Overview
Ahmed and colleagues measured cobalt and lead in 41 cosmetic samples representing four product types (henna/lawsone, foundation cream, kajal/kohl, and skin-whitening cream) collected from local markets in Al-Ahsa, Northern Province, Saudi Arabia. Analysis used flame atomic absorption spectroscopy (FAAS) with IAEA-V-10 hay powder as a certified reference material. This paper provides one of the few peer-reviewed cobalt occurrence datasets for cosmetic personal care product matrices in the Gulf region.
Key numbers
Cobalt concentrations (µg/g, wet weight)
| Product type | n | Mean (µg/g) | Range (µg/g) |
|---|---|---|---|
| Henna (non-brand) | 9 | 141.71 ± 4.86 | 138.22 to 144.91 |
| Foundation cream (non-brand) | 9 | 59.33 ± 4.84 | 57.19 to 62.05 |
| Kajal/kohl (non-brand) | 6 | 39.02 ± 4.06 | 36.71 to 41.33 |
| Skin-whitening cream (non-brand) | 6 | 55.62 ± 15.07 | 42.97 to 68.26 |
Brand reference samples: henna 66.10, foundation cream 66.35, kajal 21.14, skin-whitening cream 114.33 µg/g.
All 41 samples had cobalt concentrations exceeding 5 µg/g, the proposed cosmetic limit from Iwegbue et al. (2016). The literature comparator of 10 µg/g (Basketter et al. 2003) was also exceeded in all samples. The paper notes no binding international regulatory limit for cobalt in cosmetics currently exists; the 5 µg/g figure is a literature-proposed threshold.
Lead concentrations (µg/g, wet weight)
| Product type | n | Mean (µg/g) | Range (µg/g) |
|---|---|---|---|
| Henna (non-brand) | 9 | 2.60 ± 0.48 | 2.21 to 3.04 |
| Foundation cream (non-brand) | 9 | 2.79 ± 0.86 | 2.27 to 3.82 |
| Kajal/kohl (non-brand) | 6 | 7.22 ± 3.81 | 3.83 to 10.60 |
| Skin-whitening cream (non-brand) | 6 | 1.75 ± 0.56 | 1.32 to 2.18 |
22% of kohl samples (2 of 9) exceeded the US FDA cosmetic lead limit of 10 µg/g. All henna and foundation cream samples were within FDA limits. Lead data are secondary to the cobalt focus of this deposit.
Methods summary
Wet digestion with HNO3 and HClO4 (3:1 volume ratio), 200 to 300 degrees C hot plate, 4 to 28 hours depending on matrix. FAAS iCE 3000 series instrument at 240.7 nm for cobalt and 217 nm for lead, air-acetylene flame. IAEA-V-10 hay powder SRM recovery: 115.4% for cobalt and 118.8% for lead. The recoveries are slightly elevated above the ideal 100%, which the authors note is within acceptable analytical range. Measurements in triplicate.
Limitations
The sampling frame is a single province in Saudi Arabia (Al-Ahsa) during an unspecified collection period; the paper does not provide a sampling year. The sample counts per product type are small (6 to 12 non-brand samples), so the means and ranges are not representative of the broader Saudi or Gulf market. Brand samples (3 per type) are international commercial products, not local market samples, limiting their comparability to the non-brand group. The SRM recoveries above 115% indicate possible matrix interference or systematic positive bias. The paper proposes a 5 µg/g cobalt limit drawing on a cited threshold from Iwegbue et al. (2016) rather than a regulatory instrument; no binding international cobalt limit for cosmetics existed at the time of publication.
Implications for the wiki
This paper provides the first cobalt occurrence data in personal care product matrices on this wiki. The cobalt concentrations are substantially higher than the proposed 5 µg/g threshold across all four product types. Kohl concentrations (mean 39 µg/g) are relevant to the Traditional/imported eye cosmetics (kohl, surma, kajal) — extreme-Pb platform product page. The henna and skin-whitening cream data contribute contextual evidence for personal care product cobalt exposure that is distinct from dietary exposure.
Related evidence
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