Human exposure
to Cr(VI) compounds is associated with a higher incidence
of respiratory cancers (IARC, 1990). Cadmium is
associated with nephrotoxic effects particularly at high
exposure levels; long-term exposure may cause bone damage
as well (Friberg, 1985). High concentrations of mercury
can lead to neurobehavioural disorders and developmental
disabilities including dyslexia, attention deficit hyperactivity
disorder, intellectual retardation (Weiss and Landrigan,
2000).