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Californian authorities want ban on cleaning fluid to reduce smog

BMJ 2002; 325 doi: (Published 02 November 2002) Cite this as: BMJ 2002;325:990
  1. Deborah Josefson
  1. Nebraska

    California's environmental regulators are moving towards a total ban on the common dry cleaning solvent and probable carcinogen perchloroethylene, claiming that it is a major constituent of smog and pollutes both the air and ground water.

    In California, 99% of dry cleaners use the chemical to clean clothes. The South Coast Air Quality Management District wants to impose a total ban on perchloroethylene by 2019. The agency monitors and regulates air quality in southern California, including Greater Los Angeles, infamous for the worst smog in the United States.

    The proposed ban, known as rule 1421, would phase out perchloroethylene gradually, so that dry cleaners have a chance to switch to less toxic alternatives. These include organic solvents, as well as liquid carbon dioxide and a silicone based aqueous system known as “wet cleaning.”

    About 2200 tonnes of perchloroethylene are produced each year by dry cleaners in southern California, and an estimated 850 tonnes would be eliminated if the measure was passed.

    Perchloroethylene is a probable carcinogen and probable teratogen which has been linked in occupational studies to cervical, lung, oesophageal, and bladder cancers. It can also cause respiratory ailments, contribute to kidney disease, and act as both a neurotoxin and hepatotoxin. Perchlorate anion can also cause thyroid disease.

    Perchlorate (CLO4-) itself is a relatively non-labile anion that dissolves in aqueous solutions and persists in that environment because it is resistant to chemical reduction. In addition to dry cleaning, other major sources of perchlorate include chemical fertilisers and rocket propellant fuels.

    The South Coast Air Quality Management District contends that the perchloroethylene fumes emitted by dry cleaning premises pose a greater carcinogenic risk than oil refineries, power plants, and the aerospace industry. Dry cleaning associations, however, believe that the risk of perchloroethylene is overstated. Moreover, they fear that strict regulations on emissions would hurt small family-run dry cleaners and believe that alternative solvents and cleaners are substandard.

    The air quality management district estimates that the conversions will cost the industry $4.3m (£2.8m; €4.4m) a year. A public hearing on the issue is scheduled for early November, and the air quality management district will vote on rule 1421 shortly afterwards. If passed, the measure will be the first to call for a total ban on the solvent, with the phase out beginning on 1 January 2003.

    Fourteen US states currently have emissions limits for perchloroethylene, but none has imposed a total ban. Current Environmental Protection Agency guidelines call for no more than 18 parts per billion of perchlorate in drinking water.

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