Don't Ban Chlorine—Use It Wisely

Recently, various activist and environmental groups have called for a ban on the use of chlorine and chlorine-containing compounds (1,2). The questions at issue are 1) is it possible, and 2) is it wise? Of course, chlorine, as chloride ion, is an essential component of the body, where it occurs at high levels in plasma and interstitial fluid. There probably is no controversy concerning this aspect of chlorine. However, is it really possible to ban chlorine-containing compounds from the environment? Many do not realize the great number and ubiquitous presence of such substances in the environment (3,4). Burning of wood, a fuel with possible increased use, both for domestic and industrial purposes, leads to the release of methyl chloride, a weak alkylating agent (5). Marine organisms form chloroform, carbon tetrachloride, chlorine-containing haloforms, and longer-chain compounds containing various halogens. It was once estimated that the natural formation of carbon tetrachloride was greater than industrial production in the entire Northern Hemisphere (6). The comment might be made that these examples are all aliphatic compounds; that only the more persistent cyclic compounds containing chlorine should be banned. But nature, the consumate master of synthesis, has an appreciable number of cyclic organics which contain chlorine in the repertoire. Ochratoxin, made by the fungus Aspergillus ochraceus (7), is an example of a toxic material with chlorine on an aromatic ring. On the other hand, naturally occurring chlorinated compounds such as chloramphenicol, chlortetracycline, and griseofulvin have been used to advantage against bacterial or mycotic diseases of humans (8). Various chlorinated phenols with antibiotic properties have been isolated from naturally occurring organisms, especially marine algae (9,10). A survey of many marine organisms showed that numerous products with antiviral, antimicrobial, and antineoplastic properties were present (11). Not only marine organisms synthesize chlorinated substances; lichens (12,13), and even some plants, seem capable of incorporating chlorine atoms into their metabolites (14). Furthermore, a substance with a structure akin to that of a chlorinated dibenzofuran has been isolated from soil under decomposed roots of a type of eucalyptus tree (15,16). Thus, nature furnishes chlorinated compounds similar to some of the hazardous materials presumed to result only from technological activity. Is it wise to ban chlorine and chlorine-containing compounds? Part of the reason for the longer life span of our population is the availability, due to chlorination, of a water supply free of the organisms that cause typhoid, cholera, and other infectious …