All PCB isomer total of 210 species, 102 species that have been determined.