Humic Acid in the water supply of South-Western Taiwan has raised the question of whether or not it is the cause of a disease known as Blackfoot disease. This disease only occurs in this location. Some studies have named Humic Acid as a causative agent in this disease.

Data available from scientific literature suggest that Blackfoot disease is at least a multifactoral illness, because the waters in that area clearly have extremely high arsenic content and this is much more common in this area than elsewhere: thus this disorder is strongly linked to arsenism.

The laboratory tests that "confirmed" Humic Acid as a cause of Blackfoot disease used extremely high doses of Humic Acid. The amounts used were far greater than the level of Humic Acid that would be found in a person's blood, even if they were using a Humic Acid product on a daily basis.

The various qualities of humic acids, and their differences in terms of age, method and place of origin, and structure, must also be taken into account. The Humic Acids from the area where the Blackfoot disease is endemic are unique when compared to Humic Acids isolated from other areas.

Humic Acid preparations are widely used in many other countries, but the Blackfoot disease occurs only in this specific part of Taiwan, where there is an overload of arsenic. Humic acids of different origins produced strongly differing results in identical biological test models.

The disease has been known as Blackfoot Disease since 1958 and had been thought to be caused by arsenism up to that time. More recent data indicate that the incidence of the disease increased in this specific area after the replacement of artesian water supply with piped water system: a fact that points against humic acid exposure being the causative factor.

The author sees no evidence from the studies done that Humic Acid is the cause of Blackfoot disease. The author states that Humic Acid can be used safely.