Concern is mounting over the safety of popular food additive 171, otherwise known as titanium dioxide.

The substance, which is used for food colouring, can be found in almost 1000 products on supermarket shelves, including mayonnaise, chocolate, toothpaste and even some lollies.

Now, research published yesterday by the University of Sydney suggests the additive could lead to bowel disease or cancer, Nine News reports.

Unlike other food colourings, which are chemical-based, titanium dioxide contains nanoparticles, which can also be found in anything from scratch-resistant sunglasses, car paint and medicines.

Associate Professor Wojciech Chrzanowski, a co-lead author of the study, said its consumption has been linked to "auto-immune disease, asthma, allergies and reproductive issues."

"We've been exposed to nanoparticles all our lives. Mr Chrzanowski said. "However, we are sort of entering the stage where we are over-exposed.

"They should be aware of the potential risk associated with these (products) and maybe when possible limit the consumption of these products."