Melanie Pearson, Ph.D.

Describe your study and the findings.

We were interested in dietary exposures to pesticides in children.  And the way that we tested this dietary exposure was we had children who ate conventionally grown foods continue to eat those conventionally grown foods for three days while we had them provide urine samples for us.  And then after those three days, we actually substituted their diets with organic foods.  And we bought the foods and substituted it for them, and the children ate the organic foods for five days.

And then we switched them back to their conventional diets for the next seven days.  And looking at their pesticide exposures via pesticide metabolites in their urine, we actually found a beautiful result scientifically, meaning that when they were eating conventional foods, we were able to detect the OP pesticide metabolites in their urine, and when we switched them to the organic foods, these went down to non-detectable levels.

And essentially took one full day for the OP pesticides to no longer to be detected in the children’s urine.  They remained at non-detectable levels throughout the organic diet period, and then increased after a day of returning to conventional foods.

Every child followed the same pattern.

And was this test conducted more than once?

The actual results that we’ve published are only based on our summer data so far, but we had also conducted it with the same children during the fall season.  We got the exact same results with the OP pesticides.  And then that was conducted in Seattle, Washington.  We have recently repeated the study here in Atlanta, Georgia with another cohort of children.  We do not have the results of that study back, yet.

Why would there be pesticides on the conventional produce?

Primarily because the farmers growing the foods are using these chemicals to help fight insects and the problems the insects cause on their foods, as far as damaging their crops and so forth.

Why do you suppose with an organic diet that there would be less or no pesticides in their urine?

The organic foods are not grown with pesticides, and therefore the pesticides were not found on those foods and were not entering into the children’s bodies when they were eating it.

Residues of pesticides found in urine, can we assume that those residues spread beyond just what’s excreted?

Okay.  So, I don’t know the form of kinetics of the residues that well, but essentially there’s two parts to your question.  One, there are actually metabolites.  We’re measuring the metabolites of pesticides in the urine, after they’ve been metabolized by the body.  There are actually metabolites already on the foods.  So, there’s a little bit of confound there.  It doesn’t mean that all the metabolites that are found in the urine come from parent compounds of the pesticide being ingested.

But as the parent compounds are ingested into the body, they’re broken down like other foods in the body, so they’re broken down and then excreted by the body, but they certainly are also found in the blood, and can cross the blood-brain barrier.  And for pregnant women, can cross the placenta and things like that.  So, they’re ubiquitous in the body, once they’re in the body, until they’re excreted out.

Well, I can actually address that in another way, which is during the conventional diet period, they were excreting them.  The biological half-lives of these pesticides are very short.  The problem is we’re chronically being re-exposed to them.  So, that’s the good news.  We do excrete the pesticides very quickly.  The bad news is we’re chronically exposed to it.  We’re continuously eating foods that have these pesticides in them.

What kind of foods are we talking about?

We definitely tried to match what the children normally eat in their conventional diet, meaning qualitatively.  So, they mainly ate a lot of produce, apples, strawberries, grapes, blueberries, and some oranges.  So, they ate what I would suspect are very normal diets with children. We also bought them some processed foods, cereals, snack foods, a lot of juices.

We did not replace milk, meat or sodas.  Those are the three things that we did not replace.  We did replace all of their vegetables. It seems that we bought quite a bit of frozen pizzas, things like that.  All organic.

Could you just name a few of the vegetables?

I remember peas, broccoli, green beans, carrots, and corn.  Pretty standard, I believe for a child’s diet.

You mentioned to me that you heard the argument that chemicals are ubiquitous in the environment.  But you made the point on the phone yesterday that we ought perhaps be more concerned about pesticides, because after all, they are designed to harm living things.

Sure.  So, as I mentioned when we spoke earlier, there are many chemicals in our world that we’re all exposed to. Prenatally exposed.  We come out exposed to these chemicals.  But the one reason to be really concerned with pesticides is that the pesticides are the one chemical that is actually designed to kill.  It’s designed to kill insects, and to harm insects.  And although insects are obviously much smaller than we are and so forth, the actual neurological mechanisms involved in killing these insects are also in the human body.

So, it’s an obvious difference on scale, but they do have some more effects and mechanisms of actions in our bodies.

With regard to what’s in literature, are there other studies that have been done, with regard to the pyrethroids?  What is an immune suppressant?

So, in the literature research by other groups have shown that both OPs and pyrethroids have potential adverse health outcomes.  And particularly for some of the pyrethroids, they’re known immunosuppressant, which essentially means that it reduces the body’s ability to fight disease.

And what is endocrine disrupting?

Okay. I don’t know as much about the endocrine system, for sure. So the endocrine system is part of our hormone system.  We can think of it in those terms.  And so essentially, pyrethroids have been shown to alter this system.

