What Is Anthracene?

Anthracene is a polycyclic aromatic hydrocarbon, or PAH, made of three fused benzene rings. It is a solid, crystalline organic compound that occurs in coal tar, petroleum-derived residues, combustion byproducts, creosote, and contaminated industrial wastes. In drinking water work, anthracene is usually treated as part of the broader PAH and semi-volatile organic compound group rather than as an isolated household chemical.

Anthracene has historically been used as an intermediate in dye manufacturing, pigments, scintillation materials, organic semiconductors, and specialty chemical production. It is also present in coal tar fractions, asphaltic materials, soot, petroleum residues, and byproducts from coking, gasification, and high-temperature industrial processes. Because it is hydrophobic and poorly soluble in water, it often binds strongly to soil, sludge, sediments, and organic matter rather than remaining evenly dissolved in water.

Anthracene is important in drinking water because its presence can signal industrial contamination, coal tar releases, petroleum-related contamination, or a larger PAH mixture. Even when anthracene itself is not the most toxic PAH in a plume, it can occur beside more hazardous compounds such as benzo[a]pyrene, fluoranthene, pyrene, phenanthrene, naphthalene, and alkylated PAHs. A detection of anthracene in a well should therefore prompt evaluation of the complete PAH profile, not just the single compound.

Scientific Identity

Anthracene has the molecular formula C₁₄H₁₀ and a molecular weight of approximately 178.23 g/mol. It is one of the three-ring PAHs, structurally related to phenanthrene but arranged in a linear fused-ring configuration. It is not an element and does not have a chemical symbol in the way metals such as lead or arsenic do.

From a water-quality perspective, anthracene is classified as a semi-volatile organic compound and a hydrophobic organic contaminant. It has low aqueous solubility, commonly reported in the tens of micrograms per liter range under ambient conditions, and a relatively high organic carbon partitioning tendency. These properties cause anthracene to sorb to aquifer solids, suspended particulates, pipe deposits, sediments, and granular activated carbon. It may persist in oxygen-poor subsurface environments, especially where it is trapped within coal tar, oily residues, or non-aqueous phase liquids.

Anthracene can degrade under sunlight through photochemical reactions, which is one reason it may be less persistent at the surface of sunlit waters than in dark aquifers or buried sediments. In groundwater, however, photolysis is absent and biodegradation can be slow, particularly if oxygen, nutrients, and adapted microbial communities are limited. Its environmental behavior is therefore strongly site-specific: dissolved concentrations may be modest, but contaminated sediments, tar lenses, or organic-rich soils can act as long-term sources.

How Anthracene Enters Drinking Water

Anthracene enters drinking water sources primarily through industrial releases rather than through routine municipal water treatment. Important sources include former manufactured gas plants, coal tar disposal areas, coking plants, wood-treatment facilities that used creosote, asphalt and roofing-material operations, petroleum refineries, rail yards, bulk fuel terminals, hazardous waste sites, and areas where PAH-contaminated fill was placed. In these settings, anthracene may be part of a complex mixture containing lighter PAHs, heavier carcinogenic PAHs, petroleum hydrocarbons, phenols, cyanide, metals, and solvents.

Groundwater contamination often occurs when coal tar, creosote, petroleum waste, or industrial sludge migrates into soil and reaches the water table. Because anthracene binds strongly to organic matter, it may move slowly compared with more soluble contaminants. However, dissolved organic carbon, colloids, oily phases, and fine suspended particles can enhance transport. A water well screened near contaminated sediments or within an industrial plume can draw anthracene into raw water, particularly if pumping changes hydraulic gradients.

Surface-water sources can be affected by stormwater runoff from industrial yards, contaminated sediments in rivers and harbors, atmospheric deposition from combustion sources, and erosion of PAH-contaminated soils. Anthracene is often concentrated in sediment rather than in the overlying water column, but disturbance from dredging, floods, construction, boat traffic, or high-flow events can resuspend particle-bound PAHs. Surface-water intakes located downstream of industrial corridors, ports, gasworks sites, or urban stormwater channels may require PAH monitoring when historical contamination is known.

Vapor intrusion is not usually driven by anthracene alone because it is less volatile than many petroleum hydrocarbons and chlorinated solvents. However, anthracene may occur in the same plume as volatile compounds such as benzene, toluene, naphthalene, or light petroleum fractions. For properties near coal tar or petroleum plumes, vapor intrusion investigations may be relevant even if anthracene is mainly a groundwater and sediment indicator.

