The established regulations identify cosmetic ingredients as either safe, unsafe, or also undecided when further information is required to establish safety. Unfortunately, there are many websites publishing lists of "unsafe cosmetic ingredients" based on no scientific evidence, thereby discrediting many good and acutally completely safe ingredients. True and validated scientific evidence about the safety of both natural and chemical cosmetic ingredients can be found only at the following resources:
 

EEC Cosmetic Directives: European directives formulated by the European Union consisting of a series of principles, rules, and lists of safe and unsafe ingredients.

IFRA (International Fragrance Association): Association of manufacturers of fragrances. Its Technical Advisory Committee issues recommendations about the safety of various fragrances.

Determination of toxic potential is the first step in the hazard assessment of an ingredient and consists of a series of toxicity studies, specific to distinct toxicological end points. The following tests are needed to develop specific toxicity evaluation and indicate the current methodologies used for the safety evaluation of cosmetic ingredients as suggested by the EEC Cosmetic Directives:
 

• Acute toxicity
• Percutaneous absorption
• Skin irritancy
• Eye irritancy
• Skin sensitisation and photosensitisation
• Subchronic toxicity
• Mutagenicity & genotoxicity
• Phototoxicity & photoirritation
• Photomutagenicity  photogenotoxicity
• Metabolism studies
• Long-term toxicity studies
   

Thus, before any safety evaluation and risk assessment of a finished product is made, the degree and route of consumer exposure must be ascertained. This has to be done on a case-by-case basis but the following may provide guidance. In calculating the exposure the following factors must be considered:
 

• Class of cosmetics in which the ingredient may be used
• Method of application: rubbed-on, sprayed, rinse-off etc.
• Concentration of ingredients in product
• Quantity of product used at each application
• Frequency of application
• Total area of skin contact
• Site of contact (e.g., mucous membrane, sunburnt skin)
• Duration of contact (e.g., rinse-off products)
• Foreseeable misuse which may increase exposure
• Nature of consumers (e.g., children, people with sensitive skin)
• Quantity likely to enter the body
• Application on skin areas exposed to sunlight

Prohibited or Highly Restricted Ingredients
FDA regulations specifically prohibit or restrict the use of the following ingredients in cosmetics: Hexachlorophene (preservative), mercury compounds (preservative), chlorofluorocarbon (propellant), zirconium-containing complexes, halogenated salicylanilides (di-, tri-, metabromsalan and tetrachloro-salicylanilide), bithionol, chloroform, vinyl chloride, and methylene chloride.

Ingredients that Should Not Be Used
In addition to the ingredients that are controlled by regulation, cosmetic and fragrance trade associations have recommended eliminating or limiting maximum levels of certain ingredients associated with health risks. For example, the CIR and IFRA Expert Panels have found the following ingredients unsafe: Chloroacetamide (preservative), ethoxyethanol and ethoxyethanol acetate (solvent), HC Blue No. 1 (hair coloring ingredient), p-hydroxy-anisole (antioxidant), 4-methoxy-m-phenylenediamine, 4-methoxy-m-phenylenediamine HCl, and 4-methoxy-m-phenylenediamine sulfate (hair dye ingredients), pyrocatechol (used in hair dyes and skin care preparations), acetylethyl-tetramethyl-tetralin (AETT), musk ambrette, 6-Methylcoumarin (6-MC).
 

Ingredients that Should be Limited in Their Use
There are many cosmetic ingredients which do not exert a toxic effect as such, but may have unwanted effects if used at too high concentrations. Thus, such ingredients can still be used and can have favorable effects if added to cosmetics at the concentration as indicated. Some of them are mentioned below. In addition, the CIR Expert Panel has published a list of recommended limits for the use of a number of other ingredients which are still being widely used. You can purchase this list at CIR. A quick reference table can be founded here (PDF file to download).
 

Sodium chloride (table salt): frequently used as cheap but effective thickener in cleansing products including shampoos or shower gels. If used at too high concentrations it can cause eye and skin irritation

Bentonite: This porous clay able to absorb water is commonly used in cosmetic foundations and facial masks. At high concentrations, it may scratch the skin surface, clog pores, and dry out the skin.

Lanolin: Although widely used as emollient and emulsifying agent in creams and lotions, lanolin can be irritating to the skin and can cause allergic rashes.

Sodium Laureth Sulfate / Ammonium Laureth Sulfate (SLES, ALES): The CIR Panel has recently stated that SLES and ALES produce eye and/or skin irritation in some human test subjects. The severity of the irritation appeared to increase directly with concentration. However, SLES and ALES have not evoked adverse responses in any other toxicologic testing. It was concluded that both surfactants are safe as presently used in cosmetic products.