Evaluation Of Heavy Metals in Cosmetic Products And Their Health Risk Assessment

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Hamna Arshad a, Moniba Zahid Mehmood a, Munir Hussain Shah b, Arshad Mehmood Abbasi

Abstract

Heavy metals contamination in cosmetic products is a serious threat. The present study was conducted to evaluate the concentrations of heavy metals (HMs) in various brands of cosmetic products with special emphasis on their health risk assessment. Five heavy metals including Cd, Cr, Fe, Ni, and Pb were quantified in different brands of lotions, foundations, whitening creams, lipsticks, hair dyes, and sunblock creams using atomic absorption spectrometry. Risk to the consumer’s health was determined using systemic exposure dosage (SED), the margin of safety (MoS), hazard quotient (HQ), hazard index (HI), and lifetime cancer risk (LCR). On a comparative basis, different brands of sunblock creams depicted the highest concentration of Ni, Pb, and Cr (7.99 ± 0.36, 6.37 ± 0.05 and 0.43 ± 0.01 mg/kg, respectively), whereas lipsticks had elevated levels of Feat 12.0 ± 1.8 mg/kg, and Cd was maximum in lotions (0.26 ± 0.02 mg/kg). Multivariate analysis revealed strong associations among Cr, Ni, and Pb, while Cd and Fe showed a disparity in distribution and sources of contamination. MoS, HQ, and HI values were within the permissible limit apart from for lotions and sunblock creams, while LCR value was higher than the permissible limit in all cosmetic products except lipsticks. Regular use of these products can cause serious threats to human health, particularly skin cancer on long-time exposure. Therefore, continuous monitoring of cosmetic products, particularly with reference to HMs adulteration should be adopted to ensure human safety and security.

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1. Introduction

The application of different cosmetics for personal care is as old as human civilization. With the passage of time, demand for cosmetics has increased many folds throughout the world. This is mainly owing to the increased awareness about methods to enhance the outlook of the body (Ullah et al., 2017). Today the use of cosmetics for personal grooming and body care has become the norm throughout the world (OJEU, 2009). The global market for beauty products has shown an average increase of about 5% per year. It is an interesting fact that the market for cosmetics and personal care products has shown constant and stable growth ever since its origin and has progressed even in unstable economies (Barbalova, 2011).

Cosmetic products are composed of different organic and inorganic materials including hydrophilic and hydrophobic substances. In the manufacturing of colored cosmetics, mineral pigments are commonly used which leads to the contamination of cosmetic products with heavy metals (HMs) such as Cu, Ni, Co, Pb, Cr, Cd, and other elements. These HMs become a part of cosmetic products intentionally in the form of pigments, preservatives, UV filters as well as antiperspirant, antifungal, and antibacterial agents (Burger et al., 2016). It has been reported that human exposure to UV radiations can cause chronic as well as acute health effects on human skin, eye, and immune system. Thus, cosmetic manufacturers use UV filters as important ingredients in sunscreens and other daily used cosmetic products. Though UV filters are designed for cosmetic products that are intended to apply on topical skin surfaces but derivatives of the products can bind to plasma protein and get circulated in the blood, then through a phase, I and II biotransformation reactions get metabolized in the liver. Afterward, they may either be excreted through urine or they can be bio-accumulated within the organism (Locatelli et al., 2019). Some metals as well as parabens are incorporated as preservatives in cosmetic products because they possess antibacterial and antifungal properties. Through recent studies, it has been evaluated that metals and parabens used as preservatives are also endocrine disruptors and can get easily absorbed through the skin thus causing adverse effects on human health (Tartaglia et al., 2019; Iavicoli et al., 2009). Some metallic compounds are routinely used in cosmetics as they possess the properties to peel and whiten the skin (Burger et al., 2016). However, the use of metals components is based on the regulatory laws of a particular country (OJEU, 2009). Heavy metals are also added accidentally as impurities at various stages of cosmetic production. As the sort of raw material used in the manufacturing process, particularly the addition of additives and color minerals causes contamination. In addition, water used for their preparation may also contain metallic impurities. Moreover, the use of different instrumentation in cosmetic industries during sorting, manufacturing, and packaging processes may also cause HMs contamination (Łodyga Chrus´cin´ ska et al., 2018).

