Surface Active Agent Manufacturing (U.S.) — NAICS 325613

A Histometrics industry primer for public-market and private investors.

1. Overview

Surfactants — short for surface-active agents — are the workhorse molecules that let water mix with oil and grease. One end of each molecule likes water; the other end grabs onto oils and dirt. That single trick makes surfactants the active cleaning ingredient in almost every detergent, shampoo, and hard-surface cleaner, plus a critical additive in farm chemicals, oilfield fluids, paints, plastics, and textiles.[1][2]

This NAICS code covers the bulk chemical producers who make surfactants and sell them by the tanker-load to product formulators — it is a business-to-business intermediate-chemicals industry, not the maker of the bottle on your shelf. In 2022, U.S. establishments in this code shipped about $10.2 billion of surface-active agents.[3] It is a small, capital-intensive, and highly concentrated corner of the chemical sector: roughly 106 plants and 6,200 workers generate that $10 billion, which works out to about $1.7 million of revenue per employee — a sign of large, automated, continuous-process plants rather than a labor-heavy business.[4]

Why an investor should care: surfactant demand is unusually durable because so much of it feeds consumer staples — people keep buying soap and shampoo in a recession — yet a meaningful slice serves cyclical end markets (agriculture, oil and gas, construction) that swing with the economy. That blend of a defensive core and a cyclical kicker, combined with heavy consolidation, defines the industry's economics.

Ways in. For public-market investors there is essentially one U.S.-listed pure play, Stepan Company (NYSE: SCL), plus large diversified chemical majors for whom surfactants are one line of business. Most of the rest of the industry sits inside privately held specialty producers and foreign-listed multinationals. Private-market and strategic buyers have been the more active owners here — the last decade's biggest surfactant transactions were private-equity and cross-border acquisitions, not public listings (details in Sections 4 and 8).

2. What it is and how it's structured

Scope. NAICS 325613 covers establishments primarily making bulk surface-active agents used as wetting agents, emulsifiers, detergent actives, foaming agents, and penetrants, plus textile and leather finishing agents and sulfonated oils and fats.[1] The output is chemistry, sold to formulators. Products are usually grouped by the electrical charge of the water-loving head:

• Anionic (negative charge) — the biggest volume class; the powerful, foamy cleaners in laundry detergent and shampoo (e.g., LAS, or linear alkylbenzene sulfonate, and lauryl sulfates).[2]
• Nonionic (no charge) — alcohol ethoxylates and similar; low-foam, hard-water-tolerant, heavily used in industrial cleaning and as emulsifiers.[2]
• Cationic (positive charge) — fabric softeners, hair conditioners, disinfectants.[2]
• Amphoteric (both charges) — mild surfactants for baby shampoo and facial cleansers.[2]

Manufacturing process. Production generally involves chemical conversion followed by neutralization, purification, and blending. Sulfonation or sulfation plants react alkylbenzene, olefins, fatty alcohols, or ethoxylated alcohols with sulfur trioxide or sulfuric-acid chemistry, then neutralize the acid intermediate with caustic. Ethoxylation or broader alkoxylation adds ethylene oxide or propylene oxide to an alcohol or other initiator under pressure and controlled temperature. Plants then adjust active concentration, salt, pH, viscosity, and residual impurities and ship bulk liquids, pastes, powders, or customer-specific blends by tank car, tank truck, drums, or totes.[5]

What it EXCLUDES. This is the most important structural point. The code stops at the raw surfactant. It does not include:

• Finished soaps and detergents — the boxed and bottled cleaning products — which are NAICS 325611 (Soap and Other Detergent Manufacturing).
• Polishes and sanitation goods — NAICS 325612.
• Cosmetics, shampoos, and toilet preparations as finished consumer goods — NAICS 325620 (Toilet Preparation Manufacturing).[1]

