In the fine print of most labels they manufacturers allude to the precautions necessary when using their products, but without a magnifying glass and good lighting, the labels are often difficult to read and easily ignored. While these products can be bought at home-improvement and general retail stores across the U.S., the specialty respirators and polyvinyl-alcohol gloves needed to handle them safely are not usually available from those same retailers. OSHA and the National Institute for Occupational Safety and Health say only a full-face respirator with a separate air supply, or exhaust ventilation to remove the fumes, will provide sufficient protection.
Setting aside longer-term health concerns, such as cancer, the danger posed by methylene chloride is its one-two punch when fumes accumulate. Because it turns into carbon monoxide in the body, it can starve the heart of oxygen and prompt a heart attack. The chemical also acts as an anesthetic at high doses, so its victims slump over, no longer breathing, because the respiratory centers of their brains switch off.