Mercury chloride, biological effects

Salts. In general, salts are completely ionized in dilute solution of the few exceptions, the halides of mercury, cadmium, and lead are the most notable. Because salts are completely ionized, they have no biological properties other than those of the individual ions of which they are composed. Thus calcium chloride can have no conceivable physiological effects other than those peculiar to calcium ions and to chloride ions. This simple conception needs modification when a salt is derived from either a weak acid or a weak base, because some of the uncharged species is liberated by hydrolysis (see below), thus adding its own biological effect to those of the constituent ions of the salt. 

Dawson, DC Mount Desert Island Biological Salsbury Cove, ME Effect of mercury on thiazide-sensitive sodium chloride cotransporter in flounder. NIEHS... 

The reaction between methylcobalamin and metal compounds plays a major role in biological transmethylation and may also be involved in the geochemical cycling of metals. The kinetics and mechanism of this reaction have been reported in detail for mercury(II) salts, [PdCU] , and chloroplatinum(IV) compounds. The effect of the chloride ion concentration on the reaction of Hg(OAc)2 with CH3B12 has now been investigated in detail. The reaction rate decreases markedly as the [Cr]/[Hg(II)]totai ratio is increased. 

Whether or not a substance is inhibitory depends on factors such as concentration and the presence of other chemicals that have synergistic or antagonistic effects. Some substances, such as mercury, even when present in wastewater at a very low concentration can disrupt one or more functions of a biological treatment system. Others, such as chloride ion, are inhibitory only at relatively high concentrations. Special phenomena that may alter the inhibitory nature of a substance include synergism, antagonism, and acclimation. These are described below. 

---