Agriculture official says one-fifth of Pearl River Delta's vegetables contain poisons like arsenic, cadmium, copper and mercury…a provincial agriculture official…said the spread of heavy metals used in manufacturing…was a "regional problem…"As a result, about 10 to 20 per cent of vegetables grown in nine vegetable production centres…were tested to contain more heavy metals than the country's safety levels allow,"…Traces of lead, chromium, zinc and nickel were also found in some vegetables. Such heavy metals can accumulate in the body over years, causing organ and nerve damage, and even cancer…Ma Jun , director of the Institute of Public and Environmental Affairs, said pollution in the Pearl River Delta was among the worst in the country due to its large concentration of electronics manufacturers, electroplating plants, and leather and textile workshops…