Trace quantities of some toxic metals (such as Cd and Pb) have been found in many products including toothpaste, face makeup, lipsticks, etc. (Li et al., 2015). It has also been reported that natural ingredients like plant-based materials are the major source of heavy metal contamination in cosmetics (Bocca et al., 2014). It has been recommended by International Organizations to measure the number of toxic metals in the plants used as raw material as well as in the final products. As previously reported that toxic metals may be present in herbs and plants as a result of pre-existing use of fertilizers, insecticides or due to their cultivation near industrial zones. Therefore principal analytical procedures should be followed to reduce heavy metal concentration in raw material and to ensure the quality of final products (Locatelli et al., 2014).

In past, it was assumed that cosmetics are only associated with local effects but in the last few decades concerns were raised after the fact that certain substances in cosmetics may penetrate deep into the skin and get exposed to the organs. This stirred skin tests to check the penetration/adsorption capability of certain substances from the products as well as their toxicity (Nohynek et al., 2010). Although the outermost protective layer of skin (stratum corneum) does not allow large penetration, traces of HMs present in cosmetic products may reach the circulatory system (Bocca et al., 2014). Some of the metals have the tendency to get accumulated with the stratum corneum and cause allergic effects while others are diffusible in sweating, tears, and sebum excretion and may penetrate through the skin appendages or through trans-cellular and intracellular pathways and reach the blood circulatory system of the human body. Therefore, the daily application of many cosmetic products may result in increased exposure of HMs to the human body (Brzóska et al., 2018).

Elevated exposure to heavy metals may result in numerous health problems including skin allergies, severe redness, swelling/ skin ulcers, cellular death, DNA damage, oxidative stress, neurotoxicity, memory loss, reproductive failure, and carcinogenic health effects (Kim et al., 2015; Bocca et al., 2014; Senesse et al., 2004; Agoramoorthy et al., 2008; Amry et al., 2011; Smith et al., 2015). In this context, the present study was focused on the determination of heavy metal concentrations in selected cosmetic products and appraising health risks associated with exposure to metals in cosmetic products. It is anticipated that the present study would provide pivotal information related to the health risks associated with the prolonged use of cosmetic products.

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2. Material and methods

2.1. Sample collection

Most commonly used cosmetic products (more than 70% frequency) were considered and collected for analysis in the present study. The usage frequency was calculated based on the data extracted from the questioner filled by more than 100 users during this study. It was ensured that the selected samples were representatives of the most available, popular and commonly used product types. Locally manufactured and imported cosmetic products (n = 189) were collected in triplicates from local communities and markets of Abbottabad, Haripur and Mansehra, Pakistan. The cosmetic products were sampled into six different groups; lotions (30 brands), foundations (9 brands), whitening creams, lipsticks, hair dyes and sunblock (6 brands each). Samples were stored at room temperature before analysis.

2.2. Washing

Washing is the most critical step for accurate heavy metal analysis. Washing of all accessories was done following the protocol of Olmedo et al. (2010). All glassware was washed first with detergent and then rinsed repeatedly with tap water. Afterwards, glassware was soaked in a solution of HNO3 (5%) for about 24 h. Then rinsing was done using deionised water and dried at 80 C for 48 h before use.

2.3. Sample preparation

The collected samples were digested using acids mixture (HNO3, H2SO4 and HClO4 in ratio of 1:1:1) following the procedure reported by Saeed et al. (2011) and Ayenimo et al. (2010) with modifications. Approximately, 1.0 g of each sample (in triplicate) was taken in 50 mL conical flask, followed by the addition of 5 mL of HNO3 and the mixture was kept overnight at room temperature. Subsequently, the contents were heated on a hot plate by slowly increasing the temperature up to 90 C and after the appearance of brown fumes, the mixture was allowed to cool. Then H2SO4 (5 mL) was added and heated again for 30–60 min followed by cooling to room temperature. Finally, then 5 mL of HClO4 was added and the contents were digested until a clear solution was obtained. After digestion, the samples were cooled to room temperature and filtered through Whatman filter paper No. 41 and the final volume (50 mL) was adjusted by deionized water. Blanks were also prepared following the same procedure with each batch of samples (n = 5). All the digested samples were stored in a refrigerator till further analysis.

