Gezahegn and Sadiq measured 14 trace elements by ICP-MS in 39 plant-based personal care products purchased in Calgary, Alberta. The study covers deodorants, sunscreens, face and eye creams, lip moisturizers, body lotions, and insect repellents. Products were described by retailers as plant-based or natural. This is a finished-product occurrence study with hazard-quotient screening; it is not a dermal absorption study.
Key numbers
Deodorant concentrations (n equals 5; Table 3, p. 3; units micrograms per kilogram unless noted)
Aluminum mean 7,400 plus or minus 3,900, range 1,620 to 40,900 micrograms per kilogram. Zinc mean 220 plus or minus 110, range 63 to 300. Nickel mean 0.69 plus or minus 0.38, range 0.07 to 0.82. Lead mean 0.34 plus or minus 0.10, range below the limit of detection to 0.3. Cadmium mean 0.09 plus or minus 0.03, range below the limit of detection to 0.1. Total arsenic mean 0.09 plus or minus 0.04, range below the limit of detection to 0.2. Mercury was below the limit of detection in all five deodorant samples.
The aluminum range for deodorants (1,620 to 40,900 micrograms per kilogram) reflects that the category included both deodorizing-only and antiperspirant formulations; the upper end is comparable with measurements in conventional aluminum-salt antiperspirants, while the lower end represents products with minimal intentional aluminum.
One hemp-based face cream contained mercury at 28 plus or minus 6 milligrams per kilogram (stated in the abstract), exceeding regulatory limits. This is not a deodorant sample.
Hazard assessment for deodorants (Table 4 and Table 5, pp. 5 to 6)
Systemic exposure dosage (SED) for aluminum from deodorants: 6.15 times 10 to the negative 3 milligrams per kilogram body weight per day. Hazard quotient for aluminum: 3.08 times 10 to the negative 2, using a minimum risk level and assuming 100 percent bioavailability. Hazard Index for all metals combined in deodorants: 3.26 times 10 to the negative 2. All deodorant hazard quotients were below 1, indicating no non-carcinogenic concern at the assumed 100 percent bioavailability. The authors acknowledge that assuming 100 percent bioavailability is conservative and that actual dermal absorption fractions for most elements are substantially lower.
Regulatory limits opened in the paper (Table 1, p. 2)
Maximum concentrations in cosmetics for the five jurisdictions reviewed: lead, Health Canada 10 milligrams per kilogram, FDA 10, EU 2.0, WHO 10; arsenic, Health Canada 3, FDA 3, EU 0.5; mercury, Health Canada 3, FDA 1, EU 0.1, WHO 1; cadmium, Health Canada 3, EU 0.1, WHO 0.3; chromium, FDA 0.1, EU 0.1. No specific regulatory limit for aluminum in cosmetics was cited in Table 1.
Methods (brief)
Plant-based personal care products were purchased from major retailers in Calgary, Alberta, Canada. Samples (0.20 to 0.25 g) were digested by microwave-assisted acid digestion (MARS 6) in a 110 mL vessel and analyzed by ICP-MS (Agilent 7850). Fourteen elements were measured: aluminum, vanadium, chromium, manganese, iron, cobalt, nickel, zinc, arsenic, selenium, molybdenum, cadmium, mercury, and lead. Instrument limits of detection included aluminum 0.07 micrograms per kilogram and lead 0.01 micrograms per kilogram (Table 3, p. 3). No certified reference material recovery data were reported for the deodorant matrix specifically. Hazard quotients used minimum risk levels (MRLs) for aluminum and zinc where reference doses were unavailable; this means hazard quotients for those two elements are not directly comparable with quotients derived from oral reference doses.
Evidence fitness
This source supports occurrence data for aluminum and trace elements in plant-based deodorants at the category level. The deodorant concentration range (1,620 to 40,900 micrograms per kilogram aluminum) is relevant to antiperspirant context, with the lower end representing non-aluminum-active products. The 100 percent bioavailability assumption in the hazard screening is conservative and not an absorption measurement. This source cannot support inferences about conventional aluminum-salt antiperspirant concentrations (which are substantially higher, in the range of 1 to 5 percent aluminum), brand-level rankings, or dermal absorption fractions.
Limitations
n equals 5 for deodorants; the category is not stratified by aluminum-active versus non-active formulation. Bioavailability was assumed at 100 percent, an overestimate for most dermal scenarios. No CRM recovery data for the deodorant matrix were reported. The plant-based sampling frame may systematically underrepresent high-aluminum formulations. The study did not report speciation for arsenic, chromium, or mercury.
Related evidence
- Antiperspirant (Al-salt, dirty sibling of r9 deodorant)
- Deodorants (sticks, roll-ons, gels, creams, wipes, sprays)
- Aluminum
- Lead
- Nickel
- Cadmium
- Mercury, Total
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