{
  "spore": "profile",
  "id": "boric-acid",
  "spore_version": "0.2",
  "family": "boron-compounds",
  "name": "Boric acid (H3BO3)",
  "role": "neutron poison and soluble boron source",
  "category": "shielding",
  "type": "water-and-ice",
  "summary": "Boric acid (H3BO3, also written B(OH)3) is a boron compound that dissolves in water. Wikipedia says it is used in some nuclear power plants as a neutron poison. PubChem gives its density as 1.435 g/cm3 at 25 °C and its first pKa as 9.24, and its GHS record classes it as a reproductive toxicant (H360FD).\n",
  "best_for": "Soluble boron for neutron absorption in water (Wikipedia: used in some nuclear power plants as a neutron poison)",
  "weakest_at": "Handling: classed as a reproductive toxicant (H360FD) by PubChem, and the dust irritates the eyes, skin and airways",
  "identity": {
    "formula": "H3BO3 (orthoboric acid, written B(OH)3)",
    "cas": "10043-35-3",
    "designations": [],
    "source": "nist-webbook",
    "where": "NIST WebBook, Formula and CAS Registry Number 10043-35-3 (its molecular weight prints with no unit and is not used)"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": []
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density, boric acid",
      "value": 1.435,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "temperature": "25 °C, as printed on the PubChem entry (1.435 @25 °C)"
      },
      "method": "Experimental value printed in the PubChem record; no test standard named",
      "status": "ground",
      "source": "pubchem-boric-acid",
      "where": "Chemical and Physical Properties, Experimental Properties, Density",
      "source_detail": {
        "title": "PubChem compound record, Boric acid (CID 7628), full property and safety data",
        "id": "CID 7628; CAS 10043-35-3",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/7628/JSON",
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point, boric acid (Wikipedia infobox)",
      "value": 170.9,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed as 170.9 °C (339.6 °F; 444.0 K); ICSC instead gives decomposition at 171 °C"
      },
      "method": "Value printed in the Wikipedia infobox; no test standard named",
      "status": "ground",
      "note": "Two sources differ on the thermal behaviour: this melting point (Wikipedia) and the decomposition temperature from ICSC are both recorded.",
      "source": "wikipedia-boric-acid",
      "where": "Infobox, Properties, Melting point row",
      "source_detail": {
        "title": "Boric acid (Wikipedia)",
        "id": "en.wikipedia.org/wiki/Boric_acid",
        "url": "https://en.wikipedia.org/wiki/Boric_acid",
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "decomposition_temperature",
      "label": "Decomposition temperature, ICSC card",
      "value": 171,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed as 'Decomposes at 171°C' where a melting point would normally appear"
      },
      "method": "Value printed on the ICSC card; no test standard named",
      "status": "ground",
      "source": "icsc-0991",
      "where": "Physical and Chemical Information, melting point line",
      "source_detail": {
        "title": "International Chemical Safety Card 0991: Boric acid",
        "id": "ICSC 0991",
        "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991",
        "kind": "database",
        "license": "ICSC card, cited not reproduced"
      }
    },
    {
      "benchmark": "decomposition_temperature",
      "label": "Decomposition onset, PubChem chemical dangers text",
      "value": 100,
      "bound": "lower",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "basis": "printed as 'Decomposes above 100 °C' in the PubChem chemical dangers text"
      },
      "method": "Summary statement in the PubChem record; no test method printed",
      "status": "ground",
      "note": "The same PubChem record also prints 'Stable up to 100 °C' in its stability line, which conflicts with the 171 °C figure from ICSC.",
      "source": "pubchem-boric-acid",
      "where": "Safety and Hazards, Safety and Hazard Properties, Chemical Dangers",
      "source_detail": {
        "title": "PubChem compound record, Boric acid (CID 7628), full property and safety data",
        "id": "CID 7628; CAS 10043-35-3",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/7628/JSON",
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "molar_mass",
      "label": "Molar mass, boric acid",
      "value": 61.83,
      "bound": "exact",
      "unit": "g·mol−1",
      "scope": "material",
      "conditions": {
        "basis": "printed in the Wikipedia infobox as 61.83 g·mol−1"
      },
