by Marion Nestle

Currently browsing posts about: Pesticides

Apr 25 2011

Do farm pesticides reduce kids’ IQs?

The Environmental Working Group announces the publication of three studies finding a correlation between diminished IQ and blood levels of pesticides.

The studies were done separately by groups of researchers from the Mt Sinai School of Medicine, University of California Berkeley’s School of Public Health, and Columbia University’s Mailman School of Public Health.  All were published in Environmental Health Perspectives and are available at that site (although sometimes with a delay and you have to look hard for the pdf of the whole article).

All three studies examined levels of organopesticides in the blood of pregnant women.  All looked at one or more measures of IQ taken when the children were 1 to 9 years old.

The Berkeley study, Prenatal Exposure to Organophosphate Pesticides and IQ in 7-Year Old Children, examined Latino farmworkers and their children.  Researchers found a difference of 7 IQ points between children with the highest and lowest levels of organopesticides.

The Mt. Sinai study, Prenatal Exposure to Organophosphates, Paraoxonase 1, and Cognitive Development in Childhood, was done with a prenatal population in New York City.

The Columbia study, 7-Year Neurodevelopmental Scores and Prenatal Exposure to Chlorpyrifos, a Common Agricultural Pesticide, also was done on an inner-city population.

It has been difficult to demonstrate demonstrable harm from agricultural pesticide use except among farmworkers exposed to very high doses.  These studies mean that lower doses experienced by people who merely eat agricultural products also can cause harm.

The study will undoubtedly be criticized for not adequately controlling for socioeconomic variables that influence IQ—they were all done with low-income populations—and, more importantly, for not explaining precisely how pesticides might influence childhood learning and achievement.  And some will surely argue that a 7-point IQ difference is well within experimental error.

But at the very least, pesticides are a marker for poorer cognitive outcome.  The fact that three independent groups of investigators arrived at similar conclusions means that the results need to be seriously considered.

Organic vegetables anyone?

And just for the record, here’s the Environmental Working Group’s list of the foods with highest and lowest levels of pesticides:

Highest Levels Lowest Levels
Celery
Peaches
Strawberries
Apples
Blueberries
Nectarines
Bell Peppers
Spinach
Cherries
Kale/Collard Greens
Potatoes
Grapes (imported)
Onions
Avocado
Sweet Corn
Pineapple
Mangos
Sweet Peas
Asparagus
Kiwi
Cabbage
Eggplant
Cantaloupe
Watermelon
May 7 2010

Presidential panel says: choose organics!

Thanks to Nicholas Kristof of the New York Times (“New alarm bells about chemicals and cancer“) for telling readers about a report on chemicals and cancer just released by the President’s Cancer Panel.

I had never heard of this panel – appointed during the Bush Administration, no less – and went right to its 2008-2009 annual report.

The Panel says that the “risk of environmentally induced cancer has been grossly underestimated,” that “nearly 80,000 chemicals [are] on the market in the United States, many of which are…un- or understudied and largely unregulated,” and that “the public remains unaware…that children are far more vulnerable to environmental toxins and radiation than adults.”

evidence suggests that some environmental agents may initiate or promote cancer by disrupting normal immune and endocrine system functions. The burgeoning number and complexity of known or suspected environmental carcinogens compel us to act to protect public health, even though we may lack irrefutable proof of harm.

I’m guessing this report will cause a furor.  Why?  “Lack irrefutable proof” means that the science isn’t there.  In this situation, the Panel advises precaution.  Check out these examples selected from the recommendations:

  • Parents and child care providers should choose foods, house and garden products, play spaces, toys, medicines, and medical tests that will minimize children’s exposure to toxics.  Ideally, both mothers and fathers should avoid exposure to endocrine-disrupting chemicals.
  • It is preferable to use filtered tap water instead of commercially bottled water.
  • Exposure to pesticides can be decreased by choosing…food grown without pesticides or chemical fertilizers [translation: organics] and washing conventionally grown produce to remove residues.
  • Exposure to antibiotics, growth hormones, and toxic run-off from livestock feed lots can be minimized by eating free-range meat [translation: don’t eat feedlot meat].

Expect to hear an uproar from the industries that might be affected by this report.  The American Cancer Society (ACS) doesn’t like it either, since the report implies that the ACS hasn’t been doing enough to educate the public about this issue.  The ACS said:

Elements of this report are entirely consistent with the recently published “American Cancer Society Perspective on Environmental Factors and Cancer”…Unfortunately, the perspective of the report is unbalanced by its implication that pollution is the major cause of cancer, and by its dismissal of cancer prevention efforts aimed at the major known causes of cancer (tobacco, obesity, alcohol, infections, hormones, sunlight) as “focussed narrowly”…it would be unfortunate if the effect of this report were to trivialize the importance of other modifiable risk factors that, at present, offer the greatest opportunity in preventing cancer.

ACS says the Panel does not back up its recommendations with enough research [but see May 14th note below].  Maybe, but why isn’t ACS pushing for more and better research on these chemicals?   However small the risks – and we hardly know anything about them – these chemicals are unlikely to be good for human health.   Doesn’t precaution make sense?  I think so.

Addition, May 7: Here’s Denise Grady’s take on the report from the New York Times: “Cancer society criticizes federal panel as overstating risks.”

Addition, May 14: I received a note from Michael Thun,  retired Vice President for Edemiology & Survey Research of the American Cancer Society requesting a clarification of my statement.  He says:

I hope that you can correct your report to say that ACS actually is pushing for more and better research, and has never discouraged people who choose to eat organic food from doing this. The only thing we object to is unsupported claims that the effect of current level of pollution on cancer has been “grossly underestimated”.

In 1996, I chaired an ACS committee writing dietary guidelines for cancer prevention and worked with Dr. Thun on our report.  I’d take his word for this.

National Home Office | American Cancer Society, Inc.

 







Mar 11 2009

EWG’s guide to pesticides on produce

The Environmental Working Group has just issued its guide to coping with pesticides on fresh fruits and vegetables.  It’s handy shopping card identifies the Dirty Dozen (highest in pesticides) and the Clean Fifteen (lowest).  Organics, it says, are still the best choices!

And here’s how they did the study.

Dec 22 2007

Organic mushrooms?

Today’s question: “How important is it to select organic mushrooms?  Any specific risks to conventional versus organic?

My immediate thought is that mushrooms are no different than any other vegetable.  Organics have fewer pesticides and a good chance of tasting better. But I don’t know anything more specific.  Anyone else want to weigh in on this?

Aug 19 2007

More Pesticides in Dried Fruit?

It’s a slow news Sunday, so I’ll just answer a couple of questions, both of them using USDA’s food composition data. Here’s a question from a reporter: “There seems to be consensus from the sources I’ve so far read that dried fruit contains higher levels of pesticides than fresh. What I can’t figure out is if that is only because typically one eats more dried fruit in a sitting (6-8 dried apricots as opposed to 1-2 fresh, for example) and that when you dry fruit there’s less volume but the same amount of pesticide, or if more pesticides are used on dried fruit for some reason.”

Answer, of sorts: This is a concentration issue. There can’t be more pesticides on dried fruit than there were on the fresh; there is just less water so the amount per weight appears greater. The same is true of nutrients. Some will be more concentrated (calories!). Others will be lower because of losses during processing (vitamin C, for example). For nutrient composition, USDA data are easy to use. Unfortunately, no such thing exists for pesticides.