by Marion Nestle

Currently browsing posts about: Pesticides

Oct 2 2011

What to do about food chemicals eaten in tiny amounts?

My once-a-month, first Sunday Food Matters column in the San Francisco Chronicle is about the difficulty of figuring out the health effects of food chemicals consumed in low doses.

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Taking steps on food chemicals

Editor’s note: Nutrition and public policy expert Marion Nestle answers readers’ questions in this monthly column written exclusively for The Chronicle. E-mail your questions to food@sfchronicle.com, with “Marion Nestle” in the subject line.

Q: I don’t understand why the FDA does not ban aspartame, food colors, BPA, pesticides and all those other nasty chemicals in food. I can’t believe they are good for us.

A: I can’t, either. But the Food and Drug Administration is required to make decisions on the basis of science, not beliefs.

You eat these chemicals in tiny amounts – parts per billion or trillion. Whether doses this low cause harm is hard to assess for two reasons: science and politics. Scientists cannot easily measure the health effects of exposure to low-dose chemicals. And the industries that make and use these chemicals don’t want to give them up.

Food chemicals elicit plenty of public dread and outrage. But are they harmful?

Controlled clinical trials at normal levels of intake would require vast numbers of subjects over decades. Nobody would fund them.

Instead, researchers use animals consuming much higher doses. I can remember how the diet soda industry ridiculed studies suggesting that saccharine caused bladder cancer in rats: the doses were equivalent to drinking 1,250 12-ounce diet sodas a day.

The difficulties of doing research on low-dose chemicals – and the food industry’s insistence that such doses are safe – explains the FDA’s reluctance to act.

Some examples illustrate the problem.

Aspartame

Some studies suggest that aspartame might cause cancer in rats when consumed at levels typical of diet soft drinks, as well as other problems. But researchers performing better controlled studies have given aspartame a clean bill of health.

Despite public concerns, the FDA’s assessment of the evidence “finds no reason to alter its previous conclusion that aspartame is safe as a general purpose sweetener in food.”

Food dyes

These have been considered a possible cause of hyperactivity in children since the 1970s. Some studies show improved behavior among children placed on additive-free diets. But behavior is difficult to judge objectively, and even controlled studies gave mixed results.

A recent study funded by the British Food Standards Agency is typical. It found most children to be unaffected by removing additives. But a small percentage seemed to get better.

The FDA can only conclude that there is not enough science to decide whether food dyes cause hyperactivity.

BPA (Bisphenol A)

BPA is a component of hard plastic used to make baby bottles and food and beverage cans. It is also an endocrine disrupter. Last year, the FDA concluded that BPA is safe at current exposure levels.

At the same time, the FDA advised children and pregnant women to reduce exposure to BPA. It advised the infant formula and soda industries to find ways to replace it.

The California Legislature has passed AB1319 banning BPA from baby bottles and sippy cups; it’s awaiting Gov. Jerry Brown’s signature.

Recent studies raise concerns about BPA’s effects on the brain and behavior of fetuses, infants and young children, and on cancer, obesity and infertility in adults. Some studies suggest that exposure to BPA is higher than previously estimated. Just last week, the Breast Cancer Fund released a study finding BPA in canned foods designed for children.

Studies by university scientists tend to find harm from BPA at low doses, whereas those by government regulatory agencies and the food industry do not. In the absence of compelling science, regulators have two choices: exercise the “precautionary principle” and ban the chemical until it can be proven safe, or approve it until it can be shown to be harmful.

The United States and European safety agencies – and the food industry, of course – prefer the latter approach.

Pesticides

Research clearly demonstrates that pesticides harm farmworkers exposed to high doses. But recent studies report slightly lower IQ levels in children born to urban women with higher blood levels of pesticides. Although these studies did not control for socioeconomic and other variables that might influence IQ, they raise the possibility that even low levels might be harmful.

What to do?

While waiting for the science to evolve, you can take both personal and political action.

You don’t want potentially harmful chemicals in your foods? Read labels and don’t buy foods with artificial sweeteners or food colors. Kids don’t need them anyway.

Consumer action has already induced baby bottle makers to get rid of BPA. This strategy can work for food colors, too.

