Fungitoxicity of Metal Ions

Abstract

IN a recent communication, Somers¹ has again considered the hypothesis first proposed by Mathews², that the toxicity of metal ions is related to the electrode potential of the metal. He has plotted the negative logarithms of the ED50 values of the applied molar concentrations of 21 elements for conidia of Alternaria tenuis against the electronegativity of the elements. An examination of the curve indicates clearly a correlation between the electronegativity and toxicity in the data presented. This is especially fortified by the low electronegativity of magnesium, strontium, lithium, sodium, barium and potassium ions which are basically not toxic to fungus conidia. If, however, attention is confined to that part of the curve which deals with ions toxic to fungus conidia (ions as toxic and more toxic than zinc), it is apparent that in a number of instances, the ED50 values are several orders of magnitude higher or lower than if they fell on the line drawn. As a matter of fact, examination of the data for these 15 elements, by calculating the rank correlation coefficient (calculated by Dr. F. Wilcoxon, Boyce Thompson Institute), shows that there is no significant correlation between electronegativity and toxicity in the area in which the toxic elements are found.