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Is chlorine — in any form — a threat to the environment?

Dear Cecil:

I was a little disappointed by your recommendation to use so many chlorine products in your column on toilet plumes. Chlorine is an extremely toxic chemical and is listed in the 1990 Clean Air Act Amendments as a hazardous air pollutant. It's also on the EPA's Community Right-to-Know list, and in 1993 the American Public Health Association issued a resolution calling for the gradual phaseout of most organochlorine compounds. Chlorine bleach contains sodium hypochlorite, a chemical precursor to chlorine. Any use of it will create pure chlorine in the environment. In addition to its direct toxic effects on living organisms, chlorine also reacts with organic materials in the environment to create other hazardous and carcinogenic toxins, including chloroform and other trihalomethanes (THMs) and organochlorines, an extremely dangerous class of compounds that cause reproductive, endocrine, and immune system disorders. Chlorine and chlorinated compounds are also a prime cause of atmospheric ozone loss. How about the straight dope on chlorine?

Cathy Hudzik, Chicago

Illustration by Slug Signorino

Cecil replies:

Life is full of trade-offs. Sure, excessive chlorine use may destroy the planet. But at least you’ll have really clean kitchen counters.

For some environmental groups the choice is just that simple. Greenpeace, for one, has adopted the slogan “chlorine kills.” But the more reasonable view is that chlorine offers both dangers and benefits, and we’d better make sure we don’t halt the thinning of the ozone layer just so we can all die of cholera instead.

The campaign against chlorine began when environmentalists noticed that chemicals such as DDT, PCBs (polychlorinated biphenyls), CFCs (chlorofluorocarbons), and dioxin have two things in common: they’re environmental hazards and they contain chlorine. Ergo, chlorine is bad. OK, there’s chlorine in table salt, but this argument isn’t as silly as it sounds. Chlorine is a highly reactive chemical that’s poisonous in its pure state. Many of its compounds persist in the environment and accumulate in body fat. Of the 15,000 commercially available organochlorines (a term meaning merely that they contain both chlorine and carbon), the World Health Organization has classified 59 as carcinogenic and another 58 as suspect. Greenpeace et al argue that this number would surely rise substantially if all were thoroughly tested. Since that’s not practical given the numbers, hey, ban ’em. Most scientists and officials don’t go that far, but there’s a growing consensus that chlorine use should be scrutinized and if possible reduced.

That won’t be easy. For example, recent studies suggest that by-products in chlorinated water can lead to an increase in certain cancers. Chlorine opponents urge a switch to other water treatments, but the alternatives aren’t necessarily safer. Ozonation, one commonly cited method, can also produce carcinogens in some circumstances.

That brings us to household disinfectants. Use of chlorine cleansers and bleach in the modest amounts I suggested is not going to add significantly to environmental chlorine. If you’re concerned, though, you can substitute a quaternary ammonium-based cleanser. The ones I’ve seen also contain chlorine, but generally much less than you find in bleach. “Quats” aren’t as effective against some viruses, but they work fine against the enteric bacteria that are a more serious problem, provided you follow the directions. (Usually after applying the stuff you have to let it sit for awhile, which isn’t necessary with chlorine bleach.)

Whatever you do, don’t get the idea that keeping the germ count down is silly or that exposure to bacteria “builds up your resistance” or other such nonsense. Potentially life-threatening bacterial infections are rising rapidly in North America for a variety of reasons: industrialized animal husbandry crams thousands of animals into small spaces, promoting the spread of disease; food imports from countries with less stringent sanitary standards are increasing; and the vulnerable population is growing, particularly the elderly. Some strains of bacteria are becoming resistant to antibiotics, which adds to the danger. Don’t go overboard, but just because no one in your family has been hospitalized for salmonella (yet) doesn’t mean you’re completely safe.

Cecil Adams

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