2.4. Quantification of HMs

Quantification of selected metals was done using atomic absorption spectrophotometer (Perkin Elmer AAnalyst 700) at their specific wavelength. The calibration line method was employed under optimum analytical conditions (Table S1) for the analysis of selected HMs. Standard stock solutions (1000 mg/L) of the metals were used to prepare the working standards freshly on the day of analysis. Countercheck of the results was ensured through the internal standard analysis as well as by standard reference materials (NIST SRM 1515) which showed very good recovery (97–102%). Blanks were routinely analyzed for the metal's contents and the final results were appropriately corrected. All the measurements were made in triplicate.

2.5. Statistical analysis

The statistical parameters related to the distribution of metals in the cosmetic products were computed using STATISTICA (StatSoft Inc, 1999). Other statistical analyses including correlation and ANOVA were done using SPSS (V13.0), while graphs were plotted through Sigma Plot (V1 2.5) and Bio-Vinci (1.1.5). The analytical data were presented as mean ± SD for triplicate analysis of each sample.

2.6. Health risk assessment

2.6.1. Margin of safety (MoS)

According to World Health Organization (WHO), MoS value up to 100 is acceptable and product with MoS value above 100 is considered safe for use. The scientific committee on consumer safety (SCCS) recognizes that in many conventional calculations of MoS, the oral bioavailability of an element is assumed to be 100% if oral absorption data are not available. Standard values of skin surface area (SSA) and amount applied (AA) established by SCCS for cosmetic products are given in Table S2. However, it is considered suitable to assume that not more than 50% of an orally administered dose is systemically accessible (SCCS, 2012).

2.6.2. Hazardous quotient (HQ) and hazard index (HI)

2.6.2. Hazardous quotient (HQ) and hazard index (HI) Hazard quotient (HQ) is the ratio of systemic exposure dosage (SED) of a substance to the dermal reference dose (RfD) of each metal (USEPA, 2011; Liu et al., 2013). The HQ value <1 is considered to be safe while the greater than 1 is unsafe for human health. The HQ level was calculated using the formula: HQ ¼ SED=RfD ð4Þ Hazard index (HI) is the summation of hazard quotients for all the metals under study. It is computed in order to evaluate human health risk due to the exposure of all metallic impurities. The HI value was calculated using the following relationship as reported previously (El-Aziz et al., 2017): HI ¼ XHQ ¼ HQCd þ HQCr þ HQ Ni þ HQFe þ HQPd ð5Þ 2.6.3. Lifetime cancer risk (LCR) Lifetime cancer risk is usually investigated for carcinogenic metals. In the current study, LCR was determined by using following relationship (El-Aziz et al., 2017): LCR ¼ SED  SF ð6Þ where SF represents the carcinogenicity slope factor (mg/kg/d)1 and it approximates the cancer risk per unit intake dose of an agent to cause cancer over an average lifetime. The reported slope factor for Pb, Cr, Ni and Cd are 0.0085, 0.5, 0.91 and 6.7 (mg/kg/d)1 , respectively (IRIS, 2007; USEPA, 2010; WHO, 2008).

