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Black iron oxide, also known in the industry as magnetite, takes root deep in the history of mining and metallurgy. Our ancestors found uses for naturally occurring black minerals long before modern chemical processing. Ancient Egypt, Greece, and Rome all valued iron oxides for pigments and primitive metallurgy. Industrial practices brought new standards during the 19th and 20th centuries, sharpening focus on purity and consistent properties. The pharmaceutical sector started demanding better quality controls, leading to grades recognized under BP (British Pharmacopoeia), EP (European Pharmacopoeia), and USP (United States Pharmacopeia). As regulatory agencies evolved, so did the methods of refining, labeling, and tracking this fine black powder, ensuring it could meet the strictest requirements in drug formulation and medical device manufacturing. Today, black iron oxide enjoys a place in both legacy applications and high-tech production, echoing centuries of trial, error, and evolving scientific needs.
In pharmaceuticals, black iron oxide behaves as a color additive and occasionally acts as a fortifying agent for iron. The BP, EP, and USP certifications matter because they guarantee traceability, low impurity content, and reliable composition. Only a few minerals make the cut for pharma usage, and even fewer compounds maintain their status across regulatory bodies worldwide. This standardization doesn't just reassure scientists; it matters to manufacturers and, ultimately, patients. I have seen production batches fail to qualify for USP grades due to minor contamination or weak color, causing bothersome delays and rework, reminding us how high the bar stands for anything added to medicinal products.
Black iron oxide has a black or dark-brown shade, fine powder texture, and notable magnetic properties (thanks to its Fe3O4 structure). With a molecular weight of 231.53 g/mol and density around 5.2 g/cm³, it handles a range of formulation demands without unwanted reaction to light, air, or moderate heat. As Fe3O4, it contains both Fe2+ and Fe3+, offering chemical flexibility. Its melting point above 1,500°C adds stability, and this high thermal resistance offers safety in varied processing environments. What catches most people off guard is how little it interacts with common excipients in tablet making. Analysts value its insolubility in water and organic solvents, which prevents migration or unwanted dissolution in finished products.
Suppliers work to meet BP, EP, and USP specifications through rigorous quality assurance and control. Every drum or pouch needs a label listing the product’s batch number, assay value (often above 95% Fe3O4), trace metals profile, particle size, and manufacturer details. Typical trace elements (like arsenic, lead, or mercury) must fall below stringent ppm or even ppb limits — reflecting a zero-tolerance approach to toxins. Labels don’t stop at purity; they also declare origin and regulatory status, keeping things transparent for downstream companies and inspectors. In practice, pharma companies insist on certificates of analysis with independent verification, not just what the producer says on paper.
Black iron oxide is not just “mined and used.” Producers usually start with iron salts, using co-precipitation or controlled oxidation methods. For the common co-precipitation route, ferrous sulfate or ferric chloride solutions undergo reaction with alkali, then oxidation. Each step requires precise temperature, pH, and agitation, with intermediate washing to remove sodium and chloride. In larger operations, engineers use continuous precipitation and multiple filtrations to reach the highest levels of purity. Regulatory-grade black iron oxide sometimes gets micronized or milled again before packaging, and strict control over granule size gives better dispersibility for tablet or capsule coatings. Every stage gets monitored by techs with experience in analytical chemistry, and systematic deviation from process protocols brings flags from both internal QA and outside auditors.
Black iron oxide does more than serve as a pigment. The Fe3O4 backbone can act as a starting material for manganese ferrites, cobalt ferrite, or even as a substrate for catalytic particles in research settings. As a reducing agent, it can react under anoxic conditions to convert nitrates or organics, and when subjected to hydrogen, can produce elemental iron — an important reaction in powder metallurgy. Surface modification is very common in pharma and diagnostics; chemists sometimes functionalize the surface of iron oxide with silanes, carboxylates, or polymers to enhance dispersing or target binding in blood tests. I’ve seen research projects where even small tweaks to Fe3O4’s surface altered its compatibility with other excipients, showing that “inert” doesn’t always mean “inactive.”
