Tissue distribution of absorbed humic acids

Distribution of humic acids (HA) in rats was studied using radioiodinated HA injected intraperitoneally. Distribution of 125I was also studied for comparison. The distribution pattern of HA differed greatly from that of 125I. Except in the thyroid and skin, 125I was excreted from the body within 24 hours, whereas a large proportion of HA remained in the liver, kidney, skin, thyroid, bone and muscle. The difference in the distribution pattern and organ/serum radioactivity ratio suggests different kinetics for 125I and 125I-HA. The distribution pattern of HA correlated very well with the increased prevalences of organ diseases in the blackfoot disease endemic area, as reflected in epidemiologic studies. It is hypothesised that HA-metal complexes are possible etiological factors of diseases such as goitre, hepatoma, bladder cancer, vascular disease and diabetes mellitus, and that free radicals are the common causative factor. ? 1995 Chapman & Hall.