So when a market report cites a "U.S. surfactants market" of $9–16 billion, it is usually measuring surfactant consumption including imports and captively made volume, not this code's shipments.[6][7] The federal $10.2 billion measures what dedicated U.S. surfactant plants ship.[3]

Ownership mix. The industry splits into three groups: (1) merchant producers who make surfactants to sell — Stepan is the archetype, and its own description as a "leading merchant producer" captures the model;[8] (2) integrated chemical majors (Dow, BASF, Evonik, Indorama) that make surfactants alongside the ethylene oxide and other feedstocks they already produce; and (3) captive producers — large detergent and personal-care companies (Procter & Gamble, Unilever, Colgate) that make some surfactant volume inside their own plants for their own use. Stepan identifies large customers' captive surfactant plants as competitors to merchant producers and notes that competition rests on performance, price, technical assistance, ability to meet customer-specific needs, and available capacity — not price alone.[9]

3. How big it is

Core federal figures for NAICS 325613:

Concentration is high. The largest four firms account for 62.5% of industry receipts, the top eight for 73.6%, the top twenty for 90.4%, and the top fifty for 99%.[10] In plain terms, a handful of companies dominate, and past the top twenty there is almost nothing left. (The Herfindahl-Hirschman Index, a standard concentration statistic, is suppressed in the federal data for this code, so we do not report a value.[10])

The undercount caveat. The $10.2 billion figure understates total U.S. surfactant tonnage. Federal statistics classify each plant by its primary activity, so surfactant volume made captively inside an integrated detergent plant or a petrochemical complex — for example ethylene-oxide-derived nonionics produced on-site at a large chemical site — is often booked under a different code. The federal number is therefore best read as the merchant-plus-dedicated-plant surfactant industry, not every pound of surfactant made in the country. This is why third-party "market" estimates that include captive and imported volume run higher.[6][7] The industry is also not dominated by government or by tiny individual operators — it is a private, mid-cap-and-larger industrial business — so the usual small-operator undercount does not apply here.

4. The investable universe

There is one U.S.-listed company for which surfactants are the core business. Everyone else is either a diversified major where surfactants are a segment, a foreign-listed multinational, or private.

U.S.-listed pure play

U.S.-listed diversified chemical companies with a surfactant business

Foreign-listed multinationals active in the U.S. surfactant market

Major private / privately controlled producers

Bottom line for stock pickers: public exposure is thin. Stepan is the only way to own the industry directly on a U.S. exchange; the majors give diluted exposure; and the fastest-growing niches (biosurfactants, specialty personal care) sit largely in private hands and foreign listings.

5. How the money works

Surfactant making is a volume-and-spread manufacturing business, and the metrics that matter are the ones common to commodity-and-specialty chemicals:

• Capacity utilization / fixed-cost leverage. Plants are expensive, continuous, and run best when full. Because a large share of costs is fixed, profitability is highly sensitive to how many tons flow through the asset. When Stepan's Millsdale, Illinois complex had operational problems and lower volumes in 2024, earnings took a direct hit; the same operating leverage works in reverse when volumes recover.[12]

• The feedstock spread (raw-material margin). The single biggest cost is feedstock, and producers earn the gap between selling price and input cost. Two feedstock families dominate: oleochemical (natural oils — coconut and palm kernel oil, prized for their lauric acid) and petrochemical (ethylene oxide and linear alkylbenzene, derived from oil and shale gas).[2][23] Palm kernel oil is the industry's swing input — it traded around $1,695 per metric ton CFR Houston in mid-2025 — and its price is treated as a barometer for oleochemical-based surfactant margins.[23] Stepan states that raw materials, natural gas, and electricity represent a substantial portion of operating costs.[9] Producers pass raw-material moves through to customers, but usually with a lag, so margins compress when inputs spike suddenly and expand when they fall.

• Volume and mix. Commodity anionics (like LAS) are lower-margin and competitive; specialty and custom blends (mild amphoterics, personal-care esters, agricultural and oilfield surfactants) carry higher margins. Shifting the mix toward specialties is the main lever producers pull to lift profitability without adding tonnage.

