Particleboard and medium-density fiberboard (MDF) are almost always made with a urea formaldehyde (UF) binder. This is one of the largest in-home sources of formaldehyde gas—a known human carcinogen. These products can off-gas for 5 years or more into the living space. UF-based particleboard and MDF are typically used for cabinet boxes, substrates for countertops, shelving, and stair treads. If possible, these materials should be avoided. Any UF-based materials used in a building should be sealed with a low-toxic, low-permeability coating.
A few formaldehyde-free particleboard and MDF products are available, including some made with straw instead of wood fiber. These are made with a urethane-type (MDI) resin. Be aware that MDI is highly toxic before it cures, so its use increases the health risk to factory workers if a manufacturer doesn’t have good safety standards. Once cured, MDI-based wood panel products are very stable, without measurable off-gassing.
Conventional drywall is quite attractive from an environmental standpoint. It is typically made from 100 percent recycled paper backing and natural gypsum, which is plentiful and can be low-impact to extract. More and more drywall today contains pre-consumer waste in the form of synthetic gypsum created by sulfur removal systems in the smokestacks of coal-burning power plants. This material is sometimes referred to as flue-gas desulfurization gypsum.
The joint compound used to finish drywall contains synthetic additives that may affect some chemically sensitive people; specialty alternatives are available. Dry-mix, setting-type joint compounds, which are sold in powder form and mixed on site, contain fewer additives.
Cabinets made from nontoxic materials and finishes or solid wood are available. People with chemical sensitivities often find enameled-metal cabinets to be the least problematic.
Clear wood trim materials are increasingly difficult to find (or more expensive), and they place a high demand on virgin timber. On the other hand, this is an application where high-quality wood can be fully seen and celebrated. Finger-jointed trim for painted applications, and veneer-covered, finger-jointed trim for stain applications, are good substitutes.
Using FSC-certified woods
Whenever possible, woods used in interior finish and trim should be from certified well-managed forests. Third-party certification to standards developed by the Forest Stewardship Council provides a way that users can verify environmental claims. Currently there are two U.S.-based organizations that certify forest operations (and wood products): Scientific Certifications Systems, and the Rainforest Alliance (SmartWood).
Tropical hardwoods should be avoided unless they come from FSC-certified sustainable sources, as their harvest can cause irreparable damage to tropical rainforests., well-managed tropical forests are increasingly becoming certified.