Baby Safety / Compounds / Methylisothiazolinone (MIT)

Is Methylisothiazolinone (MIT) safe for babies and kids?

Elevated risk for kids

Infants are exposed to Methylisothiazolinone (MIT) through personal care products (lotions, wipes) and food. Immature skin barrier and hepatic metabolism increase effective dose per body weight.

What is methylisothiazolinone (mit)?

The IUPAC name is 2-methyl-1,2-thiazol-3-one.

Also known as: 2-methyl-1,2-thiazol-3-one, Methylisothiazolinone, 2-Methyl-4-isothiazolin-3-one, 2-Methyl-3(2H)-isothiazolone.

IUPAC name: 2-methyl-1,2-thiazol-3-one
CAS number: 2682-20-4
Molecular formula: C4H5NOS
Molecular weight: 115.16 g/mol
SMILES: CN1C(=O)C=CS1
PubChem CID: 39800

Risk for babies

Elevated risk

Infants are exposed to Methylisothiazolinone (MIT) through personal care products (lotions, wipes) and food. Immature skin barrier and hepatic metabolism increase effective dose per body weight.

Neonates and infants up to 12 months have incomplete blood-brain barrier development, immature Phase I/II metabolic enzymes (particularly CYP3A4, UGT1A1), and higher gastrointestinal permeability. Equivalent doses produce higher internal concentrations and longer residence times.

What to do: Minimize infant exposure through source control. For breastfeeding mothers: reduce maternal exposure. For formula-fed infants: use certified low-migration bottles and verified water sources. Consult pediatrician regarding any concerns.

Risk for pregnant and nursing people

Elevated risk

Prenatal exposure to Methylisothiazolinone (MIT) through personal care products and food is a concern. Some preservatives (parabens) exhibit weak estrogenic activity that may affect fetal endocrine development.

Suspected reproductive toxicant (GHS H361) or suspected endocrine disruptor. Precautionary approach warranted. Animal studies or limited human data suggest developmental toxicity potential.

What to do: Minimize exposure during pregnancy and lactation. Consult healthcare provider regarding specific risks. Consider alternative products with lower hazard profiles.

Regulatory consensus

15 regulatory and scientific bodies have classified Methylisothiazolinone (MIT). The classifications differ — that's the data.

Agency	Year	Classification
US EPA	2000	not classifiable as to human carcinogenicity (Group D)
EFSA	2016	not evaluated for carcinogenicity; strong contact sensitizer regulated under EU Cosmetics Regulation (EC) No 1223/2009; banned from leave-on cosmetics effective 2016 (Commission Regulation EU 2016/1198); restricted to 0.0015% (15 ppm) in rinse-off cosmetics; SCCS 2014 opinion found 15 ppm safe for rinse-off but no safe level established for leave-on applications; MI-alone sensitization epidemic coincided with shift away from MCI/MI combination
EPA CTX / Genetox	—	Genotoxicity: negative (Ames: negative, 1 positive / 9 negative reports)
EPA CTX / Genetox	—	Genotoxicity: negative (Ames: negative, 1 positive / 9 negative reports)
EPA CTX / Skin-Eye	—	Skin Sensitization: Sh (score: high)
EPA CTX / Skin-Eye	—	Skin Sensitization: SkinSens1 (score: high)
EPA CTX / Skin-Eye	—	Skin Irritation: Skin corrosion - category 1B (score: very high)
EPA CTX / Skin-Eye	—	Skin Sensitization: Skin sensitisation - category 1 (score: high)
EPA CTX / Skin-Eye	—	Eye Irritation: Category 8.3A (Category 1) (score: very high)
EPA CTX / Skin-Eye	—	Skin Irritation: Category 8.2B (Category 1B) (score: very high)
EPA CTX / Skin-Eye	—	Skin Sensitization: Category 6.5B (Category 1) (score: moderate)
EU SCCS	—	NOT SAFE for use in leave-on cosmetics at any concentration. Safe in rinse-off products at ≤15 ppm (2013 SCCS opinion)
EU CLP	—	Acute Tox 3 (oral), Acute Tox 3 (dermal), Skin Corr 1B/C, Skin Sens 1A (extremely potent sensitizer), Aquatic Acute 1, Aquatic Chronic 1
EU Cosmetics	—	Banned in leave-on cosmetics (2015). Allowed in rinse-off at ≤15 ppm (MIT alone, not combined with MCI)
ACDS	—	Contact Allergen of the Year 2013 (American Contact Dermatitis Society)

