From a survey of Spanish villagers aged 15 or older who lived near an organochlorine chemical plant from which relatively high air levels of hexachlorobenzene emanated, Herrero et al1 have concluded that such exposures were insufficient to trigger significant alterations of porphyrin metabolism. That conclusion was not really justified, being based on only urine porphyrin measurements. Fecal porphyrin measurements are crucial for adequate screening for porphyrinopathy.2,3 Failure to screen with fecal porphyrin measurements will miss about half the cases of porphyria cutanea tarda (PCT). Normal urine porphyrins are no guarantee that abnormal fecal porphyrins will not be found. The same limited urinary porphyrin test was done for most if not all cases tested in the 1955-1959 Turkish porphyria epidemic,4 but that investigation did not attempt to identify safe limits of exposure, as did this one. The Spanish study significantly underestimated the effects of exposure by failure of adequate screening, so that exposure tolerance was overestimated.
Morton WE. Fecal Porphyrin Measurements Are Crucial for Adequate Screening for Porphyrinopathy. Arch Dermatol. 2000;136(4):554. doi: