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CAS 1309-42-8

CAS 1309-42-8 matches 0 EU annex records across Annex II–VI of Regulation 1223/2009.

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Chemical identity and properties

PubChem 2D chemical structure for CAS 1309-42-8
CAS 1309-42-8PubChem CID 73981

Magnesium Hydroxide

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. — ChEBI

IUPAC name
magnesium dihydroxide
Molecular formula
H2MgO2
Molecular weight
58.320 g/mol
Exact mass
57.9905210 Da
Topological polar surface area
2.0 Ų
Hydrogen-bond donors
2
Hydrogen-bond acceptors
2
Covalent units
3
Defined stereocentres
0

Also known as

Milk of magnesiaMagnesium hydrateMagnesium hydroxide (Mg(OH)2)Magnesium(II) hydroxidePhillips magnesia tabletsMagnesium (as hydroxide)Magnesii hydroxidumINS NO.528
16 more reported names
Phillips milk of magnesia liquidINS-528NBZ3QY004SCHEBI:6637E-528Hydrate, Magnesium215-170-3Hydroxide, MagnesiumMagmexDulcolax LiquidGentle LaxativeMagLaxMagmilax PowderAntacid-LaxativeMVT PowderWalgreens Childrens
Open full PubChem recordPubChem annotations3D structure image
External database identifiers

Evidence from additional scientific databases

NIH PubChem PUG-View
Exact identifier match73981

Attributed physical-property, hazard, environmental and use annotations.

  • GHS Hazard Statements: Not Classified; Reported as not meeting GHS hazard criteria by 630 of 736 companies Source: European Chemicals Agency (ECHA)
  • ECHA C&L Notifications Summary: Aggregated GHS information provided per 736 reports by companies from 13 notifications to the ECHA C&L Inventory.; Reported as not meeting GHS hazard criteria per 630 of 736 reports by companies.; There are 10 notifications provided by 106 of 736 reports by companies with hazard statement code(s).; Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website. Source: European Chemicals Agency (ECHA)
  • Cosmetic Ingredient Review Conclusion: The CIR Expert Panel concluded that ... Magnesium Hydroxide is safe in hair straighteners and depilatories under conditions of recommended use; users should minimize skin contact. These ingredients are safe for all other present practices of use and concentration described in this safety assessment when formulated to be nonirritating. Source: Cosmetic Ingredient Review (CIR)
  • Cosmetic Ingredient Review Finding(s): Safe for use in cosmetics, with qualifications Source: Cosmetic Ingredient Review (CIR)
  • Consumer Uses: CBI; Other; Lubricating agent; Intermediate; Absorbent; Flux agent; Flame retardant; Soil amendments (fertilizers); Not Known or Reasonably Ascertainable; Filler Source: EPA Chemical Data Reporting (CDR)
  • Industry Uses: Processing aids not otherwise specified; Antioxidant; pH regulating agent; Fuel agents; CBI; Other; Lubricating agent; Processing aids, specific to petroleum production; Intermediate; Flux agent; Absorbent; Flame retardant; Reducing agent; Filler; Not Known or Reasonably Ascertainable; Corrosion inhibitor; Soil amendments (fertilizers) Source: EPA Chemical Data Reporting (CDR)
  • Cosmetic Ingredient Review Link: CIR ingredient: Magnesium Hydroxide Source: Cosmetic Ingredient Review (CIR)
  • Sources/Uses: Found naturally as brucite; [Hawley] Used to make magnesium metal and compounds (dead-burned and caustic-burned magnesia and magnesium oxide, chloride, carbonate, and sulfate), and as an antacid and laxative, a clarifier in sugar refining, and as a residual fuel oil additive; Also used for uranium processing, wastewater treatment, sulfur dioxide removal from waste gases, and neutralization of acids in the chemical industry; Also used in toothpastes and dentrifrices, in foods as a drying and color-retention agent, in frozen desserts, in the pulp and paper industries, and in other products (ceramics, pharmaceuticals, plastics, and flame retardants/smoke suppressants); [HSDB] Used as an alkali and color adjunct; [JECFA] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Industrial Processes with risk of exposure: Metal Preparation and Pouring [Category: Foundry]; Pulp and Paper Processing [Category: Industry]; Sewer and Wastewater Treatment [Category: Industry] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Activities with risk of exposure: Ceramics making [Category: Hobbies] Source: Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
  • Uses: CHEM INT FOR DEAD-BURNED & CAUSTIC-BURNED MAGNESIA, MAGNESIUM CHLORIDE & MAGNESIUM CARBONATE; RAW MATERIAL FOR MAGNESIUM METAL; INGREDIENT IN TOOTHPASTE; NEUTRALIZATION OF ACIDS IN THE CHEMICAL INDUSTRY; ... CLARIFIER IN SUGAR REFINING Source: Hazardous Substances Data Bank (HSDB)
  • Uses: RESIDUAL FUEL OIL ADDITIVE; SULFITE PULP; URANIUM PROCESSING; DENTRIFRICES; IN FOODS AS DRYING AGENT, COLOR RETENTION AGENT; FROZEN DESSERTS Source: Hazardous Substances Data Bank (HSDB)
  • Uses: MEDICATION (VET) Source: Hazardous Substances Data Bank (HSDB)
  • Uses: MEDICATION Source: Hazardous Substances Data Bank (HSDB)
  • Uses: For more Uses (Complete) data for MAGNESIUM HYDROXIDE (6 total), please visit the HSDB record page. Source: Hazardous Substances Data Bank (HSDB)
  • Uses: Plastics -> Typical concentration range in plastic materials -> 4.0 - 8.0% Source: NORMAN Suspect List Exchange

Mapped by: Existing checksum-valid CAS to unique PubChem CID match. Retrieved: 2026-08-31. Open source record

Scientific classifications and hazard annotations provide context and do not replace the market-specific regulatory decision shown above.

Additional source coverage and match status
SourceResultChecked
NIH PubChem PUG-ViewExact match2026-08-31

A recorded no-match is useful evidence that the source was checked; it is not a claim that the substance does not exist elsewhere.

Retrieved from NIH PubChem on 2026-08-31 by checksum-valid CAS matching. Chemical properties do not replace the regulatory decision on this page.

Records for CAS 1309-42-8

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How CAS 1309-42-8 is used on this site

CAS 1309-42-8 is the Chemical Abstracts Service identifier used to pin this page to a specific substance. In the current dataset, 0 EU annex records share this identifier, which helps you cross-check whether the same substance appears under one regulatory context or several.

Use this page when a supplier specification, SDS or raw-material dossier gives you CAS 1309-42-8 and you need to see every linked Annex II–VI record in one place. The entry cards above are the quickest route to concentration limits, warnings, annex placement and product-type conditions.