Swimming, effect

Tetrasilver tetroxide is a powerful oxidizer for sanitizing swimming pools, hot tubs, and industrial cooling system waters (see Water, treatment of SWIMMINGPOOLS, SPAS, AND HOT tubs). This oxide is slightly soluble and its dissociation into silver ions is enhanced by the addition of the oxidizer KgSgOg. Bivalent and trivalent silver disinfectants have been shown to be from 50 to 200 times more effective as sanitizers than monovalent silver compounds. 

NaOH for stabiUty which has only a small effect on pool pH. It is a commonly used sanitizer for swimming pools. In pool water, it produces hypochlorite ion and hypochlorous acid ... 

Calcium Hypochlorite. This chemical, marketed since 1928, is one of the most widely used swimming-pool water sanitizers. Calcium hypochlorite, a crystalline sofld, is a convenient source of available chlorine and is sold in granular or tablet form for use in home, semiprivate, and commercial pools. When dissolved in water, Ca(OCl)2 forms hypochlorous acid and hypochlorite ion similar to NaOCl. It contains small amounts of stabilizing Ca(OH)2, which has a very small effect on pool pH (7). Calcium hypochlorite has superior storage stabiUty and much higher available CI2 concentration than Hquid bleach, which reduces storage requirements and purchasing frequency. 

For optimum disinfection in swimming pools, the pH is maintained in the 7.2 to 7.6 range where HOCl represents 69—47% of the FAC. By contrast, the HOBr fraction varies from 97 to 93%. Nevertheless, the bactericidal effectiveness of HOCl is greater than that of HOBr below pH 8 on a molar basis (8). However, above pH 8 the superiority of HOCl is overcome by the fact that the concentration of C10 exceeds that of HOCl above pH 7.5, whereas the concentration of HOBr stiU exceeds that of BrO up to pH 8.7. Hypochlorous acid is a better viricide than HOBr, but HOBr is more effective against certain algae (9). 

Although pH determines the ratio of hypohalous acid to hypohaUte ion, the fraction of the total available halogen present as HOX is dependent on of the halamine as well as the concentration of excess amine. In the case of chloroisocyanurates, which are the most widely used /V-ch1oramine disinfectants in swimming pools and spas, the extent of hydrolysis at 1 ppm av CI2 (as monochloroisocyanurate) is - 34% but only - 1% when 25 ppm cyanuric acid is added (4). Nevertheless, effective disinfection can stiU occur with chloroisocyanurates if a sufficient FAC is maintained, eg, 1—3 ppm. The observed reduction in disinfection rate because of cyanuric acid (6) has been shown to be direcdy related to the concentration of HOCl formed by hydrolysis of chloroisocyanurates (10). 

Water Tests. In colorfastness to water, ISO 10S-E01, the test specimen is placed in contact with the chosen adjacent fabrics, immersed in water, and placed wet between glass plates and left for 4 h at 37°C. After drying, the effect on the test specimen and stain on adjacents are assessed. The test, colorfastness to seawater, ISO 10S-E02, is the same as EOl but uses 30 g/L anhydrous sodium chloride solution instead of water. To test for colorfastness to chlorinated seawater/swimming baths water, ISO 10S-E03, the specimen is immersed in sodium hypochlorite solution containing either 100, 50, or 20 mg of active chlorine per Hter at pH 7.5 for 1 h at 27°C, rinsed, dried, and assessed. 

CBs, like OPs, can cause a variety of sublethal neurotoxic and behavioral effects. In one study with goldfish Carrasius auratus), Bretaud et al. (2002) showed effects of carbofuran on behavioral end points after prolonged exposure to 5 pg/L of the insecticide. At higher levels of exposure (50 or 500 pg/L), biochemical effects were also recorded, including increases in the levels of norepinephrine and dopamine in the brain. The behavioral endpoints related to both swimming pattern and social interactions. Effects of CBs on the behavior of fish will be discussed further in Chapter 16, Section 16.6.1. 

Grandjean E. 1963. The effects of short exposures to trichloroethylene on swimming performances and motor activity of rats. Am Ind Hyg Assoc J 24 376-379. 

---