A Facebook post that has resurfaced about the dangers of "bunspice essence" used in hot cross buns is misleading, according to an Adelaide toxicologist.

Key points: A Facebook post warns people about consuming bunspice essence

A Facebook post warns people about consuming bunspice essence The chemical is used to flavour hot cross buns

The chemical is used to flavour hot cross buns A toxicologist and the product's manufacturer say the concentrations are too low to be harmful

Thousands of people have shared an image on social media highlighting the safety warnings on a bottle of the essence, made by company Keith Harris.

Bunspice essence contains alcohol, cinnamon oil and caraway oil and is sometimes used to flavour hot cross buns.

The image — which has been posted online in recent years — warns that the essence is flammable, might cause cancer and is toxic to aquatic organisms.

It follows another social media post earlier this month which warned about false breathalyser readings from eating hot cross buns.

In one post, a user called for a boycott of hot cross buns and another urged people to "know what's in the food you eat and buy for your family".

"And we wonder why the rates of cancer and autoimmune disease are ever increasing," one social media user said.

However, University of Adelaide toxicologist Ian Musgrave said the small concentration of the essence in hot cross buns was "incredibly safe" for consumers.

"The materials found in bunspice essence are basically what's found in the spices themselves," Dr Musgrave said.

"This is a bit of a case of chemophobia.

"When you see a name '3-Phenylpropanal' everyone goes 'that must be incredibly bad for you', but it's otherwise known as hydrocinnamic aldehyde because it comes from cinnamon.

"It's one of the compounds that form the cinnamon flavour."

He noticed a friend's Facebook post warning about bunspice essence and calculated that you would have to eat 100 kilograms of hot cross buns in one sitting to get sick.

"If you've eaten 100kg of hot cross buns in one sitting, you have bigger problems than the trace amounts of hydrocinnamic aldehyde in your system," he said.

The image has been shared more than 7,000 times on social media. ( Facebook )

Recipe changed since picture first shared

A spokeswoman for Ixom, which owns the Keith Harris brand, said the warning related to drinking the essence straight and in "copious quantities".

"In a kilo of hot cross buns, the cinnamon oil is around… half a millilitre per kilogram of buns," she said.

"The active ingredient in the cinnamon oil is parts per billion.

"You would need to eat literally tonnes of hot cross buns on a regular basis for any ill effects.

"Keith Harris changed its formulation back in 2016 reducing the cinnamon oil to such a very low level, such that the warning is not required."

The photo being shared is of a bottle manufactured in 2015.

A spokeswoman for Food Standards Australia New Zealand said the warning label on the bottle was "written only for the concentrated flavouring preparation, not for its use on food".

"The ethanol is used as the flavour carrier, or solvent, which again is very common for flavour preparations or concentrates and is permitted for this purpose," the spokeswoman said.

"Such flavour preparations will be used at very small amounts to provide flavour to the food, in this case hot cross buns.

"The ethanol used as the solvent will mostly be lost during the baking process as it has a reasonably low boiling point and very small quantities will be used."

Some bakeries don't use bunspice essence

In response to a post on its Facebook page, bakery chain Brumby's said it did not use bunspice essence.

The owner of Belair's Banana Boogie Bakery, Jason Spencer, said he did not use the essence in his hot cross buns.

He instead used his own mix of cinnamon, nutmeg, mixed spice and liqueur in his Easter treats.

"Some people like it, some people don't and if you use too much of it it can be really over the top," Mr Spencer said.

Kytons Bakery owner Darren Sutton also said he measured his own spices rather than using the essence.