Is hexachlorobenzene human overload related to porphyria cutanea tarda? A speculative hypothesis

After the epidemic outbreak of Porphyria Turcica from 1955 to 1961, the porphyrinogenic effect of hexachlorobenzene (HCB) on humans and animals has been fully confirmed. HCB is an environmental contaminant originated from its use as fungicide or obtained as a by product from industrial residues. Measurement of HCB levels in adipose tissue and maternal milk is a useful tool for monitoring its body stores which are clearly higher in Spain than in other European or American countries. At least in the Spanish area of Catalunya, the HCB fat tissue concentration decreased from more than 5 ppm in 1981-1982 to less than 3 ppm in 1986-1987. Porphyria cutanea tarda is a relatively frequent disease in Spain. More than 700 cases were observed in Madrid from 1964 to 1988. Before 1970, less than 10 cases were annually detected, a figure that rose up to 60-70 annual cases from 1977 to 1982 and decreased to less than 25 annual cases from 1985 to 1988. Based on all these previous data, a speculation is tempting: the high and variable incidence of porphyria cutanea tarda in Spain may be related to environmental contamination with HCB.