      "method": "Infobox value; no measurement method printed",
      "status": "calculated",
      "source": "wikipedia-boric-acid",
      "where": "Infobox, Properties, Molar mass row",
      "source_detail": {
        "title": "Boric acid (Wikipedia)",
        "id": "en.wikipedia.org/wiki/Boric_acid",
        "url": "https://en.wikipedia.org/wiki/Boric_acid",
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "pka",
      "label": "Acid dissociation constant, first proton (pKa)",
      "value": 9.24,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "basis": "first proton (Wikipedia gives 9.24 for the first proton); PubChem prints pKa = 9.24",
        "temperature": "25 °C, as printed for the dissociation constant"
      },
      "method": "Value printed in the PubChem dissociation constants entry; Wikipedia also prints 9.24",
      "status": "ground",
      "source": "pubchem-boric-acid",
      "where": "Chemical and Physical Properties, Experimental Properties, Dissociation Constants",
      "source_detail": {
        "title": "PubChem compound record, Boric acid (CID 7628), full property and safety data",
        "id": "CID 7628; CAS 10043-35-3",
        "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/7628/JSON",
        "kind": "database",
        "license": "public domain (NCBI)"
      }
    },
    {
      "benchmark": "water_solubility",
      "label": "Solubility in water at 20 °C (Wikipedia)",
      "value": 4.72,
      "bound": "exact",
      "unit": "g/100 mL",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "solvent": "water"
      },
      "method": "Value printed in the Wikipedia infobox; no method named",
      "status": "ground",
      "note": "ICSC gives 5.6 g/100ml at 20 °C, a different value; both are recorded and neither is averaged.",
      "source": "wikipedia-boric-acid",
      "where": "Infobox, Properties, Solubility in water row, 20 °C entry",
      "source_detail": {
        "title": "Boric acid (Wikipedia)",
        "id": "en.wikipedia.org/wiki/Boric_acid",
        "url": "https://en.wikipedia.org/wiki/Boric_acid",
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "water_solubility",
      "label": "Solubility in water at 20 °C (ICSC)",
      "value": 5.6,
      "bound": "exact",
      "unit": "g/100ml",
      "scope": "material",
      "conditions": {
        "temperature": "20 °C",
        "solvent": "water"
      },
      "method": "Value printed on the ICSC card; no method named",
      "status": "ground",
      "note": "Disagrees with the 4.72 g/100 mL at 20 °C printed by Wikipedia; both are recorded.",
      "source": "icsc-0991",
      "where": "Physical and Chemical Information, Solubility in water, g/100ml at 20°C line",
      "source_detail": {
        "title": "International Chemical Safety Card 0991: Boric acid",
        "id": "ICSC 0991",
        "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991",
        "kind": "database",
        "license": "ICSC card, cited not reproduced"
      }
    },
    {
      "benchmark": "water_solubility",
      "label": "Solubility in water at 100 °C (Wikipedia)",
      "value": 27.53,
      "bound": "exact",
      "unit": "g/100 mL",
      "scope": "material",
      "conditions": {
        "temperature": "100 °C",
        "solvent": "water"
      },
      "method": "Value printed in the Wikipedia infobox; no method named",
      "status": "ground",
      "source": "wikipedia-boric-acid",
      "where": "Infobox, Properties, Solubility in water row, 100 °C entry",
      "source_detail": {
        "title": "Boric acid (Wikipedia)",
        "id": "en.wikipedia.org/wiki/Boric_acid",
        "url": "https://en.wikipedia.org/wiki/Boric_acid",
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "tlv_twa",
      "label": "TLV, time-weighted average, inhalable fraction",
      "value": 2,
      "bound": "exact",
      "unit": "mg/m3",
      "scope": "material",
      "conditions": {
        "basis": "inhalable fraction, as TWA, as printed on the ICSC card"
      },
      "method": "Occupational limit printed on the ICSC card",
      "status": "ground",
      "source": "icsc-0991",
      "where": "Exposure Control and Personal Protection, TLV row",
      "source_detail": {
        "title": "International Chemical Safety Card 0991: Boric acid",
        "id": "ICSC 0991",
        "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991",
        "kind": "database",
        "license": "ICSC card, cited not reproduced"
      }
    },
    {
      "benchmark": "tlv_stel",
      "label": "TLV, short-term exposure limit, inhalable fraction",
      "value": 6,
      "bound": "exact",
      "unit": "mg/m3",
