Uptake of aluminum, cadmium, copper, lead, and zinc by human scalp hair and elution of the adsorbed metals.

Uptake of aluminum (Al), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) from aqueous solutions by human scalp hair (water/hair = 100:1) has been studied in the concentration range 0-50 mg/L. Hair metal levels were determined by a wet digestion procedure and atomic absorption spectrometry. Under conditions used, uptake followed a sigmoid concentration-response relationship. The order of binding capacity of hair to the metals was as follows: Al greater than Cd greater than Cu greater than Pb greater than Zn. Using logit transformation 50% saturation was evaluated at the following metal concentrations (hair metal concentration of saturation is given in parenthesis): 0.34 mg/L for Al (0.154 mg/g); 1.82 mg/L for Cd (0.363 mg/g); 2.21 mg/L for Cu (0.651 mg/g); 2.52 mg/L for Pb (0.986 mg/g); 23.84 mg/L for Zn (1.616 mg/g). Percentage elution of trace metals from hair after treatment with metal-enriched solutions by five different procedures ranged from 14.5 to 46.5% for Al, from 11.1 to 28.9% for Zn, from 11.5 to 28.4% for Pb, from 8.9 to 13.6% for Cd, and from 0.1 to 11.8% for Cu. In addition, trace element concentrations were measured in tap water samples and shampoos.