by Marion Nestle
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.


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, 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.


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.


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.


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

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


  • Fern Gale Estrow MS, RD, CDN

    Excellent explanation and thank you for including children and pregnancy. Adding related tags might help reach populations that are not aware enough to yet ask the question. Feeding-children, feeding-infants, food-safety and food-labels come to mind. Thanks for an explanation easy to share with many.

  • Nice reply!

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

    Then what about organic pesticides? Why would natural pesticides be inherently safer than synthetic? Not according to Bruce Ames and Lois Gold (

    Plants have evolved to produce thousands of chemicals (pesticides) that kill insects and plant eaters. Natural pesticides, like copper sulphate and rotenone, are also harmful to farmworkers etc.

  • Pedro Sun CSCS

    Thank you Marion Nestle 🙂

    This topic seems to be coming up a whole lot more in the last couple of months. Went to FNCE 2011 and there was a session on these very topics. The only problem was that it was a one sided presentation (most would say the industry side) with no representation from the folks that publish the dirty dozen list. I’m going to speak for the health professionals in the audience and I think most, if not all, were very insulted from the lack of fairness. Come to find out that ADA had not contacted any one from EWG according to Don Carr to defend their position. Talk about food politics!

  • Michael Bulger


    An important fact to realize is that organic certification requires farmers to forego the application of pesticides until they have tried to intervene with control and monitoring methods such as crop rotations, beneficial intercropping, specific crop breeds, insect traps, predators, etc. This results in lower in pesticide residues, or none at all.

    Organic pesticides that are approved for use in organic farming are different from pesticides employed by conventional farmers, and should be used only as a final option. Discussion of their relative dangers, environmental persistence, and whether they are widely used or even on the market (despite being on the National List), is of interest. However, allow me to address a concept that I have encountered. This idea seems to be presented by those arguing that synthetic pesticides are a non-issue. They state that plants naturally produce pesticides. This, they seem to suggest, means that pesticides are not worth avoiding.

    You wrote: “Plants have evolved to produce thousands of chemicals (pesticides) that kill insects and plant eaters.”

    I’d ask, what relevance does this have to the avoidance of harmful synthetic pesticides?

    If natural pesticides are harmful, they are also inherent in the plant. Adding a synthetic pesticide does not necessarily eliminate the natural pesticide, correct? These synthetic pesticides are designed to eliminate pests, not naturally occurring plant toxins.

    Therefore, the pesticides are adding a layer of toxicity. Irregardless of whether or not any toxicity existed, toxicity is enhanced and increased by added toxicity. This is a simple truism of logic and mathematics.

    As I mentioned above, I have seen the suggestion that the existence of natural toxicity in plants renders discussion of added synthetic toxicity null. I’d offer this metaphor in an attempt to help readers understand the fallacy of such a proposition:

    If you were driving 30 mph above the speed limit, would you believe that it was safe to drive another 30 mph above the rate at which you were already speeding along?

    No, it would only compound the danger. Driving 60 mph around a legal limit 30 mph curve does not mean that driving 90 mph equals the same amount of risk.

  • timjbd

    I suspect Erik was referring to the “natural pesticide” extracts that are sprayed on plants which do not inherently produce them. Strawberries do not produce “natural pesticides” so they have to be sprayed with extracts from plants that do.

  • Michael Bulger

    Understood. From what I gather, copper sulfate is approved for limited use. Any reports on how often it is used?

    What I’ve found on rotenone is indicating it is rare:

    Do certifiers even approve any rotenone products anymore? Have any products been reviewed by OMRI?

  • On October 1st, Connecticut became the first state to ban BPA in reusable food containers – including those for infant formula and baby food. An important first step.

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  • foodie

    Good job describing the difference between science and politics. This is an excellent example of a POLITICALLY correct answer.

  • Average Farmer

    What I have found is that so many of these discussions on food take place with only a one sided presentation. No give and take. One has to be “like minded” to be invited. Where does that get any of us?

  • Michael

    Erik, Michael, timjbd:

    The EU banned rotenone for almost all uses in 2007, so it won’t be used in any crops, organic or otherwise. Rotenone began to be withdrawn from the market in the USA in the USA the same year, by a *voluntary* agreement between the big manufacturers and the EPA. Prior to that, it had swung back and forth in organic crops: originally, it was allowed to be used by the National Organic Program, but then suspended in 2005 — only to be re-approved.

    Those agreements were not for an immediate withdrawal, however, but only initiated the process, and they only finally came to an agreement to actually stop selling the stuff earlier this year — and the agreement lets manufacturers keep selling it until the end of this last July. If you’re a farmer and have a large stockpile of rotenone sitting in your shed, you can keep using it until you run out of it.

