Cr was
also present in relatively elevated levels, along with Zn, whereas
Cd showed much lower values and Hg was detected only in two
samples. Cr, Cd, Pb and Hg results were below permissible concentration
limits set by the RoHS Directive for components of electr(on)
ic products, that are 1000 mg/kg for Pb, Hg, Cr6+ and 100 mg/kg
for Cd (European Commission-RoHS Directive, 2003a; Hester and
Harrison, 2009).