translate English to French: Assuming an average contamination level of between 100 ppm and 200 ppm, the total quantity of PCBs destroyed would have been in the order of 3.5 to 7 tonnes.
En supposant que le niveau moyen de contamination se situe entre 100 ppm et 200 ppm, la quantité totale de BPC détruits serait de 3,5 à 7 tonnes.