They have been documented to interact with over 50 elements from the periodic table including nutrients, toxic metals, radionuclides (including the transuranium series) and the halogens. The latter can interact with humic substances in drinking water treatment to produce halogenated carcinogens (such as chloroform and bromoform) which are then directly introduced into the public drinking water with negative health consequences. The effect on toxic metals and micronutrients is unpredictable and often paradoxical - at times making them more available to organisms while at others acting as a sequestering agent so as to reduce their toxicity or beneficial value.
These compounds are most commonly used in fertilizers and soil conditioners. And they can interfere with industrial processes such as Aluminum processing. Their role in environmental and health issues (humic substances are used in the treatment of many animal maladies) is being explored.
Although they have been touted as a health supplement, their use at this time should be considered risky. Humic acid is considered the culprit in the mutagenic toxicity of chlorinated water supplies on bacterial assays. And the following abstract would indicate a direct toxic effect of humic acid on the cell DNA.
F. Bernacchi, et al. Universita di Pisa, Via S Giuseppe 22, 56100 Pisa, Italy :
As humic compounds are naturally widespread in the environment and present in surface water, studies on their genotoxicity are justified. Humic acid (HA) has not been demonstrated to be genotoxic either in vitro or in vivo. In the present paper we investigated its activity both in intestinal and bone marrow cells following a single dose (100 mg/kg b.w. corresponding to 0.5 ml per animal of an aqueous solution of 4 g/l) of HA administered to mice by gastric intubation, to mimic the most likely route of human exposure. HA induced structural and, in particular, numerical chromosome abnormalities in intestinal cells. A marginal, non-significant induction of aneuploidy was also found in bone marrow cells.