      "scope": "material",
      "conditions": {
        "basis": "inhalable fraction, as STEL, as printed on the ICSC card"
      },
      "method": "Occupational limit printed on the ICSC card",
      "status": "ground",
      "source": "icsc-0991",
      "where": "Exposure Control and Personal Protection, TLV row (6 mg/m3 as STEL)",
      "source_detail": {
        "title": "International Chemical Safety Card 0991: Boric acid",
        "id": "ICSC 0991",
        "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991",
        "kind": "database",
        "license": "ICSC card, cited not reproduced"
      }
    },
    {
      "benchmark": "mak_limit",
      "label": "MAK, inhalable fraction (German limit, as printed)",
      "value": 10,
      "bound": "exact",
      "unit": "mg/m3",
      "scope": "material",
      "conditions": {
        "basis": "inhalable fraction, as printed on the ICSC card"
      },
      "method": "Occupational limit printed on the ICSC card",
      "status": "ground",
      "source": "icsc-0991",
      "where": "Exposure Control and Personal Protection, MAK row",
      "source_detail": {
        "title": "International Chemical Safety Card 0991: Boric acid",
        "id": "ICSC 0991",
        "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991",
        "kind": "database",
        "license": "ICSC card, cited not reproduced"
      }
    },
    {
      "benchmark": "boron10_abundance",
      "label": "Boron-10 share of natural boron (element-level figure)",
      "value": 19.9,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "natural boron, as printed: boron has two naturally occurring and stable isotopes, 11B (80.1%) and 10B (19.9%)"
      },
      "method": "Element-level figure printed in the Wikipedia Boron article; boric acid carries boron with this isotope mix, and no isotope measurement on boric acid itself was read",
      "status": "ground",
      "source": "wikipedia-boron",
      "where": "Characteristics of the element, Isotopes",
      "source_detail": {
        "title": "Boron (Wikipedia)",
        "id": "en.wikipedia.org/wiki/Boron",
        "url": "https://en.wikipedia.org/wiki/Boron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    },
    {
      "benchmark": "boron11_abundance",
      "label": "Boron-11 share of natural boron (element-level figure)",
      "value": 80.1,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "basis": "natural boron, as printed in the same sentence as 10B (19.9%)"
      },
      "method": "Element-level figure printed in the Wikipedia Boron article",
      "status": "ground",
      "source": "wikipedia-boron",
      "where": "Characteristics of the element, Isotopes",
      "source_detail": {
        "title": "Boron (Wikipedia)",
        "id": "en.wikipedia.org/wiki/Boron",
        "url": "https://en.wikipedia.org/wiki/Boron",
        "kind": "web",
        "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Metal surfaces in contact with boric acid solution",
      "headline": "PubChem says boric acid attacks metals and that this produces hydrogen.",
      "effect": "The PubChem chemical dangers summary says that the solution in water is a weak acid, that boric acid attacks metals, and that this produces hydrogen and a fire and explosion hazard. It prints no corrosion rate, metal, concentration or test condition.",
      "rating": "unknown",
      "conditions": {
        "basis": "qualitative summary in the PubChem record; no test method or corrosion rate printed"
      },
      "source": "pubchem-boric-acid",
      "where": "Safety and Hazards, Safety and Hazard Properties, Chemical Dangers"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Reproductive toxicity: the PubChem GHS summary gives hazard statement H360FD, 'May damage fertility; May damage the unborn child', with signal word Danger and Reproductive toxicity category 1B. ICSC prints 'May damage fertility or the unborn child' in its Classification and Labelling section.",
        "ghs": [
          "H360FD"
        ],
        "source": "pubchem-boric-acid",
        "where": "Safety and Hazards, Hazards Identification, GHS Classification (signal word, hazard statements); ICSC Classification and Labelling"
      },
      {
        "text": "Skin and eyes: PubChem prints 'Boric acid irritates the eyes, skin, and the respiratory tract.' ICSC lists redness and pain for the eyes, and says repeated or prolonged skin contact may cause dermatitis.",
        "ghs": [],
        "source": "pubchem-boric-acid",
        "where": "Safety and Hazards, Skin, Eye, and Respiratory Irritations; ICSC Exposure and Health Effects"
      },
      {
