Toxics: The Long Term, Low Dose Question

(This post first appeared on Sustainablog on 7/26/11)

Each year, the USDA generates an extensive set of data which demonstrates that modern American consumers face no real threat from toxic pesticide residues on their food.  This is particularly true in terms of "acute toxicity," or short-term poisoning.  Someone would have to eat thousands to millions times their own body weight to kill themselves with produce.

To many people, that still leaves a troubling question:  "what about long term exposure to low doses of toxic chemicals and combinations of those chemicals?" This question is more difficult to answer.

What We Can't Know about Toxins and Our Health

When my son was small, he would often answer questions by saying, "I can't know."  In a way, that is where we sit on the "long-term, low-dose question."  Based on the testing that we can practically afford, wee "can't know"  all the long term outcomes where the rates of cancer or other chronic diseases might be in the range of 1 per million people or less.  We can do a good job of predicting which chemicals are reasonably potent carcinogens and the like, because such toxicity can be detected in a relatively short term feeding study at fairly high rates of the chemical.  Those tests give us a good deal of protection from truly dangerous substances, but it is not really possible to answer the "low-dose, long-exposure" question with this sort of test.  Does that mean that we have to live in fear of the trace levels of man-made chemicals that are in our water and in our food? No.  Here is why.

What We Can Know

Just because we can't answer this question using rats in a laboratory does not mean we are without encouraging "data."  This comes in the form of common life experience, and from what we know about protective chemicals in nature.

Want to Avoid All Toxics? Good Luck With That

I have often seen people write that they are trying to "avoid all toxics" in their life.  That is actually impossible. Almost all the foods we eat contain naturally toxic chemicals that are made as defense mechanisms by the plants or animals in question.  These toxins are present at levels which are too low to cause us any problem in the short term.   But what about the fact that we are consuming low, mixed doses of dozens of natural toxins every day?    Few of these chemicals have ever been evaluated for any kind of chronic toxicity.  What if we ask the "long-term, low-dose" question about these chemicals?

The calm response is to realize that our bodies are well equipped for living in a moderately toxic world. The cells of our skin and in the lining of our digestive track only live a few days before they are replaced.  That minimizes the potential to become cancerous because of exposure to toxins.  We also have powerful liver enzymes that chew up toxins of all kinds.  On the whole our bodies do a great job of dealing with the wide variety of toxins that we eat at low rates.  The same is true for both natural and man-made toxins.

Don't Forget About The Good Chemicals

The other encouraging bit of information is that we are far from helpless when it comes to maintaining our health while eating small doses of toxic substances.  It turns out that fruits and vegetable are excellent sources of other special chemicals which help us to fight cancer and a host of other ills.  Many people turn to the poorly regulated "supplements market" to get these chemicals, but that is not necessary.  The much more natural option is simply to enjoy the diverse and relatively low cost produce which is available to us today.  The bonus is that these products taste great and also provide basic minerals, vitamins, and fiber in our diet.  I will list just five examples of the foods which help to protect us against a wide variety of chronic diseases:

• Tomatoes: the largest dietary source of lycopene - a chemical that reduces risk of cancer, osteoporosis and cardiovascular disease
• Grapes: resveratrol in red grapes and wine enhances cardiac health
• Berries: berries have extremely high levels of various antioxidants that reduce the risk of cancer, improve urinary tract health, and help with memory and healthy aging
• Asparagus: rutin in asparagus can ameliorate the effects of diabetes and lower blood pressure among other benefits after the body converts it to quercetin-3-glycoside
• Broccoli: contains lots of vitamins A and C, but also isothiocyanates which stimulate the enzymes in the body that neutralize many potential cancer causing substances

There has probably never been a human society with such ready access to the foods that can protect health and counteract the effects of toxins - natural and man made.  That is why it is tragic when something like the "Dirty Dozen List" discourages significant numbers of people from buying fruits and vegetables.  These consumers then fail to get the very phytochemicals which could protect them - both from the trace chemicals they fear, and from the fearsome chemicals they may not even appreciate (e.g. aflatoxin).

Putting This In Perspective

I am not just saying: "Don't Worry, Be Happy."  There are very real toxic threats in the world - both man-made and natural.  We need to pay attention to what the toxicologists and public health experts tell us.  What we don't need to do is to worry inordinately about trace levels of pesticides or about low levels of most natural compounds.  What we do need to do is to eat our fruits and vegetables!

Vegetable market image from a trip I took to Switzerland a few years ago

You are invited to comment here or to email me at savage.sd@gmail.com

A Sad Day For Bread. A Sad Day For Science

(This post originally appeared on Sustainablog on 7/15/11)

On July, 14, three Greenpeace activists dressed in hazmat suits scaled a fence, and used weed whips to destroyed a GMO wheat experiment in Canberra, Australia.  The experiment was being conducted by CSIRO (the USDA equivalent for Australia).  The activists posted video of the attack on You Tube.  They also posted "explanations" by activists who could be easily identified.  Although this is technically a criminal activity, it was more likely about publicity.  Greenpeace has been at the forefront of the anti-GMO movement since the late 1990s, and it has claimed victory for stopping the development of GMO wheat varieties.  It accomplished this by threatening miller/baker brands in Europe so that they put pressure on their suppliers.  Those heady days are fading for Greenpeace. 15 years and billions of acres into the GMO revolution, Greenpeace may just be attempting to defend conquered ground.  

