ABSTRACT
Cadmium (Cd) is a naturally occurring heavy metal in minerals and
soils, and produced as a byproduct in zinc ore refinery process.
World Cd production was 17,441 tonnes in 2007, and it was
mainly produced by South Korea (20.1%), China (17.2%), Japan
(11.1%), Mexico (9.1%), and Canada (8.0%) (People’s Association
on Countermeasures of Dioxin & Endocrine Disruptors, Japan,
unpublished data). Cd is widely used for electrode in Ni-Cd battery,
alloys, coating, pigment, and other industries. Among them, the use
of Cd for Ni-Cd battery has been increasing up to more than 90%
of the total consumption (People’s Association on Countermeasures
of Dioxin & Endocrine Disruptors, Japan, unpublished data). Once
Cd is ingested, it is slowly excreted, resulting in its quite long
biological half-life (BHL). In case of human, BHL is estimated for 20
years.1 In human body, Cd is mainly accumulated in liver and kidney.
The highest accumulated concentration is observed especially in
kidney. Cd accumulation in kidney exceeding an undisclosed level
causes adverse effect to kidney function, especially renal tubular
dysfunction such as reabsorption of calcium, phosphorus, and other
minerals.1 As a result, osteomalacia, well known in Minamata
disease, and osteoporosis develop due to decrease of minerals in
bone. Other chronic diseases such as emphysema and proteinuria
can also be caused.2 In addition, Cd and its compounds were
classified as a human carcinogen (Group 1) by International Agency
for Research on Cancer in 1993.