• Backward integration. Owning your own ethylene oxide or fatty-alcohol supply removes a middleman's margin and secures supply; the majors' advantage over merchants is partly this integration.[7] Merchants like Stepan counter by investing in their own alkoxylation capacity — Stepan started up a $220 million, 75,000-metric-ton-per-year alkoxylation plant in Pasadena, Texas in April 2025 to make more of its own nonionic surfactant intermediates.[24][25]

• Toll and custom manufacturing. Producers also run customers' recipes on contract, earning a conversion fee rather than taking feedstock risk — a steadier, capital-light revenue stream.

Segment-level economics. Stepan's global surfactants segment is the best public benchmark. In 2025 the segment generated $1.666 billion of sales, $168.7 million of gross profit, and $67.4 million of operating income — calculated margins of 10.1% gross and 4.0% operating, down from 5.6% operating in 2024. Segment capital expenditure was $88.7 million and depreciation and amortization was $85.7 million, showing a business in which maintenance and growth capital are material. Surfactant sales rose 9% in 2025, largely because higher prices passed through higher raw-material costs, while volume fell 2%; operating income nevertheless fell 21% as North American unit margins were hurt by start-up expense at the new alkoxylation plant, higher oleochemical costs, and an environmental-reserve adjustment.[9]

Price trends. The BLS bulk-surfactants producer-price index was 428.0 in May 2026, versus 419.5 in May 2025 and 297.3 in May 2020 — a 2.0% increase over the latest year but a 44% rise over six years. The index is not seasonally adjusted and measures selling prices rather than volume or profitability.[26]

A useful tell of the industry's quality: Stepan has raised its dividend for 58 consecutive years, a track record only possible because the underlying demand is steady even as quarterly earnings swing with volumes and feedstock costs.[27]

6. What drives demand

• Consumer staples (the defensive core). Laundry detergent, dish soap, shampoo, and household cleaners are non-discretionary; their surfactant demand grows roughly with population and household formation and holds up in downturns.[2][6]
• Personal care and "clean/mild" formulation trends. Growth in sulfate-free, mild, and premium personal-care products pulls demand toward higher-value amphoteric and specialty surfactants.[7]
• Agriculture. Surfactants are adjuvants that help herbicides and pesticides spread and stick; demand tracks crop prices, planted acreage, and farm income — a cyclical driver that was soft in 2024 but stronger in 2025.[9][12]
• Oilfield. Surfactants are used in drilling, enhanced oil recovery, and well treatment; demand follows drilling activity and oil prices — stronger in 2025.[9][12]
• Construction and industrial. Surfactants go into concrete admixtures, coatings, adhesives, and industrial cleaners — tied to the building and manufacturing cycle.[12]
• Sustainability shift. Brand owners are reformulating toward bio-based and readily biodegradable surfactants, a structural demand pull toward oleochemical and fermentation-derived products (Section 8). Sustainability is altering feedstocks and product selection rather than eliminating surfactants — customers want renewable carbon, lower life-cycle emissions, better biodegradability, reduced aquatic toxicity, and supply-chain certification.[7][18][21]

7. Regulation

Surfactant makers operate under standard U.S. industrial-chemical regulation plus a few chemistry-specific pressures:

