EDITORIAL A perspective on chlorination Potential hunian health risks from the use of chlorine in the water supply industry have resulted in extensive and costly new regulations on the levels of chlorination byproducts in drinking water. Generations of sanitarians have urged the wholesale use of chlorine, guided by an image that equates chlorine-like odors with microbiological purity. Water supplies are routinely dosed with chlorine as are sewage effluents and freshly processed meat and poultry carcasses, although the latter practice is not permitted in Canada. In both the USA and Canada, chlorine is also used to bleach cake flour, and dental practice over the last 30-40 years has routinell, eniployed a strong hypochlorite solution (27% NaOCI) for the irrigation of root canals. Clearly, a potential exists for a wide variety of channels of human exposure to chlorinated organic material. The problem stems not so much from the hunian health risks from HOC1 itself or its chemical forms but froni reaction byproducts. A growing number of research reports establish that human exposure to chlorinated organics by water consumption is apparently dominated by the trihaloniethanes (and CHC13 in particular), which is surprising considering the reactivity of chlorine and the complex characteristics of the natural product materials generally held to be the principal reaction reductant. Recently EPA has gathered Total Organic Chlorine Data for 50 raw and finished waters in US. cities. The range of TOCl values for the raw water u a s less ( 5 - 122 p g / L ) than that for finished waters ( 14-3 10 pg/L). The fraction of the TOCl not accounted for by trihaloniethanes is apparently variable, 38% for relatively high TOCl raw water and 85% for relatively low TOCl raw water. This data and current research on the chlorination of natural aquatic humic material establish that most of the chlorine demand is not accounted for by the trihalomethanes, and the balance appears in relatively nonvolatile fractions.
The chemical consequences of chlorine use in the food processing industry are not as well established. Cereal chemists have long recognized that the baking qualities of cake flour improve upon storage and that similar improvements result from exposure of processed flour to chemical oxidants during preparation. Years ago, nitrogen trichloride was abandoned after Mellanby observed that flour treated with NC13 induced hysteria in dogs. Chlorine and chlorine dioxide have become more widely used since that time and present commercial practice employs 1200-2500 ppm Clz for flour treatment. Recent animal feeding studies suggest that chlorinated whole cake flour, flour lipids, and wheat gluten have toxic effects on rats in short-term feeding studies. Chlorinated lipids are apparently absorbed by the body, although at reduced levels compared to unchlorinated material, and are stored in body adipose tissues for time periods similar to natural flour lipids. Chlorine water (up to 200 ppm) is also used in the U S . to cool freshly slaughtered meat and poultry carcasses. Cunninghain has exposed beef, pork, and poultry to water containing 200 ppni labeled with 36CI and observed 24-hour uptakes of 8% (beef), 7%)(pork), and 6% (chicken). In all cases a large fraction of chlorine reaction products was water soluble. The total body burden of chlorinated organic materials resulting froni society’s use of chlorine is clearly u n d e t e r m i ned and substantia 11y in or e co m p 1ex than the effort to control chlorination of drinking water has led us to believe. Given the present animal feeding data on food-processing chlorination, it is surprising that there has not been a federal response of equivalent magnitude to the EPA effort launched in 1974 on the basis of less substantial information.
Volume 14, Number 1, January 1980
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