Concentration of arsenic, selenium, zinc, iron and copper in the urine of blackfoot disease patients at different clinical stages.

Atomic absorption spectrophotometric methods were developed for the determination of arsenic, selenium, iron, zinc, and copper in the urine samples. Data collected from blackfoot disease patients at five clinical stages were compared with those from healthy controls. Spectrophotometry was also used to compare the concentrations and detection levels of these elements in blood and hair samples. The copper concentration in urine changed slightly for all clinical stages, whereas the concentrations in blood and hair showed less correlation with the stages of blackfoot disease. The zinc concentration in urine increased with the clinical stage, the fourth stage having the highest concentration. The zinc concentrations in urine were not correlated with those of blood and hair samples. Zinc appears to be associated with the occurrence of scaling and cracking of the skin of the fingers or feet, and is even closely correlated with the degree of ulceration and gangrene of blackfoot disease patients. The more advanced degrees of blackfoot disease patients were associated with a greater zinc concentration in the urine. Arsenic, which is claimed to be a major causative agent of blackfoot disease, increased from the zero stage and showed a particularly high concentration in the second stage. The arsenic concentration in urine showed a positive correlation with that in the blood and the hair. Arsenic is indicated as major causative agent of blackfoot disease. The selenium concentration decreased from the zero stage, showing its lowest value during the second stage, then increased in the later stages. Changes in the selenium concentration in the urine were the inverse of those observed for the arsenic concentration in blood and hair. The decrease of selenium is attributed to the antagonistic effect of arsenic; selenium is retained during the initial stages. Iron increased from the zero stage to the second stage and showed the highest concentration of all the measured elements. It then decreased in the advanced stages of the disease. Iron may have an interactive effect with arsenic in the initial stages, resulting in loss of haemoglobin during the advanced stages. The antagonistic effect of selenium and the interactive effect of iron on arsenic warrant further study.