The Influence of Humic Substances on the Absorption and Distribution of Cadmium in Mice

Abstract

Abstract; The complex binding of cadmium ions to humic and fulvic acids in water may influence the absorption and distribution of drinking-water Cd in humans. Thus, in the present study mice were given a single oral dose of Cd ('O9CdCI2, 25 pgil) in 100 p1 Millipore@ water containing different concentrations of humic compounds (0, I , 10 and 100 mg dissolved organic carbod). The complex binding of Cd was studied by dialysis. At neutral pH, 1 mg dissolved organic carbonil caused complex binding of more than 50%) of the Cd. whereas more than 90% of Cd was bound at 10 and 100 mg dissolved organic carbonil. At pH 3 the complex binding of Cd decreased somewhat, but over 90% of the Cd was bound at 100 mg dissolved organic carbonil. Complex binding of Cd increased the lipid solubility of Cd, expressed as an octanoli water partition coefficient, Nevertheless, more than 99% of the bound Cd was present as hydrophilic binding forms. Irrespective of the bound of Cd. the intestinal uptake and intracellular distribution (gel filtration on Sephadex G-75 column) were not affected by the humic substances 6 hr after dosage. Moreover, complex binding did not influence the intestinal absorption of Cd 24 hr after exposure. The median Cd retention in the kidneys of the 100 mg dissolved organic carbonil group was 23%) and 46% lower than that of the control group 6 and 24 hr after administration, respectively, indicating alterations in the distribution of Cd after absorption. Thus humic substances may affect the metabolism of toxic heavy metals, such as Cd, in vivo in mice, indicating that the presence of humic and fulvic acids in drinking water should be considered in future risk assessments of metals in drinking water.Humic materials in drinking water are mainly composed of humic and fulvic acids (Driscoll & Letterman 1988; Reiber et a/. 1995). Although the composition of humic material differs considerably depending on sources, mixtures of humic macromolecules are similar in properties and structure. They contain carboxylic acid groups, phenolic and alcoholic hydroxyls, ketone and quinone groups, and a skeleton of aromatic rings (Livens 1991). The division of humic compounds into humic and fulvic acids depends on the acid solubility of the compounds, i.e. fulvic acids are acid-soluble and humic acids precipitate after acid treatment of the water (Saar & Weber 1982). Thus, the pH of the water determines the composition of the humic material, with both humic and fulvic acids present at neutral pH and the contribution of fulvic acids to the humic mixture increasing with decreasing pH.In a previous study we found that humic substances extracted from peat reduced the intestinal absorption of Cd in situ in rats cance for the intestinal absorption of heavy metals present in drinking water. No study has, however, determined if humic substances affect the intestinal absorption of toxic metals, such as Cd, in vivo in animals.The purpose of our study was to determine whether the absorption and organ distribution of drinking water Cd in vivo i...

Model trial investigating retention in selected tissues using broiler chicken fed cadmium and humic acid

“…Various studies deal with the binding of dangerous metals by humic acids (Stevenson, 1977;Kerdorff and Schnitzer, 1980;Klocking, 1980Klocking, , 1994Lind and Glynn, 1999;Alvarez-Puebla et al, 2006;Hizal and Apak, 2006). The changes in the toxicological qualities of metal ions bound to humic acids are particularly important.…”

“…They exert their protective effects on the intestinal mucosa, possessing anti-inflammatory, adsorptive, anti-toxic and antibacterial characteristics (Klocking et al, 1992). The ability for humic acids to bond with metals motivated various authors to study their possible use for excluding undesirable metals from the gastrointestinal tracts of animals, or a decrease in their availability (Beveridge and Pickering, 1980;Marinski et al, 1982;Livens, 1991;Herzig et al, 1994;Glynn, 1995;Hudak et al, 1997;Lind and Glynn, 1999). Ridwan (1977) and Rochus (1983) observed that low concentrations of humic acids (0.1%) in feed were sufficient for a significant decrease of lead and cadmium uptake by rats.…”

Model trial investigating retention in selected tissues using broiler chicken fed cadmium and humic acid

“…Various studies deal with the binding of dangerous metals by humic acids (Stevenson, 1977;Kerdorff and Schnitzer, 1980;Klocking, 1980Klocking, , 1994Lind and Glynn, 1999;Alvarez-Puebla et al, 2006;Hizal and Apak, 2006). The changes in the toxicological qualities of metal ions bound to humic acids are particularly important.…”

“…They exert their protective effects on the intestinal mucosa, possessing anti-inflammatory, adsorptive, anti-toxic and antibacterial characteristics (Klocking et al, 1992). The ability for humic acids to bond with metals motivated various authors to study their possible use for excluding undesirable metals from the gastrointestinal tracts of animals, or a decrease in their availability (Beveridge and Pickering, 1980;Marinski et al, 1982;Livens, 1991;Herzig et al, 1994;Glynn, 1995;Hudak et al, 1997;Lind and Glynn, 1999). Ridwan (1977) and Rochus (1983) observed that low concentrations of humic acids (0.1%) in feed were sufficient for a significant decrease of lead and cadmium uptake by rats.…”

