Other Basic Organic Chemical Manufacturing (U.S.) — NAICS 32519

An investor's rollup primer for public- and private-market readers. NAICS = North American Industry Classification System, the U.S. government's standard code for industries. Figures are the most recent available; forward-looking statements are labeled as judgments, not facts.

1. Overview

NAICS industry 32519 is a bookkeeping bundle, not a single market. It groups three very different businesses that share one trait: each makes basic organic (carbon-based) chemicals that the Census Bureau did not give a more specific code. Together they ship about $156 billion a year [1], which sounds like one industry but is really three:

• Fuel and industrial ethanol (corn distilled into a gasoline blendstock) — a policy-anchored, farm-linked commodity fuel;
• A residual "everything else" bin of large-volume intermediates — acetic acid, methanol, formaldehyde, plasticizers, silicones, fatty acids, refrigerant blends — sold by the ton to other manufacturers; and
• A tiny byproduct-chemistry niche — coal-tar distillation and pine (rosin/tall-oil) chemicals, plus charcoal briquettes.

Why an investor should care: the value inside this code is wildly uneven, and the interesting story is the contrast. One child (the residual bin) is two-thirds of the money and four-fifths of the jobs; another (ethanol) is a third of the money but a tenth of the jobs because its plants are almost fully automated; the third is a rounding error that is quietly shrinking. All three are cyclical, capital-intensive, spread-margin businesses, but they answer to different feedstocks, different customers, and different parts of Washington.

Ways in: there is no single clean way to own 32519, and no fund tracks it. Exposure is assembled child by child — a few ethanol pure-plays, a roster of diversified chemical majors, and, for much of the real capacity, private, foreign-owned, or farmer-cooperative ownership. This primer leads with how the three children differ, then treats the level as a whole.

2. What's inside — the three children and how they differ

The level contains three NAICS industries (six-digit codes). They are grouped for administrative tidiness, not because they compete or share supply chains.

Shares computed from the child figures below against the level ground truth; establishment, employment, and receipts subtotals reconcile exactly to the level [1][2][3][4][5].

The single most important thing this table shows: 325199 is the industry by money and by people, 325193 (ethanol) punches far above its headcount because ethanol plants run with ~40–50 workers each, and 325194 is a small, consolidating niche. They also differ in who you'd buy: ethanol has the most genuine public pure-plays but the most private/co-op ownership; the residual bin is almost entirely "a segment inside a bigger chemical company"; the gum-and-wood niche has no U.S. pure-play at all.

3. How big it is

Federal statistics for the whole of NAICS 32519 (our ground truth):

(A note on the firm count: the three children list 118 + 40 + 663 = 821 firms, but the level shows 806 because a firm operating in more than one child is counted once at the level. Establishments, employment, and receipts, by contrast, add up exactly across the children [3][4][5].)

The undercount / boundary caveat — two directions, both honest. First, this is not an industry with a hidden tail of tiny or informal operators — these are permitted, capital-heavy industrial plants, so the federal picture of the dedicated processors is broadly complete. Second, and more important, headcount badly understates the industry's economic weight, for two reasons that differ by child:

• Automation. Ethanol (325193) generates ~$4.7 million of shipments per worker because biorefineries are highly automated; the ~10,700 plant workers sit atop a farm economy that the Renewable Fuels Association estimates supports roughly 317,000 total jobs and ~$50 billion of GDP once suppliers and corn growers are counted [6]. Census plant-worker counts are accurate but tell you little about that footprint.
• The "residual" boundary. Because 325199 is defined as not elsewhere classified, organic chemicals made inside large petrochemical complexes are often booked under petrochemicals (325110) or plastics resins instead — so the $100 billion residual bin understates true U.S. basic-organic-chemical output rather than overstating it [5]. And for the gum-and-wood niche (325194), the key feedstocks are byproducts made outside the code — coal tar at steel-mill coke ovens (NAICS 331110), crude tall oil at kraft pulp mills (NAICS 322) — so the upstream supply base is invisible here [4].

One more caveat: receipts are from the 2022 Economic Census while employment and payroll are 2023 County Business Patterns, so the years are mixed by a year.

4. The investable universe — where the value concentrates

There is no pure-play for the level and no dedicated fund. Exposure is built child by child, and it concentrates very differently in each. (Per house style, tickers and scale appear only in this section and Section 10.)