        "text": "Ingestion and inhalation: ICSC lists nausea, vomiting, diarrhoea, abdominal pain and skin rash after ingestion, and cough and sore throat after inhalation of dust. It says the substance can be absorbed into the body by inhalation of dust and by ingestion.",
        "ghs": [],
        "source": "icsc-0991",
        "where": "Exposure and Health Effects, Inhalation and Ingestion rows"
      }
    ],
    "failure_risks": [
      {
        "mode": "Heating the powder or solution to decomposition",
        "trigger": "Heating above the decomposition temperature (PubChem: above 100 °C; ICSC: 171 °C)",
        "consequence": "PubChem says decomposition produces water and irritant boric anhydride. The chemical dangers text also says the solution in water is a weak acid.",
        "severity": "low",
        "source": "pubchem-boric-acid",
        "where": "Safety and Hazards, Safety and Hazard Properties, Chemical Dangers"
      },
      {
        "mode": "Dust drawn into the airways or eyes during handling",
        "trigger": "Handling dry powder without dust control",
        "consequence": "ICSC lists cough and sore throat as inhalation symptoms and redness and pain as eye symptoms. It notes the substance can be absorbed into the body by inhalation of dust.",
        "severity": "moderate",
        "source": "icsc-0991",
        "where": "Exposure and Health Effects, Inhalation and Eyes rows"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Spill clean-up: PubChem advises dampening the solid spill with water, then transferring the dampened material to a suitable container.",
        "source": "pubchem-boric-acid",
        "where": "Safety and Hazards, Handling and Storage, Nonfire Spill Response"
      },
      {
        "text": "Respiratory protection: PubChem advises a particulate filter respirator adapted to the airborne concentration of the substance.",
        "source": "pubchem-boric-acid",
        "where": "Safety and Hazards, Accidental Release Measures, Spillage Disposal"
      },
      {
        "text": "Storage: PubChem advises storing in well-closed containers, separated from strong bases.",
        "source": "pubchem-boric-acid",
        "where": "Safety and Hazards, Handling and Storage, Storage Conditions and Safe Storage"
      },
      {
        "text": "Airborne limits printed by ICSC for dust: TLV 2 mg/m3 as TWA, 6 mg/m3 as STEL (inhalable fraction), and MAK 10 mg/m3.",
        "source": "icsc-0991",
        "where": "Exposure Control and Personal Protection, TLV and MAK rows"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "radiation-shielding",
      "device": "Neutron poison in some nuclear power plants",
      "example": "Wikipedia: boric acid is used in some nuclear power plants as a neutron poison, and the boron in it reduces the probability of thermal fission by absorbing some thermal neutrons.",
      "source": "wikipedia-boric-acid",
      "where": "Nuclear power section"
    },
    {
      "application": "electronics-and-chips",
      "device": "Semiconductor production (boron chemicals)",
      "example": "USGS says boron minerals and chemicals were used as a component in abrasives, cleaning products, insecticides, insulation, and in the production of semiconductors in the United States. The source treats this as boron in general, not boric acid alone.",
      "source": "usgs-mcs2026-boron",
      "where": "Domestic Production and Use paragraph"
    }
  ],
  "supply": [
    {
      "subject": "Boron (borates and boric acid)",
      "producers": [
        {
          "country": "Turkey",
          "year": 2025
        },
        {
          "country": "China",
          "year": 2025
        },
        {
          "country": "Chile",
          "year": 2025
        },
        {
          "country": "Bolivia",
          "year": 2025
        },
        {
          "country": "Peru",
          "year": 2025
        },
        {
          "country": "Russia",
          "year": 2025
        },
        {
          "country": "Argentina",
          "year": 2025
        },
        {
          "country": "Germany",
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (boron added in the final list, per usgs-mcs2026-boron and usgs-crit2025)",
          "listed": true
        },
        {
          "list": "EU critical raw materials list, Boron/Borate (per ec-crm)",
          "listed": true
        }
      ],
      "recycling": "USGS: recycling of boron is listed as 'Insignificant.'",
      "substitutes": [
        "USGS: substitution of other materials for boron is possible in detergents, enamels, insulation, and soaps; sodium percarbonate can replace borates in detergents."
