The men who failed were smoking about twice as many cigarettes per day, an average of 19 per day, compared to the smokers who passed the [test].

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Like other cells in the body, human sperm carry a receptor for nicotine, which means they recognize and respond to nicotine.

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In a direct fertility testing situation, we can show that two-thirds of smokers have lost some or a lot of their fertilizing capacity.

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