Research Dossier 01: Hair Color, Chemical Services, and Chemical Safety/Regulation

Research date: September 17, 2026 Scope: Oxidative color, lighteners, developers and toners; PPD/hair-dye allergy and patch-test guidance; bond builders (Olaplex, K18) and the lilial/Olaplex lawsuit issue; formaldehyde and releasers in smoothing treatments (FDA proposed ban, OSHA, state laws); chemical relaxer cancer research and MDL 3060 litigation; MoCRA implementation; EU Cosmetics Regulation restrictions relevant to hair; salon occupational exposures (NIOSH-affiliated research, IARC). Method note: WebSearch and WebFetch only. Late in the session, the web search budget ran out and WebFetch returned persistent HTTP 429 rate-limit errors. As a result, the bond builder section and some EU hair-dye regulation and IARC details depend on background knowledge and search-result titles rather than fetched pages. Those items are flagged [not re-verified] and given lower confidence. All litigation and regulatory status items are "as of September 2026" and were checked against 2026 sources.

Key findings

1. No federal U.S. formaldehyde ban for hair smoothing products exists as of Sept. 2026. FDA's proposed rule (RIN 0910-AI83) first appeared on the Spring 2023 Unified Agenda (NPRM target April 2024) and has never been published in the Federal Register. Missed targets: Oct 2023, Apr 2024, Nov 2024, Mar 2025, Jul 2025, Dec 2025. A July 31, 2026 industry report says the 2026 agenda targets November 2026. Confidence: High (not published); Medium (Nov 2026 target, not verified on Reginfo.gov). Reginfo; Powers Health/HealthDay; Certified Cosmetics; Marin Murphy Law
2. State bans are already in force. California (AB 2762) and Maryland (HB 643) ban intentionally added formaldehyde, paraformaldehyde, methylene glycol and quaternium-15 in cosmetics from Jan. 1, 2025. Washington's TFCA restricts formaldehyde and methylene glycol from Jan. 1, 2025 and 25 more formaldehyde releasers from Jan. 1, 2027 (retail sell-through to Dec. 31, 2027). Confidence: High. WA Ecology; Md. Code via Justia; CA DTSC
3. Hair relaxer MDL 3060 is large and pre-trial. 12,129 actions pending (16,561 total ever filed) on Sept. 1, 2026 before Judge Mary M. Rowland (N.D. Ill.). 10-case bellwether pool selected April 2, 2026; defendants' Rule 702 motions to exclude general-causation experts filed May 5, 2026 (ruling not reported as of research date); no trial held and no global settlement. Arizona AG sued L'Oréal USA (filed Sept. 9, announced Sept. 11, 2026). Confidence: High (counts, bellwether pool, AZ suit); Medium (downstream schedule dates from law-firm trackers). JPML; Joint Status Report May 2026; AZ AG
4. Relaxer–cancer evidence shows associations, not established causation. Sister Study 2022: frequent straightener use linked to about 2x uterine cancer risk (est. 4.05% vs 1.64% by age 70). BWHS 2023: significant only in postmenopausal long-term users (HR 1.64–1.71). Sister Study ovarian (HR 2.19) and 2025 non-reproductive cancers (pancreatic HR 2.66, thyroid HR 1.71). No study had brand/ingredient data. Confidence: Medium-High for association; Low for causation/ingredient. NIH; BWHS
5. MoCRA is half-implemented. In effect: registration and listing (enforced from July 1, 2024; 14,299 facilities / 992,907 listings as of Jan. 6, 2026), serious adverse event reporting within 15 business days, safety substantiation, recall and records authority. Delayed: GMP rule (long-term action), fragrance allergen labeling (not proposed). Withdrawn: talc asbestos-testing proposed rule (Nov. 28, 2025). Confidence: High. FDA; Foley; Federal Register
6. PPD allergy: 0.8% general-population prevalence in five European countries (black henna tattoo aOR 9.33). 5.6% positive among 54,917 NACDG patch-tested patients (1994–2018); hair dye was the source in 73.5%, and hairdressers/cosmetologists made up 72.8% of occupational cases. Confidence: High. JID 2016; Dermatitis 2023
7. "PPD-free" claims are unreliable: 5 of 51 dyes contained unlisted PPD, 4 of those labeled PPD-free (Dermatitis, 2025). Confidence: High (for that sample). Needle et al.
8. Glyoxylic acid (common "formaldehyde-free" smoothing active) was confirmed by France's ANSES (Jan. 2025) as very likely responsible for acute kidney failure cases; the EU SCCS has a mandate to assess safety up to 16%, with a data call open until May 2027. Confidence: High. ANSES; COSlaw
9. Occupational: IARC classifies occupational exposure as a hairdresser/barber as "probably carcinogenic" (Group 2A); personal hair dye use is "not classifiable" (Group 3) (Vol. 99, 2010). UK IIAC (2014) found bladder cancer relative risks of only about 1.2–1.7 and did not recommend prescription. Confidence: High for IIAC (fetched); Medium-High for IARC Vol. 99 wording [not re-verified]. IIAC; IARC Vol 99
10. Bond builders: Mechanism claims (disulfide re-linking by bis-aminopropyl diglycol dimaleate; K18 peptide) are mainly brand-supported. Independent head-to-head blinded evidence was not found. Olaplex Feb. 2023 hair loss suit (LA Superior Court): final outcome NOT verified. EU lilial ban effective March 1, 2022. Confidence: Low-Medium [not re-verified].

