Murray, methylene chloride and methyl ethyl ketone are two different things. I'm also in the environmental/safety business in the states, and run into this stuff all the time. Use it in a well-ventilated area, don't spill it on anything, etc., and you should be fine. A lot of times the hazards associated with these substances are primarily for long-term chronic exposures, either in the workplace, in your drinking water, or some other pathway that continue for a long stretch at relatively low concentrations. Acute exposures to high concentrations are also of concern, but with reasonable precautions, the occasional application shouldn't alarm you too much.

Rick, if the folks at your hardware store have never heard of MEK or toluene, it's time to change hardware stores -- these have been among the most common industrial solvents for decades (toluene was probably the most commonly used industrial solvent before they developed chlorinated petroleum-based solvents during World War II).