Child 325193 — Ethanol: the only child with real public pure-plays, but mostly private.

• Pure-plays: Green Plains (Nasdaq: GPRE), REX American Resources (NYSE: REX), Alto Ingredients (Nasdaq: ALTO) [9].
• Diversified exposure: Archer-Daniels-Midland (NYSE: ADM) and Valero Energy (NYSE: VLO) each run ~1.7 billion gal/yr as one segment; The Andersons (Nasdaq: ANDE) blends ethanol into broader agribusiness [3].
• Private / non-listed: POET is the largest single U.S. producer (~3 billion gal/yr, roughly a fifth of national output); Marquis Energy and Koch's Flint Hills Resources are private; and hundreds of plants are farmer cooperatives and single-plant LLCs [3].

Child 325199 — All Other Basic Organic: value spread across diversified majors, almost no pure-plays.

• U.S.-listed majors whose products fall partly in this code: Celanese (NYSE: CE, world's largest acetic-acid maker), Eastman Chemical (NYSE: EMN, non-phthalate plasticizers), Dow (NYSE: DOW, silicones), LyondellBasell (NYSE: LYB), Methanex (Nasdaq: MEOH, methanol — ~20% of non-China global demand), Chemours (NYSE: CC, low-GWP refrigerants), Stepan (NYSE: SCL), Ingevity (NYSE: NGVT), Balchem (Nasdaq: BCPC) [5].
• Private / foreign: Cargill, INEOS, Wacker Chemie (Germany), Momentive, Perstorp, BASF, Evonik, plus private-equity specialty platforms [5].
• The low-effort route is a broad materials-sector index fund, which holds Dow, Eastman, Celanese, and peers.

Child 325194 — Cyclic crude, gum & wood: no U.S. pure-play; partial or foreign only.

• Partial U.S. exposure: Koppers Holdings (NYSE: KOP, coal-tar distillation, ~a fifth of the company), Clorox (NYSE: CLX, Kingsford charcoal — immaterial to the parent) [4].
• Changed status: Ingevity (NYSE: NGVT) sold its North Charleston crude-tall-oil refinery and most of its Industrial Specialties product line to Mainstream Pine Products in January 2026 for ~$110 million; Ingevity now has reduced direct CTO-refining exposure and tilts toward pavement technologies and automotive activated carbon [4].
• Foreign-listed / private: Synthomer (LSE), Rain Industries/Rain Carbon (India); and privately held Kraton (owned by South Korea's DL Chemical), DRT (Switzerland's dsm-firmenich), Mainstream Pine Products, Royal Oak, Harima [4].

Bottom line. The value concentrates overwhelmingly in the diversified chemical majors (child 325199), with a distinct, more directly investable ethanol cluster alongside (child 325193) and a small niche best reached through corporate parents or private capital (child 325194).

5. How the money works

All three children run the same underlying machine: buy a feedstock, convert it in a high-fixed-cost plant, sell a higher-value output, and earn the spread × throughput. Two levers dominate the P&L everywhere in the level:

• Feedstock spread (unit margin). Profit is the gap between input cost and product price, per ton or per gallon — not a retail markup. What sits on each side of that spread differs by child: corn vs. ethanol, feed, and corn oil (the ethanol "crush margin") [3]; natural gas, olefins, and natural oils vs. methanol, acetyls, plasticizers, and fatty acids (325199); and byproduct coal tar or crude tall oil vs. creosote, pitch, rosin, and tackifiers (325194).
• Capacity utilization (operating rate). Fixed costs are high, so earnings swing far more than revenue. A world-scale plant is very profitable near 90–100% and loss-making in the 60s. Ethanol fleets run near 90%+; Green Plains ran at 97–100% of capacity in 2025 [3]. The whole level is dominated by this operating leverage.