1. How oxidative color, lighteners, developers and toners work

(Background chemistry; standard cosmetic science. Confidence High for general mechanisms; no single fetched source. Recommend the site's color-theory cluster add a textbook/SCCS citation.)

• Permanent (oxidative) color: Primary intermediates ("precursors" such as p-phenylenediamine [PPD], toluene-2,5-diamine [PTD/PTDS], p-aminophenol) and couplers (resorcinol, m-aminophenol, etc.) are mixed with hydrogen peroxide developer in an alkaline base (ammonia or monoethanolamine). The alkali swells the cuticle; small precursors diffuse into the cortex, are oxidized, and couple into larger colored molecules trapped in the fiber. Peroxide also lightens natural melanin (typically 1–3 levels, depending on developer volume).
• Developer strengths (U.S. convention): 10 vol (3%), 20 vol (6%), 30 vol (9%), 40 vol (12%) hydrogen peroxide. Higher volume means more lift and more damage.
• Demi-permanent: Oxidative but low-alkaline, lower peroxide, deposit-only or minimal lift. It may still contain PPD/PTD.
• Semi-permanent/direct dyes: Preformed color molecules (HC and basic dyes). No developer is needed, and color gradually washes out. Some contain azo or nitro dyes that may cross-react with PPD.
• Lighteners (bleach): Persulfate salts (ammonium/potassium/sodium persulfate) plus hydrogen peroxide at high pH oxidize eumelanin and pheomelanin. They damage keratin by oxidizing cystine disulfide bonds to cysteic acid and lifting the cuticle. Persulfates are recognized causes of occupational asthma and rhinitis in hairdressers.
• Toners: Usually demi- or semi-permanent deposit shades used to neutralize unwanted warmth (violet cancels yellow, blue cancels orange) after lightening.
• Henna and progressive dyes: Pure henna (lawsone) and bismuth citrate are FDA-approved color additives for hair. Lead acetate was delisted, effective Jan. 6, 2022. FDA Hair Dyes
• U.S. coal-tar dye exemption: Oxidative "coal-tar" hair dyes need no FDA approval if labeled with the statutory caution and patch-test instruction. They may not be used on eyelashes or eyebrows. FDA says it lacks "reliable evidence showing a link between cancer and coal-tar hair dyes on the market today." FDA (updated Sept. 25, 2025)

Personal hair-dye cancer epidemiology (context): The CIR Expert Panel (industry-funded via PCPC) reviewed the literature in its 2025 cycle and concluded the data "do not provide sufficient evidence to support a causal relationship between personal hair dye use and cancer." It cited the Nurses' Health Study (117,200+ nurses, 36 years; no overall solid-cancer association) and the Sister Study breast cancer finding (45% higher risk among Black women using permanent dye vs 7% among White women). CIR, Aug. 15, 2025. Limitation: industry-funded body; use alongside independent reviews.

