Chlorinated water, exposure

The interactions of chloroform with other chemicals are an issue of great importance as with many chemicals, exposure to chloroform alone seldom occurs. This is especially true when considering exposure to chlorinated water, which usually contains other trihalomethanes and may contain other potential toxicants. 

This thin-film-composite membrane has been found to have appreciable resistance to degradation by chlorine in the feed-water. Figure 2 illustrates the effect of chlorine in tap water at different pH values. Chlorine (100 ppm) was added to the tap water in the form of sodium hypochlorite (two equivalents of hypochlorite ion per stated equivalent of chlorine). Membrane exposure to chlorine was by the so-called "static" method, in which membrane specimens were immersed in the aqueous media inside closed, dark glass jars for known periods. Specimens were then removed and tested in a reverse osmosis loop under seawater test conditions. At alkaline pH values, the FT-30 membrane showed effects of chlorine attack within four to five days. In acidic solutions (pH 1 and 5), chlorine attack was far slower. Only a one to two percent decline in salt rejection was noted, for example, after 20 days exposure to 100 ppm chlorine in water at pH 5. The FT-30 tests at pH 1 were necessarily terminated after the fourth day of exposure because the microporous polysul-fone substrate had itself become totally embrittled by chlorine attack. 

The EPA has conducted four major studies of actual human exposure using monitors worn by random samples of people. The results are shocking. Smoking, clothes that had been dry cleaned and hung in closets, and heated water in showers and clothes washers (i.e., chloroform from chlorinated water) are major sources of human exposure to volatile organic compounds (VOCs), all of which exceeded outdoor exposure sources by two to five times at the median exposure level. The major sources of exposure to another VOC, p-dichlorobenzene, are toilet fresheners and mothballs. Pesticide exposure stems from two main sources (1) vapors emitted by soil into homes through basements and (2) soil tracked into buildings on shoes. Major stationary and mobile sources account for only 2 to 25 percent of personal exposure to the two dozen or so VOCs and pesticides that the EPA studied (Wallace 1993, 138 Ott and Roberts 1998). 

The photochemical decomposition of chlorine water, bromine water, and iodine water.—In 1785, C. L. Berthollet20 noticed that chlorine water is gradually decomposed by exposure to light, forming aq. hydrochloric acid and oxygen. He said ... 

F. Wohler 23 found that when chlorine hydrate in a sealed glass tube is exposed to sunlight, it forms two liquids, but does not decompose, since, after a summer s exposure, the two liquids re-form chlorine hydrate when winter returns. The same phenomena occur if the chlorine hydrate is warmed and cooled under similar conditions. A cone. soln. of chlorine water is far less prone to decomposition on exposure to sunlight than is a more dil. soln. J. M. Eder found the same to be the case with bromine water, but he also found that a cone. soln. of chlorine water lost 53 95 per cent, of chlorine while a dil. soln. lost 41 87 per cent, under similar conditions, but he does not state the concentration very exactly. A. Pedler further showed that soln. more cone, than one mols. of chlorine with 64 mol. of water had not decomposed perceptibly after a two months exposure to tropical sunlight, and with that increasing dilution, the action became progressively greater, as illustrated in Table VII. 

By exposure in thin shreds to the sun s rays, or in a finely-divided state to chlorine water, or by rediicing it to a fine powder, suspending in water and passing hydrochloric acid vapor into the menstruum, tlie dark-oolored varieties are bleached. When this is done, howovor, the resin loses many of those qualities that so admirably recommend it for some kinds of varnishes, but it answers well for malting sealing-wax. 

Information regarding the excretion of chromium in humans after dermal exposure to chromium or its compounds is limited. Fourteen days after application of a salve containing potassium chromate(VI), which resulted in skin necrosis and sloughing at the application site, chromium was found at 8 mg/L in the urine and 0.61 mg/100 g in the feces of one individual (Brieger 1920). A slight increase (over background levels) in urinary chromium levels was observed in four subjects submersed in a tub of chlorinated water containing 22 mg chromium(VI)/L as potassium dichromate(VI) for 3 hours (Corbett et al. 1997). For three of the four subjects, the increase in urinary chromium excretion was less than 1 pg/day over the 5-day collection period. 

Figure 2. Oxidation induction time (OIT not the log-scale) for samples taken at a certain depth (0.9-1.0 mm from the inner wall from PB pipes pressure-tested at 90 C with internal chlorinated water (0.5, 1.0 and 1.5 ppm Cl) as a function of the exposure time. The line is a linear fit of the data. The insert figure shows the results of extrapolation to 01T= 1 min based on OIT data from exposures shorter than tfnax- From Lundback et al.(12) and with permission from Elsevier, UK.

CN is a white solid with low vapor pressure that can be dispensed as a fine powder or as a jet or stream of solution from small or large spray tanks, as well as aerosols or smokes by pyrotechnic generation. Its solubility in water is limited, but it is soluble in organic and chlorinated organics. Exposure of eyes, nose, mouth, skin, and respiratory tract produces irritation and pain. If swallowed, CN may produce vomiting. 

White or grayish-white powder strong odor of chlorine. On exposure to air it becomes moist and rapidly decomposes. Most of it dissolves in water Or alcohol. Keep dry and tightly closed. 

Sulfone-hased polymers show a very good resistance to prolonged chlorine exposure at elevated temperatures. The weight change after an exposure of 6 months to static chlorinated water at 60°C at chlorine levels of up to 30 ppm is essentially zero for Udel , whereas e.g., poly(acetal) exhibits a weight loss of ca. 5% at 30 ppm chlorine in water after 6 months. This property suggests applications in water delivery systems. 

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