Chemical constitution and toxicity

Abstract

Unicellular organisms, Colpidium colpoda and Glaucoma scintillans, were used to determine toxicity. The organisms were grown on a synthetic medium and used 10-12 days after inoculation[long dash]when they numbered 3000-5000 per cc. Measure of toxicity was established as the concentration necessary to stop all movement in 3 min., 10 drops of the culture being placed on a watch glass and drops of the toxic solution added until required concentration was determined. Changes in temp. and p H affected the toxicity to organisms, but the changes were not sufficient to cause a measurable error in technic over the experimental range. Great care was required in inoculating the media, as foreign cultures reduced the killing property of the tested substance, probably by adsorption. Tables are given showing the toxicity of many As, Sb, and Hg compounds. Aromatic derivatives are more toxic than aliphatic; tervalent than quinquevalent; secondary than primary or tertiary; and primary than tertiary. Sb compounds are more toxic than As or Hg. A study was made of the mode of action of arsenicals. Sulphydryls act as detoxicating agents, the presence of Na thioglycollate decreasing the toxicity of diphenyl-chloroarsine proportional to the amount used. This is explained by the property of highly toxic compounds being susceptible to oxidation, and probably that their toxic property can be accounted for by their interfering with the oxidation-reduction action of the cell.