| Abstract|| |
Background: This study highlights the presence of heavy metals as metal impurities in the skin-lightening product. The presence of metal impurities leads to accumulation in human vital organs and produce harmful effects to humans even at low concentration. Aim and Objectives: The aim of this study was to determine the concentration of heavy metals impurities (Pb, Cd, and Ni) in skin-lightening products available in Malaysian market and to assess the risks of application of products that contain heavy metals. Methods: This study sampled 33 skin-lightening products (facial moisturizing cream). Samples were tested for heavy metals using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). Health risk was assessed using Margin of Safety (MoS) and Hazard Quotient (HQ). Results: In general, all heavy metals were slightly higher in non-local samples. For example, the mean ± standard deviation (SD) of Ni in non-local samples was 0.207±0.15 mg/kg, slightly higher than local samples (0.180±0.17 mg/kg). Cd was determined as 0.018±0.02 mg/kg in non-local samples and 0.014±0.01 mg/kg in local samples. Pb was determined as 0.107±0.08 mg/kg in non-local samples and 0.049±0.03 mg/kg in local samples. All heavy metals were not exceeding the guideline referred. The MoS value of metal presence in the samples was higher than 100 and thus indicates that the presence of metal impurities was within an acceptable risk. The HQ for Ni and Cd were less than 1, whereas HQ for Pb was greater than 1, which indicates potential for adverse health effects. Conclusion: Heavy metals impurities detected in the samples were within the safe limit and at an acceptable risk to human except for Pb. Care should be taken as heavy metals are able to accumulate in human body and the health effects remain as concern.
Keywords: Heavy metals, Skin lightening products, Health risk assessment, Margin of Safety, Hazard Quotient
Key messages: This study highlights the presence of heavy metals impurities in skin-whitening products, but no toxicological concern for systemic toxicity is reported. The potential adverse health effects were reported from Pb exposure from the samples studied.
|How to cite this article:|
Rusmadi SZ, Ismail SN, Praveena SM. A case study of selected heavy metals (lead, cadmium, and nickel) in skin-lightening creams and dermal health risk in Malaysia. Ann Trop Med Public Health 2017;10:95-100
|How to cite this URL:|
Rusmadi SZ, Ismail SN, Praveena SM. A case study of selected heavy metals (lead, cadmium, and nickel) in skin-lightening creams and dermal health risk in Malaysia. Ann Trop Med Public Health [serial online] 2017 [cited 2019 Oct 17];10:95-100. Available from: http://www.atmph.org/text.asp?2017/10/1/95/205550
| Introduction|| |
Human is exposed to heavy metals mainly via ingestion and inhalation. Exposure through skin absorption also occurs from re-suspended particles of powder, which come from soils, or through skin contact with clothes. Nevertheless, other less obvious sources of exposure have to be considered, including the use of beauty products. Indeed, heavy metal traces can be detected in most beauty products as impurities. In Malaysia, under the Guidelines for Control of Cosmetic Products in Malaysia, Annex II listed that heavy metals including Cd, Pb, Ni, Hg and also its compound are prohibited to be used as ingredients in cosmetics because they are considered unsafe. Given that heavy metals used as intentional cosmetic ingredients has been addressed accordingly, attention is drawn to the presence of these substances as traces or impurities. In the Malaysian guidelines, it has been indicated that the presence of traces of substances listed in Annex II shall be allowed, provided that such presence is technically unavoidable in good manufacturing practice and that it comply with the Article 3 of the ASEAN Cosmetic Directive. However, concerns arise over the “technically unavoidable traces.” Several publication has pointed out that the “technically unavoidable traces” of heavy metals are rather ambiguous, subject to different interpretation and largely dependent on the technology used during the production. Thus, the presence of heavy metal impurities in the skin-lightening products especially in Malaysian market may lead to direct exposure of a large number of individuals. Heavy metals such as Ni, Cd, and Pb are common contaminants in various beauty products,,, and skin lightening is a popular beauty practice worldwide with Asia being the largest consumer of skin-lightening products. African and Latin American countries also consume high levels of skin-lightening products. The aim of this study was to assess the level of heavy metals impurities (Pb, Cd, and Ni) in skin-lightening products available in Malaysian market and to determine the dermal health risk from continued application of the creams.
| Materials and Methods|| |
Facial moisturizing creams were selected as the skin-lightening samples in this study because they fulfill a broad set of performance attributes, including dryness reduction, improvement in dull appearance, and so on. The formulation also involved a handful of ingredients. A total of 33 samples of facial moisturizing creams available in Malaysian market were purchased from the outlets most preferred by consumer such as department store, beauty store, drugstore, and online purchase and convenience shop. The samples consist of 17 local manufactured creams, and 16 samples were non-local manufactured.