• TSCA (Toxic Substances Control Act), administered by the EPA. New chemistries require review, and existing ones can be re-evaluated. The most consequential recent action concerns 1,4-dioxane, a trace by-product formed during ethoxylation (the same reaction used to make many nonionic and anionic surfactants). In November 2024 the EPA finalized a determination that 1,4-dioxane presents an unreasonable risk to human health and specifically included byproduct exposure from ethoxylation in the evaluated conditions of use — a forward-looking regulatory overhang that could require producers to further purify ethoxylated surfactants.[28][29]
• State limits. New York sets the strictest U.S. caps: household cleaning and personal-care products must contain ≤ 1 part per million of 1,4-dioxane (tightened from 2 ppm at the end of 2023), with cosmetics capped at 10 ppm — pushing formulators toward low-dioxane surfactant grades. Suppliers have invested in process modification and stripping technology, but regulation can accelerate substitution away from some ethoxylated products.[9][29]
• PFAS reporting. EPA's TSCA reporting rule covers entities that manufactured or imported PFAS or PFAS-containing articles in any year since 2011, requiring information on volumes, uses, disposal, exposure, and hazards. This matters primarily to the narrower fluorosurfactant niche, coatings, and firefighting applications rather than the much larger hydrocarbon-surfactant base.[30]
• Environmental and safety permitting. Air, water-discharge, and hazardous-materials rules (EPA, OSHA, Clean Air Act, RCRA, CERCLA) govern the plants; ethylene oxide handling in particular is tightly controlled. Stepan reported $9.8 million of environmental capital expenditure and approximately $44.9 million of recurring waste-treatment, disposal, and environmental-compliance costs globally in 2025.[9]
• Biodegradability and eco-labels. Detergent-grade surfactants have long been engineered to be readily biodegradable, and voluntary eco-certifications increasingly shape which chemistries brand owners will buy. EPA's Safer Choice criteria explicitly combine aquatic toxicity with biodegradation rate: more aquatically toxic surfactants must biodegrade faster and without products of concern.[2][31]

Regulation here is a cost-and-reformulation pressure rather than a rate-setting regime — it does not cap prices, but it steadily raises the bar on which molecules are acceptable.

8. Competitive dynamics and consolidation

The federal concentration data (top four firms = 62.5% of receipts) reflects a decade of consolidation.[10] Two defining recent deals:

• In January 2020 Thailand's Indorama Ventures completed its ~$2 billion acquisition of Huntsman's surfactants and chemical-intermediates business, taking over major U.S. Gulf Coast plants at Port Neches, Dayton, and Chocolate Bayou, Texas.[17] That single transaction removed a large U.S. producer's name from the field and put its assets under a foreign-listed owner.
• In December 2023 South Korea's Samyang Holdings acquired Verdant Specialty Solutions — the amphoteric-surfactant business that OpenGate Capital had carved out from Solvay — for roughly $250 million, with expected annual revenue of ~$210 million at the time.[20]

Competition splits along two lines:

• Integrated majors vs. merchants. Majors (Dow, BASF, Indorama, Sasol) compete on scale and backward integration into feedstocks; merchants (Stepan, Pilot, Colonial) compete on service, custom formulation, and specialty chemistry. Stepan's answer to the integration gap has been to build its own alkoxylation capacity.[24][25]
• Commodity vs. specialty. High-volume anionics are commoditized and price-competitive; the value migrates to mild personal-care surfactants, agricultural adjuvants, and — increasingly — biosurfactants made by fermentation. The global biosurfactant market was about $1.5 billion in 2024 (Europe ~65% of it), still small but growing.[32] Evonik has launched rhamnolipid and sophorolipid product lines, and Locus Ingredients supplies fermentation-made sophorolipids to Dow while scaling toward 2,500 tons per year.[7][18] Pilot Chemical's exclusive North American license for Kao's Bio IOS and its 2025 partnership with Novvi to commercialize biobased alpha-olefin sulfonates are signs of the specialty/bio land-grab.[19][21]

Expect continued consolidation and technology-licensing partnerships rather than new entrants — the capital intensity and regulatory burden make greenfield entry hard.

