How can we do pesticide-conscious grocery shopping?

Hi Everyone,

First of all, let me wish you all a very Happy and fruitful New Year, may it be filled with lots of love and success!

During this time of year most of us reflect on the past year, draw our conclusions from the lessons we have learned and set new goals and challenges for the next year. Some of these so called New Year’s resolutions are directed towards living a healthier lifestyle. People want to make better choices regarding their eating habits, do more exercise, spend more time in nature, be more present in their everyday lives, etc. In one of my previous blogs ( I have already explained to you the main roles of pesticides and the importance of their detection, but I haven’t spoken about the pesticide content of the different food items, so I thought this blog would provide a great opportunity to introduce you to the so called “dirty dozen” and “clean fifteen”.

During the application of pesticides, the amount of residues (detectable traces of chemicals) that remain in or on our food can vary based on the different pesticides that have been used, their method of application and the type of food itself. The most determinative parameter of pesticides is their persistency, which is the indicator of how long they take to decompose. Regarding the application, the crops are not only treated with pesticides when the crop is in its growing phase but can also be subject to seed treatments or post-harvest treatments that can help with transportation, storage or the appearance of the product. The different food items may contain the residues of only one pesticide or the residues of multiple pesticides as well. Furthermore, due to the new systemic type of pesticides unfortunately nowadays pesticides don’t just remain on the surface of the food items but are present in the inner parts of the products as well, which means that peeling or washing the fruits and vegetables before eating them is often not enough to protect us from the harmful effects of the pesticides. The people who are the most susceptible to these harmful effects are generally young children and expectant mothers. If they are exposed to certain pesticides at critical stages in their development, it can interfere with particular organs and their functions. The pesticides that are of particular concern are the ones that can affect the hormone system of the body (endocrine disrupting chemicals) causing cognitive and brain development problems, learning disabilities and attention deficit disorder.

Driven by the above mentioned health reasons, the Environmental Working Group (EWG) of the United States has established a so called “dirty dozen” and “clean fifteen” list which they actualize each year. The list is based on the analysis of pesticide-testing data that has been generated by scientists in the U.S. Department of Agriculture and the Food and Drug Administration. Using the obtained data, they rank the different foods according to how likely they are to contain pesticide residues. The list is especially useful for those of us who can’t afford to buy everything organic, as it can help you decide which products (the ones that are most likely to be contaminated) are safer to buy organic and which are the ones that can also be bought from non-organic shops/markets.

You can see the lists of dirty dozen and clean fifteen of 2019 below:


Since these lists were done based on data that has been obtained in the US, (and the regulation of pesticides is different in every geographical region) I have also looked into the situation in Europe and have found similar lists that have been assembled by the government of the UK based on their data of a five-year period. (They have put their focus on multi-residues due to the fact that our regulatory system can only assess the safety of one pesticide at a time and misses the so called “cocktail effect”.)

The dirty dozen and clean fifteen of the UK

Comparing the two lists you can see that in the UK citrus fruits are the ones that contain the most amount of pesticides (mainly on their peels), which can be due to the fact that the US version doesn’t include the testing of the non-edible parts of foods. Apart from this difference the two lists are fairly similar, in our case (for people living in Europe) the list based on the data of the UK could be more accurate.

I hope that all this data hasn’t scared you away from eating fruits and vegetables, because that wasn’t my intention at all. I only wanted to make you aware of the current situation regarding pesticide residues in/on our foods and I hope that these lists will be of use for you in deciding which products to try to buy organic and which ones are safe to buy commercial (non-organic) when you are going to the supermarket or your local markets.

As you can see, pesticide residue detection is of utmost importance nowadays being the main reason why within the FoodSmartphone project I am working on the development of a sensor that will be able to detect even low amounts of pesticides and could be used on-site (by the farmers to directly test their own products), helping us in avoiding that food items containing pesticide residues above the maximum residue limits (MRLs) could reach the market.

Thank you very much for reading my blog and see you next time,




1 comment on “How can we do pesticide-conscious grocery shopping?

  1. Stephanie May

    Could you post a blog showing the dirty dozen and clean fifteen for New Zealand please?


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