What about fetus development?

So, again, I’ve actually done very little research in this area.  But the OP pesticides have been associated with the prenatal exposure, and early life exposure of OP pesticides have been shown to delay some neurodevelopmental abilities.  And these tests that are usually conducted are conducted in array of abilities like, vocabulary, different cognitive abilities of the children, and then they’ve kind of taken index.

And so there’s not one ability that you can really pinpoint as well, but it does look like there’s an overall decline in these abilities with high levels of prenatal exposure.

Have these studies had an impact on your own parenting sensibilities?

Definitely this research and my research, in particular, have influenced my behaviors as a parent.  We buy primarily organic produce; our fruits and vegetables are all organic.  Our juices are organic. In addition to that, we do not use pesticides in or around the home just because I know that’s another additional exposure path in addition to the diet.  And so, I’m trying to reduce their exposures as much as possible.

We don’t buy all organic foods.  There’s a lot more foods out there that are available, but they’re costly, unfortunately.  And so we essentially do a cost-benefit analysis where we chose to buy foods that we know have higher levels of pesticides in them.  We chose to buy those foods grown organically.  And there’s an organic carrot.

The levels of which you guys found in the urine apparently don’t alarm the EPA because it’s within their tolerance levels.

It’s primarily true.  A lot of our results haven’t been completely published yet.  And, in general, our findings are below the EPA’s tolerance level and that’s true.  But the other part that’s different with our data versus the national studies is that we are finding higher levels of exposure in the children than what’s reported in the national studies.  And that’s primarily an etiological difference we believe.  But our methods are more sensitive and able to actually pick up more of the peaks of exposure.

I think our studies do represent the true exposure more, and primarily because we take more urine samples, and the timing of our urine samples are different.  So, we take the morning urine samples, which of course are more concentrated, as well as the bedtime urine samples.  And from that, we can really get a very good estimate of the daily exposure.  Where as in the national studies, unfortunately, what they have available to them is convenient samples, which are just spot samples anytime during the day.

And so we don’t know when the previous void was, and the concentration is hard to determine at that level.  And the pesticides could have already been metabolized and excreted prior to that void.

The EPA certainly does acknowledge that pesticides are dangerous.

The EPA definitely is concerned about pesticide exposure in children.  In fact, the EPA has been funding our studies.  And so they are very interested in finding out what the exposure levels are in the population and so forth, and obviously it’s their job to protect the public. They’re aware that at high levels, these pesticides are very toxic, and they’re trying to protect the children and strike a balance between the benefits of pesticides and also the adverse health effects and the potential adverse health effects, which we’re not quite sure of at this point.

Why are kids more at risk?

Children are more at risk at pesticide exposure for several reasons.  One, because of their developing bodies, and they eat more fruits and vegetables and fruit juices than adults do.  And they eat a lot of food relative to their body size. Furthermore, their ability to metabolize these chemicals is reduced relative to adults’ abilities, and there’s a lot more hand and mouth contact, a lot more proximity to the floor and to the ground where pesticides are actually found. And so they have greater exposures because of that.

As a parent, would you support a farm bill that might encourage more of a transition to organic agriculture?

It’s hard for me to only answer that as a parent, but I can say I would support that sort of bill to transition or support farmers to grow their foods organically, but even more so to strike a balance.  I’m very interested in integrated pest management, in trying to allow that to be the transition, and support farmers using that methodology.  So, let’s reduce our exposures, but let’s don’t tie the farmer’s hand if there is some insects or something else that can really damage their crop, but let’s try to take the first step and reduce the use of pesticides the best we can.

Is there anything you would like to add?

Dr. Lou has done a lot of work with exposure in farm families, looking at children of farm worker’s exposure pathway, from the farm into the home. We found more pesticides in the house dust of farm families versus in suburban families.

The interesting thing is, though, in the one study that we actually looked at increased pesticide exposure or the association with pesticide exposure in spraying seasons, we did find increased pesticide exposures during spraying seasons, as you might expect in agricultural regions.  But the interesting thing was the families that lived closer in proximity to the farms, didn’t necessarily have the highest exposure, so that let’s you know what the spray drift is like.  And that it’s not just the homes that are very close to the farms, but it’s the entire region that’s affected.

How has it affected your prenatal?

During both of my pregnancies, I was very aware of my exposures, not only to pesticides, but to most of the chemicals that I’ve become familiar with in the environment.  And so as far as pesticides go, I primarily ate organic foods.  I increased my intake of organic produce, as well as organic milk during that time, yes.

Oh, and we definitely did not use any pesticides in or around our home during that time, and I was very aware of pesticide use at other people’s homes and properties when I would go there.

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