Evaluation of human exposure to metals from some commonly used hair care products in Nigeria

The concentrations of nine metals, namely, cadmium (Cd), lead (Pb), chromium (Cr), copper (Cu), cobalt (Co), nickel (Ni), manganese (Mn), zinc (Zn), and iron (Fe), were determined in 26 brands of hair care products including hair relaxers, conditioners and shampoos. The study was aimed at providing information on the possible risks arising from heavy metals associated with the use of these products. The concentrations of the metals were determined by means of atomic absorption spectrophotometry after digestion of the samples with a mixture of acids. The concentrations of the respective metals in hair relaxers, shampoos and conditioners were found to be 0.8–2.5, 0.6–3.0, <LOQ-2.8 μg g(−1) Cd; 4.5–26.0, <LOQ-28.0, <LOQ-425 μg g(−1) Pb; <LOQ-0.6, <LOQ-3.4, <LOQ-4.2 μg g(−1) Cr; <LOQ-3.5, <LOQ-6.0, <LOQ-3.5 μg g(−1) Cu; <LOQ-7.0, <LOQ-7.0, 0.5–4.5 μg g(−1) Co; 1.0-5.5, <LOQ-10.5, 1.5–6.0 μg g(−1) Ni; <LOQ-9.0, 2.0–25.5, <LOQ-15 μg g(−1) Mn; 36.5–48.0, 35.5–1080 μg g(−1), 30.0–69.0 μg g(−1) Zn; and 84.5–123, 66.7–284, 57.6–153 μg g(−1) Fe respectively. The systemic exposure dosage (SED) values of the studied metals were below their respective provisional tolerable daily intakes (PTDI)/recommended daily intakes (RDI), while the margins of safety were greater than 100 which indicate that these products are safe to use.