useful

Found in various creams.
Purpose: a preservative.
Harmful effects: carcinogenic, mutagenic, and toxic.

Found in various creams and deodorants.
Purpose: an antioxidant that inhibits oxidation and extends shelf life.
Harmful effects: a synthetic antioxidant that causes allergic reactions. It's advisable to use natural antioxidants in place of BHT, such as vitamin E, C, etc.

Found in various creams, deodorants, and shampoos.
Purpose: used as a alkali for the pH regulation in cosmetics, and as a solvent.
Harmful effects: possibly irritating. Isopropyl Mystrate (and oily, softening substance) is often used in cosmetics, and together with TEA or DEA can create carcinogens or cancer-causing compounds - nitrosamines.

Found in all kinds of creams, massage oils, and the main ingredient of baby oil.
Purpose: skin softening, lubricating.
Harmful effects: a cheap by-product of the petroleum industry, coats the skin with "non-breathing" layer, causes blackheads and infection. May contain polycyclic aromatic hydrocarbons (PHA), are carcinogenic and mutagenic. Used in cosmetics mainly because it is a cheap alternative to quality vegetable oils.

Found in tonics and face, eye, and body creams.
Purpose: used as a skin moisturiser and additive thinner in the manufacture of cosmetics, but also used in the manufacture of antifreeze, brake fluid, and lacquer.
Harmful effects: is toxic, causes liver anomalies and kidney damage (in animal tests), has a small molecular weight, which means that it easily soaks into tissues. Absorbs moisture, including from the skin, making it dry. It's advisable to use vegetable glycerine in the place of propylene glycol.

Found in shampoos, shower gels, and other soaps and detergents
Purpose: an active ingredient that causes the product to foam. The most popular substances in the market are Sodium Lauryl Sulfate (SLS) and Sodium Laureth Sulfate (SLES).
Harmful effects: Japanese studies have indicated that SLS is a mutagen (it can cause gene mutation). In accordance with the views of toxicologists, any substance that is a mutagen increases the risk of cancer. Moreover, SLS and SLES have been shown in studies to be the only substances in soaps to get into the circulatory system.

Found in nearly all cosmetics.
Purpose: a preservative that extends the shelf life of the product.
Harmful effects: causes allergic reactions, acts as a mutagen, imitates feminine hormone activity, damages the endocrine system, and is toxic. Parabens are able to soak into the deepest layers of skin, be absorbed by the circulatory system, and be accumulated in body tissues. In this way, these substances can reach a heightened concentration and considerably damage the immune system, facilitate various illnesses, and the development of anomalies. Moreover, these substances can travel through a mother's body and affect her children (they have been found in breast milk, also), which cause the immune system of the newborn to be damaged.

Approximately 8,000 various substances are used in the manufacture of cosmetics today. Some of these are of natural origin - vegetable oils, plant extracts, waxes, and essential oils - but a large part is synthesised compounds from a laboratory. More often than not, synthetic substances are harmful, and, when used long-term, can damage the immune system, cause allergies in both parents and their children, and can facilitate the growth of cancer cells. It's impossible to memorise all the ingredients and their effects, but it's important to have some knowledge of the most dangerous and often used.
Ingredients of a product are listed in diminishing order; this means that the more of a substance a product contains, the closer to the beginning of the list it will be mentioned. Many products list their first ingredient as distilled water (Aqua or Aqua purificata), and then comes everything else. In creams, an oily ingredient usually follows water (pay attention whether vegetable oil has been replaced with cheap mineral oil or silicon oil - dimethicone, cyclomethicone, or other substances with similar names). The end of the list usually includes preservatives and colouring agents. It's important to look for parabens.
It's good if the ingredients list contains the names of plant ingredients. Plants are listed by their Latin names, and the English translation is often listed afterwards, in parenthesis. For example: Chamomile Recrutita (Chamomile) Extract; Persea Gratissima (Avocado) Oil.
There is a trick to approximately figure out how much of a certain substance a product contains. The maximum allowed amount of parabens in a product is 0,5%. If the manufacturer claims that a product contains chamomile, but the extract of it is listed in the ingredients after parabens, we can conclude that the cream contains less than 0.5% chamomile - less than enough to have any real effect. That's why this cream is not worth buying.

Natural cosmetics that were available before some time weren't easy to use - they smeared, didn't soak in well, were sticky, and had a short shelf life. Natural cosmetics available in the market today are busting these myths - they're just as easy to use as synthetic products. The shelf life will never be longer than a few years, because the chemicals have been replaced with natural preservatives - enzymes or salts. The shelf life is lengthened with the aide of the packaging, utilising vacuum pumps - the product doesn't come in contact with air or dirty fingers, and therefore is protected from microorganisms that would cause it to spoil. Manufacturing technologies of natural cosmetics in the world have advanced so far that there is no chemical substance that is still necessary to the manufacture of cosmetics.

The body "understands" what's natural

One of the main reasons why natural cosmetics are better than synthetic products is that the body understands and recognises the substances present. Protection, renewal, and metabolic processes in plant cells are similar to those in human cells, and so the human cells recognize plant cells as suitable and are able to utilise them as such. Still, it must be taken to account that natural cosmetics may cause allergic reactions because of the possibility of a person's already present allergy to any of the ingredients. For example, if someone is allergic to calendula, it is possible that a product containing it will cause an allergic reaction.

Natural mixed with toxic substances

There is a difference between what are simply called natural cosmetics, and those made with ecologically certified ingredients. Chamomile can just as well be grown on a farm, but also sprayed with chemicals to facilitate growth. These chemical substances stay in the plant, but ecologically certified ingredients are safe in this sense. As of this moment, the cosmetics market in Europe is unorganised. Manufacturers can print "biological product" on their labels even if only one of the many ingredients is natural. The only way the consumer can protect himself if by cautiously reading the ingredients label.
The effects of natural cosmetics on skin are similar to those of synthesised products, but their effects on health are very different. Even though synthetic beauty care products sometimes have a more intense or fast effect, because of added chemicals whose goal is to more quickly infuse active ingredients, it's important to avoid these products, as they contain harmful ingredients, like mineral oil, a by-product of the petroleum industry. These substances do no good to skin - at best, they are inert and don't have any effect; at worst - they soak into the skin and are stored in the body, like the preservatives called parabens, which can cause serious health problems. These ingredients often are used because they are cheap and extend the shelf life of the product considerably.
Harmful substances can be in both completely synthetic products, as well as those containing some natural ingredients.