    Rotenone is still perfectly legal for conventional and agricultural use in Australia, although it is ‘under review:”

    It is still legal for fruit and vegetables in Chile, including organic produce, and apparently in Argentina as well.

  • Michael Bulger

    Thank you, Michael.

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  • tmana

    As a diabetes health activist, I have learned that there is a high coincidence of celiac with type 1 diabetes (aka “juvenile diabetes” — this is an autoimmune disease that, except for some symptoms, is completely different from the much more common type 2 diabetes). Poking around the celiac and gluten-free communities, I’ve learned that some individuals are (or appear to be) sensitive to extremely low concentrations of particular food {ingredients, additives, and contaminants} — some naturally-occurring (such as gluten), some not.

    Without specific analysis, one might argue that those pressing for increasingly lower limits on those items may be alarmist or responding psychosomatically, except that many are parents’ observations of their children’s behavior, and those children are naive to the chemical composition of their food. Still, we are talking about a small subset of a relatively small community.

    This suggests to me that any individual claim of harm from, or sensitivity to, a particular trace ingredient is likely valid; however, the extrapolation of this to the majority (even where the majority community is a minority community) needs to be viewed with scientific skepticism, and no assumption of liability should be made unless a product is deliberately mislabeled, or — in the case where the ingredient or contaminant poses a severe threat to a known community or sub-community — undeclared.

  • Dr. Marion Nestle,

    This is an excellent and thought provoking post about the biological and economical nature of chemical additives. One point especially struck me: chemicals are indeed innocent until proven guilty a hundred times over. I realize it is not in the best interest of companies to pull products off the shelves every time a scientific article is published, but I wonder if they fully acknowledge these papers or consume their own products. You mentioned in your post that “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”–are there any sort of meetings held where they discuss the discrepancies in the information face to face? Or do they just submit data quietly from behind a computer? As a senior majoring in biology at the University of Southern California I am no stranger to scientific studies which expose unrealistic amounts of chemicals to lab animals–amounts that humans will never consume even over a life time. With LD-50s of 10,000mg/ml and observationally low mutagenic properties, it makes sense that companies and the FDA deem such information insufficient to cease the use of a certain additive. But in the case of BPA, even low dosages are causing harm and this fact should not be ignored.

    I am currently taking a course in advanced molecular biology and we have been focusing on epigenetics. Many studies have been published on the epigenetic effects of BPA. Most notably, one paper showed how a mouse fed a BPA diet without any methyl-donating supplements expressed the agouti gene which phenotypically causes the mouse to be much larger and more susceptible to diabetes and cancer than an identical twin fed a different diet. Since BPA has been in commercial use only since the 1960’s, I wonder if this chemical is contributing to the obesity epidemic. What if BPA is causing, in addition to mimicking estrogen and exacerbating hormonal issues, hypomethylation of some human genes making one susceptible to obesity and diabetes later on in adult life? I realize research on this topic would be very costly, and difficult to conduct for the reasons stated in your post, but it is important for companies to take all of this into account when providing consumers with products. Personally, I follow “if I cannot read it and understand it, then do not eat it” rule when perusing the ingredient list of foods or surveying the containers they come in. Not everyone is a scientist, but it is important that the general public be aware of these issues, and start caring about what they are being exposed to. Who knows what chemical that seems safe today will show mutagenic properties forty or fifty years later?

  • Margeretrc

    “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.”
    That would have nothing to do with industry shills in the regulatory agencies, of course… I vote with my pocket book, rather than wait around for the science and the regulatory agencies to catch up. I buy mostly local or organic, ask the local vender about their practices, and stick to pretty much whole foods, which I prepare myself. I don’t buy bottled water and we use stainless steel or BPA free reusable bottles to carry water, and never, ever drink or eat anything that has artificial sweeteners in it. I don’t expect science, which is more often than not funded by industry, nor government regulatory agencies to do anything any time soon. Yes, I’m cynical. Having been lied to by science and regulatory agencies for years has a tendency to make me that way.

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  • As with drug trials, any testing and published studies done on the affects of chemical additives – low doses or high – are going to reflect the “average” result.

    If a majority are not affected, that typically becomes the conclusion and ends up being the published as such. And of course, depending on who does the study, who funds it, etc. there could be some bias in data interpretation.

    There will always be some number in any given study that will show some affect even though the majority may not. But if the affected number is small, it’s washed under the rug or becomes a disclaimer – e.g., all the disclaimers we all hear at the end of advertisements for drugs.

    Experimental design is such that only one variable can be tested at a time so it’s very hard to factor in everything else that might affect a person’s reaction to a drug or food additive – all the background “noise” (e.g., genetics, daily habits, environment, etc) that can affect how any one individual’s body reacts.

    Personally, as someone who has developed chemical sensitivities I’m learning to error on the side of caution – limit exposure as much as possible…

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