Black iron oxide appears under many commercial and scientific titles. Magnetite stands as the mineral form. In technical contexts, it goes by synthetic magnetite, ferric ferrous oxide, or simply Fe3O4. Color Index Pigment Black 11 features on pigment lists. Each synonym gets picked up in different industries; a paint chemist may talk magnetite, while pharma folks prefer the systematic chemical name or talk in terms of the pharmacopeia grade. On pharma labels, you often see “Iron Oxide Black BP/EP/USP” as a catch-all. These names matter because even a mix-up between genuine magnetite and “black rust” (FeO) can affect both performance and safety.
Black iron oxide demands strong handling standards, from the warehouse to the production floor. As a heavy metal, it gets stored in sealed, inert containers with humidity controls. Operators rely on dust masks, gloves, and occasionally goggles, since inhaled iron oxide dust can irritate lungs or, in rare cases, cause siderosis after chronic exposure. While not classed as mutagenic or carcinogenic by major agencies, it still falls under COSHH (UK), OSHA (US), and EU REACH guidelines. Plant hygiene and air monitoring mean nobody takes chances with airborne dust, especially during drum transfer or blending. Strong SOPs include spill containment and periodic medical checks for workers, reducing risk for those making the world’s tablets, capsules, and coated pills.
The biggest splash black iron oxide makes is in coloring oral pharmaceuticals — think of charcoal black or deep brown tablets and capsules. Without it, drug makers would struggle to offer high-contrast markings or protect light-sensitive actives. But its uses stretch beyond medicine: nutrition brands sometimes add it as an iron source for fortified foods. Security inks, MRI tracer particles, and even some dental cements take advantage of its magnetic signature or coloring effect. My background in pharmaceutical tech shows that, every time a company discusses reformulating a medicine for patient compliance, someone brings up color stability and regulatory colorants. Black iron oxide always sits near the top of the preferred list because of decades of known behavior and few nasty surprises.
Every year, researchers publish studies on iron oxide nanoparticles as drug delivery vehicles, contrast agents, or biosensors. Unlike bulk magnetite, nanoscale Fe3O4 particles interact differently with biological systems, binding specific proteins or navigating magnetic fields for targeted therapies. Many in R&D still rely on traditionally processed black iron oxide as a benchmark for biocompatibility or a base layer for further surface chemistry. Current grant-funded projects look at optimizing particle size to increase absorption or reduce dustiness in manufacturing settings — recalling headaches encountered when a dusty batch led to facility shutdowns over air quality. Another line of research targets green production methods, aiming to cut down chemical waste in precipitation and washing, using recycled iron or bio-based solvents.
Black iron oxide’s toxicity profile consistently shows low risk at recommended exposure levels. After years reviewing MSDS sheets and toxicology reports, the main human hazard appears only with occupational overexposure, such as in mining or heavy industry. Chronic inhalation may lead to benign siderosis, mostly in welders or pigment plant staff, but pharma-grade powders, handled under proper GMP, rarely cause problems. Oral ingestion studies in rodents — with doses much higher than those in drug coatings — show minimal systemic toxicity and little evidence of carcinogenicity. Still, scientists continue to monitor for trace contamination and possible interactions with drug molecules, given the complexity of some new medicinal formulations. Periodic re-evaluations form part of pharmacovigilance, making sure no unexpected risks sneak in as production scales up or new applications emerge.
Looking ahead, black iron oxide’s role as a pharmaceutical colorant will stick around as long as regulators favor proven, stable compounds over experimental pigments. The growing market for iron oxide nanoparticles in diagnostics and imaging means black iron oxide will keep fueling both bulk and high-tech production lines. As regulations tighten on trace impurities, expect improved synthesis and purification routes to become the norm. Another trend sees digital labeling and full supply chain traceability, so every lot of Fe3O4 links back to its source and production method. More sustainable manufacturing, possibly drawing from recycled scrap iron with cleaner downstream chemistry, stands close on the horizon. Some research circles watch for new uses in targeted therapy, tracking, or responsive drug formulations. If black iron oxide keeps up with evolving purity standards, innovative surface chemistry, and safe handling, its long history will just become the foundation for the next wave of applications in medicine and industry.
Black iron oxide, with its deep, rich color, is a familiar ingredient for anyone who reads pharmaceutical compositions. I’ve seen it on pill labels and ingredient lists for years, though many people overlook its role. The pharma grade version—manufactured to BP (British Pharmacopoeia), EP (European Pharmacopoeia), and USP (United States Pharmacopeia) standards—meets strict guidelines to show safety, consistency, and purity. These aren’t just nice-sounding acronyms. They spell out the minimum standard for what we put into our bodies.
