Update and correction to my last post. I just read a medical report about methylene chloride causing deaths of workers using it to refinish bathtubs. Of the 13 bathtub refinishing workers who were reported to have died from methylene chloride exposure in 2000 - 2011 in the US, most or all did not have highly elevated carbon monoxide in their blood. In addition to causing carbon monoxide poisoning in some people, methylene chloride is now believed to cause sudden death by cardiac arrhythmia or by respiratory depression. Cardiac arrhythmias can occur at much lower exposure levels, it takes pretty high levels to cause respiratory depression (anesthesia-like cessation of breathing). Most of these deaths were in young workers below age 50, not in elderly people who have existing heart disease. The problem occurs when methylene chloride is used in an enclosed space like a bathroom with a bathtub being refinished. These 13 deaths were only in bathtub refinishing workers, and were only the ones diagnosed and reported as related to methylene chloride. Deaths or near deaths occur in many other occupations using methylene chloride, these 13 are just among bathtub refinishers. In addition to reported cases, there are probably many other cases in which the causal link between methylene chloride and sudden death is never made by the treating physicians and the cases are never reported. Given what we are learning about methylene chloride toxicity, it may be that in addition to occupational exposures, hobbyists and home renovators also experience unreported deaths and heart attacks due to methylene chloride, although there are only a few case reports actually documenting this.
In spite of these fatal cases, I still say methylene chloride can be used safely WITH PROPER PRECAUTIONS. This means it must be used with proper ventilation, preferably outside, and with a NIOSH-approved respirator rated for use with methylene chloride. Also methylene chloride can be absorbed through the skin, not just by breathing it. So you need to wear protective gloves and not get any on your skin. Even though many of us have used methylene chloride paint strippers for years without too much concern, the medical evidence is now accumulating that these much more intensive precautions are necessary. Generally this means use should be limited to professional refinishers following OSHA standards with proper precautions, or for home hobbyists, working outdoors or installing a dedicated local exhaust ventilation system in your home workshop and confirming with measured air levels that the ventilation is adequate while the stripper is being used. You can hire an industrial hygienist with a local environmental company to do the testing. The air testing for methylene chloride should be done while using the maximum amount of methylene chloride under the conditions you plan to use it. Check the ingredients list of all paint strippers you consider using for methylene chloride.
Here is a link to an article published last month describing the 13 fatalities.
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6107a2.htm