      ],
      "source": "usgs-mcs2026-boron",
      "where": "World Production and Reserves table, 2025 column (production printed without units; the world total is marked XX, which USGS says cannot be calculated; the United States is marked W, withheld); Recycling; Substitutes. Lists from usgs-mcs2026-boron, usgs-crit2025 and ec-crm."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "ICSC 0991: Boric acid (International Chemical Safety Card)",
      "type": "database",
      "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991"
    },
    {
      "title": "PubChem compound record: Boric acid (CID 7628), GHS and property sections",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/Boric-acid"
    },
    {
      "title": "Mineral Commodity Summaries 2026: Boron (USGS)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf",
      "year": 2026
    },
    {
      "title": "NIST Chemistry WebBook: Boric acid (identifiers)",
      "type": "database",
      "url": "https://webbook.nist.gov/cgi/cbook.cgi?ID=C10043353&Units=SI"
    }
  ],
  "gaps": [
    "No neutron-capture cross section for boric acid or for boron-10 was read in a fetched source, so the neutron-absorption role has no number of its own in this record.",
    "Corrosion of carbon or low-alloy steel by boric acid in reactor coolant has no source here: the NRC Bulletin 2002-01 PDF and HTML addresses both returned HTTP 404 and the NRC glossary returned HTTP 403.",
    "The CDC ATSDR Toxicological Profile for Boron could not be read (the server rejected the download), so no animal toxicity dose or reproductive-effect level is recorded.",
    "The EPA boric acid page returned not found, and the web search budget ran out, so no manufacturer safety data sheet for boric acid was read. The hazard data rest on ICSC and PubChem.",
    "Vapour pressure: ICSC gives 'negligible' and PubChem prints it in scientific notation, so no vapour-pressure value is recorded.",
    "Melting point is not settled by one source: Wikipedia gives a melting point and ICSC gives decomposition. Both are recorded side by side and the question is left open.",
    "Solubility at 20 °C differs between Wikipedia and ICSC; both values are recorded and neither is averaged.",
    "Decomposition onset differs: PubChem says it decomposes above 100 °C and is stable up to 100 °C, while ICSC gives 171 °C. Both are recorded.",
    "USGS producer tonnages are printed without units and the world total is marked XX, so producer shares are not calculated and only the countries are listed.",
    "No space flight, vacuum or radiation-test data for boric acid were found; the uses listed are terrestrial, so no space environment tags are set.",
    "The boron-10 and boron-11 shares are element-level figures from Wikipedia's Boron article, not isotope measurements on boric acid.",
    "No designations other than the CAS number (10043-35-3) were printed in the sources read, so no UNS, EN or trade names are listed."
  ],
  "story": {
    "why": "Boric acid (H3BO3, also written B(OH)3) is a boron compound that dissolves in water. Wikipedia says it is used in some nuclear power plants as a neutron poison, because the boron in it absorbs some thermal neutrons. Boron-10 makes up 19.9% of natural boron. This record covers the acid itself, which ICSC and PubChem both treat as a reproductive hazard.",
    "uses": [
      {
        "where": "Nuclear power plants",
        "line": "Wikipedia says boric acid is used in some nuclear power plants as a neutron poison. The boron in it reduces the probability of thermal fission by absorbing some thermal neutrons."
      },
      {
        "where": "Semiconductors and other uses",
        "line": "The USGS Mineral Commodity Summaries say boron minerals and chemicals were used in abrasives, cleaning products, insecticides, insulation and the production of semiconductors in the United States. That statement covers boron in general."
