Wood composite materials are widely used in construction and furniture, raising concerns about potential chemical emissions and associated health effects. This article explores the nature of wood composites, the chemicals involved, exposure pathways, health implications, and strategies for reducing risks.
Understanding Wood Composite Composition
Wood composite materials are manufactured products created by combining wood fibers, particles, or veneers with adhesives and resins. Common types include particleboard, medium-density fiberboard (MDF), and plywood.
Particleboard is made from wood chips or sawmill shavings pressed with a synthetic resin. MDF is produced by combining wood fibers with wax and a resin binder under high temperatures and pressure. Plywood consists of multiple layers of cross-laminated wood veneers bonded with moisture-resistant adhesives. These materials often utilize sawmill scraps and wood waste, contributing to resource efficiency.
Key Substances and Their Role in Toxicity
Formaldehyde is a primary chemical of concern in wood composite products, commonly used in the adhesives and resins that bind wood particles. Urea-formaldehyde (UF) resins are frequently employed in particleboard and MDF, while phenol-formaldehyde (PF) resins are typically found in plywood and oriented strand board (OSB), especially for construction where moisture resistance is needed. This gas can contribute to indoor air pollution through a process called off-gassing.
Volatile organic compounds (VOCs) are another group of chemicals emitted from wood composites and other building materials. Regulations have been established to address concerns about formaldehyde emissions. The California Air Resources Board (CARB) implemented strict standards, known as CARB Phase 2, to limit formaldehyde emissions from composite wood products such as particleboard, MDF, and hardwood plywood. The U.S. Environmental Protection Agency (EPA) later established the Toxic Substances Control Act (TSCA) Title VI, which sets national formaldehyde emission standards identical to CARB’s limits. Products compliant with these regulations are typically labeled as “CARB Phase 2 Compliant” or “TSCA Title VI Compliant.”
Pathways of Exposure
Exposure to chemicals from wood composite materials primarily occurs through off-gassing and dust generation. Off-gassing releases chemicals like formaldehyde and VOCs into the air from the materials over time. This release is particularly noticeable when products are new or in warm, poorly ventilated conditions, leading to a “new home smell.” Formaldehyde can be released from composite wood furniture, especially in areas with limited airflow, where emissions can accumulate.
Another significant pathway of exposure is the generation of fine dust particles during activities such as cutting, sanding, or demolition of wood composite products. The primary airborne hazard during these mechanical processes is the wood dust itself.
Addressing Health Concerns
Exposure to substances released from wood composite materials can lead to various health effects. Short-term exposure to formaldehyde, for instance, can cause irritation of the eyes, nose, and throat, often leading to coughing, sneezing, and wheezing. Some individuals may also experience skin rashes.
Volatile organic compounds (VOCs) can also cause immediate symptoms such as headaches, dizziness, nausea, and irritation of the eyes, nose, and throat. For those with pre-existing respiratory conditions like asthma, exposure to these irritants can worsen symptoms. Poor ventilation in indoor spaces can allow these harmful vapors to build up, compromising air quality.
Long-term exposure to certain chemicals, particularly formaldehyde, has been linked to more serious health concerns. The International Agency for Research on Cancer (IARC) has classified formaldehyde as a Group 1 human carcinogen, based on sufficient evidence that it can cause nasopharyngeal cancer and myeloid leukemia. While occupational exposure to high levels over many years is primarily associated with these risks, increased sensitivity to formaldehyde can also develop over time.
Reducing Exposure and Safe Use
Several steps can help minimize risks associated with wood composite materials. Ensuring adequate ventilation in indoor spaces is important, especially when new products are introduced, as this helps dissipate off-gassed chemicals. Opening windows and using fans can bring in fresh air and prevent the accumulation of pollutants.
Choosing products certified for low emissions is another strategy. Consumers can look for labels indicating compliance with standards such as CARB Phase 2 or TSCA Title VI, which signify adherence to strict formaldehyde emission limits. Some manufacturers also offer products made with ultra-low emitting formaldehyde (ULEF) or no-added formaldehyde (NAF) resins, which further reduce chemical release. Applying a non-toxic sealant to exposed surfaces of wood composite furniture or products can create a barrier that limits off-gassing of harmful fumes. During installation, cutting, or removal of wood composite materials, proper handling is important. Wearing respiratory protective equipment, such as masks, can help prevent the inhalation of fine wood dust particles.