Drug manufacturers value black iron oxide as a pigment for tablets and capsules. A tablet’s color isn’t merely decorative or for branding. It helps pharmacists, patients, and doctors tell one pill from another. Mistaking a medication because two tablets look alike puts health at risk. Color coding stops that confusion and makes compliance honest and simple, even for those who take multiple medications each day. When someone in a retirement community shared with me their system for sorting daily meds, I realized how much a color can relieve anxiety. Black iron oxide has a deep tone that covers other ingredients’ natural tints. It doesn't fade as fast under sunlight or fluorescent lighting either. That sort of stability gives medical packagers peace of mind, since product recalls due to appearance problems can create headaches for both businesses and patients.
Some have asked about safety, since iron oxides turn up in industrial uses too. Pharma-grade black iron oxide is tested to exclude impurities, like heavy metals or toxins. This way, it avoids the contamination risks seen in lesser, lower-cost pigments. Manufacturers can’t just swap in pigment from a paint store. Pharma rules keep the risk of allergic reactions and toxicity low when added in controlled amounts. Food and Drug Administration and European Medicines Agency endorse it at set levels, after seeing years of research and use. Any product that lands on pharmacists’ shelves passes rigorous scrutiny—critical for drugs going into the most vulnerable people.
In my view, some people underestimate black iron oxide because it looks simple. In addition to pigmenting, it also helps shield light-sensitive drugs from early breakdown. Certain medications lose potency fast when exposed to light. Black iron oxide can block wavelengths that harm the active ingredient. This feature keeps pills stable and ensures the medicine inside works as intended, even if someone accidentally leaves a blister pack out on the counter for a weekend. That’s not marketing—just basic chemistry and practical know-how. The pigment, being iron-based, also lends slight strength to tablet coatings. If you’ve ever dropped a bottle of pills, you’ll appreciate tablets that don’t crumble from a minor bump.
Businesses relying on black iron oxide will see more demand in personalized medicine and advanced packaging. As regulators press for even lower contaminant levels, suppliers adjust their production for extra quality checks and traceability. The industry pushes its partners upstream for not just compliance, but proof of safety in every batch. I see many pharmaceutical firms focusing on environmental impact, too. Iron oxides are less toxic than organic dyes, and can be handled in greener manufacturing cycles, decreasing waste and limiting pollution. The next step calls for transparency on sourcing and more efficient pigment processing, ensuring every black tablet tells a story of safety, reliability, and steady care.
Walk through any pharmacy and look at the medicine shelves. You’ll notice tablets and capsules in a surprising number of colors, some white or beige, others deep red, brown, or black. Black iron oxide, registered under different pharmacopeia standards like BP, EP, and USP, adds color to these formulations. Its role goes beyond aesthetics—recognizable color helps with product identification, both for patients and healthcare staff, reducing the risk of medication errors.
Iron oxides can serve in several industries, but only specific grades meet the strict requirements for use in pharmaceutical products. This matters. Pharma-grade black iron oxide undergoes tests for purity, heavy metals, microbial contamination, and residual solvents. For a supplier to claim BP, EP, or USP grade, their production process has to hit benchmarks set by international pharmacopoeias. The standards cover trace elements and impurities, limits for arsenic, lead, and mercury, as well as checks for contaminants that might cause harm when ingested over time.
I remember touring a plant making colorants for medicines. The equipment itself had to meet hygiene controls. Separate storage ensured no cross-contamination with pigments for industrial paint or ceramics. Each batch involved a ton of paperwork, and not once did anyone skip recording a deviation or test result. That level of transparency keeps the risk of adulteration very low.
The FDA and the European Medicines Agency both recognize iron oxides for coloring pharmaceutical products. They add these compounds to short and long lists of permitted colorants, provided the grade ticks all boxes for purity and safety. Reports from regulators occasionally point out safety incidents—usually, these relate to improper grades used, or manufacturers operating outside approved limits.
Discussion about heavy metals in mineral-based pigments crops up often. Some folks fear that chronic exposure to trace elements can build up in the body. Trusted data do not back up significant risk where manufacturers stick to high-purity grades. Scientific reviews show black iron oxide doesn’t react with other drug ingredients or break down into harmful byproducts in the digestive system. The human body handles iron as an essential mineral, and the amounts present as residual ions in pharmaceutical-grade oxide rarely shift the body’s iron pool in any meaningful way.