Chromium(III)‐, iron(II)‐ and selenium‐humic acid/fulvic acid chelate and supplemented humifulvate added for nutritional purposes to food supplements

“…The petitioner stated that research indicates that humic acid is absorbed in vivo (Frimmel and Christman, 1988;Visser, 1987;Lind and Glynn, 1999;Lehninger et al, 1993).…”

Effects of humine compounds on iodine utilisation and retention and on the function of the thyroid gland

“…They are products of chemical and biological degradation of dead plant and animal tissues and of microbial activity and bind with metals and inorganic and organic substances including toxic pollutants to form chelates (Huang et al, 1994;Schulten, 1994). Oral intake of humines can result in the formation of metaloorganic complexes which affect the absorption of minerals and trace elements from the gastrointestinal tract (Spencer and Nichols, 1983;Livens, 1991;Lind and Glynn, 1999).…”

Model trial investigating retention in selected tissues using broiler chicken fed cadmium and humic acid

“…Various studies deal with the binding of dangerous metals by humic acids (Stevenson, 1977;Kerdorff and Schnitzer, 1980;Klocking, 1980Klocking, , 1994Lind and Glynn, 1999;Alvarez-Puebla et al, 2006;Hizal and Apak, 2006). The changes in the toxicological qualities of metal ions bound to humic acids are particularly important.…”

“…They exert their protective effects on the intestinal mucosa, possessing anti-inflammatory, adsorptive, anti-toxic and antibacterial characteristics (Klocking et al, 1992). The ability for humic acids to bond with metals motivated various authors to study their possible use for excluding undesirable metals from the gastrointestinal tracts of animals, or a decrease in their availability (Beveridge and Pickering, 1980;Marinski et al, 1982;Livens, 1991;Herzig et al, 1994;Glynn, 1995;Hudak et al, 1997;Lind and Glynn, 1999). Ridwan (1977) and Rochus (1983) observed that low concentrations of humic acids (0.1%) in feed were sufficient for a significant decrease of lead and cadmium uptake by rats.…”

Chromium(III)‐, iron(II)‐ and selenium‐humic acid/fulvic acid chelate and supplemented humifulvate added for nutritional purposes to food supplements

“…The petitioner stated that research indicates that humic acid is absorbed in vivo (Frimmel and Christman, 1988;Visser, 1987;Lind and Glynn, 1999;Lehninger et al, 1993).…”

Effects of humine compounds on iodine utilisation and retention and on the function of the thyroid gland

“…They are products of chemical and biological degradation of dead plant and animal tissues and of microbial activity and bind with metals and inorganic and organic substances including toxic pollutants to form chelates (Huang et al, 1994;Schulten, 1994). Oral intake of humines can result in the formation of metaloorganic complexes which affect the absorption of minerals and trace elements from the gastrointestinal tract (Spencer and Nichols, 1983;Livens, 1991;Lind and Glynn, 1999).…”

Model trial investigating retention in selected tissues using broiler chicken fed cadmium and humic acid

“…Various studies deal with the binding of dangerous metals by humic acids (Stevenson, 1977;Kerdorff and Schnitzer, 1980;Klocking, 1980Klocking, , 1994Lind and Glynn, 1999;Alvarez-Puebla et al, 2006;Hizal and Apak, 2006). The changes in the toxicological qualities of metal ions bound to humic acids are particularly important.…”

“…They exert their protective effects on the intestinal mucosa, possessing anti-inflammatory, adsorptive, anti-toxic and antibacterial characteristics (Klocking et al, 1992). The ability for humic acids to bond with metals motivated various authors to study their possible use for excluding undesirable metals from the gastrointestinal tracts of animals, or a decrease in their availability (Beveridge and Pickering, 1980;Marinski et al, 1982;Livens, 1991;Herzig et al, 1994;Glynn, 1995;Hudak et al, 1997;Lind and Glynn, 1999). Ridwan (1977) and Rochus (1983) observed that low concentrations of humic acids (0.1%) in feed were sufficient for a significant decrease of lead and cadmium uptake by rats.…”

Chromium(III)‐, iron(II)‐ and selenium‐humic acid/fulvic acid chelate and supplemented humifulvate added for nutritional purposes to food supplements

“…The petitioner stated that research indicates that humic acid is absorbed in vivo (Frimmel and Christman, 1988;Visser, 1987;Lind and Glynn, 1999;Lehninger et al, 1993).…”

Effects of humine compounds on iodine utilisation and retention and on the function of the thyroid gland

“…They are products of chemical and biological degradation of dead plant and animal tissues and of microbial activity and bind with metals and inorganic and organic substances including toxic pollutants to form chelates (Huang et al, 1994;Schulten, 1994). Oral intake of humines can result in the formation of metaloorganic complexes which affect the absorption of minerals and trace elements from the gastrointestinal tract (Spencer and Nichols, 1983;Livens, 1991;Lind and Glynn, 1999).…”