Overview
Fischer and colleagues measured total mercury by direct AAS in 111 cosmetic clay powders of ten color types sold in Poland. Mercury was found in every product, with a mean of 28.91 µg/kg and a range of 1.87 to 200.81 µg/kg. Green and white clays had the highest means and purple and blue the lowest, and levels differed significantly by manufacturer.
Key numbers
- All 111 clays: mean “28.91 ± 39.34”, median “23.72”, range “1.87” to “200.81” µg/kg (Table 2, p. 5).
- Green clay: mean “53.26 ± 57.45”, maximum “200.81” µg/kg; white clay mean “52.80 ± 64.97” µg/kg (Table 2).
- Purple clay: mean “2.56 ± 0.46” µg/kg, the lowest (Table 2).
Methods (brief)
About 50 mg of each powder was analyzed in triplicate by thermal decomposition AAS (AMA 254) without digestion. The certified reference material INCT-MPH-2 gave 92.22 percent recovery. The absolute detection limit was 0.01 ng mercury.
Evidence Fitness
Direct evidence for cosmetic-clay: retail clay powders sold for cosmetic use, a large sample with full descriptive statistics and CRM recovery. Only mercury was measured, inter-batch variability was not assessed, and not every color was available from every manufacturer. The Discussion misstates the mean as 28.91 mg/kg; the table unit is µg/kg.