The main categories of organic pollutants are (a) Polycyclic aromatic hydrocarbons (PAHs) arise from incomplete combustion or pyrolysis of organic substances such as wood, carbon or mineral oil. Such combustion processes include food preparation in households and food shops; etc. and (b) Polychlorinated Biphenyls further subdivided in to two category for its sources as Directly manufactured PCBs used as hydraulic liquids(hydraulic oils), emollients for synthetic materials, lubricants, impregnating agents for wood and paper, flame protective substances, carrier substances for insecticides and in transformers and condensers, and The other main source of PCBs in the environment are combustion processes, from waste incineration plants, fossil fuel burning and to other incomplete combustion processes. A journal is a periodical publication intended to further progress of science, usually by reporting new research. Most journals are highly specialized, although some of the oldest journals publish articles, reviews, editorials, short communications, letters, and scientific papers across a wide range of scientific fields. Journals contain articles that peer reviewed, in an attempt to ensure that articles meet the journal's standards of quality, and scientific validity. Each such journal article becomes part of the permanent scientific record.