Patent Blue V E131
synthetic — Primarily synthetic.
Sodium or calcium salt of [4-(α-(4-diethylaminophenyl)-5-hydroxy-2,4-disulfophenylmethylidene)-2,5-cyclohexadien-1-ylidene] diethylammonium hydroxide inner salt
CAS: 3536-49-0
Factual Regulatory Reference
This database provides factual regulatory information compiled from official government sources. It does not constitute medical, nutritional, or safety advice. Regulatory status varies by country and is subject to change. Always refer to your local regulatory authority for the most current information.
? Did You Know?
Beyond food, Patent Blue V is also used in medicine, industrial applications, household products. Its versatility makes it one of the most multi-purpose chemical compounds in everyday life.
Regulatory opinions differ: Patent Blue V is approved in EU but banned in USA, JAPAN, CANADA. This reflects different risk assessment philosophies between regions.
To reach the Acceptable Daily Intake limit, a 60kg adult would need to consume approximately ~100 shots of blue liqueur (30ml) in a single day. (This is a mathematical illustration, not a safety recommendation.)
Regulatory Analysis
Patent Blue V is unusual among food dyes because its most consequential safety data comes not from food use but from medical procedures, where its 2.7% anaphylaxis rate during sentinel lymph node biopsies provides real-world adverse event data rarely available for food additives. JECFA's 1975 withdrawal of the temporary ADI -- never replaced with a permanent value -- stands in direct tension with EFSA's 2013 decision to set an ADI of 5 mg/kg, highlighting how two expert bodies can indefinitely disagree on whether available data supports any safe intake level. The dye's persistence in EU food law despite negligible actual food use raises the question of whether regulatory approvals can outlive their practical relevance.
Detailed Regulatory Assessment
European Union (EFSA)
Permitted in limited food categories; rarely used in practice due to poor stability and allergy concerns
Official EFSA LinkUnited States (FDA)
Never authorized for food, drugs, or cosmetics. Insufficient safety evidence.
Japan (MHLW)
Not approved for food use in Japan
Acceptable Daily Intake (ADI)
International Standard (JECFA)
mg/kg body weight per day
European Standard (EFSA)
Everyday Perspective
For a 60kg adult, this limit is roughly equivalent to consuming:
Natural Occurrence
This additive is not known to occur naturally in significant quantities.
Manufacturing
Synthesized from benzene and naphthalene derivatives through condensation reactions with sulfonic acids. Additional reagents are added to form the triphenylmethane structure. The product is stabilized with calcium or sodium salts to achieve water solubility, yielding a dark blue powder or granules.
Applications Beyond Food
Lymphangiography (medical imaging); sentinel lymph node biopsy during cancer surgery
Limited textile applications
Dental disclosing tablets (plaque visualization)