Pesticides Linked to ADHD: Salad with a Side of Suspected Toxins

I try to buy organic fruits and veggies, at least the dirty dozen.  Organic milk too. Pasta, once or twice. Pajamas, never.  So you may not be surprised to learn I read the new study linking ADHD to pesticides as my children gobbled up grapes that were not organic, this being New Jersey and not the West Coast where I imagine pesticide-free is an achievable if not cost-effect lifestyle.  After finishing the article published in the current Pediatrics, I didn't wince too much, the grapes flown in fortunately from California and not Chile.  

The technical language did scare me.
Organophosphate Pesticides. 
Diethyl Alkylphosphate.
Dimethyl Alkylphosphate.

Get set. Here's the deal.  Data taken from a large public health study.  Over 1,100 kids aged 8 to 15.  Urine samples taken in the same general time period their parents completed a telephone survey with questions about their impulsivity, inattention, and other behaviors and traits.  Kids with higher concentrations of  a couple of the chemicals in their urine were more likely to exhibit ADHD-like symptoms according to their parents.  Yes, according to their parents.  So not an official ADHD diagnosis.

Okay study.  Not great.  Could have been better if we'd had independent, professional verification of the ADHD.  If we'd gotten urine over a period of time, say three different times, say before the phone interview with momma.  Maybe the ADHD symptoms measured over time.  See where I'm going?  Cue the correlational caveats.  Faithful readers, I will only briefly remind you this is a correlational study with the usual directional/causal obstacles. 

More important, this correlational confusion is compounded by this pesky problem of pesticides often rather quickly leaving the body via pee.  We gotta know they stay there and do something other than tantalize researchers.  So to establish pesticides as a trigger for ADHD we'd have to have evidence that it was in not only the pee, but the body (and thus, brain) before the symptoms appear.  Long before some stranger rang and asked some time-pressured mom if her child often, sometimes, or rarely had difficulty waiting for his or her turn in line at school/home/ other social situation, would you like me to repeat the question, ma'am?

My other concern here involves the nature of ADHD as a complex neurodevelopmental disorder that doesn't tend to just show up overnight after a salad with a side of suspected toxins.  It's not often first diagnosed in teens or even preteens, but younger kids. 

Thus the whole time line of the study's just not quite convincing.  If pesticides promote neurological changes culminating in ADHD then that's one thing, and we'd have to assume that starts pretty early in life, prenatally perhaps, but it's a whole other hypothesis that the toxins tend to stick around in kids with ADHD or that the chemical culprits show up now and again and somehow perpetuate the disorder that we don't think of as coming and going, waxing or weaning.  A jolt of diethyl alkylphosphate here and there most likely does not ADHD a make.  It's not how we understand the cluster of symptoms.  Hence, my nagging about the timing of the toxin. 

And what about that recent study showing kids who take up pesticide-free diets rid their bodies readily of the toxins?  Carrying this logic further, no toxin, no ADHD.  That, my friends, we know doesn't just happen with a tweak of the grocery list.

We really need to better explain the presence, albeit even temporary, of the organophosophates in the urine.
One more niggling nit-picky thought.  I serve my kids pretty much the same foods, organic or non-organic. They're all exposed to the same toxins.  As it is in many families - so how to explain same food with one child diagnosed with ADHD?  Curious and curiouser....maybe those prone to ADHD are also somehow more susceptible to environmental toxins?  Hmmm...

Again, I buy the dirty dozen organic when I can.  Mea culpa. Remember this is New Jersey, aka, The Garden State.  Rich with industry and no shortage of toxic waste dumps.  I try to do the organic thing but am not always sucessful.  I repeat, I am no friend to the chemical companies.  Not on the pesticide payroll.   But, this being the real world, in my case the decidely ungarden-like garden state, I make choices and sometimes buy the pesticide-grown blueberries or whatever my child is finally agreeing to eat.  After nearly a decade of parenthood, I have learned to live with some uncertainty and some level of risk, otherwise, I'd have to homeschool my children.

Check out Seeking an Objective Test for Attention Disorder (NY Times, Science, May 31).  Good discussion about how an objective test might impact diagnoses and treatment.  Current tests include monitoring physical responses (e.g., head movement, blood flow via MRI) to boring tasks.

Should you find yourself without a worry in the world, a text to return or a Tweet to retweet, by all means, read the original journal article while it's free online:
Bouchard, M., Bellinger, D., Wright, R., & Weisskopf, M. (2010). Attention-Deficit/Hyperactivity Disorder and Urinary Metabolites of Organophosphate Pesticides PEDIATRICS, 125 (6) DOI: 10.1542/peds.2009-3058


TherExtras said...

Well done, Polly - per your usual. Going to tweet this. Barbara

Polly Palumbo, Ph.D. said...

Barbara, thanks! My refrigerator and grocery bill thanks you too!

The Fearless Formula Feeder said...

You know, I live in CA, and I have the hardest time finding organic grapes. And most of the grapes I do find in local stores are from Chile. Go figure.

Anyway... great breakdown of the inherent flaws in this study. I think your point about siblings in the same family is a great one. A dear friend (now in his 30s) has severe ADD, only controlled by meds. He's a successful attorney and dad, but skip a dose, and wow... let's just say you don't want to be in a pick-a-mix candy store with him when that happens. I know from experience.

I digress... his sister, on the other hand, is the calmest, most model-student type woman you've ever met. And his parents were crazy CA hippees who fed their kids farm-fresh, local foods before it was popular to do so.

As you say... curiouser and curiouser.

I tend to think that so many of these behavioral conditions - autism spectrum, ADHD - are misdiagnosed - that they are instead reactions to other things in the world that may resemble these conditions but are not actually them, you know what I mean? Case in point, your favorite Playboy Bunny and mine, J-Mac. Her son's condition may have resembled autism, but it wasn't... or so they're suggesting now. So while his condition may have been triggered by a vaccine (not that I believe it was, but even if...), that means he had some weird OTHER reaction/condition, not autism.

Does this make any sense? I guess what I'm trying to say is, maybe the chemicals in these grapes made the kiddos a bit hyper... but it could have been a short-term reaction, and definitely not a diagnosis of ADHD. Thanks for walking us through the study and helping us not jump to conclusions!

Now, I'm craving grapes....

Polly Palumbo, Ph.D. said...

I often wonder about the over/under-diagnosis of autism, ADHD, and other disorders. The newish theory is that many of these can be viewed as part of a continuum of human behavior. So at one end we have the intense, serious cases, those easily diagnosable folks and at the other, those who show some mild symptoms that wouldn't meet all the diagnostic criteria should they or their parents ever think about seeking treatment, who may never need professional help. This is a long way of saying that we probably both over- and under-diagnose people on the sub-clinical side.

Judith Warner argues in her new book that we're not over-medicated (and overdiagnosing) as she originally thought but missing alot of kids who could use help. I've written before that she may be correct we're missing some, especially those from families with other issues, but we're also probably too quick to label sub-clinical cases in others. And it's always surprising to me how often ADHD is diagnosed in kids with other diagnoses, esp. autism. Not sure about how often it looks like something else but it shares symptomotology with several other disorders including autism and sensory perception disorder.

As for this study, it's very unclear why and how traces of pesticides in urine would be higher in children who appear to have ADHD.

BTW, these kind of studies (okay, fishing expeditions) always make me suspicious about how many other substances/toxins (in addition to disorders) were measured and analyzed. The more the related outcomes, the greater the chance one will turn up signficant.

Enough ranting...would you believe I too ate grapes today for the first time in forever.