Arsenic, insect bodies or even wood - the next time you're munching on your favourite sneaky snack, take a moment to consider what you're really eating.
A quick squint at any ingredients list will more than likely reveal at least one or two strange substances with questionable origins. In Australia, hundreds of such food additives can make their way into our diet.
While some of these items may rate highly in yuck factor, they aren't necessarily harmful. Dr Leigh Henderson, the section manager of product safety standards at Food Standards Australia New Zealand, says food additives face a wide-ranging risk assessment before they are approved for use in Australia. They are also monitored for any ongoing safety concerns.
"We do assess them all for safety and the fact they might be from strange sources doesn't necessarily mean there's anything unsafe about them," she says.
That's not to say all additives are necessarily healthy or that there is no debate about their use but many play key roles as fillers, preservatives, sweeteners and so on.
Here's a look at some of the weirdest additives and ingredients found in everyday foods.
Yep, silicon dioxide. Probably not the mucky kind you shake from your towel at the beach, but at a base level it is the same substance nonetheless.
"It functions as an anti-caking agent so it allows free flow so you don't get clumping of dry components," Henderson says. It's also used to clarify beer and wine and can be used as an anti-foaming agent in liquid products, she says.
Look for: additive number 551
2. Laughing gas
You may have met this one in the dentist's chair. Nitrous oxide is a colourless gas with a sweet, pleasant odour, which apart from inducing a happy disposition, can also be used as an antioxidant, foaming agent, food propellant and packaging gas in processed meat and vegetables.
Look for: additive number 942
This one caused ripples across the web lately when an American website outed cellulose as "wood pulp", calling it a "stealthy" ingredient hidden on fast-food menus. But the furore settled down when it became clear that while, yes, it is sometimes derived from wood, the dietary fibre occurs naturally in all plant-cell walls.
As an additive, it can be used to thicken processed foods or improve their texture.
Look for: additive number 460
Not an additive per se, arsenic is a chemical element found naturally in water and soil. As such, it is unavoidably present in the food chain.
In recent years, a Food Standards survey found seafood, cereal and grains were the highest contributors in our diets, albeit at very low levels.
"As with any other contaminant the efforts are to keep them as low as reasonably possible so we do have controls in the Food Standards Code to try and limit levels of [arsenic]," Henderson says.
Ever wondered where "natural colouring" comes from? If it's red, chances are it's carmine (cochineal). This vivid crimson pigment is obtained from cochineal, the dried bodies of female scale insects native to tropical and subtropical America.
"These bodies are crushed to produce the red colour," Henderson says.
Like many food additives, carmine has been put to use in many creative ways over the years - it was once used in watercolour painting, for example. But don't go looking for insect legs on your plate.
As with all additives, the extracted substance "must meet purity specifications", Henderson says.
Look for: additive number 120
6. Animal skin and bone
Watch out vegetarians - gelatin is a clear, tasteless animal protein used widely in soups, desserts and anything else that needs thickening or gelling. It is derived from collagen, a protein found in animal skin and bone, and is extracted by boiling that tissue.
Gelatin can also be whipped into a foam and acts as an emulsifier and stabiliser. Humans have used it for so long that it is regarded as an "animal-derived ingredient" rather than a food additive, Henderson says.
A vegetarian alternative is carrageenan, which is extracted from red and purple seaweeds found around the world. It's used as a thickening or stabilising agent in puddings, syrups and any number of gel-based foods.
Look for: gelatin or gelatine
7. Cow stomach lining
Rennet has long been used in the manufacture of cheese but that doesn't make it any less wince-worthy. What is it exactly? It's a preparation of enzymes that's extracted from the stomach membrane of cud-chewing animals, such as cows.
When mixed with milk, it kicks along the curdling process.
"These days it can also be produced by fermentation of microbes rather than having to be obtained from animal sources," Henderson says.
Look for: enzyme/rennet
8. Fish bladders
See how that wine almost sparkles it's so crystal clear? You can thank our fishy friends for that one. Isinglass is a clarifying agent obtained from the bladder of certain species of fish and is used to rid some beverages - mostly wines and beers - of cloudiness or haziness.
People with fish allergies no longer need to worry, however - current evidence shows isinglass won't set off a reaction.
"People with fish allergies [can] take wine without any adverse effects," Henderson says.
Unlike additives, processing aids such as isinglass do not usually require labelling though some brands may choose to label it.
What - nail polish? Turns out it's good for more than colouring your nails. It also works well as a glazing agent for polishing food. The resin is made from flakes derived from the secretions of the lac insect.
"It's used on fruit like apples to give it a polished appearance but also on some confectionary like jelly beans and so on," Henderson says. Beeswax can also be used for a similar purpose.
Look for: additive number 904
10. Silver and gold
Huh? As in those precious metals often adorned with diamonds and rubies? Yes, indeed. Don't worry, you're not about to choke on a nugget dug straight from the ground. They're usually used to decorate expensive confectionary, cakes and chocolates, most likely made for special occasions.
Because of the price attached, you're most likely to see just "a little bit of glitter in your food", Henderson says.
Look for: additive numbers 174 and 175
- Good Food