2. PPD and hair-dye allergy

Prevalence and risk factors

• General population (Europe): 10,425 surveyed; 2,739 randomly patch-tested across five countries; PPD allergy 0.8% (95% CI 0.6–1.0). No significant association with hair-dye use or gender. Black henna tattoo: 3.2% vs 0.6%, aOR 9.33 (3.45–25.26). Clinically relevant dye-linked reactions: 0.1%. Diepgen et al., JID, 2016
• Clinic population (North America): NACDG 1994–2018, 54,917 patients, 5.6% positive (3,095). Female OR 1.52; age >40 OR 1.55; White OR 0.66. Source: hair dye 73.5%, apparel 3.9%. Occupational 8.3%, of which hairdressers/cosmetologists 72.8%. Sites: face 25.5%, hands 21.9%. Co-reactions: benzocaine 11.3%, disperse dye mix 6.5%, black rubber mix 5.1%. Warshaw et al., Dermatitis, 2023
• Cross-reactors: PTDS (tolerated by ~50% of PPD-allergic people), azo dyes, PABA, benzocaine/procaine, sulfonamides. Diagnostic patch test uses 1% PPD in petrolatum. Rare systemic reactions include anaphylaxis and acute kidney failure (the latter linked to ingestion/black henna contexts). DermNet, July 2024
• "PPD-free" products: Of 51 dyes (39 marketed PPD-free), 7 had undisclosed allergens. 5 contained unlisted PPD (4 labeled PPD-free), 1 of them above 2%. Two had undisclosed p-aminophenol, and one each had 2-nitro-PPD and henna. Needle et al., Dermatitis, online June 24, 2025
• ME-PPD (2-methoxymethyl-PPD) is studied as a lower-sensitizing alternative. JAAD 2018 [not re-fetched; check funding — ME-PPD was developed by industry].

Patch/skin allergy test guidance

• U.S. statutory caution (FD&C Act coal-tar exemption): "Caution – This product contains ingredients which may cause skin irritation on certain individuals and a preliminary test according to accompanying directions should first be made. This product must not be used for dyeing the eyelashes or eyebrows; to do so may cause blindness." FDA says to test before each application. FDA
• EU labeling (Directive 2009/134/EC, now Regulation 1223/2009 Annex III): "Hair colorants can cause severe allergic reactions. Read and follow instructions. This product is not intended for use on persons under the age of 16. Temporary 'black henna' tattoos may increase your risk of allergy." There are also "Do not colour your hair if…" warnings. Cosmetics & Toiletries. A dermatology study cited there found test site "practically irrelevant" for interpretation.
• EU PPD limit: Maximum 2% (as free base) on-head after oxidative mixing (Annex III). [not re-verified in this session; high background confidence]
• Manufacturer (L'Oréal Paris/Garnier): "Always perform a hair allergy test 48 hours before each use of a colourant product"; allergies "can develop suddenly." Be Colour Safe
• NHS (reviewed Dec. 29, 2025): Symptoms may take up to 72 hours. Test at least 48 hours before each use. Call 999 for swelling of lips/throat or breathing difficulty. Rashes on darker skin may look brown, purple or grey. NHS
• AAD: Could not retrieve AAD-specific hair dye guidance in this session. Open item.
• State laws: CA AB 2762 / MD / WA restrict "phenylenediamine" salts (m- and o-phenylenediamine). Our reading is that PPD (para-) itself is not banned. [Medium confidence; verify statutory text]

3. Bond builders

[Section largely not re-verified: web search budget exhausted and fetch rate-limited]

• Chemistry of damage: Covered in §1. Bleach converts cystine to cysteic acid, so those bonds can't simply re-form.
• Olaplex: The active is bis-aminopropyl diglycol dimaleate (patented; developed by materials scientists). The brand claims it links broken disulfide bonds. Outside scientists have suggested alternative mechanisms (ionic crosslinking of maleate with protein amines, damage limitation). Confidence: Medium (mechanism debate); independent clinical evidence not located.
• K18: Proprietary "K18Peptide" leave-in mask, claimed to reconnect keratin polypeptide chains. Company-supported data. Confidence: Low-Medium; no independent trial located.
• Lilial (butylphenyl methylpropional): Classified CMR 1B (reproductive toxicant). Banned in EU cosmetics from March 1, 2022 (Omnibus IV, Reg. (EU) 2021/1902). Olaplex removed it from No.3 in 2022. Also added to California's AB 496 list ("lily aldehyde"), effective Jan. 1, 2027 (Keller & Heckman, fetched). Confidence: High (CA); Medium-High (EU date, not re-fetched).
• Olaplex hair loss lawsuit: Filed Feb. 2023, Los Angeles County Superior Court, by a group of consumers (reported initial count ~28, later more) alleging hair loss/scalp injury and citing lilial and other ingredients. Olaplex denied it and publicized third-party testing. Outcome NOT verified. Search results listed CBS News, Dermatology Times, BeautyMatter, and a ConsumerShield 2026 update, but these could not be opened.