Where the children diverge:

• The policy layer is decisive only for ethanol. Every gallon earns a tradable Renewable Identification Number (RIN) credit under the federal mandate, and low-carbon-intensity plants can earn the federal 45Z production credit — real income streams layered on top of the crush margin [7][6]. The other two children have no comparable production subsidy.
• The commodity-to-specialty spectrum runs through 325199. At the commodity end (methanol, acetic acid) margins are thin and globally set; at the specialty end (non-phthalate plasticizers, low-GWP refrigerants, silicones) margins are higher and steadier, protected by formulation know-how, patents, and regulatory approvals [5]. Producers deliberately tilt their mix toward specialties to smooth earnings. The divergence shows in recent results: Celanese's Acetyl Chain reported a 12.7% operating margin in 2025, down from 19.9% in 2024, on commodity-price weakness; Eastman's Chemical Intermediates segment posted an adjusted EBIT loss of $38 million in 2025, while its more differentiated Additives & Functional Products segment earned $516 million [5].
• 325194 is a byproduct-arbitrage squeeze. Its feedstocks are cheap byproducts, but with inelastic and declining supply, so margins compress from the input side when coal tar or tall oil tightens [4]. Koppers' 2025 Carbon Materials segment results illustrate the squeeze and the utilization lever: segment sales fell 18% year-over-year but adjusted EBITDA margin rose from 7.4% to 11.2% on lower raw-material costs and improved plant performance [4].

The metrics that matter across the level are the same commodity-processor set: gross/conversion margin, operating rate, EBITDA margin, return on invested capital (ROIC), and free cash flow — plus the discipline of not commissioning new capacity into a down-cycle.

6. What drives demand

Demand is derived from downstream industries, so the whole level tracks the industrial cycle with amplification — but each child leans on a different mix.

• Broad cyclical end-markets (all three): construction and housing, packaging, automotive, and general manufacturing pull on plasticizers, silicones, adhesives, coatings, and pitch. Volumes and prices fall together in a downturn.
• Fuel and energy policy (325193): the federal Renewable Fuel Standard sets a demand floor; almost all U.S. gasoline is E10 (10% ethanol), so base demand tracks miles driven — a mature, slowly declining base. EPA projects conventional ethanol consumption of approximately 14.2–14.3 billion gallons in 2026–2027, below the 15-billion-gallon implied standard [3]. Growth comes from higher blends (E15/E85), record exports (2.13 billion gallons in the 2024/25 marketing year), and, prospectively, sustainable aviation fuel [6][3].
• Regulation-driven substitution (325199): arguably the biggest structural demand story in the level. The phase-down of high-global-warming refrigerants shifts volume to next-generation low-GWP products, and phthalate restrictions have driven a multi-year switch to non-phthalate plasticizers [5].
• Bio-based substitution (325194): because pine chemicals are renewable, rosin tackifiers are winning share from petroleum-based resins in adhesives and coatings — a genuine multi-year tailwind, even as the feedstock base shrinks [4].
• U.S. gas-cost advantage and exports (325193 + 325199): cheap shale gas makes domestic methanol, acetyls, and ethanol globally competitive, so the international price cycle matters as much as U.S. consumption [5].
• Inventory (de-stocking/re-stocking) cycles: because customers hold chemical inventory, volumes overshoot in both directions; the 2023–24 downturn was largely a de-stocking event still working through 325199.

7. Regulation

This is a permit-driven, heavily regulated level, and the common thread is the U.S. Environmental Protection Agency (EPA) plus an accelerating decarbonization agenda — but the specific regimes differ by child.

• Renewable-fuel policy (325193). The EPA's Renewable Fuel Standard sets annual Renewable Volume Obligations enforced through RINs; the 45Z Clean Fuel Production Credit rewards low carbon intensity (extended through 2029); and carbon-capture pipeline permitting is a live, contested upgrade path (a major multistate CO₂ pipeline was denied by South Dakota regulators in 2025) [7]. This child's demand and much of its margin are policy-created.
• Chemical and air rules (325199). The Toxic Substances Control Act (TSCA) governs what can be made and sold, with PFAS reporting now underway (submission period beginning July 2025); the AIM Act mandates an HFC (hydrofluorocarbon) refrigerant phase-down (60% of baseline 2024–2028, 30% for 2029–2033, 15% from 2036); and the 2024 Clean Air Act "HON" rule tightened emissions standards for ethylene oxide and chloroprene and added fenceline monitoring at roughly 220 chemical plants [5]. These raise compliance capital spending but also act as a moat against higher-emitting foreign supply.
• Toxics and carcinogen rules (325194). Coal tar and coal-tar pitch are listed human carcinogens (they contain polycyclic aromatic hydrocarbons); creosote is a restricted-use pesticide in EPA review (the EU has moved to ban most creosote uses); and a growing list of states and cities ban coal-tar pavement sealants [4]. Legacy tar sites carry Superfund cleanup liability.

