Cosmetic is any preparation that is used externally to cleanse or beautify our physical appearance and become more attractive. Usually, the cosmetic preparation or product is applied to the part of our skin that is the most exposed to the environment. Therefore, it is important that the product be compatible with our skin type. A cosmetic can be unsuitable, even harmful, if its usage adversely affects our skin. The correct usage of a cosmetic depends upon our knowledge of the ingredients used in its preparation.

The list of ingredients in cosmetics given in this article represents only some of them that are used today. Cosmetics typically use between 5,000 to 10,000 types of chemicals in their preparation.

You should know about the ingredients used in a cosmetic because of two reasons, your health and the correct usage. Some substances may adversely affect the skin at the area where you apply them. For example, beauty creams containing the active ingredient hydroquinone is effective in removing dark spots from the face. However, many side effects have been observed. In a study conducted in the United States , creams containing about 2 to 5% hydroquinone were applied on 56 individuals who had dark spots on their faces. The results showed that the cream was effective in removing spots from the skin of 44 individuals while the 5% hydroquinone in the cream caused skin irritation in the rest of them. At low concentrations, the side effects are seen to be minimal. But at higher concentrations, effects such as burning sensation can occur. When used for a longer period of time, compounded by the exposure of the treated skin to the sun, yellowish spots and swelling were observed on the skin. This condition is called ochrosis. If left untreated, the skin is damaged permanently. Hydroquinone not only affects the skin adversely but it is also poisonous. If an amount of 5 to 15 gm of hydroquinone is swallowed, trembling and anaemia haemolytic (damage to the red blood cells) will result.

Cosmetics often contain solvents such as alcohol. Although alcohol cannot be avoided in the preparation of certain cosmetics, Muslim users must be certain that, when they pray, they do not use cosmetic preparations containing this substance. Fats such as wax and oil are also used to prepare cosmetics. FUNCTIONS AND USES

Fats can be either from an animal source or a plant source. This determines whether the cosmetics are suitable for Muslim users.

Knowledge of the properties of the substances used to prepare cosmetics is as important as the knowledge about these substances. Broadly, these substances can be classified under seven categories:

PRESERVATIVES

These are used to ensure that cosmetics remain bacteria-free and have a longer shelf life. The preservatives used in cosmetics include paraben, ammonium quartenary, alcohols such as ethanol and isopropanol, and derivatives of phenol such as p-chloro-m-cresol. In addition to preventing bacterial growth, preservatives prevent the oils from turning rancid. Examples of such preservatives are benzoic acid, BHA and tocopherol or vitamin E.

pH REGULATORS

These maintain the pH balance of cosmetics to ensure compatibility with the skin. Without these substances, any changes in the pH balance can cause corresponding changes in the acidity or alkalinity of the product, which could adversely affect the skin. Some of the substances that are used to regulate the pH level are citric acid, an acid substance, and ammonium carbonate, a base substance. In addition to acids or bases, pH regulators can be in the form of a salt such as ammonium bicarbonate or calcium carbonate and tartaric acid.

MOISTURE REGULATORS

These are used to prevent loss of moisture from the preparation. Substances such as glycerine and propylene glycol in lotions and moisturising creams make it easy to apply them on the skin.

PROCESSING AIDS

These are used to make the cosmetic products look attractive. Most cosmetic preparations consist of a mixture of oil and water. Without a processing aid, these substances do not mix, making the product appear unattractive. An emulsifying agent such as sodium lauryl sulphate or alumina gel is used to make the mixture homogenous. Examples of other processing aids include dodecyl benzene sulfonic acid that is used in shampoos to form lather. COLORANTS These are used to make cosmetic products colourful. Colorants can be chemical such as Red FD &C or natural such as carotene, alkanet and saffron.

SEASONINGS

These are used to disguise the unpleasant taste of some of the ingredients in cosmetics. Seasonings include amyl acetate and ethyl acetate.

FRAGRANCES

These are extensively to prepare perfumes. In most perfumes, the fragrances used are often not stated to protect the copyright interests of the perfume developer.