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3. Results and discussion

3.1. Heavy metals’ distribution in lotions

In total 30 different brands of lotions (n = 90) were analyzed and measured levels of HMs were significantly different at p < 0.05 from one brand to another (Table 1). L1 depicted the highest level of Cd (2.13 ± 0.15 mg/kg), followed by L19 and L20 (0.27 ± 0.02 and 0.26 ± 0.01 mg/kg, respectively), while in L4 to L11, L22 and L23 brands Cd metal was below the detectable limit. Measured levels of Cd in all samples of lotion were within the permissible limit of 3 mg/kg set by the Canadian authority in cosmetic products (HCSC, 2012). The range of Cd observed in the current study was almost comparable as reported earlier by Ababneh and Al-Momani (2018), but was lower than the reported by Borowska and Brzóska (2015). Results showing Cr concentration revealed that in 12 brands of lotions (L4 to L13, L22, and L23), Cr level was below the detection limit. Maximum concentration of Cr was quantified in L20 (0.69 ± 0.02 mg/kg). Comparatively, Cr level was slightly higher in our samples than a previous report (Borowska and Brzóska, 2015). However, Cr was within the safe limit of 50 mg/kg set by USFDA (USFDA, 2013). Generally, Fe is considered an essential mineral but its exceeding level may cause serious health issues (Miyajima et al., 2002). In all samples of lotion, measured levels of Fe varied from 0.27 to 7.01 mg/kg. The highest concentration was detected in L24 (7.01 ± 0.14 mg/kg), while the lowest was in L23 (0.27 ± 0.19), imported from South Africa.

The concentration of Ni was maximum in L17 (6.29 ± 0.12 mg/kg), whereas the lowest level was calculated in L27 (0.01 ± 0.05 mg/kg). However, in L18 Ni was below the detectable limit (Table 1). It was noted that Ni concentration in our samples was comparable with previous reports (Ababneh and Al-Momani, 2018; Borowska and Brzóska, 2015). Recommended level of Ni set by USFDA and Cosmetica Italia is 200 mg/kg (USFDA, 2013) in cosmetics. However, it is suggested that for skin protection Ni and Cr concentration should be <1.0 mg/kg in cosmetic products, particularly those that come in direct contact with skin, and 0.5 mg/kg of Ni concentration is enough to cause dermatitis (Basketter et al., 2003). The measured level of Pb ranged from 0.07 to 8.29 mg/kg. The highest concentration of Pb was in L20 (8.29 ± 0.09 mg/kg), followed by L19 (7.94 ± 0.10 mg/kg) and L17 (7.53 ± 0.31 mg/kg), while L27 had lowest level (0.07 ± 0.17 mg/kg). Measured levels of Pb in our samples were within regulatory limits set by Canada and USFDA, which are 10 mg/kg and 20 mg/kg, respectively (USFDA, 2013). In addition, the range of Pb concentration in lotion samples was almost similar to the previously reported level (Borowska and Brzóska, 2015), but was lower than reported by Ababneh and Al-Momani (2018) in body lotions.

3.2. Heavy metals’ content in hair dye

Measured levels of HMs in 6 brands of hair dyes (n = 18) are presented in Table 1. A comparatively wide variation of Cd was observed among the analyzed samples of hair dye. Wherein, D6 had the highest Cd level (0.17 ± 0.02 mg/Kg), which was significantly different from other samples of hair dye (p < 0.05). However, Cd was below the detection limit in D1 and D3. Almost similar Cd concentrations were reported previously (0.01– 2.47 mg/kg) by Brzóska et al. (2018) and Ozbek and Akman (2016) in different brands of hair dye. The Cr metal was highest D5 (0.13 ± 0.02 mg/Kg), while in other samples descending order of Cr was: D4 > D3 > D2 > D6. Whereas, in D1 Cr was below the detectable limit. Additionally, measured levels of Cr in our samples were much less than reported earlier (Borowska and Brzóska, 2015; Brzóska et al., 2018). Iron was detected in the majority of the samples of hair dye except for D6. The highest concentration of Fe was in D5 (0.42 ± 0.22 mg/Kg). Conversely, in D1, D2, D3, D4, and D5 there was no significant difference in Fe concentration (p < 0.05).