The forward-looking read: regulatory tightening is a rising structural cost across the whole level, but it is also a competitive moat — it disadvantages higher-emitting or higher-carbon supply and rewards producers who own the compliant next-generation chemistry (low-CI ethanol, low-GWP refrigerants, bio-based resins).

8. Competitive dynamics and consolidation

At the level, 32519 looks fragmented and unconcentrated: the four largest firms hold just 18.8% of receipts, the top eight 28.3%, the top twenty 45.3%, the top fifty 65.5%, and the HHI is 157 — far below the 1,500 that U.S. antitrust agencies treat as "unconcentrated" [1].

But that number is an artifact of bundling three unrelated businesses. Concentration inside each child — and inside individual product lines — is much higher:

• 325194 is the most concentrated child: CR4 of 57.1%, CR8 of 77.2%, CR20 of 97.5%, and an HHI of 1,294.9 across just 40 firms [4].
• 325193 (ethanol) is moderately concentrated: CR4 of 35.5%, HHI ~470; the FTC's 2025 review found the largest producer at ~17% of capacity and concluded national price-fixing is unlikely [8].
• 325199 looks fragmented in aggregate (CR4 24.6%, HHI 254.6) but is an oligopoly within any single product line — Celanese alone makes roughly a fifth of the world's acetic acid; U.S. citric acid comes from three firms; low-GWP refrigerants are essentially a Chemours/Honeywell duopoly [5].

Consolidation direction differs by child. 325194 is consolidating a shrinking base — pine chemistry has passed through Ingevity, Kraton/DL Chemical, and Synthomer, and the last big U.S. gum-rosin plant (DRT/Pinova's Brunswick, Georgia facility) was destroyed by a 2023 fire and permanently closed by end-2024; Ingevity sold its North Charleston CTO refinery to Mainstream Pine Products in January 2026 [4]. 325199 runs a barbell: majors bulk up in commodity scale (Methanex's ~$2.05 billion purchase of OCI's methanol business) while spinning off and reshaping specialty units [5]. 325193 consolidates slowly, with the decarbonization race (CO₂-pipeline access, 45Z economics) tilting advantage toward well-capitalized operators [8]. Common to all three: high barriers to entry — capital cost, feedstock access, permits, and slow customer qualification.

9. Risks

Most risks are shared across the level, but their weight differs by child.

• Commodity cyclicality and operating leverage (all three). The same fixed-cost structure that magnifies profits in an up-cycle magnifies losses when utilization falls — as the 2023–24 de-stocking trough showed in 325199 [5].
• Feedstock and energy volatility (all three). Corn (325193), natural gas and olefins (325199), and coal tar/tall oil (325194) all swing; margins can invert even when volumes hold [3][5].
• Policy dependence (heaviest on 325193). Ethanol demand and a chunk of its margin rest on the Renewable Fuel Standard, RIN market, and 45Z; changes to volume obligations, small-refinery exemptions, or credits can swing profitability quickly [7].
• Feedstock decline (specific to 325194). Coal-tar supply falls as blast-furnace steel gives way to scrap-fed electric-arc furnaces; crude tall oil is capped by pulp output and increasingly bid away by renewable-diesel and sustainable-aviation-fuel refiners [4].
• Global oversupply (specific to 325199). New Chinese and Middle Eastern commodity-chemical capacity can flood markets and crush spreads regardless of U.S. demand; ICIS estimated global overcapacity at 222 million tonnes in 2024, the highest since 1978 [5].
• Demand ceiling / substitution. Domestic gasoline is mature and slowly shrinking (a blend-wall ceiling for ethanol); petroleum resins compete with rosin tackifiers; legacy high-GWP refrigerants face stranded-product risk [6][4][5].
• Environmental and litigation liability. PFAS and air-emissions exposure (325199) and legacy coal-tar Superfund sites (325194) carry real remediation and legal tail risk [5][4].
• Trade and tariff exposure. Record ethanol exports, gas-advantaged methanol/acetyl exports, and import-protected food acids all make the level sensitive to tariffs and trade disputes [6][5].

10. How to invest and the outlook

There is no way to own 32519 cleanly — the code is an accounting bin, not a market, and no fund tracks it. Build exposure by child, matched to a view on the cycle.

