Natural Products Chemistry & Research

Women are mainly used different cosmetic products of body care as a basic daily product and they are not aware of the dangers of heavy metals that contained in cosmetics. Even if cosmetic products have a tiny proportion of heavy metals; which, they could not be ignored as cosmetics are worn for a long period [1]. Thirty-five metals are of concern because of potential occupational or residential exposure; 23 of these are heavy metals: antimony, arsenic, bismuth, cadmium, cerium, chromium, cobalt, copper, gallium, gold, iron, lead, manganese, mercury, nickel, platinum, silver, tellurium, thallium, tin, uranium, vanadium, and zinc [2]. Trace amounts of these elements are common in our environment and diet and are actually necessary for good health, but large amounts of any of them may cause acute or chronic toxicity (poisoning). Heavy metal toxicity can result in damaged or reduced mental and central nervous function, lower energy levels, and damage to blood composition, lungs, kidneys, liver, and other vital organs. Long-term exposure may result in slowly progressing physical, muscular, and neurological degenerative processes that mimic Alzheimer's or Parkinson's disease, muscular dystrophy, and multiple sclerosis. Allergies are not uncommon and repeated long-term contact with some metals or their compounds may even cause cancer [3].

Lipsticks are one of the most important cosmetic product that women are commonly used to look more attractive and be in a good looking; however, they paid a high price by exposure to different heavy metals, which lipsticks are contained [1]. In 2007, the Campaign for Safe Cosmetics tested for and found-lead in numerous top-selling lipsticks [4]. It stood to reason that lipstick may not be the only product that could contain lead and not list it on the label. After reports revealed that several other countries such as Italy [5] Ireland [6] and Canada [7] found heavy metals in face paints.

Lead is harmful, particularly so to the developing brain and nervous system [6,8] Lead can cause kidney damage, has been linked to cardiovascular disease and can cause autoimmune disorders [9]. Lead mainly enters the body through ingestion or inhalation of lead-dust. Adults absorb about 11% while children absorb 30-75% of lead that reaches the digestive tract. Less than 1% of lead is known to be absorbed through the skin [10]. Lead poisoning is a global problem. It is one of the most important environmental diseases in children [11]. Pregnant women and children 6 years or younger absorb lead in the highest quantities. Even low levels of lead exposure are considered hazardous to pregnant women [12]. Lead exposure during the first trimester of pregnancy has been found to cause alterations in the developing retina, thus leading to possible defects in the visual system [13]. Lead poisoning has been linked to juvenile delinquency and behavioral problems. Young children are particularly susceptible to lead poisoning due to their normal hand-to-mouth activity and because of the high efficiency of lead absorption by their gastrointestinal tracts [14]. Chronic low-dose lead exposure was found to cause renal tubular injury in children [15], while in adults, it was associated with poorly controlled hypertension [16]. A blood lead level of 10 mg/dl is of concern [8]. Shaltout et al. [17] found 20 patients aged between 1 and 18 months suffering from lead encephalopathy in Kuwait. The blood levels in 19 children ranged between 60 and 257 mg/dl. Two of these patients died before starting treatment, and three children died during treatment. Among the children who recovered, four had neurological sequelae. The source of lead in 11 patients was confirmed to be kohl [17]. On another reference, a seven-month-old baby was found to have a blood lead level of 39 mg/dl due to use of kohl [18]. In the USA, kohl and ‘kajal’ from the Middle East were considered among the unapproved dyes in eye cosmetics that contained potentially harmful amounts of lead [19]. Similarly, certain traditional digestive remedies also contain harmful levels of lead [18]. Zakaria and Ho [1] studied lipsticks marketed in Malaysia for their heavy metal contamination. They have found lead concentrations of 0.8-15 mg/kg. There is no internationally agreed limit on permissible lead contents of lipsticks; but Health Canada stipulates it should not exceed 10 ppm.

Little is known about lead poisoning in Saudi Arabia. Studies have suggested that kohl in Saudi Arabia might be a cause of lead toxicity, [20,21] but no detailed investigation has been undertaken. The Saudi Standards, Metrology and Quality Organization issue a standard for the rouge samples, number 1871 in 2001. In this standard the concentration of As (as As₂O₂), Pb and Hg is limited to 2 mg/Kg, 20 mg/Kg, 1 mg/Kg respectively.

