The effect of fluorescent humic substances existing in the well water of Blackfoot disease endemic areas in Taiwan on prothrombin time and activated partial thromboplastin time in vitro.

Fluorescent humic substances (FHS) in well water of Blackfoot disease endemic areas were purified and fractionated by Sephadex G-25 column chromatography. Four fractions of the purified FHS were isolated. The purified FHS and their fractions were then added to normal human pool plasma in vitro separately to detect the abilities of the effects on prothrombin time (PT) and activated thromboplastin time (APTT). Results showed that all of the four fractions of the purified FHS prolonged both PT and APTT in the higher concentration ranges (10 mg/ml - 20 mg/ml), but shortened both PT and APTT in the lower concentration ranges (0.5 mg/ml - 5 mg/ml). Among the four fractions of the FHS, the fraction 1, the humic substance with the highest molecular weight among all the four FHS, showed the most obvious effects. Owing to the effects of the FHS on PT and APTT values, we supposed that there is a close relationship between the FHS and the cause of Blackfoot disease.