      }
    ],
    "can_do": [
      {
        "label": "Neutron absorption",
        "line": "The boron in boric acid absorbs some thermal neutrons, which reduces the chance of fission in the nuclear plants that use it (Wikipedia). The boron-10 share of natural boron is 19.9%.",
        "benchmark": "boron10_abundance",
        "scope": "material"
      },
      {
        "label": "Density",
        "line": "Density is 1.435 g/cm3 at 25 °C, per the PubChem record.",
        "benchmark": "density",
        "scope": "material",
        "value": "1.435 g/cm3"
      },
      {
        "label": "Melting point",
        "line": "Wikipedia prints a melting point of 170.9 °C, while ICSC lists decomposition at 171 °C instead.",
        "benchmark": "melting_point",
        "scope": "material",
        "value": "170.9 °C"
      },
      {
        "label": "Solubility",
        "line": "At 20 °C, 4.72 g/100 mL dissolves per Wikipedia, and ICSC gives 5.6 g/100ml. The Wikipedia figure rises to 27.53 g/100 mL at 100 °C.",
        "benchmark": "water_solubility",
        "scope": "material",
        "value": "4.72 g/100 mL at 20 °C"
      },
      {
        "label": "Acidity",
        "line": "The first pKa is 9.24, so the solution is a weak acid (PubChem).",
        "benchmark": "pka",
        "scope": "material",
        "value": "pKa 9.24"
      },
      {
        "label": "Exposure limit",
        "line": "ICSC gives a TLV of 2 mg/m3 as TWA for inhalable dust, with a 6 mg/m3 STEL and a MAK of 10 mg/m3.",
        "benchmark": "tlv_twa",
        "scope": "material",
        "value": "2 mg/m3 TWA"
      }
    ],
    "compare": "Boric acid dissolves in water, which is the main difference from a solid boron shield. At 20 °C it dissolves to 4.72 g/100 mL per Wikipedia or 5.6 g/100ml per ICSC, and it rises to 27.53 g/100 mL at 100 °C. Its density is 1.435 g/cm3 at 25 °C (PubChem). Its melting point is 170.9 °C per Wikipedia, while ICSC gives decomposition at 171 °C instead. The table compares density, melting point and solubility.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Water solubility at 20 °C",
        "benchmark": "water_solubility",
        "scope": "material"
      }
    ],
    "handling": [
      "Dampen spilled powder with water before sweeping it up, and use a particulate filter respirator for the cleanup.",
      "Keep it in well-closed containers, away from strong bases.",
      "Keep dust under the 2 mg/m3 TWA limit (ICSC), and avoid breathing it."
    ],
    "good_for": [
      "Soluble boron for neutron absorption in water, where Wikipedia says it is used in some nuclear power plants.",
      "Known solubility data at several temperatures, from 20 °C to 100 °C, for mixing and dosing calculations."
    ],
    "watch_out": [
      "PubChem classes boric acid as a reproductive toxicant (H360FD, signal word Danger).",
      "The dust irritates the eyes, skin and airways, per PubChem and ICSC.",
      "The sources disagree on heat behaviour: 170.9 °C melting point (Wikipedia), 171 °C decomposition (ICSC), and decomposition above 100 °C (PubChem).",
      "The sources disagree on solubility at 20 °C: 4.72 g/100 mL (Wikipedia) against 5.6 g/100ml (ICSC)."
    ],
    "verdict": "Boric acid is a soluble neutron absorber used in some nuclear power plants, but ICSC and PubChem treat it as a reproductive hazard, so it should be handled as a toxic dust.",
    "recipe": {
      "line": "Boric acid is H3BO3, also written B(OH)3 in Wikipedia's lead: one boron atom bonded to three hydroxyl groups. Wikipedia's history section says orthoboric acid was first prepared from borax by the action of mineral acids.",
      "parts": [
        {
          "name": "Boron",
          "symbol": "B",
          "role": "The central atom. Boron is the element that absorbs neutrons in the boron-10 isotope, which is 19.9% of natural boron.",
          "atoms": 1,
          "atomic_weight": 10.81,
          "source": "wikipedia-boron",
          "where": "Infobox, Standard atomic weight row, abridged value (printed without unit)"
        },
        {
          "name": "Hydrogen",
          "symbol": "H",
          "role": "Three hydrogens sit on the hydroxyl groups, which give the acid its weak acidity (pKa 9.24).",
          "atoms": 3,
          "atomic_weight": 1.008,
          "source": "wikipedia-hydrogen",
          "where": "Infobox, Standard atomic weight row, abridged value (printed without unit)"
        },
        {
          "name": "Oxygen",
          "symbol": "O",
          "role": "Three oxygens form the hydroxyl groups, which bind the hydrogen to the boron.",
          "atoms": 3,
          "atomic_weight": 15.999,
          "source": "wikipedia-oxygen",
          "where": "Infobox, Standard atomic weight row, abridged value (printed without unit)"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "ICSC and PubChem both classify boric acid as a reproductive toxicant. The powder also irritates the eyes, skin and airways.",
        "points": [
          {
            "label": "Fertility and the unborn child",
            "line": "PubChem's GHS summary gives H360FD, 'May damage fertility; May damage the unborn child', with signal word Danger. ICSC prints 'May damage fertility or the unborn child'."
