In southeastern Turkey, between 1956 and 1961, there were reports of an epidemic of PCT. Apparently; in 1954 the Turkish government distributed a supply of wheat seed that had been treated with fungicides containing 10% hexachlorobenzene (HCB). The wheat was originally intended for planting, but the shipment arrived too late in the season. Because there was a limited food supply in the Turkish provinces of Dijarbakir, Mardin, and Urfa, the seed was diverted for food production. It was difficult to quantify the extent and duration of HCB exposure from existing surveys, because the HCB-treated seed appeared no different from untreated supplies.
As many as 5000 individuals were reported to have been affected by the HCB treated seeds. They exhibited PCT-like syndromes as early as 1956. The government discontinued using the HCB-containing fungicide in 1959, but it was not until around 1961 that the PCT outbreak waned. Researchers from clinics near the area began to trace the dietary histories of the affected individuals and discovered the HCB appeared to be the cause of the acquired form of PCT.
Prior to this time, acquired Porphyria associated with exposure to environmental toxins was observed in experimental animal models but only rarely in humans. Shortly after the reports from Turkey were published, the association between the chronic administrations of HCB to induce excessive porphyrin accumulation was confirmed in animal models as well.
Although quantitative reports of HCB exposure from Turkey are incomplete, some accounts estimate that the amount of HCB ingested by the affected individuals ranged from 0.05 to 0.2 g/d over an unknown, but "relatively long period," before changes in their skin became evident. Long-term follow-up studies by Drs. Cripp and Peters and their colleagues at the University of Wisconsin indicated that the average lag time between HCB ingestion and clinical manifestation of this disease was about six months. Furthermore, their study indicated that the levels of excreted porphyrins did not correlate with the individual’s age at exposure, sex, serum HCB levels, or severity of initial symptoms.
As many as 5000 individuals were reported to have been affected by the HCB treated seeds. They exhibited PCT-like syndromes as early as 1956. The government discontinued using the HCB-containing fungicide in 1959, but it was not until around 1961 that the PCT outbreak waned. Researchers from clinics near the area began to trace the dietary histories of the affected individuals and discovered the HCB appeared to be the cause of the acquired form of PCT.
Prior to this time, acquired Porphyria associated with exposure to environmental toxins was observed in experimental animal models but only rarely in humans. Shortly after the reports from Turkey were published, the association between the chronic administrations of HCB to induce excessive porphyrin accumulation was confirmed in animal models as well.
Although quantitative reports of HCB exposure from Turkey are incomplete, some accounts estimate that the amount of HCB ingested by the affected individuals ranged from 0.05 to 0.2 g/d over an unknown, but "relatively long period," before changes in their skin became evident. Long-term follow-up studies by Drs. Cripp and Peters and their colleagues at the University of Wisconsin indicated that the average lag time between HCB ingestion and clinical manifestation of this disease was about six months. Furthermore, their study indicated that the levels of excreted porphyrins did not correlate with the individual’s age at exposure, sex, serum HCB levels, or severity of initial symptoms.