E285 (Sodium tetraborate) is a chemical compound containing boron, oxygen, sodium and hydrogen.

It appears as a white powder consisting of colourless, water-soluble crystals or as an odourless, whitish amorphous powder.

What it is used for and where

Medical

It has anti-inflammatory and antioxidant properties that have made it useful in different therapies.

Sodium tetraborate is a promising means to prevent (correct) the effects of chromodine in chromium production workers (1), it is a possible protective agent or competitive inhibitor of cardiac hypertrophy with some limitations (2), prophylactic treatment administered orally during pregnancy when there is a risk of developing fetal left ventricular hypertrophy (3).

In a recent study the combination of borax with 5-fluorouracil achieved a strong cytotoxic and apoptotic effect on the human colorectal adenocarcinoma cell line DLD-1 (4)

Food

Ingredient listed in the European food additives list as E285, preservative.

The Panel on Food Additives evaluated the safety of boric acid (E 284) and sodium tetraborate (borax) (E 285) as food additives in the EU. These additives are authorised in the EU for use as preservatives in sturgeon eggs (caviar) up to a maximum concentration of 4 g boric acid/kg.  An ADI of 0.16 mg boron/kg body weight/day was established.  The Panel concluded that boric acid and sodium tetraborate are not of concern in terms of genotoxicity (5).

Cosmetics

It is a restricted ingredient II/1395 as Relevant Item in the Annexes of the European Cosmetics Regulation No. 2019/831  (6).

Buffering agent. It is an iingredient that can bring an alkaline or acid solution to a certain pH level and prevent it from changing, in practice a pH stabiliser that can effectively resist instability and pH change.

Other uses

Sodium tetraborate is often used as a buffer component in capillary electrophoresis and microchip-based electrophoresis and is a crosslinking agent for both PVA and sodium alginate.  It is used as a melting flux in the glass bead procedure. Useful for general amino acid separation. Household cleaner.

Boric acid is widely used in the glass industry, especially for glass fibres, in ceramics to improve strength and lustre. It is also used in metal welding, electronics, precious stones and scientific research.

The most relevant studies on this ingredient have been selected with a summary of their contents:

"Sodium tetraborate studies"

• Molecular Formula    Na₂B₄O₇      B₄Na₂O₇      Na₂B₄O₇ · 10H₂O
• Molecular Weight     201.2 
• CAS  1330-43-4
• UNII    8191EN8ZMD
• EC Number   215-540-4
• DSSTox ID  DTXSID101014358
• IUPAC  disodium;3,7-dioxido-2,4,6,8,9-pentaoxa-1,3,5,7-tetraborabicyclo[3.3.1]nonane
• InChl=1S/B4O7.2Na/c5-1-7-3-9-2(6)10-4(8-1)11-3;;/q-2;2*+1
• InChl Key      UQGFMSUEHSUPRD-UHFFFAOYSA-N
• SMILES  B1(OB2OB(OB(O1)O2)[O-])[O-].[Na+].[Na+]
• MDL number  MFCD00149193
• PubChem Substance ID    329824630
• RTECS  ED4588000
• NCI    C76754
• ICSC    1229
• RXCUI      1805706

Synonyms:

• sodium diborate
• sodium meta borate
• sodium metaborate
• sodium tetraborate

References_____________________________________________________________________

(1) Maratovich, I. Y., Narimanovna, K. N., Vladimirovna, I. I., & Kapenovich, I. M. (2017). Protective action of sodium tetraborate on chrom-induced hepato-and genotoxicity in rats. Biomedical and Pharmacology Journal, 10(3), 1239-1247.

(2) Hernández-Gutiérrez, S., Roque-Jorge, J., López-Torres, A., Díaz-Rosas, G., García-Chequer, A.J. and Contreras-Ramos, A., 2020. Role of sodium tetraborate as a cardioprotective or competitive agent: Modulation of hypertrophic intracellular signals. Journal of Trace Elements in Medicine and Biology, 62, p.126569.

(3) Hernández-Gutiérrez, S., Roque-Jorge, J., López-Torres, A., Díaz-Rosas, G., García-Chequer, A.J. and Contreras-Ramos, A., 2020. Role of sodium tetraborate as a cardioprotective or competitive agent: Modulation of hypertrophic intracellular signals. Journal of Trace Elements in Medicine and Biology, 62, p.126569.

(4) Kırlangıç ÖF, Kaya-Sezginer E, Ören S, Gür S, Yavuz Ö, Özgürtaş T. Cytotoxic and Apoptotic Effects of the Combination of Borax (Sodium Tetraborate) and 5-Fluorouracil on DLD-1 Human Colorectal Adenocarcinoma Cell Line. Turk J Pharm Sci. 2022 Aug 31;19(4):371-376. doi: 10.4274/tjps.galenos.2021.29726.

(5) EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS). (2013). Scientific Opinion on the re‐evaluation of boric acid (E 284) and sodium tetraborate (borax)(E 285) as food additives. EFSA Journal, 11(10), 3407.

(6) Opinion of the Scientific Committee on Consumer Safety on boron compounds (CMR) (europa.eu)