Medium-weight components are characterised by (Michel, 1992):
Hydrocarbon compounds containing between 10 and 22 carbon atoms.
A boiling range from 150 to 400°C.
Evaporation rates of up to several days, although there will be some residue which does not evaporate at ambient temperatures.
Low water-soluble fraction.
Moderate acute toxicity because they contain diaromatic hydrocarbons (naphthalenes) which are toxic in spite of their low solubilities.
Moderate potential for bioaccumulation and chronic toxicities associated with the diaromatic hydrocarbons.
Alkanes which are easily degraded.
Medium-weight components pose the greatest environmental risks to organisms because they are more persistent in the environment, are biologically available and the PAHs have high toxicities.
