Quality and safety investigation of commonly used topical cosmetic preparations

Overview

This open-access Scientific Reports study tested 21 commercial topical cosmetic and personal-care products purchased from Riyadh, Saudi Arabia retailers for eleven elemental impurities (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Pb) by inductively coupled plasma mass spectrometry following USP General Chapter <232> / NF 35 acid-digestion procedures, alongside aerobic-plate-count microbial testing and pH/organoleptic checks. Product categories were selected by a 447-respondent online survey of mostly-female adults in Saudi Arabia identifying the most frequently used topical cosmetics; one commercial sample was tested per category (two for toothpaste). The authors compared every analyte against the US FDA cosmetic guidance limits (Pb 10 ppm in general cosmetics, 20 ppm as additive; Cr 50 ppm; As 3 ppm) and USP <232> elemental-impurity acceptance criteria (Cd 0.5 ppm, Co 5 ppm, Ni 20 ppm, Cu 300 ppm), and identified two toothpastes as the most contaminated samples in the panel — both exceeding the FDA Pb limit (75.86 and 78.31 ppm Pb) and the FDA As limit (221.96 and 209.33 ppm As) by one to two orders of magnitude. Cadmium exceeded the USP 0.5 ppm acceptance criterion in five samples, with the deodorant sample reporting an outlying mean Cd value (306.92 ppm) substantially higher than the rest of the panel. Mercury was listed in the abbreviations but was not measured. Evidence tier is B: peer-reviewed open-access journal, transparent methods, n=1 per product category (no within-category replication), and several reported values carry very large coefficients of variation that warrant cautious interpretation (see Verification notes).

Key numbers

Eleven metals quantified in all 21 products by ICP-MS, reported as mean ± SD in ppm (mg/kg) in the as-sold finished product. Calibration standards were prepared at 5, 15, 30, 70, and 150 ppb; coefficients of determination for all elements ranged 0.9995-1. LOD/LOQ were not reported numerically.

Per-product results, Table 4 of the source (ppm, mean ± SD)

Values transcribed by pdftotext -layout of page 8 of the source PDF and verified cell-by-cell. The standard deviation in nearly every cell sits at approximately √2 × the mean (consistent with two-replicate measurement with one near-zero reading); see Verification notes.

Exceedances per the source’s text discussion (p. 8-9)

The source’s Table 4 caption indicates gray-highlighted cells “exceeded the US FDA limits,” but the cell-level gray styling in the PDF table is difficult to verify cell-by-cell at the published image resolution and the discussion text appears to mix FDA and USP <232> criteria. The authoritative per-analyte exceedance list is therefore drawn from the source’s discussion text (p. 8-9), which states the specific samples that exceeded each limit:

Headline panel-level findings (authors’ synthesis, p. 8-9)

• Lead: The source states 6 of 21 products exceeded the US FDA 20 ppm Pb-in-cosmetic-additives limit; samples 3, 9, 11, 15, 19, 20 carry Pb > 20 ppm. The maximum value was 78.31 ppm in the calcium-carbonate toothpaste (sample 20). The author-cited prior literature reports 23.57 ppm Pb in toothpaste by atomic absorption spectrometry (Orisakwe et al. 2016, ref 29) — the source contextualizes its toothpaste-Pb findings against that prior measurement.
• Arsenic (tAs): US FDA limit cited as 3 ppm. Exceeded in seven samples (makeup powder 9.24, makeup mousse cream 3.81, mascara 3.74, deodorant 81.21, lipstick 4.52, both toothpastes 221.96 and 209.33). Maximum was 221.96 ppm in the sodium-fluoride/hydrated-silica toothpaste (sample 19).
• Chromium: US FDA limit cited as 50 ppm. The source narrative states “most of our tested cosmetic products exceeded this finding”; per the Table 4 values 14 of 21 products carry Cr > 50 ppm. Maximum was 1610.64 ppm in sample 19 (toothpaste). The authors note an external comparison value of 7000 ppm Cr in eyeshadow from a separate Saudi-market study (ref 34).
• Cobalt: USP <232> limit cited as 5 ppm. Source-text-stated exceedances: samples 12 (22.71), 14 (5.81), 19 (17.65), and 20 (18.29).
• Nickel: USP <232> limit cited as 20 ppm. The source narrative states “most of the tested cosmetic products in this study exceeded this limit”; per the Table 4 values 15 of 21 products carry Ni > 20 ppm. Maximum 970.83 ppm in sample 19 (toothpaste).
• Cadmium: USP <232> limit cited as 0.5 ppm. Source-text-stated exceedances: samples 1 (sunblock cream 4.40), 15 (deodorant 306.92), 19 (toothpaste 9.19), and 20 (toothpaste 8.80). The discussion does not list samples 5 (0.54), 11 (0.87), or 21 (0.61) despite Table 4 values that nominally exceed the 0.5 ppm cutoff; this is a paper-internal inconsistency between the discussion narrative and the table values.
• Copper: USP <232> limit cited as 300 ppm. The paper states copper was below the limit in every tested product; the maximum reported value in Table 4 (sample 20 toothpaste, 269.94 ppm) is below that ceiling.
• Al, Fe, Zn, Mn: No FDA or USP limit cited by the authors. The highest values for all four were concentrated in the toothpaste samples (Al up to 574,060 ppm in sample 19, equivalent to ~57% Al by mass), in mascara (Fe up to 273,733 ppm in sample 14, equivalent to ~27% Fe by mass), and in makeup powder (Fe up to 111,077 ppm in sample 12, ~11% Fe by mass). The Al and Fe magnitudes are consistent with the abrasive/pigment ingredients in the corresponding formulations (hydrated silica, calcium carbonate, iron-oxide colorants in mascara and powder makeup), but the authors do not separate inert filler from soluble impurity in their reporting and do not address the analytical implication that ICP-MS quantitation of major matrix elements is operating well outside the 5-150 ppb calibration range. See Verification notes.

