The Italian Society of Andrology and Sexuality Medicine said an analysis of three studies showed 33.4 percent of 20-year-olds were "hypofertile" and 11.7 percent "severely hypofertile," meaning their sperm counts were low or very low, Italian news agency ANSA reported Friday.
Fuel emissions and pesticides posed major risks to young city dwellers, as did drugs, alcohol, smoking and a sedentary lifestyle, said the research group, whose Italian acronym is SIAMS.
The older generations appeared to be faring better, it said.
"The fathers, in their 40s, appear to maintain standard counts," SIAMS said.
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