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CAS Number: 10043-35-3
Synonyms: Boric acid, E284, orthoboric acid, boracic acid, hydrogen borate, acidum boricum, borofax
Physical Properties: White, odorless crystalline powder or colorless, transparent triclinic plates (pearly luster). Slightly soluble in cold water (approx. 4.7 g/100 mL at 20°C); more soluble in hot water (27.5 g/100 mL at 100°C). Soluble in glycerol, ethanol (moderately), and methanol. Molecular weight 61.83 g/mol. Melting point 171°C (decomposes gradually to metaboric acid and then to boric oxide). Boiling point 300°C (decomposes). Density 1.435 g/cm³. pH of saturated solution (approx. 4.7%) is about 5.1 (weakly acidic). Volatile with steam. Weak monobasic Lewis acid (accepts OH⁻ to form B(OH)₄⁻).
Applications: Formerly used as food preservative for caviar, fish roe, margarine, and butter (now banned in most countries). Currently used in pharmaceutical preparations (eye washes, ear drops, topical antiseptic creams, diaper rash powders, vaginal suppositories). Industrial uses (buffer in chemical laboratories, neutron absorber in nuclear reactors, flame retardant in textiles and cellulose insulation, manufacturing of borosilicate glass, glaze and enamel for ceramics, metallurgy flux, lubricant additive, wood preservative). Agriculture (insecticide, herbicide, fungicide for citrus; boron micronutrient fertilizer). Cosmetics (preservative in eye shadows, face powders, and skin creams at low concentrations). Antiseptic for minor cuts and burns (dilute solution).
Description:
Boric acid (E284) is a weak, water-soluble, inorganic acid that was historically used as a food preservative, particularly for caviar (fish roe), margarine, butter, and some meat products. Its antimicrobial action derives from the ability of the undissociated boric acid molecule to penetrate microbial cell membranes and interfere with metabolic processes, including the inhibition of dehydrogenase enzymes, disruption of nucleic acid synthesis, and interference with cell wall synthesis. However, boric acid is only weakly antimicrobial and requires relatively high concentrations, typically 0.5 to 4.0 percent, to achieve preservation, which is orders of magnitude higher than modern preservatives such as sorbates or benzoates.
The use of boric acid as a food additive has been banned in virtually all developed countries due to significant toxicity concerns. The European Union prohibited E284 in food entirely, and it is not listed in the US FDA food additive regulations. The acceptable daily intake established by JECFA was withdrawn because boric acid and borates are no longer considered acceptable food preservatives. The primary toxicity concern is reproductive and developmental toxicity. Boric acid is a known teratogen, causing fetal malformations in animal studies at doses only slightly above the estimated dietary intake, including skeletal abnormalities and low birth weight. In humans, chronic ingestion of boron compounds (from accidental consumption or historical medicinal use) has been associated with testicular atrophy, reduced sperm count, and impaired fertility in males. Acute poisoning causes nausea, vomiting, diarrhea, abdominal pain, erythematous rash (boiled lobster appearance), headache, lethargy, and in severe cases, seizures, kidney failure, and death. The estimated lethal dose in adults is 15 to 20 grams, but severe poisoning has been reported with as little as 5 grams in infants.
Despite its ban in food, boric acid remains available as an over-the-counter pharmaceutical and household product. It is used in dilute solutions (typically 1 to 3 percent) as an eye wash for mild irritations, as an ear drop for otitis externa (swimmer's ear), and in topical antiseptic creams and powders for diaper rash and minor skin infections. The mechanism in these applications is mild astringent and antifungal activity, particularly against Candida albicans. However, the US FDA has classified boric acid as unsafe for use as an ophthalmic solution ingredient due to toxicity concerns, and many medical authorities recommend against its use on broken skin or for prolonged periods, especially in infants, because percutaneous absorption can lead to systemic toxicity.
