From what I read on various blogs and their comment streams, it is obvious that there are a lot of people who are very concerned about toxins in their food and water. Many say they want to live in a “toxin-free world.” Although I would be the first to say that there are some toxins that are worth worrying about, my concern is that there are a lot of people suffering from excessive angst about toxic substances because they don’t know two important facts:
Fact 1. Our world is actually full of toxins – mostly of natural origin.
Some of the natural toxins are really scary, but some of them are delicious or useful. Some of my favorite natural toxins include the caffeine in my morning coffee, the capsaicin in the spicy Mexican and Thai dishes I love, and the tomatine in the tomatoes I eat. These are all natural chemicals that are actually toxic – even quite a bit more toxic than a typical pesticide today. So why is it OK to enjoy these and many other foods that contain toxic chemicals? That is where the second fact comes in.
Fact 2. There is an important difference between hazard and risk.
The reason that so many people are troubled by the idea of toxins is that our educational system fails to teach us what we need to understand which toxins are really worth concern and which are not. We don’t tend to learn the difference between hazard and risk.
To illustrate this, consider electricity. Electricity is an extremely useful thing, but it is also extremely hazardous. People can and do die from electrocution. But although electricity will always be hazardous, we take important steps to make sure we are not exposed directly to the electricity and thus the risk is low. Our appliances can be safe even though they are powered by a very hazardous thing.
What About The Toxins in Our Food?
So even though I consume lots of plant-based chemicals that are actually toxic (a hazard), the quantities are low enough that the risk is too low to worry about. For instance, I calculated that for me (at 175 lbs), it would take 169 cups of strong coffee (~90 milligrams of caffeine in each) to get enough to be lethal (a dose of 192 mg/kg could be toxic to mammals). With a “safety margin” of 169, it is reasonable that few people worry when they consume this toxin every day.
What about the sort of toxins that people do worry about – like pesticide residues on foods? Each year a group in the USDA buys produce from stores around the US and tests it for pesticide residues. You can get the data on line. The Environmental Working Group uses this data each year to come up with their “dirty dozen” list which they successfully use to scare consumers away from buying as much fresh produce. That is unfortunate because what the USDA data actually shows is that the pesticides (which are almost all much less toxic than caffeine) are also present at such low levels as to be negligible.
To demonstrate this, I took the data for strawberries in 2008. The USDA labs tested 741 samples for hundreds of different pesticides and found some trace of around 5/sample. I took that data and calculated the safety margins for every single pesticide residue that was detected (assuming 1/2 lb of strawberries consumed by me at 175 lbs). The smallest safety margin was 5,895 – thirty five times less risky than a cup of Joe. 92% of the residues detected on the strawberries had safety margins of of over million (see chart below). Not much to be scared about here!
But What About the Long Term?
“But,” many people will say, “what about long-term exposure to low doses?” This is obviously something much more difficult to study. The best approach has been to test the medium-term (1-2 year) effects of a fairly high, but non-lethal dose. Practically speaking, this is the only way to get an answer within any reasonable time and budget constraints (still costing many millions of dollars). These tests have identified carcinogens and chronically toxic materials among both natural and synthetic chemicals. Many such tests have been conducted with caffeine and the consensus result is that, no, it is not a carcinogen or chronic toxin of concern at the levels we consume. We have learned fairly well how to screen for compounds with chronic effects and such tests are required for all pesticides.
The Professional Doubters
The Environmental Working Group ignores this data and maintains that “we just never know” whether there might be low level effects. If they are right, then we are mainly at risk from natural toxins. We consume them at far high rates, and in most cases, they have never even been studied for chronic effects. If we accept the view of the EWG, there really isn’t much of anything that we could eat without fear of some long-term downside. That sort of view is good for EWG’s fundraising efforts. It is not a good thing for encouraging the consumption of healthy foods.
I don’t know about you, but I would rather just enjoy my food – toxins and all.
Strawberry and Coffee image from smittenkittenorig
Safety Margin Graph by Steve Savage using USDA AMS PDP data
Still prefer organic? We’ve got you covered… from organic foods to bedding, bathing, and care products for the little ones in your home.
I appreciate your viewpoint here, Steve (and enjoyed our conversation about it while walking along the beach in San Diego a few weeks ago), but also thought I’d get the conversation going. One of the things I like about EWG is their willingness to provide some transparency on chemicals in products (their cosmetics database comes to mind immediately)… and I think that a combination of transparency from the corporate sector, along with more education on toxins, might do quite a bit to quell some incidents of unnecessary unrest. Do you think the agricultural sector might be willing to be more transparent about the toxins (using the term broadly, as you have) with their products?
