This past April, Economist Marc Bellemare published a paper in the American Journal of Agricultural Economics related to food borne illness and farmer's markets. He discussed this work previously in the New York Times:
"And even if our results did identify a causal relationship between farmers markets and food-borne illness, it would not be possible to identify the precise mechanisms through which this happens, and it would be a critical mistake to conclude that the foods sold at farmers markets are themselves to blame. That is because most cases of illness are caused by consumers who undercook or fail to wash their food. Indeed, our results may suggest that many people erroneously believe that food bought at farmers markets needn’t be washed because it is “natural.”
"The correlations we have identified certainly constitute an issue that farmers, distributors, vendors, consumers and academics should look into more closely. Though more research is needed to identify any possible causes, policy prescriptions could be as simple as encouraging patrons of farmers markets to wash their produce more thoroughly"
I've though more about this over the last couple years and refined a bit what I think the implications of this are as well. I agree, one explanation of the robust correlations found in this work could in fact be that 'many people erroneously believe that food bought at farmers markets needn’t be washed.'
A second important question might be, what is a motivating factor for washing produce in general? I have a hunch for at least some of the population it's....pesticides. Misinformation and propaganda from special interest groups and the Environmental Working Group's Dirty Dozen list can lead consumers to overestimate the risks associated with consuming fruits and vegetables and pesticide exposure (see: Winter and Katz,2011). It is possible an exaggerated concern about pesticides crowds out the realistic risks associated with food borne illnesses.
While I discuss empirical evidence below, I recall not long ago an anecdotal example. Just outside of a Whole Foods Market in Washington D.C. I witnessed a family opening and eating strawberries just bought without first taking them home and washing. Then I heard something astonishing..."its OK kids we don't have to wash these because they are organic."
The long term public health consequences could be much greater. In an era when we are battling childhood obesity and type II diabetes, increased consumption of fruits and vegetables is a great weapon to have in our arsenal of defenses. According to Montonen et al (2003) and Yang et al (2014)
"consuming one additional gram of fiber per 1000 calories is conditionally associated with a 9.4 percent decrease in type-2 diabetes" and consuming "3.5 fewer grams of sugar per 1000 calories is conditionally associated with a ten percent decrease in death rates from cardiovascular disease."
Additional research indicates that the negative impacts of misinformation about pesticides could have even greater impacts on low income individuals, who might opt out of consuming fruits and vegetables completely or at a much reduced rate. Yancui et. al. state:
"messages naming specific FV with pesticides shifted participants toward “less likely” to purchase any type of FV regardless whether organically or conventionally grown"
It looks like messaging by special interest groups that exaggerate the claims about pesticide exposure and risks are not encouraging increased organic fruit and vegetable consumption among lower income groups, and even worse may be leading to decreased consumption. Given the impact this could have on long term health, and the negligible differences between risks associated with organic and conventional produce consumption (Winter and Katz,2011), these special interests are doing little good and possibly doing harm from a public health perspective.
The takeaway is that both farmers markets and grocery store chains are great places to purchase fruits and vegetables both organic and conventional and consumers should be encouraged to purchase more based on their availability and affordability while practicing safe food handling practices. Nutritionists, food service providers, physicians, scientists, and public health advocates should work to countervail the misinformation campaigns of special interests and promote healthy eating as effectively as they can.
Farmers Markets and Food-Borne Illness
Marc F Bellemare Ngoc (Jenny) Nguyen
American Journal of Agricultural Economics, Volume 100, Issue 3, 1 April 2018, Pages 676–690, https://doi.org/10.1093/ajae/aay011
Montonen, J., P. Knekt, R. Jarvinen, A. Aromaa, and A. Reunanen (2003): “Whole-grain and fiber intake and the incidence of type 2 diabetes,” American Journal of Clinical Nutrition, 77, 622–629.
Yang, Q., Z. Zhang, E. Gregg, D. Flanders, R. Merritt, and F. Hu (2014): “Added Sugar Intake and Cardiovascular Diseases Mortality Among US Adults,” Journal of the American Medical Association Internal Medicine, 174, 516–524.
Winter, Carl K., and Josh M. Katz. “Dietary Exposure to Pesticide Residues from Commodities Alleged to Contain the Highest Contamination Levels.” Journal of Toxicology 2011 (2011): 589674. PMC. Web. 28 July 2018.
Low-Income Shoppers and Fruit and Vegetables: What Do They Think?
Huang, Yancui MS; Edirisinghe, Indika PhD; Burton-Freeman, Britt M. PhD, MS
Nutrition Today: September/October 2016 - Volume 51 - Issue 5 - p 242–250