Do-it-yourself enthusiasts and construction workers often use MDF, or medium-density fiberboard. It is a composite material made of glued-together wood fibres. It usually contains the adhesive formaldehyde. The dangers of MDF stem partly from the irritation to the skin and respiratory system caused by dust and wood particles. Cutting the board releases small particles of dust and wood into the air. The rest of the danger stems from the formaldehyde, which is a possible carcinogen. Working with the board releases some formaldehyde gas, but the board also emits it passively.
Cutting MDF releases particles of dust as the fibres break up. Drilling and using woodworking machines on MDF opens up the board and releases fibres and dust. These wood particles irritate the eyes, skin and respiratory system. Breathing them in sometimes triggers asthma attacks in particularly sensitive people. Even a low concentration of MDF dust can affect some individuals. Regular, long-term exposure to wood dust is not necessary to stimulate a bad reaction. Briefly breathing in a high concentration of fibrous particles can be worse than often breathing low levels of dust.
Formaldehyde resin binds together the fibres in most MDF boards. It is a carcinogen, or cancer-causing substance. The National Toxicology Program’s 11th "Report on Carcinogens" lists formaldehyde gas as "reasonably anticipated to be a human carcinogen." This means that there is some evidence of a link between formaldehyde gas and cancer in humans, but no definitive proof has been reported. Machining MDF releases a mixture of wood particles, formaldehyde gas and particles coated with formaldehyde. MDF can also release formaldehyde gas even when it is not being disturbed. Any uncoated edges of the board can release formaldehyde as a gas. Manufacturers are working to reduce this. By 2009, the amount of formaldehyde gas emitted by MDF was 80 to 90 per cent less than at the beginning of the 1980s. Formaldehyde exposure causes cold-like symptoms in the short term in addition to the possible long-term effects.
Wear a mask and work in a well-ventilated area when cutting MDF. Take extra care when sanding MDF boards as this releases particularly large amounts of dust. Reduce formaldehyde exposure. Buy pressed board products that do not contain formaldehyde and choose MDF furniture with laminated edges. Look for labels on MDF that show it meets the American National Standards Institute (ANSI) criteria for pressed board products. It should conform to ANSI A208.2-1994.