I know over the past century, people have been getting taller, not shorter, but a new study has me wondering if over the next 100 years that trend will be reversed.

The study in question links pesticide exposure with birth size, and quite frankly, I find it worrying.
According to the study, even moderate amounts of exposure to certain pesticides during pregnancy may influence an infant’s birth size.

The researchers measured pesticide exposure by testing the amount of residue present in the umbilical cords of nearly 500 infants born in Valencia, Spain between 2003 and 2006. What they found was that newborns whose umbilical cords had higher levels of pesticide residues tended to be smaller at birth compared to other babies.

The pesticides included DDT and three other organochlorines, all of which are either banned or restricted in the United States and other developed countries because of their links to cancer and other health risks.

Here’s the thing, in emerging and growing economies, pesticides seem to be inescapable. They have a way of lingering in the environment long after use.

Diet, in particular, is the main source of exposure in the U.S. Just this week, the Department of Agriculture released results from federal testing that found pesticide residues in 98 percent apples. That’s right, America’s second-most-popular fresh fruit just made the Environmental Working Group’s “dirty dozen” list of 12 fruits and vegetables.

So if you take anything away from that – remember to wash those any fruits and veggies before you eat them – especially if you plan on eating the skin.

Pesticides also have a way of creeping into other parts of our diet. They seep into the sediment of streams, lakes, rivers and coastal waters, and settle into the fatty tissue of fish. They can also be found in some dairy products – particularly those with higher fat contents.

And my worries don’t even end with mere pesticides. China, for example, recently had an outbreak of lead pollution that seriously poisoned more than 100 children.

Health officials blame industrial growth and lax regulations in factories and workshops, which compete against each other to produce products quickly and cheaply.

What nations like China – and the U.S. – need to understand is that if we don’t crack down on potential sources of exposure, we’re setting ourselves and our children up for high rates of dangerous diseases like cancer.

At the very least, this new study is heralding the possibility of a shrinking human race.

Dr. Manny Alvarez serves as Fox News Channel's senior managing health editor. He also serves as chairman of the department of obstetrics/gynecology and reproductive science at Hackensack University Medical Center in New Jersey. Click here for more information on Dr. Manny's work with Hackensack University Medical Center. Visit AskDrManny.com for more.