Studies on the concentration of arsenic, selenium, copper, zinc and iron in the blood of blackfoot disease patients in different clinical stages.

Flame atomic absorption spectrophotometric methods were developed for the determination of zinc, copper, arsenic, iron and selenium in blood samples. Data from blackfoot disease patients in five clinical stages were compared with those from healthy controls. Copper concentrations were the same for all clinical stages. Arsenic increased in the initial three stages but decreased thereafter, although arsenic was previously considered to be the major causative agent of the disease. The decrease of arsenic in the later stages was attributed to the antagonistic effect of selenium, and the decrease of iron during the progress of the disease is thought to be due to the antagonistic effect of arsenic in the initial stages and the loose of haemoglobin in the later stages.