Also known as: BRN 1210149, EINECS 247-500-7, UNII-DEL7T5QRPN, 2,3-dihydro-2-methyl-3-oxo-5-chloroisothiazole, CMIT (+2 more)
INCI: METHYLCHLOROISOTHIAZOLINONE
Methylchloroisothiazolinone (CAS 26172-55-4) is a cosmetic preservative functioning as Preservative. NOAEL 0.25 mg/kg bw/day (cross-referenced against ToxValDB ECHA IUCLID); EU Regulation 1223/2009 status: restricted, max 0.0015% in rinse-off cosmetics only as MCI/MI 3:1 blend; prohibited in leave-on cosmetics; 3 safety opinions reviewed (cir). Industrial safety data is also available in the chemical safety database.
View industrial chemical safety profile for CAS 26172-55-4 →
For full compliance data across multiple jurisdictions, use the Substance Compliance tool.
Margin of Safety, dermal absorption, and sensitization profile summaries for Methylchloroisothiazolinone.
Calculate MoS for your specific formulation with the MoS Calculator.
10 study endpoints found for Methylchloroisothiazolinone. NOAEL (No Observed Adverse Effect Level) values are used to calculate the Margin of Safety per SCCS methodology.
| Endpoint | Value | Route | Species | Study Type | Source |
|---|---|---|---|---|---|
| NOAEL | =0.00038 mg/kg bw | dermal | human | reproductive toxicity | SCCS_vision_codex |
| NOAEL | =0.00038 mg/kg bw | dermal | human | reproductive toxicity | SCCS_vision_codex |
| NOAEL | =0.00038 mg/kg bw | dermal | human | reproductive toxicity | SCCS_vision_codex |
| NOAEL | =0.00038 mg/kg bw | dermal | human | reproductive toxicity | SCCS_vision_codex |
| NOAEL | =2.6 mg/kg/day | oral | rat | repeated dose toxicity | SCCS_vision_codex |
| NOAEL | =2.6 mg/kg/day | oral | rat | repeated dose toxicity | SCCS_vision_codex |
| NOAEL | =2.6 mg/kg/day | oral | rat | repeated dose toxicity | SCCS_vision_codex |
| NOAEL | =2.6 mg/kg/day | oral | rat | repeated dose toxicity | SCCS_vision_codex |
| NOAEL | =19.6 mg/kg bw | oral | rat | reproductive toxicity | SCCS_vision_codex |
| NOAEL | =19.6 mg/kg bw | oral | rat | reproductive toxicity | SCCS_vision_codex |
Official safety assessments from the Scientific Committee on Consumer Safety (SCCS) and Cosmetic Ingredient Review (CIR).
Pre-calculated NOAEL → SED → MoS audit trail for Methylchloroisothiazolinone across SCCS product categories, with measured dermal absorption where available.
10 toxicity values from EPA ToxValDB (aggregated from CCTE, HPV, ToxRefDB, IRIS, and other regulatory dossiers).
| Endpoint | Value | Species | Route | Duration | Source |
|---|---|---|---|---|---|
| LEL | =4.4 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LEL | =2.8 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LEL | =5.5 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LEL | =4.3 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LEL | >39.1 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LOAEL | =11.8 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LOAEL | =8.5 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LOAEL | =16 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LOAEL | =13.4 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
| LOAEL | >39.1 mg/kg-day | Rat | oral | chronic (developmental) | ToxRefDB |
Adverse Outcome Pathway data across 5 assays (DPRA, KeratinoSens, hCLAT, LLNA, NESIL) aggregated from public sources.
Source: DPRA: Urbisch et al. 2015 [DOI:10.1016/j.yrtph.2014.12.008]; KS: Urbisch et al. 2015 [DOI:10.1016/j.yrtph.2014.12.008]
Cross-referenced EDC classifications, mechanism data, and dose-response evidence from EDLists, SIN List, and cosmetic-specific detail sources.
indirect modulator
| Endpoint | Target | Value | Direction |
|---|---|---|---|
| Thyroid hormone levels (T3/T4 ↓); developmental toxicity | Thyroid axis (indirect, via oxidative stress) | EC50/IC50: LOEC ≈ 0.3 µg/L (coagulation / hatching delay; thyroid at ≥30 µg/L); LOEC: 0.3 µg/L (developmental); 30 µg/L (thyroid); NOEC: not established mixed | thyroid disruptor |
| ER/AR receptor activity | ERα / AR | EC50/IC50: No significant ER/AR activity reported; LOEC: not established; NOEC: not established mixed | not active at sub-cytotoxic concentrations |
| E2 and T changes | Steroidogenesis | EC50/IC50: LOEC ≈ 0.3 µg/L; EC50 not calculated (overlaps with cytotoxicity); LOEC: 0.3 µg/L; NOEC: not established mixed | active (similar activity to MIT but higher cytotoxicity) |
Additional regulatory detail beyond the 7-jurisdiction summary: Saudi SFDA, Korea MFDS, ASEAN ACD, Japan/Korea, Brazil/India, and cross-jurisdictional restriction entries.
| Jurisdiction | Status | Max % | Product Type |
|---|---|---|---|
| CN | permitted_preservative | 0.0015 | Rinse-off products only |
| IN | permitted_preservative | 0.0015 | all cosmetics |
| AU | restricted | - | preservatives |
Cross-database dermal penetration: EPA Dryad physics-based, Roberts Mendeley permeation, and SCCS-aggregated measured values.
| Type | DA % | Method | Skin Model | SCCS Ref |
|---|---|---|---|---|
| measured | 100.0% | - | - | SCCS/0009 |
| measured | 36.2% | - | - | SCCS/0009 |
| measured | 84.5% | - | - | SCCS/0009 |
| measured | 58.7% | - | - | SCCS/0009 |
| measured | 46.6% | - | - | SCCS/0009 |
Reported concentration ranges per product category from SCCS/CIR/industry sources.
| Product Category | Typical Range | Max Reported | Source |
|---|---|---|---|
| Shampoo | <0.0015 | 0.0015 | CIR (MCI/MI combined max 0.0015%) |
4 property records from structured ingredient metadata.
Expert safety assessment and concern-level summary for Methylchloroisothiazolinone.
Public NOAEL study rows linked to Methylchloroisothiazolinone by CAS number or substance name.
Units vary across source rows: mg/kg/day, mg/kg bw
| Absorption % | Method | Vehicle |
|---|---|---|
| 100.0% | - | - |
| 36.2% | - | - |
| 84.5% | - | - |
| 58.7% | - | - |
| 46.6% | - | - |
Methylchloroisothiazolinone has a safety rating of "POOR" in our database. EU status: restricted. US status: permitted. 10 toxicological study endpoint(s) are available in our database. This ingredient has been reviewed by cir.
Methylchloroisothiazolinone EU regulatory status: restricted. Maximum allowed concentration: 0.0015% in rinse-off cosmetics only as MCI/MI 3:1 blend; prohibited in leave-on cosmetics. This is based on EU Regulation 1223/2009 and its amendments.
Methylchloroisothiazolinone functions as: Preservative. It is classified as a Preservative in our database. CAS number: 26172-55-4.
The NOAEL (No Observed Adverse Effect Level) for Methylchloroisothiazolinone is =0.00038 mg/kg bw based on a reproductive toxicity study via dermal route in human. A total of 10 study endpoints are available. Source: SCCS_vision_codex.
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