V. A. Pleshko (Sverdlovsk)

Pantocid as a Means of Disinfecting Water

The disinfection of water for individual use has long been a subject of study by hygienists. To date, however, we have not found an agent that acts reliably as a bactericide while preserving the original organoleptic properties of water.

Pantocid consists of white tablets approximately 0.7 cm in diameter and weighing an average of 180 mg. The tablets are packaged in batches of 20 in brown-glass vials, sealed with cork stoppers and coated with paraffin. Pantocid has a faint odor of chlorine and a sharp, salty taste. Its bactericidal ingredient is dichloroparasulfamide of benzoic acid.

Pantocid was investigated for its bactericidal activity, solubility, and effect on the organoleptic properties of water. The pantocid studied was manufactured on July 5, 1938, at the Semashko factory. The experiments began in July 1939, one year after the preparation was manufactured. Water for the experiments was drawn from the Iset River and a courtyard well. Its composition is given in the following table.

To determine the bactericidal effect of pantocid, 100 water cultures were prepared: 50 before chlorination and 50 after chlorination, at water temperatures ranging from 4° to 27°. One tablet was used to treat 700 cm³ of water (a flaskful). Cultures were prepared after different contact times: immediately after the pantocid had dissolved and after 10, 20, 30, and 45 minutes.

The experiments showed that a contact time of just 10 minutes was entirely sufficient. Cultures of both river and well water at different temperatures yielded highly consistent results. The E. coli titer did not fall below 700 cm³; in most cases, E. coli was not detected in 700 cm³. The colony count did not exceed 10 per 1 cm³ of water, and most often a culture of 1 cm³ yielded no growth. By contrast, the untreated water had an E. coli titer of 0.001 to 10 cm³, and the colony count was in the tens of thousands.

Similar results were obtained by Uglov, Markaryants, and Loibman when they cultured water contaminated with E. coli after treating it with pantocid (1 tablet per 1 liter of water), as can be seen from

the following results: control—180,000 colonies per \(1\ \text{cm}^3\); 5 minutes after dissolution—0; 10 minutes after dissolution—0.

Cultures of water taken immediately after the pantocid dissolved occasionally yielded isolated colonies. After treatment, the E. coli titer in some cases reached \(10\ \text{cm}^3\), while the microbial count reached tens of thousands of colonies.

The pantocid label states that each tablet contains 3 mg of active chlorine. A test of 50 tablets from different cartridges showed that the average amount of chlorine per tablet was 3.18 mg.

Pantocid retains chlorine very firmly. To test the stability of the tablets, a cartridge was kept in the pocket of a uniform tunic for two months (July and August); during that period it was opened 15 times and tablets were removed. At the end of two months, the average amount of chlorine per tablet was 3.02 mg, a loss of 5%.

In a second experiment, pantocid tablets were placed in an open dish in an incubator at \(37^\circ\) for 20 days. At the end of this period, each tablet contained an average of 2.46 mg, a loss of 22%.

Solubility tests were conducted in flasks: one tablet was dissolved in \(700\ \text{cm}^3\) of water with vigorous shaking. The solubility of pantocid depends considerably on the water temperature, as shown in the adjacent table.

Dissolution without agitation at a water temperature of \(15^\circ\) takes from 45 minutes to 1 hour.

Pantocid has little effect on the organoleptic properties of water: when one tablet is dissolved in \(700\ \text{cm}^3\), only a faint chlorine odor and taste are perceptible.