Plastic and pollution are harming men’s sperm counts right around the world.
That's according to Professor of Biochemistry at Trinity College, Luke O'Neill, who said sperm counts have dropped from around 113 million per mil to 66 million per mil between 1938 and 2000.
This figure come from new research that saw nearly 27,000 separate studies examined by scientists.
Prof O'Neill told The Pat Kenny Show the quality of the sperm is also changing.
"You need a certain count per mil if it's going to fertilise an egg," he said.
"Even more importantly, the quality of the sperm is declining as well.
"If this keeps going in the direction it's headed, our species is actually under threat".
A 3D rendering shows the moment of fertilization of an egg with a sperm. Picture by: Natalia Lukiianova / Alamy Stock PhotoProf O'Neill said pollutants are a big problem.
"There's several things: first and foremost, pollution," he said.
"There's good evidence now that it's things like insecticides in the environment, pesticides.
"Plastics release a thing called phthalates; there's evidence that that can damage your sperm.
"Phthalates are little chemicals that leach off plastics... and they can be especially worrisome.
"As you know, there's plastic everywhere... it can waft in the breeze".
'Fragmenting DNA'
Prof O'Neill said DNA in the sperm is also breaking down.
"Traffic cops, who were exposed to pollution all through the day, their sperm is being damaged," he said.
"There's two things going on: one is the count goes down, secondly the DNA in the sperm is fragmenting - and that's a bad thing.
"They're measuring that as a really good measure of the quality.
"If that goes above 25% breaking of the DNA, that sperm wouldn't fertilise the egg".
Prof O'Neill said there is also evidence of a link to obesity and a dropping sperm count.
"That puts the sperm under pressure as well - there's evidence of a link to obesity as being a damaging thing.
"Smoking was always a risk and that was known for a long time," he added.
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