<unk> s <unk> s) are a class of organic compounds with 1 to 10 chlorine atoms attached to<unk>  and a general chemical formula of C12H10-xClx. Most<unk> s were manufactured as cooling and insulating fluids for industrial transformers and capacitors, and also as stabilizing additives in flexible PVC coatings of electrical wiring and electronic components.<unk>  production was banned in the 1970s due to the high toxicity of most<unk>  congeners and mixtures.<unk> s are classified as persistent organic pollutants.
Polychlorinated biphenyl
Nitrobenzene
Vinyl chloride
Coal tar
Benzene
Toluene
Xylene
Methanol