4. Formaldehyde and releasers in keratin/smoothing treatments

Hazard

• FDA: formaldehyde appears as formaldehyde, formalin, methylene glycol. Effects include eye/nose/throat irritation above ~0.1 ppm, cough, wheeze, headache, dizziness, nausea, chest pain, vomiting, rash, and sensitization. It is a human carcinogen at high or prolonged exposure. Salons fall under OSHA's formaldehyde standard (29 CFR 1910.1048), and professional products must have SDSs. FDA, updated Oct. 15, 2024
• OSHA (2011 hazard alert era): NIOSH found ~11% formaldehyde in Brazilian Blowout Acai Professional Smoothing Solution labeled formaldehyde-free, and Oregon found ~8.5% in another sample. Manufacturers must list formaldehyde on MSDS/SDS. Salons should monitor air, use controls and respirators where needed, and wear gloves. NIOSH REL is a 0.1 ppm ceiling. OSHA Background. OSHA PEL 0.75 ppm TWA, action level 0.5 ppm, STEL 2 ppm [standard values; not re-fetched].

FDA proposed ban: timeline

A 2021 petition from salon workers/advocates preceded the agenda item (HealthDay).

State laws

• California AB 2762 (signed Sept. 2020; effective Jan. 1, 2025): bans formaldehyde, paraformaldehyde, methylene glycol, quaternium-15, and more. AB 496 (signed Oct. 8, 2023; effective Jan. 1, 2027) adds 26 substances incl. lily aldehyde. CA DTSC (May 2024) declined a separate Priority Product listing for formaldehyde straighteners, citing the forthcoming FDA and state measures, and listed ~40 potential releasers. DTSC; K&H
• Maryland HB 643 (2021; Health-Gen. §21-259.2, effective Jan. 1, 2025): same four formaldehyde-related substances, with a technically-unavoidable-trace exception. A 2026 law (SB 656/HB 1533, signed Apr. 28, 2026, effective July 1, 2026) reportedly adds lead and stronger penalties (ChemLinked; Medium confidence, paywalled).
• Washington TFCA (2023): formaldehyde and methylene glycol (plus PFAS, phthalates, lead, mercury, triclosan, phenylenediamine salts) restricted from Jan. 1, 2025. WAC 173-339 (adopted Aug. 2025) restricts 25 formaldehyde releasers from Jan. 1, 2027, incl. bronopol, bronidox, DMDM hydantoin, quaternium-15, and timonacic in heat-activated straighteners. Only WA retailers may sell through pre-existing stock to Dec. 31 of the restriction year. Cosmetologists should not pour non-compliant products down drains. WA Ecology news; Guidance for cosmetologists
• Oregon and Minnesota also appear on a May 2024 Crowell chart of formaldehyde restrictions (effective dates not given). Crowell chart

Substitutes: glyoxylic acid

• ANSES (Jan. 23, 2025): glyoxylic acid "very likely responsible" for acute kidney failure. At least 5 cases (1 initial + 4 after the Oct. 2024 alert). ANSES urges EU restriction or ban and assessment of derivatives. Symptoms to watch: abdominal or lower back pain, nausea, vomiting. ANSES
• EU SCCS mandate (published ~May 2026): assess safety up to 16% in straighteners; data deadline May 5, 2027. Notes it may release formaldehyde under certain conditions. COSlaw.eu
• Israel reporting describes continued kidney-failure cases despite a ban there (Times of Israel, not fetched). A U.S. toxicology case series (PubMed 40875963) and a systematic review (PMC12754416) exist but were not accessible (captcha).