Likewise, there was no significant difference in Ni concentration calculated for D2, D3, D4, and D5 samples (3.79 ± 1.00, 3.06 ± 0.88, 3.82 ± 0.27, and 4.18 ± 0.23 mg/Kg, respectively). Whereas, the measured level of Ni in D6 (Table 1) was lowest (0.08 ± 0.02 mg/Kg). These values were similar to previous reports in hair dyes (0.03– 0.37 mg/Kg) by Ozbek and Akman (2016), but, less than reported by Brzóska et al. (2018). Sample D5 and D4 had the highest concentration of Pb at 5.84 ± 0.19 and 5.67 ± 0.23 mg/Kg, respectively, whereas D6 contains the least amount of Pb (0.40 ± 0.11 mg/Kg), which was significantly different at p < 0.05 than other brands of hair dyes. In addition, measured levels of Pb in hair dyes were less as compared to previously reported by Brzóska et al. (2018) but were slightly higher than reported by Ozbek and Akman (2016).

3.3. Measure levels of HMs in the foundation

In nine different national and international brands (n = 27) of foundation, Cd concentration varied from 0.06 to 0.16 mg/Kg in F9 and F3 samples of foundation respectively (Table 1). In the majority of the samples, there was no significant difference in Cd (p < 0.05). Relatively, measured levels of Cd in our samples were lower than reported previously i.e. 0.18–29.1 mg/Kg (Nnorom et al., 2005) and up to 5.09 mg/Kg (Ababneh and Al-Momani, 2018) in the foundation samples collected from the markets of Nigeria and Jordan, respectively. F9 contains highest Cr level (0.30 ± 0.02 mg/Kg), followed by F5, F8 and F7 (0.28 ± 0.02, 0.26 ± 0.02 and 0.26 ± 0.01 mg/Kg, respectively). And these values were comparable with previous reports (Borowska and Brzóska, 2015). Fe content in foundation samples depicted wide variation from 45.4 ± 11.7 mg/Kg (F1) to 2.29 ± 1.00 mg/Kg (F6). However, these values were less than reported by Borowska and Brzóska (2015). Ni levels varied from 4.79 to 6.34 mg/Kg in F1 and F7, respectively (p < 0.05). Ni concentrations in our samples were comparable with previously reported in foundation (Ababneh and Al-Momani, 2018), but were less than described by Borowska and Brzóska (2015). Concentration of Pb in the analysed samples ranged from 1.94 ± 0.16 to 3.9 5 ± 0.15 mg/Kg in F7 and F5, respectively (p < 0.05). However, these values were less than previous reports (Ababneh and Al-Momani, 2018; Borowska and Brzóska, 2015).

3.4. Comparative assessment of HMs’ concentration in cosmetic products

Comparative assessment of average heavy metal contents in cosmetic products is summarized in Table 2. Cadmium exposure leads to several injurious health effects, most prominent are heart failure, kidney, liver, and brain damage (Agoramoorthy et al., 2008). In some cases, severe eye keratitis had been observed on exposure to high Cd concentration present in kohl (Amry et al., 2011). The average concentration of Cd was ranged from 0.06 ± 0.01 to 0.26 ± 0.02 mg/kg in hair dyes and lotions, respectively. These values were within the safe limit (3 mg/kg) in cosmetic products set by USFDA (2016). Both, Cr (III) and Cr (VI) have potential adverse effects on the skin and cause contact allergies and skin cancer (Bocca et al., 2014). Ascending order of mean concentration of Cr in the cosmetic products was: Sunblock > lipstick > whitening cream > lotion > foundation > hair dye. Average concentration of Cr from 0.43 ± 0.01 to 0.09 ± 0.01 mg/kg was lower than the maximum limit (50 mg/kg) set by USFDA (2016). Iron is considered as one of the essential nutrients like Zn, but a higher concentration of Fe in cosmetic products causes the death of body cells (Miyajima et al., 2002), thus leads to colorectal cancer (Senesse et al., 2004). In the present study, the average concentration of Fe varied from 0.31 ± 0.01 to 12.0 ± 1.75 mg/kg in hair dyes and lipstick, respectively. In other products decreasing order of Fe was: foundation,> sunblock > whitening cream > lotion.