A certain degree of sensitization was shown by the salts of platinum group elements, i.e., Pt, Pd, Rh, and Ir, because of their large use in dental devices, jewellery, and automotive catalysts [22-24]. Moreover, a synergic action between Pd and Ni, pertaining to the same periodic group, has been suggested as being the cause of cross-sensitization [22]. Both Cu and Mn are rare skin sensitizers; immune reactions due to Cu exposure from intrauterine devices or by handling euro coins have been described, whereas the use of prosthetic materials in dentistry has created a risk of sensitization for both Cu and Mn [25,26]. Considering toxic metals such as Cd and Hg little is known about their dermatological activities. Cases of allergic contact dermatitis (ACD) due to Cd exposure from cement dust emission [27] and ceramics material [28] and to Hg present as ammoniated mercury (HgNH₂Cl) in skin lightening creams have been reported [29]. One case of sensitization to V was found in an enameller employed in the ceramics industry [28]. Another important way of skin exposure to metals is the use of cosmetic products such as moisturizing creams, lipsticks, eye cosmetics, shampoos, cleansing milk, henna dye, etc. In these make-up product metals are present as impurities due to the particular sample formulation or the release from metallic devices used during their manufacture. In fact, the European Communities Directive 76/768/EEC and further revisions banned the use of Cd, Co, Cr, Ni, and Pb as metallic ions or salts in the preparation of cosmetic formulations [30]. Considering the prolonged contact time of cosmetic products with the skin the risk of ACD might be increased [31,32]. As a support to this, there are several studies evidencing the presence of Co, Cr, Ni, and Pb at levels of μg g^-1 in henna dye, eye shadows, and lip liners with frequent positive reactions to patch tests [31,33-36]. Some authors revealed the presence of Cd, Cr, Cu, Hg, Pb, and metal oxides in body or sunscreen creams [37-39]. If the cosmetic products are formulated as dry, this will minimize the risk of skin penetration of metal, whereas those based on fat-soluble substances (for example moisturizing creams) promote the percutaneous absorption much more. On the other hand, adverse reactions to metal-containing cosmetic products were mostly observed in patients with manifestation of pre-existing allergy to metals [40]. Patch tests revealed that a threshold limit equal to 5000 ng g^-1 or for a more protection equal to 1000 ng g^-1 for Ni, Co and Cr excluded the risk of elicitation in sensitized people [39,40]. Given these facts and the increased frequency of allergy to Ni, the challenge of the cosmetic industry was to manufacture products to be used by people pre-sensitized to Ni. For this reason, manufacturers made available on the market creams labelled with the phrase “Ni-tested” together with a declared Ni concentration of 100 ng g^-1, thus guaranteeing levels 50 times below the risk of causing allergy reactions [40].

There is increasing evidence that the chemical constituents of underarm and body-care cosmetics applied to the underarm and breast area may be involved in the rising incidence of breast cancer [41-43]. Aluminium salts, such as aluminium chlorohydrate (ACH), are the active ingredients of antiperspirant [44]. Their mode of action is thought to involve blockage of the sweat ducts which prevents the escape of sweat onto the body surface, probably through the formation of a physical plug at the top of the sweat duct, which is composed of a combination of precipitated salts and damaged cells [44-47].

Because metals can induce unwanted side effects in humans establishing their contents in body-care cosmetics products is important for quality and health controls. The European Community directives forbid cosmetic formulations containing more than 1% selenium sulfide while zinc pyrithione cannot exceed 0.5% and other zinc salts are limited to 1% [48]. In this work, we have selected nine brands, which are the most expensive of the facial cosmetics (Base jelly, Whitener, Sheen and Face powder) from the Saudi market. Twentyeight elements were detected by using Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and a flow injection mercury system (FIMS).

Sample preparation

An accurately weighed sample of (0.1-0.2 g) was transferred to a TEFLON digestion tube (120 mL) mixed with 7.0 mL of the acid mixture (HNO₃/HF/HCl, 4.5:2:0.5). The tube was sealed. The sample was digested in a microwave oven (Milestone ETHOS 1600) following a heating program shown in Table 1.

Table 1: Microwave heating program used for dissolution of the samples.

After cooling to ambient temperature, the tube was unsealed; the inside of the lid was rinsed with distilled and de-ionized water (DDW) and the mixture heated on a hotplate (120ºC) for 30 min. to evaporate residual HF and HCl. The resulting digest was filtered in a polypropylene flask using 1% HNO₃ and made up to 50 ml volume. For ICP-MS measurement the clear digest obtained were diluted 10 times incorporating 10 μgL^-1 solution of ¹⁰³Rh. In general, samples and standard reference materials (SRM) were prepared in a batch of six including a blank (HNO₃/HF/HCl) digest.

