In the past year, there have been a slew of studies showing that when a child is exposed to certain pesticides — whether before birth or while eating conventionally-grown food — his or her IQ may drop. Sometimes by several points.

But what does this really mean? As a society, what might the impacts be? In short, should we be worried? The answer, according to one recent study, is an emphatic and sobering "yes".

Dr. David C. Bellinger, professor of neurology and environmental health at Harvard, took a close look at published science linking IQ impacts to three types of environmental contaminants: organophosphate pesticides, lead and methyl mercury.

I'm not a tremendous fan of statistical analysis, but this is seriously interesting stuff. Dr. Bellinger based society-wide IQ loss calculations on an estimated 25.5 million U.S. children under the age of five.

Here's what he found:

• Exposure to organophosphate pesticides is reducing IQ by about 17 million points at the population level.
• Lead is still the most harmful environmental exposure, linked to loss of about a 23 million IQ points population-wide.
• Combined, exposure to these three types of chemicals equates to a population-wide drop of 1.6 IQ points for each child — more than 40 million points for the population as a whole.

Putting IQ loss in context

This study then goes even further, providing some provocative context. After calculating the IQ loss impacts from these environmental exposures, Dr. Bellinger compared them to what's known about how medical conditions that affect thinking and learning abilities — such as birth defects, pre-term birth and autism — affect IQ population-wide.

It turns out that societal IQ loss from pre-term birth, which affects 12% of U.S. newborns, are about 34 million points. ADHD was responsible for 17 million, autism 7 million and about 7 million points for traumatic brain injuries.

So clearly, the impact from environmental contaminants is in the same ballpark as the losses linked to these major medical conditions.

What does it all mean? I think it's safe to say that there is indeed reason to be worried about how pesticides and other chemicals are affecting the brain power of our children. The ripple effects of our children's exposure to these pollutants will be felt for years — even generations — to come. As our friends at Environmental Health News report:

Even small reductions in a person's IQ can increase the need for extra help in school or at work. At a societal level, declining IQ scores results in overall lower intellectual ability, competitiveness, career achievement and increased costs in school and health care.

Not to mention the unfathomable loss of reduced potential in an individual child. As a mother, this hits much too close to home.

Translating evidence to action

There's a powerful good news angle to this story as well. Protecting our children from pesticides and other environmental contaminants that result in IQ loss is something we can, in fact, do.

It won't be easy. Our policies and institutions aren't set up to react quickly to this kind of evidence, so it will take real pushing to get changes that protect our children in place.

And as parents and engaged citizens, we are the ones who will have to push. We need to make clear to decisionmakers that our children's health is simply more important than whatever profits are being made on the chemicals in question. And we need to do it now. Studies like Dr. Bellinger's help provide the evidence we need to make our case.

This article was posted previously on GroundTruth.