9. Risks

• Feedstock volatility. Palm kernel oil, coconut oil, ethylene oxide, and LAB prices move with commodity and energy cycles; sudden spikes compress margins until price increases pass through.[23]
• Operating leverage / plant reliability. Because costs are heavily fixed, a plant outage or soft volumes hit earnings hard, as Stepan's 2024 Millsdale problems showed.[12]
• Cyclical end-market exposure. The agricultural, oilfield, and construction slices amplify downturns even as consumer-staples demand stays steady. In 2025 Stepan reported weaker consumer-products demand in North America but stronger agricultural and oilfield demand, demonstrating the benefit — and imperfectness — of end-market diversification.[9][12]
• Regulatory / reformulation risk. The EPA 1,4-dioxane action and state limits could force capital spending on purification and drive customers away from certain ethoxylated grades.[28][29]
• Environmental liability. Legacy contamination and remediation reserves are real (Stepan booked a Millsdale remediation adjustment in 2024), and ethylene oxide handling carries safety and liability exposure. Diligence must normalize earnings for environmental provisions, and remediation history should be treated as a potential debt-like liability.[9][24]
• Substitution and sustainability disruption. Fermentation-made biosurfactants and enzyme-based cleaning could, over time, displace some conventional chemistry — an opportunity for those who invest and a threat to those who don't.[18][32]
• Customer backward integration. Large formulators can build captive capacity or use make-versus-buy economics, while reformulators can substitute another surfactant family, lower the active loading, or redesign a product entirely.[9]
• Thin public float. For equity investors, the near-absence of pure-play U.S. listings means limited, concentrated exposure and single-company risk in Stepan.

10. How to invest and the outlook

Public-market routes.

• Direct pure play: Stepan Company (NYSE: SCL) — a small-cap ($~1.1 billion) merchant surfactant maker and 58-year dividend raiser; the cleanest listed proxy for U.S. surfactant volumes and margins, but also carrying single-company operating and feedstock risk.[11][13][27]
• Diversified exposure: Dow (DOW), Innospec (IOSP), and Huntsman (HUN) in the U.S., or foreign-listed BASF, Evonik, Croda, Clariant, Indorama Ventures, Kao, Sasol, and Samyang, give surfactant exposure diluted inside larger chemical businesses.[2][7][14][16]
• There is no dedicated surfactant ETF; broad materials/chemicals sector funds are the only index-style option, and surfactants are a tiny slice of them.

Private-market routes.

• The industry's growth edge — specialty personal-care surfactants and fermentation-made biosurfactants — is mostly held by private companies (Nouryon, Pilot Chemical, Colonial Chemical) and venture/PE-backed biosurfactant developers (e.g., Locus). Private equity has been the dominant capital source here, and the last decade's marquee deals were cross-border acquisitions, not IPOs.[17][18][20][22]
• The attractive targets are usually not undifferentiated commodity capacity; they are businesses with difficult-to-replicate sulfonation or alkoxylation assets, customer qualifications, proprietary blends, strong technical service, environmental permits, and niches such as mild personal-care surfactants, agricultural adjuvants, or oilfield formulations.
• Strategic and PE buyers value these businesses on EBITDA and specialty-mix quality; the durable-demand, high-barrier profile is attractive to long-hold owners.

Near-term drivers (forward-looking).

• Volume recovery and new capacity utilization. Whether Stepan's Pasadena alkoxylation plant ramps efficiently and its Millsdale reliability improves will drive the listed pure play's earnings.[24][25]
• Feedstock direction. Softer palm kernel/oleochemical prices would widen margins; another spike would squeeze them.[23]
• The 1,4-dioxane rulemaking. The shape of the EPA's forthcoming risk-management rule is the key regulatory swing factor and could advantage producers already selling low-dioxane grades.[28][29]
• Bio-based adoption. Continued brand-owner reformulation toward bio and mild chemistries steadily shifts value toward specialty and fermentation producers.[7][18]

Net: a small, concentrated, capital-intensive industry with a defensive demand core, a cyclical kicker, and thin public exposure. It rewards owners who run their plants full, manage the feedstock spread, and keep migrating toward specialty and bio-based chemistry — and it is more a private-market and strategic-owner arena than a stock-market one.

