Is Creosote Bad for You? Health Risks Explained

Coal tar creosote is genuinely harmful. It contains hundreds of chemicals, many of them polycyclic aromatic hydrocarbons (PAHs) that are classified as probable or known carcinogens by major health agencies. Exposure happens through skin contact, breathing fumes, or even living near contaminated sites, and the health consequences range from immediate irritation to long-term organ damage. The picture gets more complicated when you realize that “creosote” refers to several different substances, not all equally dangerous, and that the dose and route of exposure matter enormously.

What Creosote Actually Is

The word “creosote” gets applied to at least three different things, and confusing them leads to real misunderstandings. The one that dominates health concerns is coal tar creosote, a thick, oily liquid distilled from coal tar and used for over a century to preserve railroad ties, utility poles, marine pilings, and fence posts. It is a complex mixture of hundreds of compounds, with PAHs making up the bulk of what makes it toxic. The dark, tarry substance you see on old railroad ties or smell near treated-wood facilities is coal tar creosote.

There is also wood creosote, derived from beech and other hardwoods, which has historically been used in small doses as a folk remedy for coughs and intestinal problems, particularly in parts of Asia. And then there is the creosote bush (Larrea tridentata), a desert shrub of the American Southwest whose leaves contain a resin sometimes marketed as “chaparral” in herbal supplements. The bush and the industrial chemical share a name but almost nothing else. Cases of acute toxic liver damage have been linked to ingestion of chaparral supplements derived from creosote bush leaves, so even the “natural” version carries risk.¹ For the rest of this article, “creosote” means coal tar creosote unless otherwise noted, because that is what most people encounter and what carries the most documented health risk.

How You Get Exposed

Creosote enters the body through two main routes: the skin and the lungs. What surprises many people is how dominant the skin route is. A study of workers at creosote-treating plants found that the amount of PAH metabolites excreted in their urine far exceeded what could be explained by inhalation alone. Dermal uptake accounted for the vast majority of the internal dose, sometimes exceeding the inhaled dose by a factor of fifty.² This means that simply handling creosote-treated wood without gloves, or getting the oily residue on exposed skin, can deliver a substantial chemical load even if you are outdoors with plenty of ventilation.

Inhalation still matters, especially for volatile components like naphthalene, which evaporate readily from freshly treated wood or heated surfaces. Workers involved in timber impregnation and subsequent processing of treated wood showed measurable internal levels of creosote components well above biological reference values, regardless of the specific task they performed.³ Hot weather makes things worse, because heat increases the volatilization of PAHs from treated surfaces.

For non-workers, exposure usually comes from living near a wood treatment plant, handling old railroad ties repurposed as garden borders, or burning creosote-treated wood. Residents within a couple of miles of an active treatment facility have been found with elevated levels of chlorinated dioxins and furans in their blood, with dioxin concentrations roughly two to three times higher than in control subjects.⁴ These compounds are not creosote itself but are co-released alongside it during the treatment process, compounding the exposure picture.

Immediate Symptoms From Short-Term Exposure

You do not need years of chronic exposure to feel the effects of creosote. Residents living near a wood treatment plant have reported acute symptoms including headaches, nausea, eye irritation, and sore throats during periods when creosote odor was strong.⁵ Direct skin contact with creosote or freshly treated wood can cause chemical burns, rashes, and a distinctive stinging sensation. The eyes are particularly sensitive: splashes or heavy fumes can cause tearing and a burning feeling that lingers for hours.

These acute effects are generally reversible once exposure stops, but they serve as an important warning signal. If you can smell creosote strongly enough to get a headache, you are inhaling volatile PAHs and other chemicals at levels that are doing more than just bothering your nose.

Cancer Risk and What the Evidence Shows

The International Agency for Research on Cancer classifies coal tar creosote as a Group 2A carcinogen, meaning it is “probably carcinogenic to humans.” The concern centers on PAHs like benzo[a]pyrene, which is itself classified as a Group 1 (definite) carcinogen. The mechanism is well understood at the cellular level: PAHs are metabolized by the body’s enzyme systems, particularly the cytochrome P450 family in the liver, lungs, skin, and kidneys. This metabolism can produce reactive chemical intermediates called epoxides that bind directly to DNA, potentially triggering mutations that lead to cancer.⁶

Research on fish exposed to benzo[a]pyrene from creosote-contaminated environments has confirmed that the primary route of DNA damage is this covalent binding of metabolites to DNA rather than oxidative stress, and that mitochondria (the energy-producing structures in cells) are also important targets of this toxicity.⁷ While that finding comes from fish studies, the same metabolic pathways exist in humans, and the result helps explain why PAH exposure can damage tissues throughout the body.