          },
          {
            "label": "Dust",
            "line": "ICSC lists cough and sore throat as inhalation symptoms and says the substance can be absorbed by inhaling dust. The TLV is 2 mg/m3 as TWA, and the STEL is 6 mg/m3."
          },
          {
            "label": "Ingestion",
            "line": "ICSC lists nausea, vomiting, diarrhoea, abdominal pain and skin rash after ingestion."
          }
        ],
        "level": 3,
        "verdict": "Reproductive toxicant (H360FD)"
      },
      {
        "title": "If the powder is heated",
        "lead": "Heated, boric acid gives off water and boric anhydride. ICSC gives 171 °C as the decomposition temperature, and PubChem says it decomposes above 100 °C.",
        "points": [
          {
            "label": "Decomposition",
            "line": "PubChem says it decomposes above 100 °C and produces water and irritant boric anhydride. ICSC gives 171 °C."
          }
        ],
        "level": 2,
        "verdict": "Decomposes above 100 °C per PubChem"
      },
      {
        "title": "Handling and spills",
        "lead": "The safety data sheets and PubChem advise limiting dust and cleaning spills wet.",
        "points": [
          {
            "label": "Spills",
            "line": "PubChem advises dampening the spilled solid with water before sweeping it into a container, with a particulate filter respirator."
          },
          {
            "label": "Storage",
            "line": "PubChem advises well-closed containers, separated from strong bases."
          }
        ],
        "level": 1,
        "verdict": "Dampen spills and keep dust down"
      }
    ]
  },
  "updated": "2026-11-02",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 14,
    "unreachable": 0,
    "caveats": 3,
    "note": "Values read by an AI assistant on 2026-11-02 from fetched pages; 3 values carry a source conflict (melting or decomposition, solubility at 20 °C, decomposition onset) and both sides are recorded."
  },
  "sources": {
    "wikipedia-boric-acid": {
      "title": "Boric acid (Wikipedia)",
      "id": "en.wikipedia.org/wiki/Boric_acid",
      "url": "https://en.wikipedia.org/wiki/Boric_acid",
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
    },
    "icsc-0991": {
      "title": "International Chemical Safety Card 0991: Boric acid",
      "id": "ICSC 0991",
      "url": "https://chemicalsafety.ilo.org/dyn/icsc/showcard.display?p_card_id=0991",
      "kind": "database",
      "license": "ICSC card, cited not reproduced"
    },
    "pubchem-boric-acid": {
      "title": "PubChem compound record, Boric acid (CID 7628), full property and safety data",
      "id": "CID 7628; CAS 10043-35-3",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/7628/JSON",
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "nist-webbook": {
      "title": "NIST Chemistry WebBook, Boric acid (identifiers)",
      "id": "NIST WebBook, CAS 10043-35-3",
      "url": "https://webbook.nist.gov/cgi/cbook.cgi?ID=C10043353&Units=SI",
      "kind": "database",
      "license": "public domain (NIST)"
    },
    "usgs-mcs2026-boron": {
      "title": "Mineral Commodity Summaries 2026, Boron",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-boron.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-crit2025": {
      "title": "About the 2025 List of Critical Minerals (USGS)",
      "id": "Final 2025 List of Critical Minerals",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "year": 2025,
      "kind": "web",
      "license": "public domain (USGS)"
    },
    "ec-crm": {
      "title": "Critical raw materials (European Commission, list including Boron/Borate)",
      "id": "Regulation (EU) 2024/1252",
      "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en",
      "year": 2024,
      "kind": "web",
      "license": "European Commission web page"
    },
    "wikipedia-boron": {
      "title": "Boron (Wikipedia)",
      "id": "en.wikipedia.org/wiki/Boron",
      "url": "https://en.wikipedia.org/wiki/Boron",
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
    },
    "wikipedia-hydrogen": {
      "title": "Hydrogen (Wikipedia)",
      "id": "en.wikipedia.org/wiki/Hydrogen",
      "url": "https://en.wikipedia.org/wiki/Hydrogen",
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
    },
    "wikipedia-oxygen": {
      "title": "Oxygen (Wikipedia)",
      "id": "en.wikipedia.org/wiki/Oxygen",
      "url": "https://en.wikipedia.org/wiki/Oxygen",
      "kind": "web",
      "license": "CC BY-SA 4.0 (Wikipedia text, cited not reproduced)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/boric-acid/"
}