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Sources

1. U.S. Census Bureau / NAICS Association, "NAICS Code 325613 — Surface Active Agent Manufacturing" (2022 definition), https://www.naics.com/naics-code-description/?code=325613
2. Elchemy / ScienceDirect, "Role of Surfactants: How They Work in Cleaning, Personal Care, and Industry" and surfactant feedstock overview (2024), https://elchemy.com/blogs/chemical-market/role-of-surfactants-how-they-work-in-cleaning-personal-care-and-industry
3. U.S. Census Bureau, 2022 Economic Census / Economic Census concentration series — NAICS 325613 receipts and firm count (2022), https://www.census.gov/programs-surveys/economic-census.html
4. U.S. Census Bureau, County Business Patterns — NAICS 325613 establishments, employment, and payroll (2023), https://www.census.gov/programs-surveys/cbp.html
5. U.S. EPA, "Development Document for Effluent Limitations Guidelines — Soap and Detergent Manufacturing" (1974), https://www.epa.gov/sites/default/files/2016-08/documents/soap-detergent-mfg_dd_1974.pdf
6. Grand View Research, "Surfactants Market Size And Share | Industry Report, 2033" (2024), https://www.grandviewresearch.com/industry-analysis/surfactants-market
7. Fortune Business Insights, "Surfactants Market Size, Share, Trends, Global Report, 2034" (2024), https://www.fortunebusinessinsights.com/surfactants-market-102385
8. Stepan Company, "About Stepan / leading merchant producer of surfactants" (2024), https://www.stepan.com/content/stepan-dot-com/en/you-stepan/about-stepan-company.html
9. Stepan Company, 2025 Form 10-K / Annual Report (filed 2026), https://www.sec.gov/Archives/edgar/data/0000094049/000119312526122731/d28067dars.pdf
10. U.S. Census Bureau, 2022 Economic Census — Concentration of Largest Firms (CR4/CR8/CR20/CR50; HHI suppressed), NAICS 325613 (2022), https://www.census.gov/programs-surveys/economic-census.html
11. StockAnalysis, "Stepan Company (SCL) Market Cap & Net Worth" (2025–2026), https://stockanalysis.com/stocks/scl/market-cap/
12. Stepan Company / PR Newswire, "Stepan Reports Fourth Quarter 2024 Results" (2025), https://www.prnewswire.com/news-releases/stepan-reports-fourth-quarter-2024-results-302379827.html
13. MatrixBCG, "How Does Stepan Company Work?" — segment revenue mix (2024), https://matrixbcg.com/blogs/how-it-works/stepan
14. SNS Insider via GlobeNewswire, "Personal Care Ingredients Market" — vendor list including Innospec (2025), https://www.globenewswire.com/news-release/2025/05/23/3087517/0/en/Personal-Care-Ingredients-Market-Projected-at-USD-20-96-Billion-by-2032.html
15. Innospec Inc., 2025 Form 10-K (filed 2026), https://www.sec.gov/Archives/edgar/data/1054905/000119312526056502/iosp-20251231.htm
16. Huntsman Corporation, 2025 Form 10-K (filed 2026), https://www.huntsman.com/investors/financials/sec-filings/content/0001437749-26-004524/hun20251231_10k.htm
17. Huntsman Corporation / PR Newswire, "Huntsman Completes the Sale of its Chemical Intermediates and Surfactants Businesses to Indorama Ventures for $2 Billion" (2020), https://www.prnewswire.com/news-releases/huntsman-completes-the-sale-of-its-chemical-intermediates-and-surfactants-businesses-to-indorama-ventures-for-2-billion-300981197.html
18. C&EN (American Chemical Society), "Biosurfactants scale up" — Locus, Evonik, Dow (2024), https://cen.acs.org/environment/green-chemistry/Biosurfactants-scale/102/i3
