Creosote is a complex chemical substance widely used in industrial applications and is also a common byproduct of burning wood. While recognized for its effectiveness as a wood preservative, its chemical nature introduces health risks. Understanding its composition and common exposure pathways is essential for assessing the true danger. Health consequences can range from immediate irritations to severe, long-term conditions, depending on the concentration and duration of contact.
What Creosote Is and Common Sources of Exposure
Creosote is a mixture of hundreds of compounds, primarily categorized as coal-tar creosote and wood-tar creosote. Coal-tar creosote is a thick, brownish-black liquid derived from coal tar distillation. This form is associated with industrial use and significant health risks because it contains high concentrations of polycyclic aromatic hydrocarbons (PAHs), which are the primary toxic components.
Public exposure to coal-tar creosote commonly occurs via preserved wood products like railroad ties, utility poles, and marine pilings. These products are treated to resist decay and insects. Exposure happens when compounds leach into the soil or when the treated wood is handled, sawed, or burned. Wood-tar creosote is the sticky, dark residue that builds up inside chimneys and flues when wood is burned. Exposure to wood-tar creosote typically happens during chimney cleaning or from inhaling combustion smoke and vapors.
Immediate and Short-Term Health Effects
Exposure to creosote, particularly the coal-tar variety, can trigger acute reactions upon contact with the skin, eyes, or respiratory system. Direct skin contact often leads to irritation, burning, redness, and a rash, sometimes resulting in chemical burns. A specific reaction called photosensitivity or phototoxicity can also occur. This makes the skin extremely sensitive to sunlight, potentially leading to exaggerated sunburn or blistering.
If creosote or its vapors enter the eyes, severe irritation, tearing, burning, and light sensitivity can result. High concentrations can cause permanent damage to the cornea or even loss of vision. Inhalation of vapors or dust, such as during chimney sweeping or burning treated wood, irritates the nose, mouth, throat, and lungs, leading to coughing and shortness of breath. Ingesting large amounts can lead to severe gastrointestinal distress, convulsions, and is considered a poisoning hazard.
Long-Term Health Concerns and Carcinogenicity
Chronic exposure to coal-tar creosote is associated with severe health consequences due to its high concentration of PAHs. The International Agency for Research on Cancer (IARC) has classified coal-tar creosote as a probable human carcinogen. This classification is based on occupational studies and animal data showing that prolonged contact can lead to various cancers.
The high PAH content is responsible for this carcinogenic potential because these compounds damage genetic material within cells. Workers with prolonged exposure, such as those in wood treatment facilities or chimney cleaning, have shown an increased risk of developing skin cancer, particularly of the scrotum. Chronic exposure, especially through breathing or swallowing, has also been linked to an increased risk of cancers affecting internal organs, including the lung and bladder. Extended exposure can cause non-cancerous internal damage, with the liver, kidney, and brain being particularly susceptible.
Minimizing Risk and Safe Handling
Minimizing health risks involves reducing both direct contact and inhalation of creosote vapors and dust. A primary preventative measure is to never use creosote-treated wood indoors, in wood stoves, fireplaces, or where it may contact food or drinking water. Treated wood should only be used for its intended purpose, such as utility poles or railroad ties, and should not be repurposed for residential projects like garden beds or furniture.
When handling creosote-treated wood or cleaning creosote buildup from a chimney, wear appropriate protective equipment. This includes chemical-resistant gloves, long-sleeved shirts, long pants, and a dust mask to prevent inhalation of sawdust or soot. Working outdoors or ensuring good ventilation significantly reduces the concentration of airborne vapors. If skin contact occurs, immediately wash the exposed area thoroughly with soap and water to remove the oily residue. For eye exposure, rinse the eyes cautiously with water for several minutes and seek medical attention if irritation persists or if creosote is ingested or inhaled.