Chemicals and reagents

High purity water (DDW) (Specific resistivity 18 MW.cm-1) obtained from an E-pure water purification system (Barnsted, USA) was used throughout the work. HNO₃, HF and HCl used for sample digestion were of Suprapureâ grade with certified impurity contents (Merck, Germany). A multi-element standard containing 27 elements were prepared from Perkin-Elmer single-element ICP standards (1000 or 10000 ppm). The Standard Reference Material (SRM), IAEA-SOIL-7 was purchased from the International Atomic Energy Agency, Vienna.

Instrumentation

A Perkin-Elmer Sciex ELAN 6100 inductively coupled plasma mass spectrometer (ICP-MS), equipped with a quadruple mass filter, a cross-flow nebulizer and a Scott type spray chamber, was used for all measurements.

Quality assurance

To assess the analytical process and make a comparative analysis, Standard Reference Materials (Soil 7) from the International Atomic Energy Agency (IAEA), Vienna, Austria was used. The quantitative analysis result is shown in Table 2. The results are generally in good agreement with certified values of the reference materials.

Table 2: Concentration of elements in Soil 7.

Hg analyses

A flow injection mercury system (FIMS) from Perkin Elmer FIMS-400 was used for determination of Hg in the samples.

The FIMS is a complicated technique depending up on synchronization of mechanical, chemical and optical operations. The system contains three major units namely the spectrophotometer coupled with the flow injection circuitry, the amalgamation unit and the computer unit for automated control of the operation and measurements. The FIAS program was optimized and the program is saved as “Mercury 2” in the computer, Table 3. The FIMS pumps program is shown in Table 4.

Table 3: FIMS program.

Table 4: FIMS pumps program.

The blank used in this process contained 2 v/v% H₂SO₄, 2 v/v% HNO₃ and approx. 1.0 mg L-1 KMnO₄ in de-ionized water. All the measuring standard and sample solutions were stabilized in the same medium.

Heavy metals are found naturally in the environment. They exist in manufactured pigments and other raw materials in all industries including cosmetics. Some of these metals have been used as cosmetic ingredients in the past. Examples include the preservative thimerosal (mercury), the progressive hair dye lead acetate and a number of tattoo pigments such as red cinnabar (mercuric sulfide) [49]. The concentration of twenty elements in ppb (μg/Kg) in the facial cosmetics (Base jelly, Whitener, Sheen and Face powder) of nine brands of facial cosmetics. In addition, the mean, the minimum and the maximum of elemental concentration are reported in Tables 5-8. Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and a flow injection mercury system (FIMS) were used to obtain the results.

Table 5: The concentration of elements on the Base jelly samples in ppb.

Table 6: The concentration of elements on the whitener samples in ppb.

Table 7: The concentration of elements on the Sheen samples in ppb.

Table 8: The concentration of elements on the Face Powder samples in ppb.

When compared to the mean concentration of elements in the facial cosmetics samples (base jelly, whitener, sheen and face powder) under investigation, we observed:

The mean concentration of elements in whitener samples were the lowest among the fifteen elements (Li, B, Al. V, Cr, Mn, Fe, Co, Zn, Sr, Ag, Ba, Pb, Sn and Hg). In this work whitener samples do not record any element with highest mean concentration. Face powder samples record the highest mean concentration of the sixteen elements (B, Mg, Al, K, V. Mn, Co, Zn, As, Se, Rb, Mo, Ag, Cd, Pb and U). Only one element, copper, in face powder samples showed the lowest mean concentration. Base jelly samples had three elements with the lowest mean concentration (K, Ca and Rb) and six elements with the highest mean concentration (Na, Cr, Fe, Ni, Sb and Sn). Sheen samples had nine elements with the lowest mean concentration (Na, Mg, Ni, As, Se, Mo, Cd, U and Sb) and six elements with the highest mean concentration (Li, Ca, Cu, Sr, Ba, Hg).

It is acknowledged that heavy metal impurities in cosmetic products are unavoidable due to the ubiquitous nature of these elements, but should be removed wherever technically feasible.

Cosmetic in general can have a high concentration of trace-metal elements. Given the significant and relatively uncontrolled human exposure to cosmetics and their ingredients, these products must be thoroughly evaluated for their safety prior to marketing [50-54].

The authors would like to acknowledge King Abdulaziz City for Science and Technology (KACST) for financially supporting this work and Professor Sayed Gary for revising this paper.