5. Chemical relaxers/straighteners and cancer research

A 2025 systematic review in the Journal of Applied Toxicology (Hernandez et al.) on relaxers and hormone-sensitive outcomes in Black women exists (Wiley) but was not accessible (403). Causation: not established.

6. MDL 3060 litigation (as of Sept. 2026)

• Court: N.D. Ill., No. 1:23-cv-00818; Judge Mary M. Rowland; Magistrate Judge Beth W. Jantz (per tracker).
• Counts (JPML): Sept. 1, 2026: 12,129 pending / 16,561 historical (JPML). Aug. 3, 2026: 11,779 pending / 16,199 total (Marin Murphy citing JPML). Trackers show ~10,948 in Jan. 2026. Note: many "resolved" actions likely reflect dismissals, duplicates or remands, not settlements.
• Defendants (May 2026 JSR): L'Oréal USA, Revlon, Luster Products, Namaste, AFAM, Beauty Bell, Strength of Nature, House of Cheatham, Sally Beauty, Avlon, Dudley Beauty, RNA Corp., John Paul Mitchell Systems, Murray's Worldwide. Revlon issues relate to its bankruptcy (a tracker cites a $44M reserve, unverified).
• Schedule (May 14, 2026 JSR): Bellwether fact discovery (10 cases) to close June 10, 2026. Combined Rule 702 general-causation motions filed May 5, 2026 (oppositions June 2, replies June 16). Class certification oppositions June 2, replies Aug. 3, 2026. State trials: St. Clair County, IL Sept. 28, 2026; Cook County Nov. 2, 2026 (then Jan. 26 and Apr. 5, 2027); DeKalb County, GA expert deadlines extended to July 17, 2026. Disputes over deficiency notices; a diversity jurisdiction issue (Beauty Bell). JSR
• Later dates (trackers, Medium confidence): Defendants' expert disclosures Sept. 3; plaintiffs' rebuttal Sept. 17; expert discovery closes Nov. 16; SJ/Daubert motions Dec. 16, 2026; first trials 2027. Mediator Ellen Reisman appointed Apr. 2025. Marin Murphy. Conflicting tracker (MDL Update) claims "initial 3 bellwether cases" selected in Sept. 2026, unverified. Projected settlement values on tracker sites are speculative and excluded.
• Rule 702 ruling: Not reported as of Sept. 17, 2026 (plaintiffs' opposition filed Aug. 3 per King Law; briefing-date inconsistency between sources).
• Arizona v. L'Oréal USA: Filed Sept. 9, 2026; announced Sept. 11. Consumer fraud / failure to disclose risks (ovarian, uterine, thyroid, pancreatic). Products named: Dark & Lovely, Optimum, Mizani (SoftSheen-Carson). L'Oréal: allegations "have neither legal nor scientific merit." AZ AG; Consumer Reports

7. MoCRA implementation status

• Enacted: Dec. 29, 2022. Most provisions effective Dec. 29, 2023. FDA enforcement of registration/listing began July 1, 2024 (EcoMundo).
• Registration/listing: Facilities renew biennially; products listed with ingredients and updated annually. 14,299 active facility registrations and 992,907 active listings as of Jan. 6, 2026 (Foley).
• Adverse events: Serious AEs within 15 business days; follow-up within 15 business days for 1 year. Public FAERS cosmetics dashboard launched Sept. 12, 2025.
• Safety substantiation: Required; no mandated methods; animal testing not required.
• Recall/records: Draft mandatory recall guidance Dec. 18, 2025; draft records access guidance Jan. 2026 (Crowell).
• GMP: Statutory NPRM deadline Dec. 29, 2024 missed. Moved to long-term actions (Spring 2025 agenda), with no NPRM expected within 12 months. Warning letter to CDL Services d/b/a Technichem (Nov. 24, 2025) cited GMP issues.
• Fragrance allergens: Statutory deadline June 29, 2024 missed. Agenda target May 2026 (Spring/Fall 2025 agendas). Industry report (July 2026): November 2026. Not published as of research date. Medium.
• Talc/asbestos testing: Proposed Dec. 26/27, 2024; withdrawn Nov. 28, 2025 (FR 2025-21407) citing scientific/technical complexities; FDA intends to reissue. MoCRA still mandates it.
• PFAS report: Published Dec. 29, 2025; insufficient data to determine safety.
• Small business exemption and exceptions, professional-use labeling wording, salon exemption, preemption scope: Described from statutory background knowledge [not re-verified in this session]. Treat as Medium confidence and verify against FDA guidance before publishing post 05 edits.
• Context for delays: FDA reorganization and staff reductions in 2025; the administration's regulatory reduction policy (Marie Gale).

