Studies on toxic action

Summary The toxicity of the normal monohydric fatty acids does not increase regularly as the series is ascended as is the case with the alcohols, aldehydes (excluding formaldehyde), ketones and esters. On the contrary, as the series is ascended, the toxicity falls from formic acid to propionic acid,...
Ausführliche Beschreibung

Summary The toxicity of the normal monohydric fatty acids does not increase regularly as the series is ascended as is the case with the alcohols, aldehydes (excluding formaldehyde), ketones and esters. On the contrary, as the series is ascended, the toxicity falls from formic acid to propionic acid, which is only one-fifth as toxic as formic acid and is the least toxic of the normal acids. On further ascending the series the toxicity increases, and pelargonic acid is actually four times as toxic as formic acid and sixteen times as toxic as butyric acid.The relationship between toxicity and position in the series of normal fatty acids is explained by the fact that the acids are partly dissociated so that free hydrogen ions are present in the solutions. The toxicity of each acid can be regarded as partly due to hydrogen ions and partly due to the undissociated acid (including the anion). As the series is ascended the acids are less dissociated so that the hydrogen ion plays less part in the toxic action while the undissociated molecules become more toxic, and play a greater part in determining the toxicity. Thus, with the range of concentrations used in these experiments, not less than 95 per cent, of the toxicity of formic acid may be attributable to the hydrogen ion, while in pelargonic acid only about 14 per cent, of the toxicity is due to hydrogen ion.The relative toxicities of the hydrogen ion and of the various acid molecules have been estimated. The toxicity of the formic acid molecule is probably from about 0.003 to 0.01 times that of the hydrogen ion while that of the pelargonic acid molecule is about 0.65 times that of the hydrogen ion. Ausführliche Beschreibung