The Future of GMO Wheat

There is now a farmer agreement to simulataneously commercialize GMO wheat in Australia, Canada and the US. That would prevent more trade black-mail 10 to 15 years from now when the renewed GMO research might yield commercial products.  The wheat that Greenpeace destroyed was a largely academic trial of a nutritional modification, but much work continues with drought tolerant and disease resistant wheats.  It is those lines that are potentially important for keeping up with ever-rising wheat demand in the developing world.  At a time when an unprecedented new food price regime is punishing the world's poor, Greenpeace may be feeling pressure from the questions, "What is the statute-of-limitations on saying that the sky is falling?" or "is it ethical to slow advances in food production when poor people are hurting because of it?"

Why Does This Matter?

Wheat matters because of its nutritional, historical, cultural, and philosophical importance to humanity.

Wheat Has a Significant Role in Human Nutrition

Wheat is not just any crop.  It is a major source of energy and protein for populations, both where it is grown, and in highly-dependent, importing countries (e.g. Subsaharan Africa, Northern Africa, increasingly in Asia).  Wheat is one of the most heavily traded of all crops, and has been since Roman times. High wheat prices effect a huge proportion of the world's population.  In its various ethnic forms, bread is truly "the staff of life."  It is also strategically important.  Nobel prize winner and Green Revolution leader, Norm Borlaug, put it well: "If you desire peace, cultivate justice, but at the same time cultivate the fields to produce more bread; otherwise there will be no peace."

Wheat Has Tremendous Historical Significance

In his ground-breaking book, "Guns Germs and Steel," Jared Diamond chronicles how some of the earliest human societies moved from a hunter-gatherer existence to a farm-based society in the Fertile Crescent or present day, Middle East.  Local, large-seeded, grain crops, and animals that could be domesticated for draft work were key to that transition.  Through simple selection for large seeds that stayed on the head for harvest, these ancient farmers (~10,000 years ago) created the first hybrid crop between wild spelt, emmer, and possibly other grains, to produce a new species - wheat.  As Diamond documents, the wheat and animals were able to help feed this version of Western Civilization as it spread East and West, eventually jumping oceans to North America, and later to the temperate zone of the Southern Hemisphere.  Wheat and Cows could not deal with the heat, diseases and insects of the tropics, and so people groups in those regions were not soon touched by the advances of Western civilization (good and bad).

Wheat Embodies Important Cultural Symbolism

In this regard, wheat shares a co-joined symbolic significance with grapes - which have also been the target of anti-GMO vandalism.  One of the earlier parings of wheat and wine (the natural storage form of grapes) is found in the story of Abraham - a figure claimed as the Father of both the Jews and the Moslems (~4,000 BCE).  After Abraham conquers five kings of Sodom to rescue his relatives, he is met by the mysterious figure, Melchizedek, who is described in the text as the priest and king of Salem (trans. Shalom, trans. Peace).  Melchizedek brings bread and wine for the victory ceremony.   Bread (unleavened) and wine are also important elements of the Passover meal with which the Jews commemorate their liberation from slavery in Egypt.  Bread and wine symbolism is also central to Christian Communion (or Eucharist) as Jesus self-identified the bread and wine of the Last Supper as representative of his body and blood.   When it comes to religious symbolism, it does not get more intense than these two targets of GMO modification and anti-GMO attacks

The Battle Over Wheat Is Representative of A Broader Philosophical Struggle In Post-Modern Society

In the early 15th century, the printing press enhanced the communication-potential of society, and accelerated the already developing, rational and pre-scientific, trends of preceeding centuries (Islamic Renaissance, European Renaissance, The Enlightenment).  One might have thought that the mega-communication potential of the internet age would have further enhanced the "Age of Reason."  Not so.  The term, "Renaissance Man," referred to the real possibility that one smart and educated individual could grasp most of human knowledge and esthetics several hundred years ago.  Today, one is lucky to be able to keep pace with whatever sub-field one chooses to pursue.

The Light of Knowledge drove out the darkness of Fear and Superstition that so characterized the "Dark Ages."  Today, Fear and Superstition are back with a vengeance.  Knowledge is often impotent because it has become too vast to access and stave off Fear, or to help most people separate real information from disinformation.  We no longer have a clear way of knowing what is true (epistemology).  Until the internet age we had a workable balance between logic (rational epistemology), experience and experiment (empirical epistemology), and accepting truth from recognized experts (authoritarian epistemology).  Now we seem to be moving towards simply choosing an authoritarian source of truth that is comfortable for our world view.  It is a sort of "don't tell me what I don't want to know" epistemology.  We pick the "news" channels, blogs, gurus or even comedians who tell us self-reinforcing information.  To open up our minds to all the different voices is just too overwhelming.

In the particular case of GMO crops, there are many people who only listen to the complete anti-GMO voices (e.g. greenpeace, agro-ecology advocates...). I wrote a blog post titled, "Way Too Much Angst About GMO Crops," which was intended to calm some people by explaining why very few crops will ever be GMO for a variety of reasons.  The post didn't have that effect at all,  as one can see in the 500+ comment stream on the Biofortified re-post of the blog.

This is Just One Front of A Much More Important Battle

But this argument about GMO wheat is a mere sub-set of something bigger than even agriculture.  It is really about the choice between risk management based on sound science or risk avoidancebased on the "Precautionary Principle."  The same is true of the Climate Change and Vaccine/Autism debates, as well as many more.  For me, as an agricultural scientist, I'm only going to try to reach open-minded people on agricultural issues.  This latest Greenpeace stunt was only a disaster for the scientists who lost a year of work.  The real stakes are about the broader struggle between science and precaution.

Wheat Field Image from Dag Endresen.  Please comment here and/or write me at applied.mythology@gmail.com