The PCBs or polychlorinated biphenyls are a family of 209 organochloride compounds, with a strong aromatic odour. They are very stable compounds which only decompose at temperatures higher than 1000°C. The PCBs are pollutants which can be persistent (a lifespan of between 94 days and 2,700 years, depending on the molecule) and which is capable of bioaccumulating in the fat of animals and notably humans, including in a mother’s breast milk. Widely used in the old days – mostly in electric material -  PCBs were banned from most countries at the beginning of the 70s. As the PCBs are stabile, we can still find some trace in the environment nowadays.