8. EU Cosmetics Regulation: hair-relevant restrictions

• Framework: Regulation (EC) No 1223/2009. Annex II (prohibited), Annex III (restricted with limits/warnings), Annex IV (colorants). Since the 2003 EU hair dye strategy, industry had to submit SCCS safety dossiers or have substances banned; well over 100 hair dye substances were prohibited as a result [background; not re-verified; exact count to confirm].
• Oxidative dye warnings: See §2 (under-16 warning, black henna, "do not colour if…"). C&T
• PPD: Max 2% on-head after mixing, professional-use labeling for some substances [not re-verified].
• Lilial ban: March 1, 2022 [not re-verified].
• Glyoxylic acid: SCCS mandate 2026 (see §4).
• Formaldehyde: EU requires labeling "contains formaldehyde" when releasers yield ≥0.001% free formaldehyde in finished product (Reg. 2022/1181, applicable from July 31, 2024) [background; not re-verified].

9. Salon occupational exposures

• IARC: Vol. 57 (1993) and Vol. 99 (2010) evaluated hairdressers/barbers. Occupational exposure = Group 2A; personal use of hair colourants = Group 3 (Vol. 99). IARC Vol. 99 page; Vol. 57 summary. Classification wording not re-fetched [Medium-High].
• UK IIAC Position Paper 31 (Feb. 2014): Bladder cancer RR in hairdressers 1.2–1.7 (meta-analyses 1.30 and 1.23; a pooled EU analysis 0.8, 0.4–1.7). Below the doubling threshold, so prescription not recommended. Notes IARC 2A (1990s). IIAC. Limitation: UK compensation-threshold framing; older exposures (pre-1980 formulations with aromatic amines) likely drive risk.
• Scoping review (Quiros-Alcala et al., 2019; CDC Stacks): Salon exposures include formaldehyde (83% of Taipei salon samples exceeded Taiwan IAQ standard), VOCs (toluene, benzene, acetates), phthalates (~3x residential), persulfates, ammonia. Most consistent outcome: respiratory (rhinitis, lung function decline, airway inflammation). Reproductive evidence insufficient. Recommends ventilation, safer products, research on stylists serving Black clientele. CDC Stacks
• Occupational PPD allergy: Hairdressers were 72.8% of occupational PPD cases in NACDG (see §2).
• OSHA formaldehyde: Air monitoring, controls, PPE (see §4). OSHA
• NIOSH-specific salon ventilation guidance: Not retrieved in this session (only a 1989 HHE surfaced). Open item.

Open questions / not verified

1. Olaplex 2023 hair loss lawsuit final outcome: Not verified (fetch blocked). Post 04 states this explicitly.
2. Independent bond-builder studies: Not retrieved. Post 04 is conservative and should get peer-reviewed citations before publishing.
3. FDA formaldehyde and fragrance allergen NPRM target (Nov. 2026): From one industry blog; Reginfo.gov page text didn't render.
4. MDL 3060 Rule 702 ruling, current state trial dates (St. Clair Sept. 28, Cook Nov. 2), and whether any state trial started: Not confirmed.
5. MoCRA small-business exemption exceptions, professional-use label wording, salon exemption and preemption: Not re-verified against FDA text this session.
6. EU details (PPD 2% limit, lilial date, formaldehyde labeling threshold, number of banned hair dye substances): Background knowledge, not re-fetched.
7. AAD hair dye allergy guidance and NIOSH salon guidance: Not retrieved.
8. Maryland 2026 law (SB 656/HB 1533) contents: Paywalled; lead addition reported by ChemLinked only.
9. Glyoxylic acid U.S. case series/systematic review details: Captcha-blocked.

Source list