Is the Dirty Dozen reliable?
The most recent version of the The Dirty Dozen has been released. This is an annual list of the “dirtiest” produce put out by the Environmental Working Group (EWG). This list claims that the produce in it has the highest numbers of conventional pesticide residues, and should be avoided. Instead, that produce should be purchased if it is organic. The Dirty Dozen list makes headlines each year and heavily influences consumer food purchases. I get asked all the time: how legit is the list? Is it worth purchasing exclusively organic produce the is on the list?
There are various reasonable concerns about whether a person should purchase organic or conventional produce, regarding nutrition, pesticides and environmental concerns. Let’s cover some common questions I get about organic vs conventional produce, as well as my take on the Dirty Dozen list.
What is the difference between organic and conventional foods?
Organic agriculture methods refers to farming practices of crops or animals without the use of synthetic (man-made) fertilizers, pesticides and other growing materials, and genetically-modified organisms (GMOs). Organic agriculture does NOT mean chemical-free or pesticide-free. Pesticides and herbicides used in organic farming are often actually used in larger quantities than conventional. The difference is they can’t be synthetically manufactured (with a few exceptions). Conventional agriculture can use both natural and synthetic growing materials.
A food may be labelled organic by the United States Department of Agriculture (USDA) if 95% of its agricultural ingredients are organic. Additionally, soil must be free of restricted pesticides for certain periods of time.
Is organic produce more nutritious than conventional?
Sometimes yes, and sometimes no. Research on the nutrient-density of organic and conventional produce finds inconsistencies to be able to make a blanket statement. Conventional produce tends to be higher in some nutrients, while organic tends to be higher than others. For example, a recent meta-analysis including 343 studies found that antioxidant and polyphenolic compounds were significantly higher in organic than conventional produce. However, levels of proteins and amino acids, fiber and vitamin E were lower in organic than conventional.
When looking at the totality of evidence, it is impossible to make a strong blanket statement about the nutrient-density of organic vs conventional produce. The only other compounds that seem to be a little higher in organic produce are antioxidant compounds, but this is not enough to say that organic is nutritionally superior because 1) of other lower nutrients and 2) higher antioxidant levels does not necessarily translate to relevance for health outcomes. To add to the nuance, nutrient-density can differ between crops of different varieties, farms, geographic location and span of time from harvest to consumption. So overall I believe we can say that all produce, no matter what growing method, is nutritious.
Is organic produce more environmentally friendly than conventional?
From a global food supply perspective, organic growing methods are not as sustainable as conventional. Farmers would never be able to feed everyone with exclusively organic growing methods. This is because they require significantly more resources to achieve the same crop yield.
Interestingly, a mix of conventional and organic agriculture practices would probably be the most environmentally sustainable. Take a look at this graphic based on a meta-analysis, describing environmental impacts of various agricultural products. You can click on the image to be linked to the source.
Is organic produce safer than conventional?
This is a hotly contested question and is at the center of the Dirty Dozen list. Let’s clarify what pesticides are first. Pesticide are used to protect crops from bugs and prevent disease.
Levels of pesticides are regulated with an upper level of pesticide residues allowed in or on a food, with the lowest exposure needed to cause no reasonable harm. Food safety policy and enforcement is fragmented in the United States, meaning that various agencies play different roles, instead of the common notion that the government acts as one giant monolith in policy. While the Environmental Protection Agency (EPA) sets limits for pesticide residues, the Food and Drug Administration (FDA) enforces those limits.
The upper level of pesticides allowed in or on foods is set far below the estimate where even no observable effect has been identified in risk assessment studies. In the most recent report on pesticides in the food supply, over 99% of tested food tested well below upper allowable limit.
Overall, is it worth following the Dirty Dozen list and/or purchasing organic products?
In my opinion, the overall scientific data we have does not support purchasing organic over conventional, or vice versa. There are trade-offs regarding nutrition and environmental impacts for each. I do not think there is a right or wrong choice. However regardless of your choice, conventional produce is safe to consume and the benefits of increasing fruit and vegetable consumption far outweighs concerns for risks from synthetic pesticide residues. This is the far larger issue at hands for the general public and should be farther up our list of priorities that whether you consume conventional or organic agricultural products. Additionally, I have had many patients who struggle with taking steps towards consuming more produce, because of the financial and emotional overwhelm that comes with confusion and a higher price tag with organic produce. This is an important factor to consider, especially currently when the cost for groceries is so inflated.
That being said, if organic fits in your budget and you feel it is right and a priority for you, there is no issue with that either. Likely a combination of conventional and organic products would address concerns of nutrition, environment and safety.
So, back to the Dirty Dozen- you probably won’t be surprised to hear me say that I don’t think it’s a relevant or useful list. Beyond conventional produce being safe to consume, simply looking at the methodology of how the EWG constructs the list does not make a whole lot of sense. They rely on number of unique residues, rather than concentrating on the amount of residues. This means that an apple that has 5 unique residues at 100x under allowable levels is called “dirty” rather than a plum with 2 unique residues at 50x under allowable levels. This makes no sense. Additionally, the EWG does not count organic pesticides into their methodology. This is important because although organic pesticides are usually not synthetic, a product being natural does not inherently make if safer.
I also have concern about bias from the EWG. It is commonly misperceived as a scientific organization when in reality it is a special interest group, receiving funding from and serving the interest of organic companies… while also not transparently disclosing all donors in its financial reporting to the public. The EWG has been highly criticized for years by the scientific community because of its gross over-exaggeration of toxicology concerns across foods, cosmetics, cleaning agents and more, which necessarily influences consumer purchasing patterns.