Anecdotally, I’ve never come across a case where a properly regulated iron oxide caused toxicity in medicine. Most adverse reactions tied to colorants involve allergies to artificial dyes, or accidental contamination at the factory. Iron oxide allergy exists but remains vanishingly rare. The main safeguard—use only vetted suppliers who trace every step of production.
Plenty of fake or non-compliant materials reach the market through gray channels. Purchasing from reputable sources, documented all the way from raw ore to final packaging, stands as the best protection. Performing incoming quality checks and random lot testing keeps everyone honest. Supply chains today face increasing stress, but the core idea never changes—cutting corners puts health at risk.
For anyone involved in pharma, picking certified colorants might feel routine, but it weighs heavily on final drug safety. Asking for technical dossiers, checking compliance certificates, and visiting suppliers goes beyond paperwork—it protects patients.
Iron oxide has earned a place in pharmaceutical manufacturing. I’ve read labels, I’ve visited labs, and every time I see “Black Iron Oxide BP EP USP” on an ingredient list, I know this isn’t the same stuff found in hardware paint. Pharmacy-grade black iron oxide, often listed as CI 77499, meets strict standards because what goes into tablets and pills flows straight into people’s bodies. This traceability gives patients, doctors, and manufacturers some peace of mind.
Whenever pharmaceuticals call for black iron oxide, the purity specifications matter beyond just being “iron oxide.” The BP (British Pharmacopoeia), EP (European Pharmacopoeia), and USP (United States Pharmacopeia) all set detailed limits. These standards demand a minimum of 95% Fe3O4. This is a high bar—no rust, no random iron dust, and no dirt that could trigger allergic reactions or disrupt other ingredients. Water-soluble substances must fall under 1%, and each batch faces tests for arsenic (less than 3 ppm), lead (less than 20 ppm), loss on ignition (less than 1%), and acid-insoluble matter.
The importance of these numbers hits home in the lab. Sloppy or impure pigment runs the risk of chemical reactions nobody planned for. There’s no room for shortcuts in compliance audits. High purity protects patents and reputations alike.
Quality assurance teams don’t simply trust a supplier’s labels. Iron oxide for pharmaceuticals takes a journey through X-ray fluorescence spectrometry, titrations, and residue on ignition trials. These steps sound tedious, but each one filters out trace elements that don’t belong in medication. Imagine a batch with a little extra lead or mercury. With chronic medication, even micro-traces stack up with time, and regulators have chased down problems like this for decades.
Pharmacopeial monographs spell out specifications for color—this might seem unimportant, but in my time reviewing drug recalls, pigment variance has trickled into warnings and withdrawals. Black iron oxide’s deep color must match approved shade cards. If not, that product fails batch release. The tiniest deviations become legal issues fast.
I’ve worked with production teams that switched pigment suppliers for cost savings, only to find higher levels of calcium, magnesium, or manganese in delivered lots. These elements don’t always break a tablet, but unexpected spikes change how tablets absorb, release active ingredients, or even taste. Skipping a single specification cost them thousands, plus trust lost with contract manufacturers. Nobody forgets that lesson quickly.
Factories use validated Standard Operating Procedures to address possible contamination. On top of this, supplier audits and Certificates of Analysis add extra checkpoints. Adding technology like real-time element detectors or near-infrared screening can tighten quality controls. Some facilities even track iron oxide from raw mining through refining and packing, demanding full traceability from start to finish. I’ve seen companies keep samples from every lot for years, providing reference points for regulatory questions or customer complaints years down the line.
Black iron oxide might look like an afterthought to some, but in pharma, even tiny mistakes carry big consequences. High purity levels give confidence—not just in the pill’s color, but its safety. I’ve seen drug launches hinge on sticking to these details, and those are lessons manufacturers never take lightly.
Black iron oxide finds its way into pharmaceuticals, cosmetics, food dyes, and even tattoo inks. Since patients trust products that end up in their bodies, every step needs scrutiny—from raw ingredient to final packaging. Inconsistent storage or sloppy handling can turn a safe material into a risky one. Having seen quality audits in pharmaceutical plants, it’s clear that even simple mistakes in packaging can stall production lines and drain budgets.
