Ingredient Dictionary

MAGNESIUM HYDROXIDE

Magnesium dihydroxide is a magnesium hydroxide in which the magnesium atom is bound to two hydroxide groups.

How much products actually contain

No product states its amount yet.

Of the products containing it, 38 list it before the 1% line and 1 after it (usually 1% or less).

Products using this ingredient

12 of 39 confirmed · likeliest to carry enough first · See all 39

Definition

Magnesium dihydroxide is a magnesium hydroxide in which the magnesium atom is bound to two hydroxide groups. It has a role as an antacid and a flame retardant.

Source: PubChem

US FDA substance register · UNII NBZ3QY004S · registered name Magnesium hydroxide · single chemical substance

Source: US FDA Unique Ingredient Identifier (UNII)

Cosmetic roles

Keeps pH steadyBUFFERINGAbsorbs water or oilABSORBENT

Safety & regulatory references

Not classified under Korea’s toxic-substance GHS list · existing chemical substance

Source: Korea toxic substances GHS register (NIER)

Reviewed by CIR: Safety Assessment of Inorganic Hydroxides as Used in Cosmetics

Source: US Cosmetic Ingredient Review (CIR)

More data — names, identifiers, properties, test records, literature

Official labels & definitions

JCIA labelling name 水酸化Ｍｇ: 本品は、マグネシウムの水酸化物であり、次の化学式で表される。

Source: JCIA labelling names (Japan)

Names & identifiers

MAGNESIUM HYDROXIDEINCI마그네슘하이드록사이드Korean label name (MFDS standard)Magnesium hydroxide (Mg(OH)2)Synonym水酸化ＭｇJapanese labelling name

CAS No.chemical registry number: 1309-42-8
EC No.EU chemical inventory number: 215-170-3
DTXSIDUS EPA chemical ID: DTXSID4049662
DTXCIDUS EPA compound ID: DTXCID1029621

IUPAC: Magnesium dihydroxide
Molecular formula: H2MgO2
Molecular weight: 58.319 g/mol

Measured properties

Appearance: CBI, Large Crystals, Other Solid, Wet Solid, Dry Powder, Liquid · Odourless, white bulky powder
Odour: Odorless · odourless
Melting point: 350 °C (decomposes) · 350 °C
Solubility: Practically insoluble in water and in ethanol · White, friable masses or bulky, white powder, at about 700 °C is converted to MgO, sol in about 3,300 parts CO2-free water, more sol in water containing CO2, sol in dilute acids with effervescence, insol in alcohol /Magnesium carbonate hydroxide/
Density: 2.36 g/mL · 2.36 @25 °C
pH: pH = 9.5-10.5 (aqueous slurry) · (9.9-10.4)
Colour: white
Melting/freezing point: 0 ℃
Initial boiling point and range: 100 ℃
Vapour density: (&amp, gt, 1)
Viscosity: 1500-3000 cP

Values measured on the substance itself. The KOSHA data are a reference for writing and reviewing safety data sheets, not a specification for a commercial raw material.

Source: PubChem · KOSHA safety data sheets (Korea)

What products actually use it for

What the 85 products reported to the US EPA with this ingredient use it for. Products outside cosmetics are included, so the top few rows are its main uses.

Flame retardant28
pH regulating agent9
Filler8
Processing aids not otherwise specified7
Adhesion/cohesion promoter5
Conductive agent4
Intermediate3
Corrosion inhibitor2

13 other uses

Soil amendments2
Propellants, non-motive (blowing agents)2
Absorbent2
Binder2
Density modifier2
Lubricating agent2
Flavouring and nutrient1
Reducing agent1
Dye1
Drier1
Thickening agent1
Catalyst1
Fuel1

Source: US EPA CompTox dashboard

Irritation and sensitisation studies

2 skin studies and 3 eye studies are on record.

Classed as highly irritating1Classed as low1

The studies disagree (the most common conclusion covers 50%), so they do not establish that this ingredient is irritating. These tests are on the raw material itself; irritation at the amount in a finished product is a different question.

See all 5 studies

Not likely to be sensitizing
skin sensitisation: in vivo (non-LLNA) · Screening · according to OECD Guideline 406 (Skin Sensitisation) according to EPA OPPTS 870.2600 (Skin Sensitisation) according to other guideline: EC No. 440/2008, L 142
High Frequency of Sensitization
skin sensitisation: in vivo (LLNA) · Screening · according to OECD Guideline 429 (Skin Sensitisation: Local Lymph Node Assay) according to EPA OPPTS 870.2600 (Skin Sensitisation) according to EU Method B.42 (Skin Sensitisation: Local Lymph Node Assay)
Category 6.4A (Category 2A)
Eye Irritation · Read Across
Studies Indicate No Significant Irritation
eye irritation: in vivo · Screening · other guideline: JMAFF guidelines (2000); including the most recent partial revisions. according to OECD Guideline 405 (Acute Eye Irritation / Corrosion) according to EU Method B.5 (Acute Toxicity: Eye Irritation / Corrosion) according to EPA OPPTS 870.2400 (Acute Eye Irritation) according to
Studies Indicate No Significant Irritation
eye irritation: in vitro / ex vivo · Screening · other guideline: OECD Guidelines for Testing of Chemicals; Guidelines no. 437: "Bovine corneal opacity and permeability (BCOP) test method for identifying ocular corrosives and severe irritants" according to