Baby oil and baby powder samples

Table 1 of the source lists the declared constituents of the two baby products. Sample 8, baby oil: light paraffin oil and perfume. Sample 9, baby powder: talcum powder, zinc oxide, salicylic acid, menthol, and perfume. The baby oil was digested with 5 mL nitric acid and 3 mL hydrogen peroxide, the baby powder with 7 mL nitric acid and 2 mL hydrogen peroxide (Table 2). Their Table 4 values are the rows 8 and 9 above. For both, as for nearly every product in Table 4, the printed SD is about 1.41 times the mean and the replicate count is not stated, so these means are recorded as printed and are not used as headline values. The source’s discussion counts sample 9 among the six products above 20 ppm lead. Microbial counts were 1471.5 cfu/ml for the baby oil and 823.5 cfu/ml for the baby powder (Table 3), and the source states that both baby products exceeded the SCCS limit for products for children under 3 years.

Microbial findings (briefly; not the primary HMTc-relevant data)

Fourteen of 21 products had aerobic-plate-count microbial loads above the FDA 500 cfu/g eye-area limit for children under 3 years (SCCS limit 100 cfu/g for eye area or children under 3); baby oil reached 1471.5 cfu/ml and hair serum 1128 cfu/ml. Staphylococcus aureus was the dominant isolate (12 of 14 contaminated products), with Bacillus species the second most common (10 of 14).

Organoleptic findings

All samples passed visual inspection (no lumps, grit, discoloration, characteristic odor). pH ranged 6.90-8.10 across the panel.

Methods

Product selection. A closed- and open-ended consent-bearing online questionnaire was distributed via social media in Saudi Arabia to identify frequently used cosmetic and personal-care products. 447 responses were collected (88.8% female, 68.9% aged 19-40 years, 70.2% bachelor’s degree). 21 product categories were selected from the survey results, and one representative commercial sample per category was purchased from local markets and drug stores in Riyadh (two samples were purchased for toothpaste, representing two different abrasive formulations). The institutional review board at Princess Nourah bint Abdulrahman University granted exempt status (Registration 21-0330).

Sample preparation and digestion (heavy metals). Sample preparation followed the elemental-impurity procedure in USP General Chapter <232> in USP 40 / NF 35 (ref 15). Each sample was first digested in a concentrated-acid mixture using closed-vessel digestion. The acid mixture ratios (HNO₃ 69%, H₂O₂ 30%, HF 37%) and sample masses varied by product matrix and are reported individually in Table 2 of the source. The patterns: samples 1-7, 10, 11, 15, and 21 (14 products) used 10 mL HNO₃ alone at sample masses of 250-500 mg; samples 8 and 9 (baby oil, baby powder) used HNO₃ + H₂O₂ (5+3 mL and 7+2 mL respectively) without HF; samples 12-14 and 18 (makeup powder, makeup mousse cream, mascara, lipstick) used 6 mL HNO₃ + 0.50 mL HF; samples 16 and 17 (silicone hair serum labeled “Oil”, shaving cream) used 10 mL HNO₃ + 2 mL H₂O₂; samples 19 and 20 (toothpastes) used 2 mL HNO₃ + 2 mL HF at 200 mg sample mass — the lowest sample mass and highest fluoride load in the panel.