Samples were digested using the wet digestion method. The wet digestion used four to one mixture of nitric acid (65%) and perchloric acid (70–72%). Solutions were allowed to cool and filtered into a volumetric flask (50 mL) by a filter paper (Whatman no. 42) and were diluted up to the mark with ultra-pure water. The samples were then analyzed using Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES).
Physico-chemical properties of the samples including moisture content, pH, spreadability, and also type of emulsion were analyzed in this study. The moisture content was determined by the oven-drying method. The weighing dish was initially weighed followed by 1 g of samples plus the weighing dish. Then, the sample was placed into an oven at 105°C for overnight. Lastly, the sample was allowed to cool down in desiccators before weighed again to get the dry sample weight. The determination of moisture content is as shown in Equation 1:
For pH, the pH meter was calibrated using the standard buffer solution with a pH of 7 and 10. About 0.5 g of the sample was weighed and dissolved in 50 mL of distilled water and its pH was measured. As for spreadability, the excess sample was placed between the two glass slides and 100 g weight was placed on the glass slide for 5 minutes to compress the sample to a uniform thickness. Weight (250 g) was added to the pan. The time in seconds required to separate the two slides was taken as a measure of spreadability as shown in Equation 2:
where m (g) is the weight tied on the upper slide, l (cm) is the length of glass slide, and t (s) is the time. On the determination of type of emulsion, the dilution test was performed. The emulsion was diluted with an equal quantity of water and the container is shaken. The oil in water emulsion dilutes in water and appear homogeneous, whereas water in oil emulsion does not dilute in water and have a nonhomogeneous appearance.
Based upon the heavy metal concentration detected in the samples, in this study the health risk assessment involving margin of safety (MoS) and hazard quotient (HQ) was calculated for 49 respondents who use facial moisturizing creams. Ethical approval from the Ethics Committee for Research involving Human Subjects of Universiti Putra Malaysia (JKEUPM) has been obtained prior conducting the study.
On assessing health risk using MoS, the risk was calculated using the formula in Equation 3:
where NOAEL is the no of observed adverse effect level and SED is the systemic exposure dosage. The NOAEL value of Ni, Cd, and Pb were obtained from the previous scientific literature, whereas the SED was calculated using the formula in Equation 4:
where I (mg/day) is the daily dermal exposure to the substance, DAp (%) is the dermal absorption of the substance expressed in percentage, and BW (kg) is the human body weight. SED of a cosmetic ingredient is the amount expected to enter the blood stream daily (and therefore be systemically available) per kg body weight. Based on the heavy metal concentration detected in the samples, the respondents' body weight and also respondents usage pattern obtained from SCCS's Notes of Guidance, the daily dermal exposure (I) of substance applied to the skin was estimated using the formula in Equation 5:
where A (g/application) is the amount of finished cosmetic product applied per application, C (%) is the concentration of ingredients under study in the finished product, and F (day-1) is the frequency of application of the substance. Margin of safety reached a value of 100 suggesting that the use of the ingredient in the products is not associated with significant risk for human health. [Table 1] lists the parameters to be included in order to determine the MoS.
|Table 1: Parameter on assessing margin of safety (MoS) and hazard quotient (HQ)|
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Hazard quotient was not an estimation of the likelihood that an effect will occur, but rather an indication of whether there is a potential cause for concern for adverse health effects. On assessing HQ, the risk was calculated as shown in Equation 6:
where ADI is the average daily intake and RfD is the reference dose. The risk calculation of average daily intake for exposure dose through dermal contact (ADID) calculation was as shown in Equation 7.
where C (mg/kg) is the chemical concentration in the exposure medium, SA (cm2) is the exposed skin surface area, AF (mg/cm2/day) is the adherence factor, ABS (unitless) is the dermal absorption factor, EF (day/year) is the exposure frequency, ED (year) is the exposure duration, BW (kg) is the human body weight, and AT (day) is the averaging time. [Table 1] lists the parameter included in determining the HQ.
| Results|| |
[Table 2] shows the heavy metal concentration and physico-chemical properties of the samples. Ni and Cd in local samples were slightly lower than non-local samples. Meanwhile the Pb concentration was significantly lower in the local sample compared to the non-local samples with Z= -2.612 and P=0.009.
|Table 2: Heavy metal concentration and physicochemical properties of skin-lightening creams (N=33)|
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The moisture content level was slightly lower for local samples compared to the non-local. pH of the local samples were slightly acidic compared to the non-local samples. The spreadability of the local samples was extremely lower compared to the non-local samples. Majority of the samples were oil in water emulsion. Spreadability (Z= -3.278, P= 0.001) and type of emulsion (Z= -2.009, P= 0.044) shows significant difference between groups.
