A small amount of zinc and arsenic can make plants grow even better. The amount of copper and zinc would have to build up to very high levels before it could have any impact on human health. It is also very difficult for lead to pass from the soil into the plants, and most of the lead in cases of high-lead rice has come from air pollution.
少許的鋅與砷，能促進作物生長更好；銅與鋅累積的量也必需很高才會影響人的健康；鉛則很難藉由土壤傳入植物體，目前發現含鉛量高的稻米，大都由空氣汙染傳來。