Cosmetics and Heavy Metals

Executive Summary

The definition of a cosmetic product is any substance or preparation intended to come in contact with the various external parts of the human body (epidermis, hair system, nails, lips and external genital organs) or be applied to teeth and the mucous membranes with purpose of cleaning, perfuming, protecting, changing their appearance or correcting body odors. Cosmetics are mixtures of some surfactants, emulsifiers, humectants, emollients, moisturisers, etc; and may be required to have effective properties such extended duration of effective usage, sun protection, etc.

The general belief is that in the regulation of cosmetic products, there are still ongoing health concerns regarding the presence of harmful chemical substances within these products. With the exception of color additives, cosmetic products and ingredients are not subject to regulation prior to market release. It is only when a product gets detected by regulatory authorities after its release, that the Ministry of Health may start imposing rectification measures. With numerous new products released into the market every season, it may be hard to keep track of the safety of every product. Some products are known to carry carcinogenic substances with many  known to contain heavy metals such as lead, arsenic, mercury, cobalt, and nickel as they exist in the raw ingredients as impurities.

Regulatory Scenario

According to a large body of research these metal impurities can easily cause skin disorders and the use of some heavy metals in cosmetics has been controversial due to the potential for biological accumulation of these metals and their toxicity in the human body.

In most countries, it is illegal to use lead, arsenic, and mercury in skin cosmetic products. The maximum allowable level of lead is 20 ppm in some jurisdictions, while there are no specific regulations on other heavy metals, such as cobalt, nickel, and copper. It  has been reported that those metals could cause allergic contact dermatitis. Acceptable limits for heavy metals vary accordingly and assessment of dermal absorption by a single component in a cosmetic product is complex and depends on impurities concentration in the final product, the amount applied onto the skin, the applicable duration on the skin and the presence of emollients and penetration enhancers in the cosmetic product. Given this complexity and the lack of well-conducted dermal absorption studies incorporating these factors, determination of heavy metal limits in cosmetics based on human health risk alone is a huge challenge.

Reports on cosmetic products tested positive for heavy metal contents are common. Heavy metals are found naturally in the environment in rocks, soil and water; therefore their existence in pigments and other raw ingredients is expected.Some of these metals had been used as cosmetic ingredients in the past. Examples include the preservative, the progressive hair dye lead acetate and a number of pigments such as red cinnabar mercuric sulphide. Since the issue of heavy metals as deliberated in cosmetic ingredients has been addressed,  most attention is turned to the presence of these substances as impurities. The metals of primary toxicological concern in cosmetics are lead, arsenic, cadmium, mercury and antimony. Dermal exposure is expected to be the most significant route for cosmetic products since the majority of cosmetics are applied onto the skin.

Dermal absorption of heavy metals is fairly minimal, while absorption of individual elements is influenced by a number of factors for instance clouding physical-chemical properties of the mixtures. Oral exposure can occur for cosmetics used in and areas around the mouth. Transfers from hand to mouth could occur as a result of application of cosmetics containing heavy metal impurities.

Inhalation exposure is considered to be negligible, though higher concentrations of heavy metals have been shown to have negative effects.

Methods of analysis

Preparation of standard solutions

Standard solutions of Lead, Cadmium, Copper, and Nickel have been prepared from 1000 ppm Standard Stock Solution with AAS Reference Standard. These stock solutions have been serially diluted to give concentrations of 0.5, 1.5, and 2 ppm for lead while 0.5, 1, 1.5, and 2 ppm for cadmium, and 0.5, 1, 1.5,2 for copper, and 0.5, 1, 1.5,2 nickel standards.

Preparation and digestion of samples

Samples  digested using the same method 0.5 gm of each sample have been carefully pipetted into digestion test tube and 10 ml of digested acid(3:1 HCl:HNO3)  added to each sample and then placed on the hot plate for 30 min. On completion,  the digested samples would be allowed to cool to room temperature and made up to 50 ml with distilled water and  filtered (using wit man filter paper No.41) with each sample then transferred into volumetric flask for analysis by flame atomic absorption spectroscopy(FAAS).

Conclusion

Cosmetic applications may be seen as a source of heavy metals' absorption into the human body. With such known observation, there is a need to investigate and study the concentration of toxic metals in some commonly used cosmetic applications. It is known that certain amount of dosage of heavy metals can be harmful and that even long-term exposure to low levels of heavy metals can cause disorders to humans. There has been growing concern about the physiological and behavioural effects of toxic metals on humans in general. For instance, the toxicity of lead at high concentrations of exposure is well documented but a major concern in recent time is the possibility that continual exposure to even relatively low levels of these toxic metals in cosmetic products may pose potential health risks. The possibility of skin allergy and contact dermatitis may increase due to the presence of heavy metals impurities in cosmetics.

The heavy metals found in most products tested are categorized as unintentional contaminants, where these metals are not intentionally added to the formulation but are simply impurities in the products and are therefore not listed on the labels. An impurity is a substance not intentionally added to a product, but rather is either a by-product during the manufacturing process, formed by the breakdown of ingredients, or an environmental contaminant of the raw ingredients.

The latter is the case for heavy metals, as their persistence in the environment and their natural presence in rocks, soil, and water cause them to be present in the manufacture of pigments and other raw ingredients used in cosmetics. Manufacturers are required to use these materials so that these impurities are well below the regulated limits. As marketing trends tend to favour heavily applicable pigments, the presence of the toxic metals in the final products would pose concerns. The trace amount of these metals in the human body may be harmful biologically if allowed to accumulate over time. These metals have the ability to accumulate in the organs and numerous reports on these metals interfering with essential nutrients of similar oxidation states do occur.

These contaminants are found in cosmetic products when poor-quality ingredients are used. Most likely, these toxic metals could have been contaminants from one or more of the inorganic base materials used in the manufacturing of raw ingredients. Since these toxic metals are found in various environments, manufacturers are advised to proactively test the raw ingredients for the presence of these toxic metals before using these raw ingredients in their final products.