辐射来自于外层空间（宇宙射线），以及在土壤，水和空气中的天然放射性物质。
The radiation comes from space (cosmic rays) as well as natural radioactive materials found in the soil, water and air.
测定了在该泉水中养殖的鱼类及用该泉水灌溉生长的农作物和其他有关环境生物样品中天然放射性物质的含量。
The natural radioactive substance content was determined for fishes, in thermal spring water, farm products irrigated with such water and other biological samples.
研究表明，绝大多数天然宝石所含放射性物质是极其微弱的，故不会对人体健康构成危害。
The research result shows most natural gems contain so little radioactive minerals that they can' t he harmful to health.
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