>> A new scientific report appears to confirm that male fertility rates have dropped by huge margins in the last 40 years. Over 50% in both total sperm count and sperm concentration among men from North America, Europe, Australia and New Zealand. It's a claim that's been made before and has often been contested due to variances in methodology and populations.
But this time, a team of researchers in Israel, the US, Brazil, Denmark, and Spain compared data from a 185 studies in 42,000 men. The trend across all of them they say, leaves little doubt. Yet to wive it all, is still in unknown. Professor Daniel Bryson is a scientific director at the University of Manchester.
>> What I think what it is, it's a wake-up call. But there may be something in our environment that's affecting health, not just male fertility, male health in general, maybe the health of all of us. And if you look back over the 50 years of these studies, a lot of things have changed in our environment with plastics introducing more chemicals into the environment, modern agriculture, hormones, pesticides.
And it's just this concern that that's what we're seeing.>> The decrease in fertility was not seen in men from South America, Africa, or Asia. But the researchers pointed out there are also far fewer studies conducted in those places, resulting in a lack of data. Professor Bryson says, while individual men shouldn't be alarmed, the root cause could go back for generations.
>> Exposure could be important when the men are in utero, when the mother was pregnant. Or even their grandmother when they're affected with germ cells, at that stage. So nutritionist use this expression that, you are what you eat. But also, you are what your mother ate, and what your grandmother ate.
We just don't know.>> The study's authors say it may act as a canary in the coal mine for men's health.