Food & Drink / Compounds / Methylmercury chloride

Methylmercury chloride in food: ingestion safety

Moderate risk

Not medical or professional safety advice, and not a substitute for a qualified clinician — consult one. Full disclaimer →

(People-specific data is limited; this page draws from human adult context.) Safety profile for Methylmercury chloride relevant to people.

What is methylmercury chloride?

The IUPAC name is Chloromethylmercury.

Also known as: Chloromethylmercury, Methylmercuric chloride, chloro(methyl)mercury, Mercury methyl chloride.

IUPAC name: Chloromethylmercury
CAS number: 115-09-3
Molecular formula: CH3HgCl
Molecular weight: 251.09 g/mol
SMILES: C[Hg]Cl
PubChem CID: 409301

Risk for people

Moderate risk

Regulatory consensus

9 regulatory and scientific bodies have classified Methylmercury chloride. The classifications differ — that's the data.

Agency	Year	Classification	Notes
EPA	—	—
IARC	—	—
IARC	1993	Group 2B — Methylmercury compounds (possibly carcinogenic to humans)	IARC Monograph Vol. 58. Inadequate human evidence; sufficient evidence in experimental animals for methylmercury chloride.
Minamata Convention	2013	Treaty on Mercury — controls on supply, trade, products, processes, releases	Multilateral environmental agreement covering mercury and mercury compounds; entered into force 2017; 140+ parties.
US EPA	2001	RfD 0.1 µg/kg-day — methylmercury	IRIS chronic reference dose derived from Faroe Islands neurodevelopmental cohort. Basis for FDA/EPA fish-consumption advisories.
Health Canada	2000	CEPA Schedule 1 Toxic Substance — Mercury and its compounds	Mercury and its compounds on Schedule 1; Canada Mercury Strategy and Products Containing Mercury Regulations.
EFSA	2012	TWI 1.3 µg/kg bw/week — methylmercury	EFSA CONTAM Panel scientific opinion on mercury and methylmercury in food (EFSA Journal 2012;10(12):2985).
WHO	2003	PTWI 1.6 µg/kg bw/week — methylmercury (JECFA)	Joint FAO/WHO Expert Committee on Food Additives provisional tolerable weekly intake; basis for international fish-consumption guidance.
MHLW	2003	Maximum residue limit — methylmercury in fish (0.3 ppm)	Japan Ministry of Health, Labour and Welfare; legacy of Minamata disease (1956 onward) drove early adoption of methylmercury-specific food limits.

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 you encounter methylmercury chloride

laboratory settings
research institutions
aquatic food chains
fish tissue

Safer alternatives

Lower-risk approaches that achieve a similar outcome to Methylmercury chloride:

Thimerosal-free vaccine preservatives (2-phenoxyethanol)
Trade-offs: Narrower antimicrobial spectrum. Single-dose vials eliminate need for preservative.

Relative cost: 1.2× (single-dose vials 3-5×)

Frequently asked questions

What products contain methylmercury chloride?

Methylmercury chloride appears in: laboratory settings; research institutions; aquatic food chains.

Why do regulators disagree about methylmercury chloride?

Methylmercury chloride has been classified by 9 agencies including EPA, IARC, IARC, Minamata Convention, US EPA, 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 Methylmercury chloride in the food app

Look up products containing methylmercury chloride, compare to alternatives, and explore the full data record.

Open in food View raw API data

Sources (1)

ATSDR Toxicological Profile — CAS 115-09-3 — reference

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