Sandalwood
A red plant pigment from red sandalwood heartwood, assigned an E number historically but never authorised for food use in the UK or EU.
E166 is not a permitted food additive in the UK or EU. Any product listing it as an ingredient does not comply with UK or EU food law.
What is it?
Sandalwood colouring is derived from the heartwood of Pterocarpus santalinus, a tree endemic to southern India and listed under international trade controls. The heartwood yields santalin, a group of deep-red polycyclic phenolic pigments (santalin A and santalin B). The pigment is soluble in alcohol but not in water and has been used historically to colour textiles, pharmaceuticals and foodstuffs. Red sandalwood is botanically distinct from white sandalwood (Santalum album), which is used separately as a flavouring.
What does it do?
Santalin pigments provide a brick-red to deep-red hue. The colour shifts with pH, moving from dark brown hues at lower acidity toward lighter tones at higher pH, which limits its stability in many food applications. It functions purely as a colourant.
Where you will see it
E166 is not authorised for use in UK or EU food products. Historically it appeared in spice powders, sauces and certain traditional preparations in South Asia. Because it is not an approved additive under UK or EU law, it should not appear on any UK food label. If you see 'E166' or 'sandalwood' listed as a colouring on a product sold in the UK, that product may not comply with UK food regulations.
What the science says
Regulatory gap: an E number without authorisation
The E-number system assigns codes to substances under review or once used historically, but authorisation requires a positive safety assessment. E166 was assigned an index number in the mid-twentieth century but has never been included in the EU or UK list of permitted food colours. EU Regulation 1333/2008 Annex II lists colours from E100 to E180 but contains no E164 through E169 entries, including E166. The UK Food Standards Agency approved-additives list likewise contains no E166 entry. An absence from the permitted list means use in food is unlawful in the UK and EU.
E166 does not appear in Annex II of EU Regulation 1333/2008 or in the UK FSA approved-additives list. The colour sequence in that legislation jumps from E163 (anthocyanins) to E170 (calcium carbonate), with no entries in between.
Source plant under international conservation controls
Pterocarpus santalinus (red sandalwood, red sanders) is listed on Appendix II of CITES, which regulates international trade in logs, wood chips, powder and extracts of the species. The IUCN Red List has assessed it as Near Threatened, with earlier assessments classifying it as Endangered due to overexploitation and illegal harvest. Export from India has been restricted by national law since 1996. These trade controls make commercial sourcing for food use effectively impractical, alongside the lack of authorisation.
Pterocarpus santalinus is listed under CITES Appendix II, regulating international trade in logs, wood chips, powder and extracts.
India banned export of red sandalwood under the EXIM Policy and CITES legislation from 1996, with limited exceptions for value-added goods in 1997-2007.
No EFSA or UK safety evaluation for food use
No formal safety evaluation by EFSA or its predecessor the UK Advisory Committee on Novel Foods and Processes has been published for santalin or sandalwood extract as a food colourant. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) evaluated alpha-santalol, the main constituent of white sandalwood oil (a different species, Santalum album), used as a flavouring, and found no safety concern at flavouring levels. That assessment does not extend to santalin pigments from Pterocarpus santalinus used as a food colour.
JECFA evaluated alpha-santalol from Santalum album as a flavouring and found no safety concern at typical food use levels, but this assessment covers white sandalwood oil as a flavour, not red sandalwood pigment as a food colour.
Santalol: contact allergen in cosmetic use
The EU Scientific Committee on Consumer Safety (SCCS) has classified Australian sandalwood oil as an established contact allergen in humans, based on the santalol content. This assessment relates to skin contact in cosmetics, not to food ingestion of santalin pigments from Pterocarpus santalinus. The two species and their active compounds are distinct. No food-relevant allergenicity data for santalin specifically has been identified in the scientific literature.
The SCCS classified Australian sandalwood oil (Santalum spicatum) as an established contact allergen in humans, based on its santalol content, with positive patch-test incidences of 0.007-1.53% when santalol was tested at up to 10% concentration.
Where it stands with the regulators
Who should be careful
Any UK consumer seeing E166 listed as an ingredient on a food product should treat it as a non-compliance flag rather than an ingredient to avoid for personal health reasons. The concern is regulatory: the substance is not authorised for food use in the UK or EU. Individuals with known sensitivity to sandalwood-derived compounds may also wish to avoid it, though there is no food-specific allergen declaration requirement for this substance under UK law (it is not on the declarable allergens list).
The honest read
E166 is unusual among E-numbers in that it represents an additive that was assigned a code historically but never went through modern regulatory authorisation. The science on santalin pigments as food colourants is thin: no full toxicological dossier has been submitted to EFSA or the UK FSA for a safety opinion, so the absence from the permitted list reflects an unexamined submission gap as much as a known hazard. The JECFA evaluation of white sandalwood oil as a flavouring ingredient (a different species and compound class) found no concern at flavouring levels, but that work does not cover santalin as a colour. No IARC classification exists for santalin. The practical situation is that sourcing the raw material is heavily restricted by CITES trade controls and Indian export law, making commercial food use almost non-existent in the UK in any case.
Related additives
Common questions
Is E166 banned in the UK?
E166 is not on the UK FSA approved-additives list, which means it is not permitted for use in food sold in the UK. It was never formally authorised under EU or UK food law, so it cannot legally be added to food products in Great Britain. There is no formal ban decision with a stated reason, but absence from the permitted list has the same legal effect.
Has E166 ever been approved anywhere in the EU or UK?
No. E166 was assigned an E number during early FAO food additive classification work in the mid-twentieth century, but it was never included in the EU permitted food colours list under Regulation 1333/2008 or any predecessor directive. The UK retained the same list after leaving the EU. It has therefore never been an authorised food additive in the UK or EU.
What foods contain E166?
No UK or EU food product should legally contain E166 as a food additive. Historically, sandalwood extract was used to colour spice powders, sauces and some traditional South Asian preparations. Products from outside the UK and EU may still use it, as the regulatory situation differs by country. In Russia and some other countries its use in food is also reported to be prohibited.
Is E166 vegan?
Yes. Sandalwood colouring comes from the heartwood of the Pterocarpus santalinus tree and contains no animal-derived ingredients. However, given that E166 is not authorised for food use in the UK or EU, the vegan status of a product using it is a secondary consideration to its regulatory non-compliance.
Sources
- UK Food Standards Agency: Approved Additives and E Numbers
- EU Regulation 1333/2008 on Food Additives - EUR-Lex
- CITES listing of Pterocarpus santalinus (PC17 Doc. 8.4)
- IUCN Red List: Pterocarpus santalinus
- Safety assessment of sandalwood oil (Santalum album L.) - ScienceDirect
- SCCS Opinion SCCS/1459/11 on fragrance allergens in cosmetic products
- Application of santalin dye from Pterocarpus santalinus as a colorimetric indicator - Plant Science Today
- Australian Industrial Chemicals Introduction Scheme: Human Health Tier II Assessment, Essential oils Australian sandalwood
- Bryant Research: EU Food Additives Listing by E Number
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