I think understanding the difference between risk and hazard is an incredibly powerful idea. I think it’s one that we as a culture have lost, applied to what we eat, but in many other areas too from child rearing to national security.
Thanks very much for the post!
I don’t know how much more transparent you can get. All the labels governing use are easily available on line as is the toxicology data in the form of MSDS documents. All the EPA analysis is available on-line. The USDA residue data is all also available on-line in both summary and raw form. I would say that EWG’s analysis is what isn’t transparent – they essentially obscure the clear message of the USDA data. The chemical companies are not allowed to make relative safety claims – that is dictated by EPA. So essentially, they are not allowed to tell their story which is that pesticide safety has improved dramatically vs what it was in the past.
Good post Steve. This is an issue that comes up over and over again. And no matter how much data I show about the chemicals in a cabbage, for example, people remain clueless.
This is a good paper about natural pesticides:
Dietary pesticides (99.99% all natural)
Have to agree on the dozen or so coffee toxins–those would be my most frequent voluntary intake ones.
Thanks! What concerns me about the public misunderstanding on this issue is that it has been shown to reduce fruit and vegetable consumption. That is clearly a bad thing.
Also thanks for the link to the PNAS paper. I’ve been invited to talk about this topic at an Ontario vegetable growers meeting in February and that will give me some more good reference points.
I think you are right about the failure to differentiate between hazard and risk in many aspects of life. It extends from the “precautionary principle” for anti-terrorism efforts.
Excellent treatment of the subject. A point of light in an otherwise dark blogosphere of bad science and invalid assumptions. As for transparency, California farmers submit use reports to their County Ag Commissioner every month detailing pesticide applications and those reports are public record. Also, as soon as an application is finished, California farmers are required to post a report that can easily viewed by their employees stating what was applied, where and when. That, along with easy web access to MSDS, pesticide labels and all the other information mentioned above makes pesticide use in California about as transparent as it can be.
Steve is bang on re: transparancy and agriculture, particularly US agriculture, more specifically California agriculture. NO one in the world informs their customers more of how their food is actually grown.
The chemicals used in farming today contrasted with those of even 15 years ago pale in comparison regarding toxicicity. Phermones, BT’s, and short lived spinosids have taken the place of carbamates and organophosphates. Evolving technology has revolutionized the ability to respond to pest threats. Workers, consumers, and the environment have been protected as never before. The EWG continues to cast aspersions on food products that offer solutions to obesity, heart disease and yes, cancer. Agriculture’s reputation is wrongly sullied by the charges of the EWG but the real victim in this tragedy is the misled consumer who in error fears the very fruits and vegetables that can save their life.
Albert and Rod,
Because of site management issue I can’t approve your comments yet, but I definitely agree with what you are saying. They should be posted soon
Great post! Thanks for putting such things into perspective.
I think the issue is less about the pesticide residues you’re eating than it is about the pesticide in the ground, the water, and the air. Producing the pesticides is a pretty toxic undertaking, too.
It’s the same with using chlorine bleach. The amount you use in your home isn’t such a big deal, but producing it is quite harmful, so I leave the use of chlorine to those who really need it (hospitals, for example, and public swimming pools).
I’m glad you brought this up. Perhaps many people are thinking as individual consumers on this, instead of thinking of it as an agricultural issue. If you’re just thinking about pesticide residues, it may not be worth the extra cost for organic foods. If you look at the overall effects, though, it’s worth the trouble.
Actually, there has been a dramatic change in pesticides over the past three decades such that most are no longer hazardous during production or in use – nothing like the bad old days before EPA and before people understood all of this. In fact, almost all modern pesticides are quite a bit less toxic than something like the copper fungicides used in Organic and much less damaging to the environment. I will be putting up a post about that tomorrow on “Red Green and Blue.”
The replacement materials I mentioned, spinosad, BT, and phermones, are all ORGANICALLY registered compounds that have been formulated so effectievely that they have become cornertones of what is called “Inegrated Pest Management”. It is a pest control strategy that borrows heavily from organic tools to manage pest populations- not fully organic but when compared to strategies of 15 years ago, the difference is drastically different. These compounds and others have provided tools to ‘conventional’ farming that have revolutionized pest control. Unfortunately, many people only see them as pesticides and lump them into an archaic class of compounds that they have no relation to. The times have been changing. Pest control has as well. The consumer of American produce has a lot to be pleased with, not only in produce quality but in food safety as well.
Steve and Rod, that’s excellent news.