Don’t stop eating fruits and vegetables. Their known health benefits greatly outweigh the potential harm of pesticides. Don’t stop eating them.

Buy organic. Pesticides, invisible and unlabeled as they are, constitute a good reason to do so.

Get political. Let your congressional representatives know that more research is needed, but you don’t want to wait for it. You want industry to find healthier alternatives.

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Marion Nestle is the author of “Food Politics” and “What to Eat,” among other books, and is a professor in the nutrition, food studies and public health department at New York University. E-mail comments to food@sfchronicle.com.

This article appeared on page G – 10 of the San Francisco Chronicle

 

Jun 14 2011

Environmental Working Group’s “dirty dozen”

The Environmental Working Group (EWG) has just published its 2011 guide to the most and least pesticide-laden fruits and vegetables.

The #1 “dirtiest”?  Apples.  The remedy?  Buy from the EWG “clean 15” list or buy organic.

The “dirty dozen” list, in order: Apples, Celery, Strawberries, Peaches, Spinach, Imported nectarines, Imported grapes, Sweet bell peppers, Potatoes, Domestic blueberries, Lettuce, Kale/collard greens.

The “clean 15” list of foods with the least pesticides: Onions, Sweet corn, Pineapples, Avocados, Asparagus, Sweet peas, Mangoes, Eggplant, Domestic cantaloupe, Kiwifruit, Cabbage, Watermelon, Sweet potatoes, Grapefruit, Mushrooms

How much should you worry about pesticides on foods?  As one reader asked,

Is it better to eat conventional fruits (cherries, berries and apples) and other veggies (peppers) that are on the “dirty” vegetable list or forego them altogether?

This is not an easy question to answer.  EWG recognizes that the science linking pesticides to health problems is limited (this is an understatement).  EWG bases its rankings on data published by USDA and FDA.  It considers:

  • Percent of samples tested with detectable pesticides
  • Percent of samples with two or more pesticides
  • Average number of pesticides found on a single sample
  • Average amount (level in parts per million) of all pesticides found
  • Maximum number of pesticides found on a single sample
  • Total number of pesticides found on the commodity

EWG explains that its

Shopper’s Guide is not built on a complex assessment of pesticide risks but instead reflects the overall pesticide loads of common fruits and vegetables. This approach best captures the uncertainties of the risks of pesticide exposure and gives shoppers confidence that when they follow the guide they are buying foods with consistently lower overall levels of pesticide contamination.

Most available research supports the health benefits of eating fruits and vegetables regardless of their pesticide loads.  Ken Cook, the president of EWG says:

We recommend that people eat healthy by eating more fruits and vegetables, whether conventional or organic,” says Ken Cook, president and founder of Environmental Working Group. “But people don’t want to eat pesticides with their produce if they don’t have to. And with EWG’s guide, they don’t.”

By EWG calculations, you can lower your pesticide intake by 92% if you avoid the dirty dozen.  No wonder.  How’s this for an observation: “Hot peppers had been treated with as many as 97 pesticides, followed by cucumbers (68) and greens (66).”  Who knew?

Where is the produce industry in all of this?  EWG reports that produce trade associations are working hand-in-glove with the pesticide industry to attempt to keep information about these chemicals out of the public eye.

I wish more research existed on the dose-response effects of pesticides and on their long-term effects on health, especially in children.  I cannot imagine that pesticides are good for health.  In high doses, they are demonstrably harmful to farm workers.

But what about the low doses on fruits and vegetables?  Here, the evidence for long-term harm is weak, uncertain, and unhelpful.

What to do?

On the personal side: if you want to avoid eating pesticides, you can stick with the EWG 15.  Washing produce before eating it is always a good idea even if it doesn’t get rid of all of the chemicals (USDA studies are done on washed produce).  When in doubt, buy organic.

As for the political, if ever there was a situation where more research was needed, this is it.  And isn’t it time for industrial food producers to find ways to use fewer pesticides?  Let the produce trade associations know that you don’t like their defense of potentially harmful chemicals and that you much prefer organic.

Addition, June 16: For anyone interested, here are the USDA’s pesticide announcements for the new data:

Press release

Consumer factsheet

Report executive summary


 

 

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.