Regulators apply different standards of evidence — animal-data weighting, exposure-pattern assumptions, epidemiological power thresholds — which is why two scientific bodies can review the same data and reach different conclusions. The disagreement is the data.

Where kids encounter methylisothiazolinone (mit)

Industrial Facilities — Manufacturing plants, Chemical storage areas, Waste treatment sites
Occupational Environments — Factories, Warehouses, Transportation vehicles
Personal Care — shampoo, conditioner, lotion, cosmetics, sunscreen
Personal Care (Rinse-Off) — Shampoo, Body wash, Hand soap, Conditioner
Household Products — Laundry detergent, Dish soap, All-purpose cleaners, Wet wipes
Paints And Coatings — Water-based paint preservative (in-can), Adhesive preservative
Industrial — Cooling tower biocide, Metalworking fluid preservative, Paper mill slimicide

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Methylisothiazolinone (MIT):

Physical/mechanical pest control (IPM)
Trade-offs: More labor-intensive. May not be sufficient for severe infestations.

Relative cost: 1.2-2×
Phenoxyethanol
Relative cost: 1.2-2×
Organic acids (benzoic/sorbic)
Relative cost: 2-5× conventional

Frequently asked questions

Is methylisothiazolinone (mit) safe for kids?

Infants are exposed to Methylisothiazolinone (MIT) through personal care products (lotions, wipes) and food. Immature skin barrier and hepatic metabolism increase effective dose per body weight.

What products contain methylisothiazolinone (mit)?

Methylisothiazolinone (MIT) appears in: Manufacturing plants (Industrial facilities); Chemical storage areas (Industrial facilities); Factories (Occupational environments); Warehouses (Occupational environments); shampoo (Personal care).

What should I do if my child is exposed to methylisothiazolinone (mit)?

Minimize infant exposure through source control. For breastfeeding mothers: reduce maternal exposure. For formula-fed infants: use certified low-migration bottles and verified water sources. Consult pediatrician regarding any concerns.

Why do regulators disagree about methylisothiazolinone (mit)?

Methylisothiazolinone (MIT) has been classified by 15 agencies including US EPA, EFSA, EPA CTX / Genetox, EPA CTX / Genetox, EPA CTX / Skin-Eye, with differing conclusions. Regulators apply different standards of evidence (animal data weighting, exposure-pattern assumptions, epidemiological power thresholds), which is why two scientific bodies can review the same data and reach different conclusions. See the regulatory consensus table on this page for the full picture.

See Methylisothiazolinone (MIT) in the baby app

Look up products containing methylisothiazolinone (mit), compare to alternatives, and explore the full data record.

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Sources (2)

US EPA Methylisothiazolinone: Group D Not Classifiable; FIFRA Pesticide Registration; Strong Sensitizer EC3 0.5–1%; Paraben-Free Preservative Epidemic; Wet Wipes Sensitization; In Vitro Neurotoxicity; Industrial Paint and Adhesive Biocide (2000) — regulatory
EFSA/SCCS Methylisothiazolinone: EU Leave-On Ban Commission Regulation 2016/1198; SCCS 2014 Safety Assessment; Rinse-Off Maximum 0.0015%; Pediatric Wet Wipes Dermatitis Epidemic; Diaper Area ACD; Aquatic LC50 0.1–2 mg/L (2016) — regulatory

Reference data, not professional advice. Aggregates publicly available regulatory and scientific data; not a substitute for veterinary, medical, legal, or regulatory advice. Why we built ALETHEIA →