[Table 3] tabulates the result of the MoS. Local samples have low MoS for Ni compared to non-local samples. However, local samples have higher MoS for Cd than non-local samples. A similar pattern was observed for Pb where MoS was higher in local samples compared to the non-local samples. [Table 4] tabulates the result for the HQ of heavy metals studied. The HQ for Ni was higher in local samples compared to the non-local samples. In contrast, the HQ for Cd was higher in non-local than the local samples. Similar to Pb, the HQ for non-local samples were higher compared to the local samples.
|Table 4: Hazard quotient (HQ) value for heavy metals in the skin-lightening creams|
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| Discussion|| |
A scientific literature proposed a value for nickel lower than 5 mg/kg as a “good manufacturing practice”. Nickel concentration in this study was within the proposed value. The highest Ni was detected as 0.7 mg/kg, which slightly lower than the “target” amount to minimize the risk of sensitization in individual sensitive to Ni (1 mg/kg). For Cd, the maximum amount of allowable Cd as impurity in cosmetics is 3 mg/kg as highlighted in Canada guideline and 5 mg/kg in Germany guideline., The Cd level in this study is within these guideline values. Though the presence of Cd in the skin-lightening creams was at a very low concentration, the slow release of Cd may cause harmful effects to the human body. Exposure to low levels of Cd over time found to cause kidney damage, bone deformity, and the ability of bones to break easily., In addition, Cd has also been shown to exert significant effects on ovarian and reproductive tract morphology even at extremely low concentration. Cd exposure during pregnancy was associated with decreased birth weights and premature birth. The maximum amount of allowable Pb as impurity in cosmetics is 10 mg/kg as in Canada guideline and 20 mg/kg in Germany guideline., Pb in this study was within the stipulated guideline values. Despite of having the recommended guideline for lead, current studies suggested that Pb may have no identifiable safe exposure level, with even the lowest levels having shown to affect the fetus and the central nervous system in children., In addition, the exposure of Pb through damaged skin was nine times higher than through intact skin and the skin decontamination with a liquid soap did not decrease the Pb skin absorption.
On health risk assessment, none of the metal detected in samples shows the MoS value below 100, suggesting that there is no toxicological concern for systemic toxicity, following topical exposure toward the used of skin-lightening creams. This was consistent with study done by Marinovich et al., where the MoS value for Ni, Cd, and Pb in several types of beauty products were above 100. This indicates an appreciable risk to the consumer, following repeated exposure, assuming that all the different products are used at the same time during a make-up session.
According to USEPA, the hazard quotient (HQ) cannot be translated into a probability that an adverse effect will occur, and it is also not likely to be proportional to risk but it is an indication that a potential may exist for adverse health effects. The HQ for Ni and Cd in both local and non-local samples in this study was less than 1 indicating that the exposures are likely to be without an appreciable risk during a lifetime. However, the HQ for Pb in the non-local samples was greater than 1 indicating that the exposures are likely to produce appreciable risk during a lifetime. To date, no safe blood level of Pb is known as with even the lowest levels having shown to affect the fetus and the central nervous system in children. Additionally, Pb has been found to be absorbed through the skin and dermally absorbed Pb has been evidenced to be distributed throughout the body., Therefore, this element was likely to cause harm in humans of the daily lifetime dose.
| Conclusion|| |
In conclusion, heavy metals can be detected in most of the samples in this study. Ni, Cd, and Pb concentration were higher in non-local samples compared to the local samples. Among all heavy metals studied, only lead shows significant difference between local and non-local samples (P < 0.05). Based on the available recommended guidelines, none of the metal detected in the samples exceed the value. The heavy metals concentration detected in samples shows the MoS value higher than 100, indicating that there is no toxicological concern for systemic toxicity, following topical exposure toward the used of the skin lightening. However, the HQ value shows that Pb have HQ greater than 1 suggesting that there were potential adverse health effects due to exposure from Pb in the samples studied. Heavy metals tend to accumulate in human body and the health effects remain a concern.
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Conflicts of interest
There are no conflicts of interest.
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Sharifah Norkhadijah Syed Ismail
Department of Environmental and Occupational Health, Faculty of Medicine and Health Sciences, Universiti Putra Malaysia (UPM), Serdang, Selangor
Source of Support: None, Conflict of Interest: None
[Table 1], [Table 2], [Table 3], [Table 4]