In whitening creams Figure (1d), Ni had the highest mean concentration of 6.24 ± 0.04 mg/kg, followed by Pb and Fe (3.25 ± 0.09, 2.15 ± 0.06 mg/kg, respectively), while Cd was relatively lower. Measured levels of Ni were comparatively higher than the previously reported levels in whitening cream from Nigeria, but Cr, Fe and Cd levels were considerably lower than those from Nigeria (Iwegbue et al., 2015; Ababneh and Al-Momani, 2018). In lipsticks, Fe was leading with an average concentration of 12.0 ± 1.75 mg/kg (Fig. 1e), followed by Ni and Pb (6.64 ± 0.03 and 4.49 ± 0.34 mg/kg, respectively). These values were within the permissible limits. In addition, mean Pb and Fe concentrations were comparable (Lim et al., 2018), but Cd, Cr, and Ni were higher than reported earlier (Ababneh and Al-Momani, 2018; Lim et al., 2018), while, Cd concentration was more or less same as reported by Ababneh and Al-Momani (2018). In the sunblock samples Figure (1f), average concentration of Ni (7.99 ± 0.36 mg/kg) was highest, followed by Pb and Fe (6.37 ± 0.05, 2.52 ± 0.04 mg/kg, respectively), whereas Cd had lowest level (0.132 ± 0.002 mg/kg).

3.5. Multivariate analysis

Different multivariate analysis viz. Pearson’s correlation coefficient, hierarchal cluster analysis (HCA), and principal component analysis (PCA) were performed to identify the natural and anthropogenic sources of HMs’ contamination in cosmetic products. Results of correlation analysis in Table 3, demonstrate there were highly significant (p < 0.01) positive associations between Cr-Pb Likewise, Pb also had a strong positive correlation with Cd and Cr in sunblock samples (Table 3).

The disparity in HMs concentration among different categories ofcosmetic products and their distribution patterns in HCA and PCA is possibly associated with the type of raw material and the sources from where the raw material is collected. For instance, compounds of Fe such as, iron carbonates, ferric hydroxide, iron oxides (iron oxide black, iron oxide red, and iron oxide yellow) and the Cr compounds including Chromium (III) oxide, chromium (III) hydroxide are added intentionally as colour pigments in cosmetic products. Likewise, Cd is used in cosmetics as it has the ability to produce different colours when combines with other components (Godt et al., 2006). For instance, the use of cadmium sulphide is because of its yellow colour, also it can develop range of colours from orange to black in combination with increased amount of selenium. Similarly, cadmium yellow is added with viridian (Cr (III) oxide) to develop a light green mixture called cadmium green (Bocca et al., 2014). The amount added is dependent on the regulatory limits (EU, 2009), but the same metal may be present an impurity or added intentionally (Bocca et al., 2014). Other metals including Pb, Cd and Ni can be accumulated as impurities at various stages of cosmetic production, predominantly the addition of additives and colour minerals. Moreover, the use of solvents, water, and different machinery in cosmetic industries during sorting and manufacturing processes may also cause HMs contamination (Łodyga-Chrus´cin´ ska et al., 2018).

3.5. Health risk assessment

3.5.1. Non-carcinogenic risk

Systemic exposure to cosmetic product predicts the amount of chemicals that enter human body through various exposure routes. The calculated values of systemic exposure dosage (SED) at 50% and 100% bio-accessibility for selected HMs in different cosmetic products are displayed in Table 4. It was noted that at 50% bio-accessibility, SED values for Cd and Cr ranged from 5.85107 to 2.21102 and 1.31106 to 3.22102 mg/kg/d respectively. However, Fe, Ni and Pb lay between 4.67105 to 1.90101, 2.59105 to 6.02101 and 1.75105 to 4.80101 mg/kg/d, respectively. Likewise, SED levels at 100% bio-accessibility for Cd, Cr and Fe ranged from 1.17106 to 4.41102 , 2.62106 to 6.44102 and 9.34105 to 3.80101 mg/kg/d, respectively. The respective SED levels of Ni and Pb lay in the range of 5.19105 to 1.20100 and 3.51105 to 9.60101 mg/kg/d at 100%bio-accessibility. The calculated values of SED were higher than the reported values by El-Aziz et al. (2017) in different facial cosmetic products. In the case of lipsticks, more or less similar SED levels were observed in the previous study (El-Aziz et al., 2017). Additionally, the SED values of HMs in the cosmetic products were almost comparable to those reported by Iwegbue et al. (2016) except for sunblock samples in which comparatively higher levels were recorded in the present study.

