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In slaughter line operations, clean and unclean operations are physically separated and individually manned to avoid contamination of carcasses and edible by-products.

在屠宰流水线作业中，清洁区与非清洁区物理隔开并分别配置人员，避免畜体和可食用副产品的相互污染。

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To avoid contamination, Wells in the Bengal Basin can be drilled into deep layers that were oxidized during the last ice age, in which the water is free of arsenic, Berg says.

为了防止被污染，孟加拉盆地的水井钻入了在上一个冰河时期被氧化的深层地层中，这一层的水是不含砷的，伯格说。

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But the government warns that private water supplies should be closely monitored to avoid contamination.

BBC: Pyre health risk warning

Simple stuff like using a smaller toothbrush to cleanse the mouth or leaving masks on to avoid contamination.

FORBES: Magazine Article

Mr Ogg then asked if police handling guns would wear gloves and a mask to avoid DNA contamination and Det Con Begley said this was the case.

BBC: Kevin Carroll