Occurrence and Exposure

Anthracene is most likely to be found in drinking water where wells or surface-water intakes are influenced by industrial contamination. Private wells near former manufactured gas plants, creosote-treated wood facilities, waste lagoons, landfills, rail yards, old industrial waterfronts, and petroleum spill areas deserve particular attention. Municipal systems may detect anthracene when source waters are affected by contaminated sediments or when a well field intersects a PAH-bearing groundwater plume.

For the general population, exposure to anthracene is often higher from food, smoke, soot, occupational contact, contaminated soil, or air particulates than from treated drinking water. Grilled or smoked foods, tobacco smoke, urban air pollution, and contact with coal tar products can contribute to PAH exposure. Drinking water becomes a more important pathway when a household uses an untreated private well in or near a documented industrial plume, or when water contains visible oily residues, petroleum odors, or elevated PAH laboratory results.

Anthracene’s low solubility means it may not produce high dissolved concentrations compared with more mobile solvents. This can create a false sense of security if only dissolved water is tested. Sediments, particulates, or well-bottom debris may contain higher PAH levels than filtered water. For private wells, sampling technique matters: samples should be collected according to laboratory instructions, without aeration, with proper containers, and with attention to whether the analysis measures dissolved-only or total recoverable PAHs.

Health Effects and Risk

Anthracene is considered a toxic organic contaminant, but its health-risk profile differs from highly carcinogenic PAHs such as benzo[a]pyrene. International and national assessments have generally found limited evidence for anthracene’s carcinogenicity as an individual compound, and it is often described as not classifiable regarding human carcinogenicity because available human and animal data are inadequate. This does not make anthracene harmless. It means that cancer risk assessment for anthracene alone is uncertain and must be interpreted with attention to the full PAH mixture.

Known toxicological concerns for anthracene include irritation of the skin, eyes, and respiratory tract, especially in occupational or high-contact settings. Anthracene and related PAHs can also participate in phototoxic reactions, where exposure to light enhances tissue irritation or cellular injury. Experimental data have raised concerns about effects on the liver, kidneys, blood, and immune or developmental endpoints at sufficient doses, although drinking-water-specific human data are limited.

The major public health concern in drinking water is that anthracene can act as a marker for broader PAH contamination. Coal tar and creosote mixtures may contain compounds with stronger evidence of carcinogenicity, mutagenicity, and long-term toxicity. Benzo[a]pyrene is the classic example, but other PAHs and alkylated PAHs can contribute to risk. Therefore, a water result showing anthracene should not be evaluated in isolation; the laboratory report should be reviewed for naphthalene, phenanthrene, fluoranthene, pyrene, chrysene, benzo[a]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, indeno[1,2,3-cd]pyrene, dibenz[a,h]anthracene, and benzo[a]pyrene where available.

The “High” risk level for this profile reflects the significance of industrial PAH contamination in drinking-water sources, the possibility of co-contaminants, and the persistence of PAH source zones. Sensitive groups include pregnant people, infants, young children, people with liver or kidney disease, and households relying on private wells near known industrial or waste sites. If anthracene is detected in a drinking water supply, users should consider confirmatory testing, full PAH analysis, and interim exposure reduction until the source and treatment performance are understood.

Testing and Monitoring

Anthracene is not reliably identified by basic home test strips, taste, odor, color, or standard mineral testing. It requires specialized laboratory analysis for PAHs or semi-volatile organic compounds. Laboratories commonly use gas chromatography with mass spectrometry, often referred to as GC-MS, following methods designed for extractable organic compounds. Depending on the jurisdiction and laboratory, anthracene may be included in EPA-style PAH/SVOC method suites such as Method 525 series for drinking water or Method 8270-type analyses for environmental samples, although exact method selection should be confirmed with the laboratory.

Sampling is critical because PAHs can adsorb to container walls, suspended solids, and organic matter. Laboratories typically require amber glass bottles, chemical preservation or chilling, limited headspace where specified, and strict holding times. Plastic containers are generally inappropriate for PAH analysis because hydrophobic organic compounds can sorb to plastic. Samples should be collected before any treatment device and, when evaluating treatment, again after the treatment unit to measure removal efficiency.

For private wells near industrial contamination, a useful monitoring plan often includes a full PAH panel, volatile organic compounds, petroleum hydrocarbons, and site-specific co-contaminants such as phenols, benzene, toluene, ethylbenzene, xylenes, cyanide, metals, or chlorinated solvents. For municipal systems, monitoring decisions are usually tied to source-water vulnerability, regulatory requirements, watershed history, and prior detections. In contaminated aquifers, anthracene concentrations can change over time as pumping patterns, seasonal groundwater levels, and plume boundaries shift.

