研究发现二手烟中含有高浓度的上述有害物质。
High concentrations of many of these chemicals are found in secondhand smoke.
环境化学的研究内容主要涉及：潜在有害物质下环境介质中存在的浓度和形态；
The research contents of the environmental chemistry mainly involve: existent forms and concentration of latent harmful materials in environmental mediums;
他说，服用同时包含有益和有害物质的高浓度萃取物似乎并不是一个明智的决定。
In the meantime, he said, consuming an extract that contains both good and bad chemicals in dense concentration seems an unwise thing to do.
他说，服用同时包含有益和有害物质的高浓度萃取物似乎并不是一个明智的决定。
In the meantime, he said, consuming an extract that contains both good and bad chemicals in dense concentration seems an unwise thing to do.
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