Blood lipid concentrations of dioxins and dibenzofurans causing chloracne.

Chloracne is caused by exposure to certain halogenated polycyclic hydrocarbons such as polychlorinated dibenzodioxins (PCDDs) and dibenzofurans (PCDFs). In chronic exposure it is not known what level of intoxication, represented by the level in blood lipids, is sufficient to cause chloracne. Blood levels of the congeners of PCDD/Fs were determined in four groups of humans. One group had clinically visible chloracne due to exposure in a hexachlorobenzene workshop of a large chemical factory. A second group was exposed in the same workshop, but had no skin changes. There were two control groups: one non-exposed group of maintenance workers from the same chemical factory, and one group of healthy individuals living elsewhere. Blood levels were converted to toxicity equivalents of tetrachlorodibenzo-p-dioxin (TCDD). In the chloracne group blood levels in toxicity equivalents (TEQs) ranged from 1168 to 22,308 pg/g blood lipid. In the exposed without chloracne this ranged from 424 to 662 pg/g. It is concluded that the level to develop chloracne is between 650 and 1200 pg/g TEQ. The contribution of TCDD was rather small, and the main causative congeners were the hexachlorinated dibenzodioxins and dibenzofurans (HxCDD/Fs); lipid-based blood levels in absolute amounts that may cause chloracne are in the range of 2-3.5 ng/g HxCDD, and 2-5 ng/g HxCDF.