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Because of concern about the ozone layer, many chlorinated organic solvents were banned under the 1987 Montreal Protocol. One of the solvents phased out was 1,1,1-trichloroethane, which was widely used by small engineering companies in metal degreasing. Many of these companies replaced 1,1,1-trichloroethane with trichloroethylene (trike), simply because they had used it in the past. However, trike is more acutely toxic and carcinogenic, and has a significantly lower occupational exposure limit than 1,1,1-trichloroethane. With a bit more thought, the degreasers could have switched to aqueous cleaning, or changed the process to avoid cleaning altogether (B. Allen, Solvents: the hidden abuse, Occupational Health Review, 1996, 64, 17). In Massachusetts, the TUR Act specifically says that substitution is not about "shifting risks between workers, consumers or parts of the environment."

A 1994 survey of degreasers by the HSE found 41% had recently changed to trike because of the Montreal Protocol. 39% of these new trike users had not reviewed (or ever done) their COSHH assessments, and only 37% were doing adequate air sampling for trike.

The Montreal Protocol also banned CFC-114, which was used as a refrigerant. In one Belgian smelting plant, CFC-114 was replaced with an HCFC mixture in the air-conditioning unit of an overhead gantry cabin. After nine gantry drivers developed hepatitis, an occupational health doctor traced the cause to the new, more environmentally friendly coolant. The new mixture contained HCFC-123, which had already been found to cause liver damage in rats. The drivers had been exposed to HCFC-123 at levels much higher than the occupational exposure limit because of a leaking hose in the air-conditioning system. The problem might have been noticed sooner if someone had realised that the unit must have been leaking because it needed to be refilled so often (Chemical and Engineering News, 25 August 1997, p. 8).

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