Instrumentation (heavy metals). Inductively coupled plasma mass spectrometry (ICP-MS). The make/model of the ICP-MS instrument is not reported. Calibration was performed against eleven calibration standards prepared at blank, 5, 15, 30, 70, and 150 ppb from a multi-element standard. Coefficients of determination for all eleven elements ranged from 0.9995 to 1. The reported elements were Al, Fe, Zn, Cr, Mn, Cu, Ni, As, Pb, Cd, and Co. Mercury and beryllium are listed in the source’s abbreviations but were not measured.

Microbial analysis. Aerobic plate count via serial dilution on nutrient agar (24 h incubation, 24 °C). Differential identification of growth used MacConkey, potato dextrose, cetrimide, Simmons’ citrate, and mannitol salt agars; S. aureus / Bacillus / fungal status was assessed by colony morphology and growth on selective media.

Organoleptic and pH testing. Visual inspection for lumps, color, odor; texture by skin rub; pH measured with a digital pH meter.

Method-quality reporting gaps. The paper does not report: instrument make/model, certified reference material recoveries, method blanks, procedural-blank limits of detection/quantification, within-run replicate structure for individual product values (the reported ± SD almost certainly represents within-replicate variation on the single product sample rather than between-product variation, but the source does not specify the replicate count), spike recovery, or duplicate sample preparation. The standard-deviation magnitudes reported (often equal to or larger than the corresponding mean) are unusually large for ICP-MS at the concentrations reported and are flagged in Verification notes as a methodological caveat to factor into evidence weighting.

Implications

Certification. The paper contributes to the Cat 2 Children Personal Care occurrence pool for several finished-product categories present in the panel (notably baby oil, baby talcum powder, sunblock cream, lipstick, lotion). Outside Cat 2, the toothpaste results (samples 19 and 20) feed the Cat 5 / oral care category pool with Pb, As, Cr, Ni, Co, and Cd values that substantially exceed both US FDA cosmetic limits and USP <232> oral-route acceptance criteria. The n=1 per product category limits the standalone weight of any single value; the paper is best treated as a contributing data point that pools with other Saudi-market and global cosmetics surveys for the per-row marginal distributions, with B-tier weighting reflecting the n=1 sample structure and the analytical-QC reporting gaps noted in Methods. The deodorant Cd reading (306.92 ppm) is a substantial outlier that warrants flagging for explicit treatment in any synthesis pass; ICP-MS Cd at that concentration in a finished cosmetic is unusual and could be either a true high-contamination finding (e.g., colored or pigmented additive) or a reporting/calibration artifact.

Courses. Useful as a worked example of how a survey-driven product-panel design generates representative-but-low-replication occurrence data for cosmetic regulatory courses. The author-cited cross-comparison values (Orisakwe 2016 Pb 23.57 ppm in toothpaste, ref 34 Cr 7000 ppm in eyeshadow, ref 13 Co in Saudi cosmetics) provide a teachable example of where this study sits in the broader literature.

App. Relevant for the consumer-facing app’s adult-cosmetics scoring layer (sun protection, lip care, hair care, oral care, deodorant). Baby oil and baby talcum powder results extend the pediatric layer. Per the app must not surface brand-level rankings; the per-product values reported here are linked to product categories (sample types), not to the manufacturer brand the authors purchased — and consistent with that, this source page reports per-category values, not per-brand.

Microbiome. Not the primary focus, but the high S. aureus and Bacillus prevalence across the panel is a relevant background signal for any future federation work on skin- and oral-microbiome interaction with cosmetic preservative systems.

Related evidence

• Lead
• Cadmium
• Arsenic, Total
• Aluminum
• Chromium
• Copper
• Nickel
• Iron
• Zinc
• Manganese
• Cobalt
• Sun/suntan products (including spray, self-tan, airbrush)
• Makeup — foundation, powders, blush/rouge
• Body/hand leave-on skin care
• Leave-on hair preparations (leave-in conditioners, tonics/dressings, styling aids, hair sprays, color sprays)
• Shampoo (general adult)
• Facial cleansers (foaming, cream, gel, oil, micellar)
• Baby Oil
• Baby Talcum Powder
• Permanent hair dyes/tints (remain in hair after application)
• Eye makeup (liners, shadows, mascara, brow products, false lash adhesives, lash/eyebrow serums)
• Deodorants (sticks, roll-ons, gels, creams, wipes, sprays)
• Shaving cream/gel/foam
• Lip products (lipstick, gloss, lip liner, adult lip balm)
• Toothpaste (Cat 2)

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