I’ve long wondered what causes ALS (amyotrophic lateral sclerosis, more commonly known as Lou Gehrig’s Disease), a progressive motor neuron disease leading to slow, painful death. It’s most certainly environmentally caused, probably combined with genetic vulnerability.

For quite a while pesticides have been suspect. But a new Harvard University study links ALS to formaldehyde exposure—a rather startling finding given the ubiquity of formaldehyde in household products. The synthetic chemical is everywhere—from toothpaste to permanent press fabrics.

Composite wood products (plywood, particleboard, fiberboard) are huge culprits because they’re put together with urea formaldehyde glue. Consequently, the chemical is found in new furniture (including baby cribs), kitchen cabinets and countertops, and wall and floor sheathing, to name a few.

Formaldehyde is a known carcinogen. Symptoms of exposure include watery eyes, headaches, and depression. It is a sweet-smelling toxin which off-gases over time, allowing people to breathe in the vapors day in and day out. People with existing respiratory conditions, such as asthma and emphysema, have increased risk. Some composite wood products take years to completely offgas.

The Harvard study found that people exposed to formaldehyde were 34% more likely to develop ALS than those who were not exposed. It also found that those with longer exposure to formaldehyde (ten or more years) were almost four times as likely to develop ALS than those with no exposure. The results (part of a 15-year study of one million people who reported their exposure to 12 chemicals, including pesticides) were framed as “preliminary” by American Cancer Society researchers.

Those studied reported being exposed to formaldehyde in 1982, at the beginning of the study period. Levels allowed in many consumer products and workplace settings has since been reduced.

Off-gassing of formaldehyde has long been on the radar screen of environmental regulators, who caution that it can add to the load of potentially-toxic fumes in the house, where air quality is often worse than outdoors. California, taking the lead as it often does, will phase out the use of formaldehyde by 2011. Currently, the U.S. Department of Housing and Urban Development is revising its standards for formaldehyde in manufactured housing, which uses a lot of composite wood products.

What’s the wise consumer to do? Avoid formaldehyde in all its forms, beginning with composite wood products-- plywood, particleboard, fiberboard. If you have cabinetry or other exposed wood products containing formaldehyde, it’s a good idea to seal exposed surfaces with a vapor-retardant sealer.

In a healthy home, cabinetry, doors, and built-ins are made of solid wood or formaldehyde-free wheat board. Formaldehyde-free exterior-grade plywood is an acceptable material choice, or use alternative materials for cabinets, such as metal with a baked-on finish. When using sheetgoods choose low-emission boards such as wheatboard, strawboard, isoboard, Fiber Tech™, Homastote™, or exterior-grade plywood.