Every year, the Environmental Working Group (EWG) releases its Dirty Dozen list of the fruits and vegetables with the most pesticides. And every year, many media outlets dutifully report on it, offering consumers what’s seen as the middle ground: Can’t afford to buy organic? Just avoid these foods.
The non-profit organization — which receives some funding from the organic food industry — has made headlines for its reports on other issues like lead in lipstick and chemicals in sunscreens, but the Dirty Dozen seems to be a perennial winner. “We think it’s notable that there are very big differences between the amounts of pesticides on the crops people eat, and that’s information that the government has generated — but it’s not formatted or presented in a way that’s [easily understandable],” says EWG senior analyst Sonya Lunder. “We’re helping people understand what has the most pesticides residue on it.”
The underlying concept — that less pesticide residue is better for you — is rarely questioned in these reports. After all, the concept is so solidly ingrained in our culture that nearly half of Canadians think organic food is both healthier and more nutritious. But are they right?
Does eating organic improve your health?
Though regulators around the world use slightly different definitions, organic produce is generally grown without synthetic pesticides and fertilizers, and organic fruits and vegetables are not GMOs. You can generally trust that if you’re buying something labelled organic, it is, says Wendy Benson, a dietitian who co-authored an evidence summary for the Dietitians of Canada‘s Practice-Based Evidence in Nutrition on Organic Foods.
But that doesn’t mean organic food is free from pesticides. A 2014 Canadian analysis found that nearly half of the organic fruits and vegetables on our grocery-store shelves had synthetic pesticide residue on them from a variety of sources, including pesticides blowing over from neighbouring farms. And organic farms also use organic pesticides, which can be chemically similar to synthetic ones. One of the most popular organic pesticides is Bt, the same pesticide engineered into many GMO crops.
Despite this, it’s widely recognized that organic produce has significantly less synthetic pesticide residue on it. It’s not clear, however, that those levels are bad for your health. To find out if pesticide on produce is dangerous “from a toxicology standpoint, we’d want to look at the levels of pesticides on the food, the amounts, and the toxicity of the pesticide,” says Carl Winter, food toxicologist at The University of California, Davis.
In a 2011 study, Winter attempted to answer that question and look at the EWG’s Dirty Dozen in a more scientific way. He approximated how much pesticides people were ingesting by calculating the levels of pesticides detected on the top foods listed and how much of that food people generally ate. He then compared those numbers against the Environmental Protection Agency’s Reference Doses, which are 1/100th of the long-term levels that cause negative effects in lab animals. (Health Canada sets similar Maximum Residue Limits.)
Winter found the pesticide residues were at “very low levels” – in fact, for 75% of levels they looked at, people’s exposures would be one million times lower than the levels that show an effect on animals. Keep in mind, this is for the produce that was flagged by EWG as particularly pesticide-laden.
Benson agrees. “The Maximum Residue Limits give us a huge buffer zone,” she says. She points to an online calculator that shows how many servings of food a person would need to eat to reach the adverse effect level when the fruits and vegetables tested highest for pesticide residue. A child would need to eat 175 servings of blueberries in a day, for example. A woman would need to eat 529 servings of apples in a day to reach an unsafe level.
Are pesticides safe?
Animal studies like those done by the EPA are one good way of estimating the effects pesticides have on humans. But the best science looks directly for a connection, delving into whether people who eat organic foods are less likely to have certain diseases. Unfortunately, there are no long-term studies that compare the impacts of eating organic and conventional foods.
But, as a 2012 systematic review pointed out, there are a few short European observational studies that looked at the impact of eating organic on rates of disease. Two looked at whether organic diets in children affected the rates of eczema, wheezing and atopic sensitization, which leads to allergies, and another looked at a common cause of food poisoning. None found any difference between organic and non-organic diets.
Some people worry about the impacts of pesticides because of the effects seen on farm workers. And indeed, the pesticides farm workers are exposed to through their work have been known to cause miscarriages, birth defects, cancer, respiratory problems and memory disorders, among other things. One well publicized 2011 study of farm workers found that prenatal exposure to organophosphate pesticides was related to lower IQ scores in their children.
That and other studies have led to concerns over pesticide exposure in pregnant women and children. A 2014 systematic review looked at those studies and found that “prenatal exposure to organophosphate pesticides may affect neurodevelopment and behaviour in infancy and childhood as well as children’s cognitive and motor function” at levels equal to those found in the top 25% of the U.S. population. It also found that the results were too mixed to draw any conclusions about the impact after pregnancy, on babies and children eating non-organic food.
Is organic food more nutritious?
Another health reason people buy organic food is the belief that it contains more nutrients. This is hard to study, because organic produce is actually quite diverse in this way, with the amount of nutrients significantly affected by the quality of the soil, the growing conditions, and when the food is harvested, among other things.
Fortunately, despite this, it has been researched. Some studies have found organic produce is higher in vitamin C and phytochemicals, but the results have been mixed — and even if that’s true, the small differences are unlikely to make you healthier. A 2012 review found there were no differences in nutritional quality between organic and conventionally grown foods, with the exception of limited evidence suggesting there may be higher omega-3 fatty acids in organic milk, and higher phosphorus in organic produce. The latter is unlikely to have an effect on health, however, since as the study noted, “near-total starvation is needed to produce dietary phosphorus deficiency.”
More recently, a 2014 meta-analysis grabbed headlines by looking at nearly 350 global studies and finding that organic produce had more antioxidants. The study’s methods were the source of a bit of controversy — and more importantly, we’re not sure how well our bodies absorb antioxidants from those foods, if antioxidants actually improve our health, or how much of them we should be eating in the first place.
Bottom line: “If consumers are buying organic foods with the fundamental belief it’s more nutritious, or healthier, and paying a premium for it, they’re being misled,” says Benson, though she does recommend rinsing produce under water before eating it to help remove remaining pesticides and bacteria.
What’s the impact of talking about organics?
Discussing the impacts of organics leaves out — and may muddy — a larger issue, which is that Canadians don’t eat nearly enough produce, with only 40% of Canadians eating at least five servings of fruits and vegetables a day.
After all, while the science behind organic foods is still in development, we do have substantial evidence that eating more fruits and vegetables can have a large impact on your health, significantly reducing your risk of cancer, cardiovascular disease and obesity.
And there’s some concern that the message that fruits and vegetables are incredibly good for you could be overwhelmed by emphasizing organics and, by extension, the pesticide content of conventional produce. A study from the Johns Hopkins Centre for a Livable Future titled “They just say organic is healthier” looked into whether organic messaging could have a negative result. They interviewed shoppers in a poor neighbourhood in Baltimore, finding that organic messaging can conflict with other messages about eating healthier, leaving people confused.
As one person they interviewed put it: “They advertised something on TV, like an apple a day keeps the doctor away. But then last week they advertised on TV the most unsuspecting foods you would think would be dangerous to you because of the levels of pesticides in it. Apples were the third one.”
Since organic produce is more expensive than conventional kinds, there’s also a concern that people will buy organic fruits and vegetables, but less of them.
“One of my biggest concerns is that the negative publicity surrounding pesticide residues in fruits and vegetables may lead a lot of consumers to reduce their consumption, which is the worst thing they could do,” says Winter. “If you’re buying for health effect, than eat lots of fruits and vegetables, period.”