Risk to human health on exposure to metallic impurities present in the cosmetic products was evaluated by applying Margin of Safety (MOS). The estimated levels of MoS for the HMs in the cosmetic products at 50% and 100% bio-accessibility are presented in Table 5. In the samples of hair dye, foundation, whitening cream, and lipstick MoS were greater than 100, which revealed that the evaluated samples were safe for use. However, in lotions and sunblock the MoS values for Cd, Cr and Pb were below 100, which indicated that these products are not safe for use, particularly with reference to HMs contamination. In different cosmetic products analyzed by El-Aziz et al. (2017) and Iwegbue et al., (2016) levels of MoS were found higher than 100 while MoS for lipsticks was almost similar to the present study.

Similarly, HI levels for the lotion and sunblock were greater than 1 at both 50% and 100% bio-accessibility, which demonstrated that excessive use of these products may cause health risks to consumers. In the case of hair dye, foundation, whitening cream and lipstick, HI levels were much <1, interpreting that the samples were safe for human health. HQ and HI values reported by ElAziz et al. (2017) were also <1 for different facial cosmetics which are more or less closer to the values obtained in the present study.

3.5.2. Lifetime cancer risk (LCR)

Chromium (Cr), lead (Pb), nickel (Ni), and cadmium (Cd) are listed as carcinogenic HMs by International Agency for Research on Cancer (IARC, 2012). Two major routes through which HMs can enter into the body are either by ingestion or through dermal absorption. HMs are non-biodegradable so they remain accumulated into the body for a long time period. As a result, they not only alter the cell functions but also cause disruption of intracellular mechanisms (Stavrides, 2006). Therefore, cancer-related diseases are enhanced by such impurities that cause oxidative stress, DNA damage, and cell death (Kim et al, 2015). Lifetime cancer risk (LCR) is the estimation of potential cancer risk to the users on exposure to HMs present in the cosmetic products. According to USEPA acceptable range for LCR is from 1  10–6 to 1  10–4 (Loh et al., 2007). The LCR was calculated for cancer-causing metals (Pb, Ni, Cr, and Cd) at 50% and 100% bio-accessibility (Fig. 5).

Among all the analyzed HMs, lifetime cancer risk was estimated higher than the permissible limit and the cosmetic products may possess lifetime cancer risk except lipsticks. The most probable reason is that the lipstick is applied on a comparatively small area in relatively less amount. Though, the condition is alarming and continuous use of these products over a long time period may cause cancer to the users. It has been reported in a previous study that LCR for different facial cosmetic products was below 106 including lipstick (Lim et al., 2018).

4. Conclusion

In general, Cr, Ni, and Pb were higher in the sunblock samples, while Cd and Fe were maximum in different brands of lotions and lipsticks respectively. The increase in the concentrations of HMs in cosmetic products was mainly due to the type and source of raw materials used, processing techniques, storage, and mode of transportation.

The close association of Cr, Ni, and Pd, and disparity in Cd and Fe assessed by multivariate analysis revealed similarity and variation in their sources of contamination in cosmetic products. Health risk assessment exposed that generally MoS, HQ, and HI values were within the permissible limit for hair dyes, foundations, whitening creams, and lipsticks, but were outside the acceptable range for lotions and sunblock creams. The LCR value was higher than the permissible limit in all cosmetic products except lipsticks. Irrespective of the fact that in studied samples HMs concentration was within the regulatory limits, daily exposure to these products may cause cumulative effects such as the high risk of skin cancer and other chronic health disorders. Therefore, safer limits for HMs along with their quality control should be obligatory. Additionally, continuous monitoring programs for cosmetic products, particularly with reference to HMs adulteration, should be adopted to ensure human safety and security.

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