Public routes.

• The ethanol cluster (325193) is the only place with genuine pure-plays: Green Plains (GPRE), REX American Resources (REX), Alto Ingredients (ALTO) — direct but margin-cyclical — with diversified exposure via ADM, Valero (VLO), and The Andersons (ANDE) [9][3]. There is no ethanol ETF.
• The residual bin (325199) is best owned through diversified chemical majors weighted to the product lines you favor — Celanese (CE) or Eastman (EMN) for acetyls/plasticizers, Methanex (MEOH) for methanol, Chemours (CC) for the refrigerant transition, Dow (DOW) for silicones and scale, Stepan (SCL) or Ingevity (NGVT) for bio-based specialties — or, most simply, a broad materials-sector index fund [5].
• The gum-and-wood niche (325194) offers only partial exposure: Koppers (KOP), Clorox (CLX), or foreign-listed Synthomer (LSE) and Rain Industries (India). Ingevity (NGVT) now has reduced direct CTO-refining exposure after its January 2026 divestiture to Mainstream Pine Products [4].

In every case, share prices, dividend yields, and valuation multiples are left to each company's own disclosures — the shared point is that these are cyclical businesses whose earnings compress in downturns.

Private routes. Much of the real capacity is off-market: farmer-owned cooperative units and single-plant LLCs in ethanol; private-equity specialty-chemical platforms and foreign-owned producers (Cargill, INEOS, Wacker, Momentive) in the residual bin; and PE- and foreign-controlled niche players (Kraton, DRT, Mainstream Pine Products, Royal Oak) in gum-and-wood. Private capital participates through control transactions, supply/toll contracts, and direct plant ownership — the durable edge being feedstock contracts and plant reliability [3][5][4].

The outlook (forward-looking judgment). Read 32519 as a mature, cyclical, cash-generative part of the U.S. chemical economy rather than a growth story. The credible growth is not secular volume — it is policy- and decarbonization-driven: low-carbon fuels and exports for ethanol, the low-GWP refrigerant transition and non-phthalate substitution for the residual bin, and bio-based tackifier substitution for the pine-chemical niche. The bear case is equally clear: commodity oversupply and de-stocking on the residual side, a structural feedstock squeeze in gum-and-wood, and policy dependence in ethanol. The durable winners across all three children are the same type: low-cost producers with feedstock advantage and specialty producers with regulatory-protected, higher-margin chemistry — and timing relative to the industrial cycle matters as much as which name you pick.

