"Fractions" is used in engineering and medicine, particularly fields that deal with chemistry, to refer to parts of a total quantity that share attributes. In blood, for instance, the three primary factions are plasma, white blood cells and red blood cells. (Wiki: Blood Fractionation)
Wikipedia defines the related term, Fractional Distillation as separation of a mixture into its component parts, or fractions.
In the petroleum industry, the fractions would be various grades of oils, gasoline, kerosene, asphalt, paraffin, etc.
In liquor distilling, the fractions are the (most drinkable) center cut, the verging-on-poisonous heads and the oily, rancid tails.
I read the sentence as Are you aware that some definable sub-portion of e-waste is hazardous and needs a special treatment in order to be safely disposed of?