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Cosmetics materials are not a modern invention. Humans have used various substances to alter their appearance or accentuate their features for at least 10,000 years, and possibly a lot longer.  

Women in Ancient Egypt used kohl, a substance containing powdered galena (lead sulphide—PbS) to darken their eyelids, and Cleopatra is said to have bathed in milk to whiten and soften her skin. By 3000 B.C men and women in China had begun to stain their fingernails with colours according to their social class, while Greek women used poisonous lead carbonate (PbCO3) to achieve a pale complexion. Clays were ground into pastes for cosmetic use in traditional African societies and indigenous Australians still use a wide range of crushed rocks and minerals to create body paint for ceremonies and initiations.

Today, cosmetics are big business. According to the 2011 Household Expenditure Survey, conducted every five years by the Australian Bureau of Statistics, Australians spend around $4.5 billion on toiletries and cosmetic products every year. Cosmetic advertising, previously directed mainly at women, is now targeting a wider audience than ever.

What is a cosmetic?

In Australia, a cosmetic is defined under the Industrial Chemical (Notification and Assessment) Act 1989 as ‘a substance or preparation intended for placement in contact with any external part of the human body' (this includes the mouth and teeth). We use cosmetics to cleanse, perfume, protect and change the appearance of our bodies or to alter its odours. In contrast, products that claim to ‘modify a bodily process or prevent, diagnose, cure or alleviate any disease, ailment or defect’ are called therapeutics. This distinction means that shampoos and deodorants are placed in the cosmetics category, whilst anti-dandruff shampoos and antiperspirants are considered to be therapeutics.

Regulation and safety

In Australia, the importation, manufacture and use of chemicals—including those used in cosmetics—are regulated by the Australian Government’s National Industrial Chemicals Notification and Assessment Scheme (NICNAS). NICNAS works to ensure that chemicals used in consumer products do not cause significant harm to users or to the environment.

In the case of cosmetics, every ingredient contained within the product must be scientifically assessed and approved by NICNAS before being manufactured or imported into Australia and before they can be used in consumer products. Where appropriate, NICNAS sets limits on the level at which a chemical can be used in a product and also conducts reviews on chemicals when new evidence arises.

Cosmetic products that make an additional therapeutic claim (such as moisturisers that also lighten the skin) are regulated by a different organisation—the Therapeutic Goods Administration (TGA).

Cosmetics and other personal care items must also be labelled in accordance with the Trade Practices (Consumer Product Information Standards, Cosmetics) Regulations 1991. This regulation requires that all intentionally added ingredients are listed on the product label, and is enforced by the Australian Competition and Consumer Commission (ACCC).

What do cosmetics contain?

There are thousands of different cosmetic products on the market, all with differing combinations of ingredients. In the United States alone there are approximately 12,500 unique chemical ingredients approved for use in the manufacture of personal care products.

A typical product will contain anything from 15–50 ingredients. Considering the average woman uses between 9 and 15 personal care products per day, researchers have estimated that, when combined with the addition of perfumes, women place around 515 individual chemicals on their skin each day through cosmetic use.

But what exactly are we putting on our skin? What do those long names on the ingredient list mean and what do they do? While the formula of each product differs slightly, most cosmetics contain a combination of at least some of the following core ingredients: water, emulsifier, preservative, thickener, emollient, colour, flavors and fragrances and pH stabilisers.

Water

If your product comes in a bottle, chances are the first ingredient on the list is going to be water. That’s right, good old H2O. Water forms the basis of almost every type of cosmetic product, including creams, lotions, makeup, deodorants, shampoos and conditioners. Water plays an important part in the process, often acting as a solvent to dissolve other ingredients and forming emulsions for consistency. 

Water used in the formulation of cosmetic materials is not your everyday, regular tap water. It must be ‘ultra-pure’—that is, free from microbes, toxins and other pollutants. For this reason your label may refer to it as distilled water, purified water or just aqua.

Emulsifiers

The term emulsifiers refers to any ingredient that helps to keep unlike substances (such as oil and water) from separating. Many cosmetic products are based on emulsions—small droplets of oil dispersed in water or small droplets of water dispersed in oil. Since oil and water don't mix no matter how much you shake, blend or stir, emulsifiers are added to change the surface tension with surfactant materials between the water and the oil, producing a homogeneous and well-mixed product with an even texture. Examples of emulsifiers used in cosmetics include polysorbates, laureth-4, and potassium cetyl sulfate.

Preservatives

Preservatives are important ingredients. They are added to cosmetics to extend their shelf life and prevent the growth of microorganisms such as bacteria and fungi, which can spoil the product and possibly harm the user. Since most microbes live in water, the preservatives used need to be water-soluble, and this helps to determine which ones are used. Preservatives used in cosmetics can be natural or synthetic (man-made), and perform differently depending on the formulation of the product. Some will require low levels of around 0.01%, while other will require levels as high as 5%.

Some of the more popular preservatives include parabens, benzyl alcohol, salicylic kojic acid, formaldehyde and tetrasodium EDTA  (ethylenediaminetetra-acetic acid).

Consumers who purchase ‘preservative-free’ products should be aware of their shorter shelf life and be conscious of any changes to the look, feel or odour of the product that may indicate it has gone off.  

Thickeners

Thickening agents work to give products an appealing consistency. They can come from four different chemical families:

Lipid thickeners are usually solid at room temperature but can be liquefied and added to cosmetic emulsions. They work by imparting their natural thickness to the formula. Examples include cetyl alcohol, stearic acid and carnauba wax.

Emollients soften the skin by preventing water loss. They are used in a wide range of lipsticks, lotions and cosmetics. A number of different natural and synthetic chemicals work as emollients, including beeswax, olive oil, coconut oil and lanolin, as well as petrolatum (petroleum jelly), mineral oil, almond oil, glycerine, zinc oxide, butyl stearate and diglycol laurate.

The inorganic metal oxide pigments are usually duller than the organic intermediate pigments, but are more resistant to heat and light, providing a longer-lasting colour.

In recent years there has been some concern about nanoparticles (NP) in sunscreens. This relates particularly to zinc oxide (ZnO) and titanium dioxide (TiO₂) nanoparticles and their ability to penetrate the skin to reach cells and the potential toxicity exerted by these chemicals.

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