19. SOCMA, "Pilot Chemical Company Announces Exclusive Partnership with Kao Corporation to Bring Bio IOS Surfactant Technology to the North American Market" (2024), https://www.socma.org/pilot-chemical-company-announces-exclusive-partnership-with-kao-corporation-to-bring-bio-ios-surfactant-technology-to-the-north-american-market/
20. C&EN (American Chemical Society), "Verdant Specialty Solutions acquired by Samyang" (2023), https://cen.acs.org/business/specialty-chemicals/Verdant-Specialty-Solutions-acquired-Samyang/101/web/2023/12
21. Pilot Chemical Company, "Pilot Chemical Company Announces Exclusive Partnership with Novvi LLC to Bring Biobased Alpha-Olefin Sulfonate Surfactant Technology to the North American Market" (2025), https://pilotchemical.com/pilot-chemical-company-announces-exclusive-partnership-with-novvi-llc-to-bring-biobased-alpha-olefin-sulfonate-surfactant-technology-to-the-north-american-market/
22. Colonial Chemical Inc., company site (2024), https://colonialchem.com/
23. PricePedia, "Why Palm Kernel Oil Prices Reflect the State of the Oleochemical Industry" (2026), https://www.pricepedia.it/en/magazine/article/2026/03/30/why-palm-kernel-oil-prices-reflect-the-state-of-the-oleochemical-industry/
24. Stepan Company / PR Newswire, "Stepan Reports Second Quarter 2024 Results" (Pasadena alkoxylation and Millsdale remediation) (2024), https://www.prnewswire.com/news-releases/stepan-reports-second-quarter-2024-results-302210820.html
25. Stepan Company, "Stepan to Expand Alkoxylation Capacity with U.S. Gulf Coast Investment" ($220M / 75,000 t-yr, Pasadena TX) (2021–2025), https://www.prnewswire.com/news-releases/stepan-to-expand-alkoxylation-capacity-with-us-gulf-coast-investment-301404293.html
26. U.S. Bureau of Labor Statistics / FRED, "Producer Price Index — Bulk Surface Active Agents" (series PCU32561332561302), https://fred.stlouisfed.org/series/PCU32561332561302
27. Stepan Company, "Stepan Reports Fourth Quarter and Full Year 2025 Results" (58th consecutive annual dividend increase) (2026), https://stepan.gcs-web.com/news-releases/news-release-details/stepan-reports-fourth-quarter-and-full-year-2025-results
28. U.S. EPA, "EPA Finalizes Solvent 1,4-Dioxane TSCA Risk Evaluation" — unreasonable-risk determination (Nov 2024), https://www.epa.gov/chemicals-under-tsca/epa-finalizes-solvent-14-dioxane-tsca-risk-evaluation
29. Bergeson & Campbell / Federal Register, "EPA Releases Final Supplement to the Risk Evaluation and Revised Unreasonable Risk Determination for 1,4-Dioxane" and New York state limits (2024), https://www.lawbc.com/epa-releases-final-supplement-to-the-risk-evaluation-and-revised-unreasonable-risk-determination-for-14-dioxane/
30. U.S. EPA, "TSCA Section 8(a)(7) Reporting and Recordkeeping Requirements for PFAS" (2024), https://www.epa.gov/assessing-and-managing-chemicals-under-tsca/tsca-section-8a7-reporting-and-recordkeeping
31. U.S. EPA, "Safer Choice Criteria for Surfactants" (2024), https://www.epa.gov/saferchoice/safer-choice-criteria-surfactants
32. DataM Intelligence / Precedence Research, "Biosurfactants Market" — ~$1.5B 2024, Europe ~65% share (2024–2025), https://www.datamintelligence.com/research-report/bio-surfactants-market

Federal figures (Sections 3) are drawn from U.S. Census Bureau County Business Patterns 2023 and the 2022 Economic Census. Market-size ranges from private research firms use broader scopes than NAICS 325613 and are presented as third-party context only.