Cadmium is one of the most toxic heavy metals and is not an essential nutrient element for plant, animal and human being.

镉是动物和植物的非必需元素，也是毒性最大的重金属之一。

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Zinc is an essential nutrient element for biological organisms, but it is toxic to plant, animal and human at excess levels.

锌是生物必需微量元素，但过多时对动植物都有毒害。

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Deficiency disease a disease caused by deficiency of a particular essential nutrient (such as a MICRONUTRIENT or trace element), usually with a characteristic set of symptoms.

由于缺乏一种特殊的必要营养物质(微量营养素或微量元素)而导致的疾病，通常表现出具有特征性的一系列症状。

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