Over several decades China's industrial boom has caused widespread contamination by heavy metals such as lead and cadmium, resulting in a silent health epidemic that can be difficult to spot.

近几十年来，中国的工业荣华已导致大面积重金属(如铅和镉)净化，形成可能难以察觉的无声的公共卫生危机。

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Officials have been able to conclude that the dolphins' deaths were not due to lack of food, interaction with fisheries, poisoning with pesticides, biotoxin poisoning or contamination by heavy metals.

CNN: Peru investigates mystery pelican deaths

Environmental baselines to enable an assessment of the degree of contamination of soils and agricultural crops by heavy metals have not been established in the majority of African countries.

UNESCO: EARTH SCIENCES FOR SOCIETY