Chloracne is an acne-like eruption of blackheads, cysts and pustules, which is caused by over-exposure to certain halogenated aromatic compounds, such as chlorinated dioxins (byproducts of many chemical possesses including the manufacture of herbicides such as Agent Orange) and dibenzofurans. The condition was first described in 1987 by Von Bettman and was believed to be caused by exposure to toxic chlorine concentrations, hence the name chloracne. Now, the substances that may cause chloracne are collectively known as chloracnegens and work as biomarkers for dioxins exposure. Chloracne normally results from direct skin contact with chloracnegens, although ingestion and inhalation are also possible causative routes. Chloracne is a chronic inflammatory condition that results from this persistence, in combination with the toxin's chemical properties. It is believed, at least from rodent models, that the toxin activates a series of receptors promoting macrophage proliferation, inducing neutrophilia and leading to a generalised inflammatory response in the skin. This process may also be augmented by induction of excess tumor necrosis factor in the blood serum. The inflammatory processes lead to the formation of keratinous plugs in skin pores, forming yellowish cysts and dark pustules. In some instances, chloracne may not appear for three to four weeks after toxic exposure; however in other cases, particularly in events of massive exposure, the symptoms may appear within days. The lesions are most frequently found on the cheeks, behind the ears, in the armpits and groin region. In advanced cases, the lesions appear also on the arms, thighs, legs, hands and feet. The skin lesions occur mainly in the face, but in more severe cases they involve the shoulders and chest, the back, and the abdomen. The severity and onset of chloracne may follow a typical asymptotic dose-response relationship curve. The associated pus is usually greenish in color. Once chloracne has been identified, the primary action is to remove the patient and all other individuals from the source of contamination. Occupational disease due to chemical exposure is a notifiable condition and the contact with the national Occupational Safety and Health Service of the Department of Labour is necessary. Further treatment is symptomatic. Severe or persistent lesions may be treated with oral antibiotics or isotretinoin. Recent research indicated that PCB poisoning, including chloracne symptoms, can be treated with fat substitute olestra. Most chloracne lesions clear up within two years providing exposure to the chemical has stopped. In some cases they persist much longer because the chemical continues to be slowly released from fat cells. However, chloracne may be highly resistant to any treatment. The course of the disease is highly variable. In some cases the lesions may resolve within two years or so, however, in other cases the lesions may be effectively permanent. Chloracne gradually leads to the degeneration of Sebaceous glands and to the hyperkeratosis of follicles, hyperpigmentation, hypopigmentation, onycholysis, porfyria cutanea tarda, hypertrichosis.