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Titanium Dioxide (E171) is a naturally occurring oxide of titanium commonly used as a white pigment due to its brightness and very high refractive index.
In the food industry, it functions primarily as a coloring agent to provide a white, opaque appearance in products such as candies, chewing gum, bakery items, and dairy-based goods.
E171 is also used in pharmaceuticals and cosmetics for similar whitening or opacifying effects.
It can be found in both pigment-grade and nano-sized forms, though regulatory status regarding its use has changed in various regions due to safety assessments.
CAS Number: 13463-67-7
Synonyms:Titanium(IV) oxide,Titania,CI Pigment White 6,Titanium dioxide (TiO₂)
Rutile (when referring to a specific crystal form),Anatase (another crystal form)
Introduction
Titanium dioxide (TiO₂), registered as E171 in the European Union, is a naturally occurring oxide of titanium extensively used as a white pigment.
It is prized for its brightness, high refractive index, and resistance to discoloration.
Initially discovered in the 18th century, its commercial use began in the early 20th century.
The compound became ubiquitous in a wide range of industries, especially in food, pharmaceuticals, cosmetics, and paints.
Regulatory bodies like the European Food Safety Authority (EFSA), the U.S. Food and Drug Administration (FDA), and the Joint FAO/WHO Expert Committee on Food Additives (JECFA) have long considered E171 safe.
However, recent concerns regarding its nanoparticle content and potential genotoxicity have led to its re-evaluation and, in some jurisdictions, restriction or ban.
Chemical Properties
Titanium dioxide exists in three primary crystalline forms: anatase, rutile, and brookite, with anatase and rutile being the most industrially relevant.
Molecular formula: TiO₂
Molar mass: 79.87 g/mol
Appearance: White powder
Melting point: 1,843 °C (rutile)
Boiling point: Decomposes before boiling
Solubility: Insoluble in water and organic solvents, soluble in concentrated sulfuric acid
The high refractive index (2.5 for anatase and 2.7 for rutile) contributes to its excellent light-scattering capabilities, making it highly effective as a pigment and UV filter.
Production Methods
TiO₂ is produced via two main industrial processes:
Sulfate Process: Involves digesting ilmenite ore with concentrated sulfuric acid to yield a solution of titanium oxysulfate, which is then hydrolyzed and calcined.
Chloride Process: Converts titanium-containing feedstock (rutile or synthetic rutile) to titanium tetrachloride (TiCl₄) using chlorine gas, which is then oxidized to produce TiO₂.
Both processes undergo subsequent purification and micronization stages to yield food- or pharmaceutical-grade E171.
Applications
Food Industry: E171 serves as a colorant in confectionery, dairy products, sauces, and bakery goods.
Cosmetics: Provides opacity and sun protection in foundations, sunscreens, and lotions.
Pharmaceuticals: Used in tablet coatings for whitening and opacity.
Industrial Uses: Common in paints, plastics, coatings, ceramics, and paper for its brightness and opacity.
Functionality
TiO₂’s optical properties stem from its ability to scatter visible light, resulting in high whiteness and brightness.
In sunscreens, it serves as a physical UV blocker.
The photocatalytic activity of anatase TiO₂ is utilized in environmental purification but can also cause unwanted degradation in some applications.
Nanoparticle Aspects
Concerns over E171 stem largely from its nanoparticle content.
Though not engineered as nanoparticles, some fractions are <100 nm.
Nanoparticles have higher surface reactivity, which may enhance biological interactions, leading to inflammation, oxidative stress, or genotoxicity.
Regulatory agencies have begun distinguishing between bulk and nano TiO₂, leading to diverging legal frameworks globally.
Health Concerns and Regulatory Reviews
EFSA (2021): Concluded that E171 could no longer be considered safe as a food additive due to uncertainties about genotoxicity.
EU Decision: Effective from 2022, E171 is banned in food products within the European Union.
Global Landscape: Contrasts with JECFA and FDA, which maintain its safety when used within specified limits.
Environmental Impact
Persistence: TiO₂ is chemically inert and non-biodegradable.
Ecotoxicity: Nanoparticles can affect aquatic organisms through oxidative stress and physical interference.
Bioaccumulation: Generally low, though long-term ecosystem impacts remain uncertain.
Analytical Methods
Spectroscopic Techniques: UV-Vis spectroscopy, FTIR, Raman spectroscopy
Particle Characterization: TEM, SEM, XRD, and DLS
Quantification in Food: ICP-MS and single-particle ICP-MS allow detection and sizing of TiO₂ particles in complex matrices
Risk Assessment and Management
Risk assessment involves determining exposure from diet, inhalation, or dermal routes and comparing these to known safety thresholds.
ADI: Previously not specified by JECFA and EFSA due to low absorption, now under re-evaluation.
Management Measures: Include reformulation, improved labeling, and use of alternative pigments.
Public Perception and Industry Response
Following EFSA’s 2021 opinion, public concern increased, leading many companies to reformulate products without E171.
Clean label trends and consumer advocacy have accelerated this shift.
Industry has responded with transparency initiatives, investment in alternative technologies, and increased compliance with emerging regulations.
Alternatives to E171
Calcium Carbonate: White, but less effective in opacity.
Zinc Oxide: Also a UV blocker but raises similar safety concerns.
Starch-Based Pigments: Biodegradable and natural, but often lack brightness.
Titanium-Free Blends: Often involve mixed natural minerals and pigments.
Each alternative poses trade-offs in cost, performance, and regulatory approval.
Future Outlook
Research is ongoing into safer TiO₂ formulations with reduced nanoparticle fractions, coatings to limit reactivity, and bio-based pigments.
Continued toxicological studies and harmonized global regulations are expected. Industry innovation and consumer demand will shape future pigment choices.
SAFETY INFORMATION ABOUT E 171 TITANIUM DIOXIDE
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
