For cadmium to be evident in rice grains as well, the soil in which it was grown must have been especially highly polluted, said Jonathan Wong, a Hong Kong biology professor who has studied soil pollution extensively on the mainland.

WSJ: Cadmium-Tainted Rice Found in Guangzhou

For cadmium to be evident in rice grains as well, the soil in which it was grown must have been especially highly polluted, said Jonathan Wong, a Hong Kong biology professor who has studied mainland soil pollution extensively.

WSJ: Cadmium-Tainted Rice Found in Guangzhou

As much as 10 percent of China's farmland is believed to be polluted, and each year 12 million tons of grain are contaminated with heavy metals absorbed from the soil.

CNN: Economic miracle, environmental disaster