In pharmaceutical supply chains, cost and safety always push against each other. Suppliers who cut corners on packaging might save pennies short-term, but some issues hit later. For black iron oxide in BP EP USP grades, contamination turns into a recall risk and even a legal headache.
Pharma-grade black iron oxide shows up in heavy-duty polyethylene or high-barrier fiber drums, usually lined with food-safe liners. These aren’t basic cartons. The lining stops leaching, blocks moisture, and keeps out airborne dust. Sometimes, I’ve seen self-seal foil bags inside these drums, especially for export loads destined for tropical climates.
Proper labeling stands out as more than a formality. Each drum carries a batch number, manufacturing date, shelf life, and storage instructions in clear print. That level of transparency meets regulatory demands and supports traceability, which helps in the rare case of an emergency investigation.
As much as standards look good in documents, there’s no shortcut for basics—keep it cool, keep it dry, keep it clean. Humidity turns fine powders clumpy, and once that happens, blending becomes a nightmare. Any water getting in the drums causes rust to form, and now the whole batch sits suspect for contamination.
Warehouses use stackable pallets to keep drums off the ground, avoiding direct contact with concrete floors that might hold moisture after cleaning cycles. Storage rooms lay out temperature and humidity monitors. Good facilities aim for below 25°C and low relative humidity. Fans and dehumidifiers kick in once readings creep up. Sure, all this takes effort, but the alternative—spoiled product—stings more.
I’ve watched how small shortcuts around packaging and storage can spiral into big issues. Drums left even slightly open lead to caking, and then workers need to scrap part of a batch. Reusing liners looks appealing for cost savings, but it invites cross-contamination. Regulatory authorities like the US FDA or EMA don’t buy any excuses.
Education remains a solid fix. Training line workers about why these steps matter often pays off more than reminders from supervisors. Investing in high-quality liners and regular audits also helps spot trouble before it spreads.
Another challenge involves counterfeiting or ingredient swaps in the global supply chain. Tamper-evident seals and secure documentation help suppliers prove their material stays pure, especially for export-bound ingredients.
From years of walking through loading bays and warehouse aisles, it’s clear that packaging and storage shape the quality story long before any lab work or tableting steps begin. Investing in reliable packaging, acknowledging real risks, and backing up procedures with strong training form the backbone for getting black iron oxide from powder to patient safely.
Growing up with a grandfather who ran a compounding pharmacy, I learned early that even the tiniest ingredient matters. Pharma-grade black iron oxide isn’t just a colorant for tablets or capsules—it plays a big role in determining the safety of finished medicines. That’s why regulators create clear lines around what goes into these products. The big question everyone keeps asking: does black iron oxide with BP, EP, and USP labels keep up with what’s required globally?
Batches marked BP, EP, or USP suggest compliance with British, European, or US standards. These pharmacopeias spell out what’s allowed: limits on impurities like arsenic, lead, and heavy metals; exact particle sizes; defined iron content; and tests for microbiological contamination. The problem comes with hidden loopholes between these standards. For instance, BP may set one upper limit on heavy metals, while USP asks for something tighter. There’s no one-size-fits-all “international” threshold. A powder passing EP requirements might still fall short in another country.
Paper records can mislead. I’ve seen raw material suppliers send glossy certificates for their black iron oxide, but the lab reports can tell a different story. Just having a compliance letter isn’t a real substitute for lot-by-lot testing. The US FDA once flagged shipments because the iron oxide, although “USP compliant,” contained higher than expected lead content that slipped through overseas production checks. End result? Product recalls and a lot of angry customers.
Trusting supply chains looks easy on a spreadsheet, but the story in real life’s a lot messier. Iron ore extraction, purification, blending, and shipping create endless chances for contamination—especially with a highly pigmented powder like black iron oxide. Cross-contamination can pop up from improper cleaning methods at the processing stage. Regulators from the EMA to Health Canada want proof that every batch never strays from pharmacopeia specifics, not just the majority.
Consistency and transparency form the backbone of trust. Quality assurance teams chase raw data, not marketing claims. They dig into heavy metal analysis, microbial tests, moisture content, and even polymorphic forms. Good manufacturers keep audit trails of every step: mining records, purification logs, and third-party lab checks. When companies cut corners, patients pay the price. Consumer trust can vanish after a single recall, leaving lasting scars.