The epidemiological picture in human workers is, perhaps surprisingly, not as dramatic as you might expect. A large retrospective study following workers at eleven U.S. wood-treating plants found that overall mortality was actually slightly lower than expected for the general population. Among hourly employees, the one cancer that stood out was multiple myeloma, a blood cancer, which occurred at about four times the expected rate. However, further analysis did not find a clear upward trend with longer employment, which weakened the case for a direct causal link. Lung cancer risk in this cohort was tied to smoking rather than to any specific job or creosote exposure category.⁸

That study does not mean creosote is safe. The “healthy worker effect” tends to make occupational cohorts look healthier than the general public, because people who are too sick to work drop out of the workforce. And animal studies, mechanistic evidence, and research on other PAH-exposed populations all point clearly toward cancer risk. The weight of evidence across agencies and review bodies is that chronic creosote exposure increases cancer risk, even if nailing down the precise magnitude in any single human cohort has proven tricky.

Chronic Effects Beyond Cancer

Cancer gets the headlines, but creosote can damage organs in ways that have nothing to do with tumors. A striking case report documented what happened to a person who chronically inhaled coal tar creosote vapors over an extended period. The patient, a 56-year-old aromatherapist, developed advanced kidney failure from a type of kidney inflammation called chronic tubulo-interstitial nephritis. After starting dialysis, she continued inhaling creosote in secret, which led to seizures, difficulty coordinating movement, cognitive decline, and pronounced shrinkage of brain tissue visible on imaging.⁹

That is an extreme example of deliberate inhalation, not typical occupational or residential exposure. But it illustrates that the kidneys and the nervous system are vulnerable targets. PAHs and their metabolites are processed by the kidneys as the body tries to clear them, and at high enough loads the filtering structures of the kidneys can become inflamed and scarred. The neurotoxicity seen in the case above is consistent with what is known about chronic solvent exposure more broadly: sustained inhalation of volatile organic compounds can erode cognitive function and cause structural brain changes over time.

Skin is also at risk for chronic effects. Prolonged repeated contact with creosote, particularly in combination with sun exposure, has been associated with increased photosensitivity and skin lesions. The PAHs in creosote absorb ultraviolet light and can produce phototoxic reactions, essentially amplifying the damage that sunlight does to exposed skin.

The Difference Between Occupational and Casual Exposure

Reading about creosote hazards can leave you wondering whether you need to worry about that old railroad-tie garden border in the backyard. Context matters here. The studies documenting serious health effects involve workers handling wet, freshly treated wood on a daily basis or people living right next to active treatment plants. These represent sustained, high-level exposures over months or years.

Old, weathered, creosote-treated wood is less hazardous than fresh material because the volatile components have largely evaporated and the surface has oxidized. That said, “less hazardous” is not “safe.” Cutting, sanding, or burning old treated wood releases PAHs in concentrated form. Burning creosote-treated wood in a fireplace or stove is particularly ill-advised, because combustion releases a dense cloud of PAH-laden smoke directly into your breathing zone or into your home if the chimney draws poorly. The general guidance from environmental agencies is to avoid burning treated wood entirely and to wear gloves when handling it.

For the backyard railroad-tie scenario, the practical risk depends on how weathered the ties are, whether anyone is in regular skin contact with them, and whether they are anywhere near a vegetable garden. PAHs can leach into surrounding soil and potentially be taken up by plants, so using creosote-treated wood as raised-bed borders for food crops is a bad idea. For purely ornamental landscaping, the risk to an adult who occasionally touches old ties is low, though you would still want to wash your hands and avoid letting children play on them.

