Creosote is a mix of several oils extracted from tar or wood.
It has long been used as a pesticide to treat wood but is now banned. However, it is found in abandoned railway lines.
It also accumulates in chimneys and can cause chimney fires (within the flue).
It is mainly composed of polycyclic aromatic hydrocarbons.
It is highly toxic and carcinogenic and can cause scrotal cancer in people who are frequently exposed to it (chimney sweeps, etc.).
Creosote is toxic and carcinogenic. DR Credits