In industrial applications, boric acid is far more valuable and widely used. It is a key component in the production of borosilicate glass (e.g., Pyrex, Duran), where it improves thermal shock resistance and chemical durability. In the nuclear industry, boric acid is used as a neutron absorber in coolant water of pressurized water reactors to control the fission rate. As a flame retardant, it is impregnated into cellulose insulation, cotton batting, and textiles, where it releases water vapor upon heating and forms a glassy char layer that insulates the material from oxygen. In agriculture, boric acid is an essential micronutrient fertilizer for boron-deficient soils, particularly for crops such as apples, broccoli, cauliflower, and alfalfa, and it is also used as an insecticide against ants, cockroaches, and termites by damaging their exoskeletons and digestive systems. The continued industrial use of boric acid is considered safe under occupational exposure limits, but environmental concerns exist regarding boron accumulation in aquatic ecosystems, where high concentrations can be toxic to fish and amphibians. The historical use of E284 as a food preservative stands as a cautionary example of a substance rejected due to reproductive toxicity and narrow safety margin, with no legitimate food use remaining in modern regulated markets.
SAFETY INFORMATION ABOUT E284 – BORIC ACID
First aid measures:
Description of first aid measures:
General advice:
Consult a physician.
Show this safety data sheet to the doctor in attendance.
Move out of dangerous area:
If inhaled:
If breathed in, move person into fresh air.
If not breathing, give artificial respiration.
Consult a physician.
In case of skin contact:
Take off contaminated clothing and shoes immediately.
Wash off with soap and plenty of water.
Consult a physician.
In case of eye contact:
Rinse thoroughly with plenty of water for at least 15 minutes and consult a physician.
Continue rinsing eyes during transport to hospital.
If swallowed:
Do NOT induce vomiting.
Never give anything by mouth to an unconscious person.
Rinse mouth with water.
Consult a physician.
Firefighting measures:
Extinguishing media:
Suitable extinguishing media:
Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.
Special hazards arising from the substance or mixture
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas
Advice for firefighters:
Wear self-contained breathing apparatus for firefighting if necessary.
Accidental release measures:
Personal precautions, protective equipment and emergency procedures
Use personal protective equipment.
Avoid breathing vapours, mist or gas.
Evacuate personnel to safe areas.
Environmental precautions:
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Methods and materials for containment and cleaning up:
Soak up with inert absorbent material and dispose of as hazardous waste.
Keep in suitable, closed containers for disposal.
Handling and storage:
Precautions for safe handling:
Avoid inhalation of vapour or mist.
Conditions for safe storage, including any incompatibilities:
Keep container tightly closed in a dry and well-ventilated place.
Containers which are opened must be carefully resealed and kept upright to prevent leakage.
Storage class (TRGS 510): 8A: Combustible, corrosive hazardous materials
Exposure controls/personal protection:
Control parameters:
Components with workplace control parameters
Contains no substances with occupational exposure limit values.
Exposure controls:
Appropriate engineering controls:
Handle in accordance with good industrial hygiene and safety practice.
Wash hands before breaks and at the end of workday.
Personal protective equipment:
Eye/face protection:
Tightly fitting safety goggles.
Faceshield (8-inch minimum).
Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
Skin protection:
Handle with gloves.
Gloves must be inspected prior to use.
Use proper glove
removal technique (without touching glove's outer surface) to avoid skin contact with this product.
Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices.
Wash and dry hands.
Full contact:
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
Splash contact
Material: Nitrile rubber
Minimum layer thickness: 0.11 mm
Break through time: 480 min
Material tested:Dermatril (KCL 740 / Aldrich Z677272, Size M)
It should not be construed as offering an approval for any specific use scenario.
Body Protection:
Complete suit protecting against chemicals, The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
Respiratory protection:
Where risk assessment shows air-purifying respirators are appropriate use a fullface respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls.
If the respirator is the sole means of protection, use a full-face supplied air respirator.
Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).
Control of environmental exposure
Prevent further leakage or spillage if safe to do so.
Do not let product enter drains.
Discharge into the environment must be avoided.
Stability and reactivity:
Chemical stability:
Stable under recommended storage conditions.
Incompatible materials:
Strong oxidizing agents:
Hazardous decomposition products:
Hazardous decomposition products formed under fire conditions.
Carbon oxides, Nitrogen oxides (NOx), Hydrogen chloride gas.
Disposal considerations:
Waste treatment methods:
Product:
Offer surplus and non-recyclable solutions to a licensed disposal company.
Contact a licensed professional waste disposal service to dispose of this material.
Contaminated packaging:
Dispose of as unused product