What Happens to the Soil and Water

Creosote does not just affect the people directly handling it. When it enters the environment, it becomes a persistent pollution problem. At a lumber mill in Libby, Montana, uncontrolled releases of creosote and pentachlorophenol between 1946 and 1969 contaminated the soil and two underlying aquifers badly enough that the EPA placed the site on its National Priorities List in 1983.¹⁰ At another creosote waste site, groundwater monitoring over two years found naphthalene concentrations above 800 micrograms per liter and methylnaphthalene above 400 micrograms per liter in wells around the facility, with contamination migrating roughly 300 feet from the source.¹¹

The stubborn persistence of PAHs in soil is part of what makes creosote contamination so difficult to deal with. Lighter, smaller PAH molecules (the two- and three-ring compounds) break down relatively quickly through natural microbial activity or engineered bioremediation. In one field-scale cleanup at a former creosoting plant, the two-ring PAHs were reduced by about 97 percent and three-ring compounds by about 82 percent through a process of mixing, aerating, and fertilizing the soil to stimulate native microbes.¹² But the heavier PAHs, the four-, five-, and six-ring compounds that include some of the most carcinogenic substances, are far more resistant. Six-ring PAHs in that same study were reduced by less than 35 percent.

Researchers have been experimenting with ways to speed up the breakdown of these stubborn compounds. Adding cyclodextrin solutions to contaminated soil enhanced the removal of larger PAHs by helping to pull them off soil particles and make them available to microbes.¹³ Other approaches, including combining bioaugmentation (adding specialized microbes) with biostimulation (feeding nutrients to existing soil bacteria), have shown that creosote levels drop in all treatment scenarios, though the most toxic heavy PAHs remain the hardest to eliminate.¹⁴ The upshot for communities near former wood-treatment sites is that cleanup is possible but slow and incomplete, and groundwater contamination can linger for decades.

Why Creosote Is Still in Use

Given everything above, you might wonder why creosote has not been outright banned everywhere. The answer is economics and effectiveness. Creosote is one of the most effective and longest-lasting wood preservatives ever developed. A creosote-treated utility pole or railroad tie can last 30 to 50 years in service, far outperforming most alternatives. Railroads alone account for an enormous volume of treated timber, and substitutes like concrete or steel ties come with their own environmental and cost trade-offs.

Regulatory approaches vary by country. The European Union restricted creosote use in 2003 and has continued to tighten regulations, though it still permits industrial use under controlled conditions with specific worker-protection requirements. In the United States, creosote remains registered as a restricted-use pesticide, meaning only licensed applicators can apply it, and consumer sale is prohibited. You cannot buy creosote at a hardware store, but you can still encounter it on treated products like railroad ties, utility poles, and marine pilings that enter the secondhand market.

Germany, as one example, has set an occupational exposure limit for naphthalene (a major volatile component of creosote) at 0.5 milligrams per cubic meter of air, reflecting the legal position that any measurable exposure requires active management.³ The trend across industrialized nations is toward tighter controls and gradual phase-out for applications where alternatives exist, while allowing continued use in critical infrastructure where no practical substitute has matched creosote’s performance and cost.

Protecting Yourself in Practice

If you work with creosote-treated materials or have them on your property, a few practical steps reduce your risk substantially. Wear chemical-resistant gloves and long sleeves whenever handling treated wood, especially if it still feels oily or smells strongly. The dominance of the dermal exposure route means that a good barrier on your skin matters more than a dust mask in many situations, though respiratory protection is still warranted during cutting, sanding, or demolition of treated material.

Never burn creosote-treated wood. Not in a fireplace, not in a fire pit, not in a brush pile. The combustion products concentrate PAHs and release them as fine particulate matter that penetrates deep into the lungs. If you need to dispose of treated wood, check with your local waste authority for accepted disposal methods, which typically involve designated landfill facilities rather than open burning.

For existing landscape timbers made of creosote-treated wood, sealing them with a polyurethane or similar coating can reduce leaching into surrounding soil. Keep them away from vegetable gardens, play areas, and anywhere that pets or children spend extended time on the ground. If the timbers are decades old, visibly dry, and not flaking, the ongoing exposure is modest for an adult who touches them occasionally. But if they are still weeping oily residue in warm weather, they are actively off-gassing and should be removed or sealed.

If you live near a current or former wood-treatment facility, checking whether the site has been assessed by your state environmental agency or the EPA is worthwhile. Many former creosoting sites are on state or federal cleanup lists, and some offer community health assessments or biomonitoring programs. Knowing whether your well water or soil has been tested gives you concrete information instead of vague worry.