Experts debate benefits, dangers of chlorine in C&EN point-counterpoint

Get a group of scientists together and mention the word “chlorine” and watch the sparks start to fly. That’s exactly what happened at a forum on a different, but related, topic of sustainability, sponsored by the news magazine Chemical & Engineering News, a publication of the American Chemical Society, the world’s largest scientific society.

As a result of a “vigorous and provocative debate” about chlorine at that forum, the magazine’s editors asked two leading experts in the field of chlorine chemistry – Terrence Collins, professor of chemistry at Carnegie Mellon University, and C.T. (Kip) Howlett Jr., executive director of the Chlorine Chemistry Council and vice president of the American Chemistry Council – each representing opposing viewpoints, to participate in a special “point-counterpoint” exchange, which appears in the magazine’s Oct. 18 issue.

Collins charges that the dangers of chlorine are not being adequately addressed by industry or academe. He says alternatives to chlorine and chlorine processes must be pursued. Howlett contends that industry is, in fact, succeeding in lessening the impact of chlorine on the environment. He cites numerous positive contributions that chlorine has made to society.

Some highlights of the exchange:

• Howlett point: “Products and services that result in 45 percent of the U.S. gross domestic product are rooted in chlorine chemistry. In addition to water disinfectants and pharmaceuticals, chlorine is critical to 25 percent of all medical plastics, 70 percent of all disposable medical applications, and 95 percent of crop protection chemicals; it also plays a significant role in the production of soaps and detergents, aluminum, and pulp and paper. The chlor-alkali sector is a solid job producer in the U.S. with a payroll of more than $360 million and more than 37,000 jobs.”
• Collins counterpoint: “The Chlorine Chemistry Council public relations initiatives that gloss over toxicity misinform people and erode public trust in chemistry.” … “By listing together perfectly safe and questionable products without distinction, accompanied by prose that only glorifies chlorine technologies, Howlett hides toxicity information the public has a right to know and that you should rightfully explain.”
• Collins point: “Approximately one-third [of global chlorine production] goes into manufacturing polyvinyl chloride.” … “PVC is extremely hazardous for multiple reasons. Space permits me to consider only the dioxins hazard associated with PVC combustion.” … “There are more than one million accidental fires each year in the U.S. alone. As more PVC accumulates in our civilization, it is hard to believe that children are not being compromised in increasing numbers by dioxins from chance PVC combustion.”
• Howlett counterpoint: “Dr. Collins focuses on accidental fires. If what he and others say about the generation and longevity of polychlorinated dibenzo-p-dioxins and -furans from PVC combustion in house fires is correct, then these materials should show up in the environmental record. But the environmental record shows that dioxins emissions and body burdens have declined over 90 percent since 1970 while PVC manufacture has tripled – and most of that manufacture goes to building and construction.”

Despite the long-standing and passionate controversy over chlorine, Collins and Howlett managed to agree on at least one thing: disinfection of drinking water supplies with chlorine has been a lifesaver for people around the world. According to Collins, “… water disinfection with chlorine probably holds the record for saving human lives …” Howlett’s response, “I agree.”

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