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Sources

1. U.S. Census Bureau. 2022 Economic Census — Concentration and Selected Statistics, NAICS 32519 (receipts $155.6B; 806 firms; CR4 18.8%, CR8 28.3%, CR20 45.3%, CR50 65.5%; HHI 157). https://www.census.gov/programs-surveys/economic-census.html
2. U.S. Census Bureau. County Business Patterns, 2023 — NAICS 32519 (1,169 establishments; 93,565 employees; ~$10.27B annual payroll; ~$2.91B Q1 payroll). https://www.census.gov/programs-surveys/cbp.html
3. U.S. Census Bureau / child primer 325193. Economic Census 2022 and County Business Patterns 2023 — NAICS 325193 Ethyl Alcohol Manufacturing (receipts ~$50.0B; 118 firms; 207 establishments; 10,719 employees; CR4 35.5%, HHI ~470); with producer detail (POET, ADM, Valero, Green Plains, REX, Alto, The Andersons); EIA January 2025 capacity (191 plants, 18.477B gal/yr); record 16.49B gallons produced 2025; Green Plains 97–100% utilization; EPA projected 2026–2027 conventional ethanol consumption ~14.2–14.3B gallons. https://www.census.gov/programs-surveys/economic-census.html
4. U.S. Census Bureau / child primer 325194. Economic Census 2022 and County Business Patterns 2023 — NAICS 325194 Cyclic Crude, Intermediate, and Gum and Wood Chemical Manufacturing (receipts $5.49B; 40 firms; 68 establishments; 5,542 employees; CR4 57.1%, CR8 77.2%, CR20 97.5%, HHI 1,294.9); with feedstock, regulation, and ownership detail (Koppers, Clorox, Kraton/DL Chemical, DRT, Rain Carbon, Mainstream Pine Products); Koppers 2025 Carbon Materials segment ($408.7M sales, 11.2% adj. EBITDA margin); Ingevity CTO-refinery sale to Mainstream Pine Products January 2026 (~$110M); DRT/Pinova Brunswick GA plant permanently closed 2024. https://www.census.gov/programs-surveys/economic-census.html
5. U.S. Census Bureau / child primer 325199. Economic Census 2022 and County Business Patterns 2023 — NAICS 325199 All Other Basic Organic Chemical Manufacturing (receipts $100.1B; 663 firms; 894 establishments; 77,304 employees; CR4 24.6%, HHI 254.6); with producer, product-line, and regulatory detail (Celanese, Eastman, Dow, Methanex, Chemours, Stepan, Ingevity); Celanese Acetyl Chain 2025 12.7% operating margin (vs. 19.9% 2024); Eastman Chemical Intermediates 2025 adj. EBIT loss $38M; Methanex ~20% of non-China global methanol demand; ICIS 222M tonnes global overcapacity 2024; AIM Act HFC phase-down schedule; 2024 HON rule. https://www.census.gov/programs-surveys/economic-census.html
6. Renewable Fuels Association / U.S. Energy Information Administration / USDA. U.S. Ethanol Production Set a Record in 2025; Industry Supported 317,000 Jobs; Ethanol Exports 2.13 Billion Gallons 2024/25 Marketing Year. 2026. https://ethanolrfa.org/media-and-news
7. U.S. Environmental Protection Agency. Renewable Fuel Standard Program: Standards for 2026 and 2027 (RFS/RVO/RIN framework); 45Z Clean Fuel Production Credit (extended through 2029) and carbon-capture permitting context. 2026. https://www.epa.gov/renewable-fuel-standard-program
8. U.S. Federal Trade Commission. 2025 Report on Ethanol Market Concentration (~100 firms; largest ~17% of capacity; producer-basis HHI 527; national price-fixing unlikely). 2026. https://www.ftc.gov/reports/2025-report-ethanol-market-concentration
9. Green Plains Inc.; REX American Resources; Alto Ingredients, Inc. — company financial disclosures for the public ethanol pure-plays (FY2025 results). https://stockanalysis.com/stocks/gpre/
10. Koppers Holdings Inc. Form 10-K, Fiscal Year 2025 (Carbon Materials & Chemicals coal-tar segment: $408.7M sales, 11.2% adj. EBITDA margin). U.S. Securities and Exchange Commission, 2026. https://www.sec.gov/cgi-bin/browse-edgar?action=getcompany&CIK=0001315257
11. Ingevity Corporation. Ingevity Announces Agreement to Sell North Charleston Crude Tall Oil Refinery and Majority of Industrial Specialties Product Line to Mainstream Pine Products (~$110M, January 2026). 2025. https://ir.ingevity.com/
12. Kraton Corporation / DL Chemical (merger, ~$2.5B, 2022); Argus Media / dsm-firmenich (permanent closure of the Pinova, Brunswick GA pine-chemical plant, 2024). https://kraton.com/newsroom/
13. Celanese Corporation. Form 10-K, Fiscal Year 2025 (Acetyl Chain $4.2B sales, 12.7% operating margin). 2026. https://investors.celanese.com/
14. Methanex Corporation. 2025 Annual Information Form (~20% of non-China global methanol demand; acquisition of OCI Global's methanol business ~$2.05B). 2026. https://www.methanex.com/
15. U.S. Small Business Administration. Table of Small Business Size Standards (NAICS 325193 = 1,000 employees; 325194 and 325199 = 1,250 employees). 2023. https://www.sba.gov/document/support-table-size-standards
16. U.S. Environmental Protection Agency. Phasedown of Hydrofluorocarbons under the AIM Act (60% baseline 2024–28; 30% 2029–33; 15% from 2036); Final "HON" Rule for Synthetic Organic Chemical Manufacturing (2024); TSCA Section 8(a)(7) PFAS reporting (July 2025). 2024. https://www.epa.gov/climate-hfcs-reduction
17. U.S. National Toxicology Program / National Cancer Institute. Coal Tars and Coal-Tar Pitches — 15th Report on Carcinogens; U.S. EPA, Creosote pesticide registration review and Coal-Tar Sealcoat and PAHs. 2021–2024. https://www.cancer.gov/about-cancer/causes-prevention/risk/substances/coal-tar