Treatment Methods

Anthracene can be treated effectively, but treatment must be designed for hydrophobic organic chemicals and verified by laboratory testing. The most appropriate technology depends on concentration, flow rate, co-contaminants, sediment load, dissolved organic carbon, and whether the goal is point-of-use drinking water protection or whole-building treatment.

Activated carbon is the preferred treatment because anthracene’s hydrophobic ring structure has strong affinity for carbon surfaces. Granular activated carbon systems can be installed as point-of-entry units for an entire home or as point-of-use systems at a drinking water tap. For a contaminated private well, a point-of-entry system is often more protective if water is used throughout the home and if the contamination includes other organic chemicals. For a municipal customer with a low-level detection or a localized concern at one tap, a properly certified point-of-use carbon system may be sufficient, but only if the contaminant profile and filter capacity are appropriate.

Activated carbon can fail when it is undersized, exhausted, bypassed, poorly maintained, or loaded with competing organic matter. High dissolved organic carbon, iron fouling, sediment, oil droplets, surfactants, or bacterial growth can reduce adsorption capacity. PAH contamination from coal tar or petroleum sites may include a mixture of compounds that compete for adsorption sites; lighter compounds may break through sooner than anthracene, while heavy PAHs may accumulate strongly. Lead-lag carbon vessels, routine post-treatment sampling, pressure monitoring, and scheduled media replacement are important for high-risk wells.

Reverse osmosis and advanced oxidation may be useful as additional treatment, but they should not be selected casually for a PAH plume. RO is commonly a point-of-use technology and does not protect showers, bathroom sinks, or all household uses unless installed at a much larger scale. Advanced oxidation is more common in engineered municipal or remediation systems than in ordinary homes. Any treatment plan for anthracene should be based on actual laboratory results for the full contaminant mixture.

Regulations and Guidelines

Regulatory treatment of anthracene varies by country, state, province, and water program. In the United States, anthracene does not have a widely recognized federal primary drinking water Maximum Contaminant Level as an individual compound in the same way that some regulated contaminants do. PAHs are addressed through a combination of drinking water monitoring, source-water protection, hazardous waste regulation, Superfund and cleanup programs, and state-level groundwater or drinking water criteria. Benzo[a]pyrene, a related PAH with stronger carcinogenic evidence, has a federal drinking water standard, but that value should not be assumed to apply directly to anthracene.

The World Health Organization and many national authorities have historically focused drinking-water guideline development on PAHs with stronger toxicological evidence or greater regulatory priority. Some guidelines address benzo[a]pyrene or sums of selected PAHs rather than anthracene alone. The European Union drinking water framework includes parameters for selected PAHs, but anthracene is not always part of the regulated PAH sum used for compliance. Local environmental agencies may still use anthracene screening levels or cleanup criteria for groundwater, soil, and contaminated sites.

Because limits and action levels vary by jurisdiction, a detection of anthracene should be interpreted using the standards applicable to the specific water supply and location. Private well owners are often not covered by routine public-water compliance monitoring, so they may need to consult a certified laboratory, local health department, environmental regulator, or qualified hydrogeologist. When anthracene is found near an industrial or waste site, regulators may require additional investigation of the plume, source removal, alternative water supply, wellhead treatment, or long-term monitoring.

Related Contaminants

Frequently Asked Questions

Is anthracene a common drinking water contaminant?

Anthracene is not common in well-managed public drinking water, but it can be important near industrial sites, coal tar contamination, creosote facilities, petroleum releases, manufactured gas plants, and contaminated sediments. It is more often a site-specific contamination problem than a widespread background drinking-water issue.

Can I smell or taste anthracene in water?

Anthracene itself is not a reliable taste-or-odor indicator at drinking-water concentrations. However, the mixtures that contain it, such as coal tar, creosote, or petroleum residues, may produce oily, smoky, tar-like, or chemical odors. Odor should be treated as a warning sign, but absence of odor does not prove the water is safe.

Does boiling remove anthracene?

No. Boiling is not an appropriate treatment for anthracene. Because anthracene is poorly soluble and not readily removed by ordinary boiling, boiling may leave residues behind as water evaporates. If lighter volatile contaminants are also present, boiling can increase inhalation exposure.

What should I test for if anthracene is detected?

A full PAH panel is recommended, along with volatile organic compounds and petroleum hydrocarbon testing if the source may involve coal tar, creosote, fuel, or industrial waste. Important related compounds include naphthalene, phenanthrene, fluoranthene, pyrene, chrysene, benzo