Harmonizing pharmacopeia standards makes sense if we want ingredient safety to be global, not regional. The International Council for Harmonisation keeps working on this, but it’s a long road. Suppliers should share transparent test results—with every shipment and not just annually. Pharmaceutical buyers might think about on-site audits or random batch sampling, even from vendors with great track records. Third-party labs have a key part in checking that “compliant” iron oxide actually measures up across borders.
Lives depend on seemingly minor tablet ingredients like black iron oxide. Meeting every international pharmacopeia benchmark takes extra effort and sometimes added cost, but protecting health means making tough calls. Shortcuts pollute the whole system—honest monitoring and transparency build trust back up. In a global marketplace, every detail matters.
| Names | |
| Preferred IUPAC name | Iron(II,III) oxide |
| Other names |
Ferrous Oxide Iron(II) Oxide Black Iron Oxide Pigment CI Pigment Black 11 Iron Oxide Black Iron Sesquioxide Iron(II,III) oxide Fe3O4 |
| Pronunciation | /blæk ˈaɪərn ˈɒksaɪd biː piː iː piː juː ɛs piː ˈfɑːrmə ɡreɪd/ |
| Identifiers | |
| CAS Number | 1317-61-9 |
| Beilstein Reference | 12709 |
| ChEBI | CHEBI:133402 |
| ChEMBL | CHEMBL1201739 |
| ChemSpider | 14129 |
| DrugBank | DB11050 |
| ECHA InfoCard | 05d399262a-5d55-45b0-98c8-9c6d5699afbc |
| EC Number | 215-277-5 |
| Gmelin Reference | Fe2O3, Gmelin 131 |
| KEGG | C07246 |
| MeSH | D006695 |
| PubChem CID | 14766 |
| RTECS number | WM9925000 |
| UNII | XM0M87F357 |
| UN number | UN3077 |
| CompTox Dashboard (EPA) | CompTox Dashboard (EPA) of product 'Black Iron Oxide BP EP USP Pharma Grade' is **"DT7R2729U8"**. |
| Properties | |
| Chemical formula | Fe3O4 |
| Molar mass | 231.53 g/mol |
| Appearance | Fine, black powder. |
| Odor | Odorless |
| Density | 4.9 – 5.2 g/cm³ |
| Solubility in water | Insoluble in water |
| log P | 4.5 |
| Basicity (pKb) | 11.8 |
| Magnetic susceptibility (χ) | +1200e-6 |
| Dipole moment | 0 D |
| Thermochemistry | |
| Std molar entropy (S⦵298) | 87.4 J·mol⁻¹·K⁻¹ |
| Std enthalpy of formation (ΔfH⦵298) | -272 kJ/mol |
| Std enthalpy of combustion (ΔcH⦵298) | -824 kJ/mol |
| Pharmacology | |
| ATC code | D08AX |
| Hazards | |
| Main hazards | Harmful if swallowed. Causes serious eye irritation. May cause respiratory irritation. |
| GHS labelling | GHS02, GHS07 |
| Pictograms | GHS07,GHS08 |
| Signal word | Warning |
| Hazard statements | Harmful if swallowed. Causes serious eye irritation. Causes skin irritation. May cause respiratory irritation. |
| Precautionary statements | Precautionary statements: P261, P264, P271, P272, P280, P302+P352, P304+P340, P305+P351+P338, P312, P332+P313, P337+P313, P362+P364, P501 |
| Autoignition temperature | Above 100°C |
| Explosive limits | Not explosive |
| Lethal dose or concentration | LD50 (oral, rat): > 10,000 mg/kg |
| LD50 (median dose) | > 10,000 mg/kg (oral, rat) |
| NIOSH | NIOSH: N0793 |
| PEL (Permissible) | 5 mg/m3 |
| REL (Recommended) | 6 - 11 |
| IDLH (Immediate danger) | 250 mg Fe/m³ |
| Related compounds | |
| Related compounds |
Red Iron Oxide Yellow Iron Oxide Brown Iron Oxide Synthetic Iron Oxide Ferrous Oxide Ferric Oxide Magnetite Hematite |
Chengguan District, Lanzhou, Gansu, China
