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A crucial part of a healthy lifestyle is generally considered to be the inclusion of plenty (5-7 portions per day) of fruit and vegetables in our diets. However current farming practices include the use of pesticides, antibiotics and hormones to treat crops in order to increase output via higher crop production and faster plant growth. Furthermore, by limiting pest damage, the use of pesticides can also enhance the looks of produce. These chemicals can remain on the surface of fruits and vegetables, even on organic varieties,[1] contaminating them and leading to pesticide ingestion by consumers.

Unfortunately, the drugs, hormones, and pesticides currently in use can be hazardous to humans if consumed in a quantity large enough. By definition, pesticides are designed to kill, and the majority are toxic to humans at some level.[2] Organophosphates (OPs) are a group of organic compounds containing phosphates that are frequently used in pesticides and are known to be toxic to humans.[3], [4], [5] 

Studies into the effects of OPs have mainly been carried out in subjects that are exposed to OPs through their occupation, for example, farm workers or crop sprayers. These studies have found the symptoms of OP poisoning to include nausea, abdominal cramps, diarrhoea, dizziness anxiety, and confusion.[6] Fortunately, as severe as the symptoms may be, they are frequently reversible.[6] There have not been as many studies in people who have not been occupationally exposed to pesticides, but those undertaken have found that exposure to a low dose over a long period of time may be associated with neurodegenerative conditions such as Parkinson’s disease.[7], [8] Furthermore, prenatal exposure may result in long term irreversible changes in the brain structure of the unborn child, resulting in a lower IQ and a poorer memory.[9], [10], [11]  One of the larger studies, examining a nationally representative sample of children exposed to a chronic low dose of pesticides, found an increased chance of attention deficit hyperactivity disorder (ADHD) in children aged 8-15 years old.[12] Increased quantities of OPs were also found in their urine, indicating systemic exposure.[12]

The degree of damage that pesticides such as OPs can inflict is directly proportional to the amount of substance ingested. It is not disputed that pesticide residues are present on fruit and vegetables, which unfortunately means that, in the quest to remain healthy by eating high proportions of fruits and vegetables in their daily diet, many consumers may also potentially be ingesting high levels of toxins. Could it be that the ‘healthier’ the diet based on a higher fruit and vegetable content, the higher the risk of toxicity? Test data obtained in 2014 from the US Department of Agriculture and the Federal Drug Agency found that as little as 1.7% of tomatoes, 2.2% of cherries, 1.7% of strawberries and 2.5% of peaches were pesticide free, meaning that over 97% of these products were contaminated with these chemicals.[13] The average potato had more pesticide residue by weight than any other produce tested,[13] which is of particular concern as many people eat potatoes most days.[14] The UK’s 2014 Pesticides Residues Committee Annual Report stated that, of 3,615 samples tested, 56.2% had no pesticides, 41.9% contained pesticides below the ‘safe’ limit and 1.9% above the limits.[1] 

Whilst these tests mean that the vast majority of pesticide residues were well below the maximum residue limit (MRL) and are therefore unlikely to be toxic, some products did exceed the MRL. Nevertheless, the health benefits of eating plenty of fruit and vegetables remain clear and rather than omitting them from the diet whatsoever, it is advisable to wash fruits and vegetables well. Some studies suggest that washing with salt water is an effective way of removing pesticides.[15], [16] Indeed one study using chinese cabbage found that washing with soda-salt water removed as much as 60% of pesticides.[17] An even better approach is to peel them when possible, to remove the potentially harmful wax that is applied during processing.[18] 

Furthermore, whilst organic produce generally contains less pesticide residues than non-organic produce, even these fruits and vegetables are not guaranteed pesticide-free.[19] Tests performed in the EU identified pesticide residues in a wide range of organic food products, even finding traces of the highly toxic dichlorodiphenyltrichloroethane (DDT)[20] Organic regulations stipulate that pesticides can be used in organic production, as long as the chemicals are ‘natural’. However one such ‘natural’ pesticide, rotenone, has been linked to the development of Parkinson’s disease in humans,[21] with such a strong effect that it is now used to create animal models of Parkinson’s disease.[22] With the help of more robust regulations governing organic production, organic fruits and vegetables should one day be the exception to the pesticide--contamination rule. However until then, care should also be taken to wash and peel organic produce.


[1] National Archives. (2016)  Retrieved September, 2016, from http://webarchive.nationalarchives.gov.uk/20151023160002/http://pesticides.gov.uk/Resources/CRD/PRiF/Documents/Results and Reports/2014/PRIF Annual Report 2014 FINAL.pdf 

[2] Damalas, C. et al. (2011) Pesticide Exposure, Safety Issues, and Risk Assessment Indicators. Int J Environ Res Public Health, 8(5), 1402 - 1419.

[3] Costa, L. (2006) Current issues in organophosphate toxicology. Clinica Chimica Acta, 366(1-2), 1-13.

[4] Kerami-mohajeri, S. et al. (2011) Toxic influence of organophosphate, carbamate, and organochlorine pesticides on cellular metabolism of lipids, proteins, and carbohydrates.Hum and Experiment Toxicology, 30(9), 1119-1140.

[5] Kamanyire, R. (2004). Organophosphate toxicity and occupational exposure. Occupational Medicine, 54(2), 69-75.

[6] Peter, JV. et al (2014) Clinical features of organophosphate poisoning: A review of different classification systems and approaches. Indian J Crit Care Med, 18(11), 735-45.

[7] Slotkin, T. et al. (2011) Developmental exposure to organophosphates triggers transcriptional changes in genes associated with Parkinson's disease in vitro and in vivo. Brain Res Bull, 86(5-6), 340-347.

[8] Berry, C. et al. (2010) Paraquat and Parkinson's disease. Cell Death and Different, 17(7), 1115 - 1125.

[9] Ruah, V. et al. (2012) Brain anomalies in children exposed prenatally to a common organophosphate pesticide. PNAS, 109(20), 7871-7876.

[10] Cecchi, A. et al. (2012) Environmental exposure to organophosphate pesticides: Assessment of endocrine disruption and hepatotoxicity in pregnant women. Ecotoxicol and Environ Safety, 80(1), 280 -287.

[11] Columbia University (2016). Prenatal Exposure to Insecticide Chlorpyrifos Linked to Alterations in Brain Structure and Cognition. Retrieved September, 2016, from https://www.mailman.columbia.edu/public-health-now/news/prenatal-exposure-insecticide-chlorpyrifos-linked-alterations-brain-structure 

[12] Bouchard, M. et al. (2010) Attention-deficit/hyperactivity disorder and urinary metabolites of organophosphate pesticides. Pediatrics, 125(6), 1270-1277.

[13] USDA (2016) Retrieved September, 2016, from https://www.ams.usda.gov/sites/default/files/media/2014%20PDP%20Annual%20Summary.pdf         

[14] King, JC. & Slavin, JL. (2013). White potatoes, human health, and dietary guidance. Adv Nutr, 4(3), 393S-401S.

[15] Aktar, W. et al. (2009) Risk assessment and decontamination of Quinalphos under different culinary processes in/on cabbage. Environ Monit Assess, 163(1), 369-377.

[16] Vemuri, SB. et al. (2014) Methods for removal of pesticide residues in tomatoes. Food Sci Technol, 2(5), 64-68.

[17] Zhang, Y-S. et al. (2013) Study on universal cleaning solution in removing blended pesticide residues in Chinese cabbage. J Environ Chem Ecotoxicol, 5(8), 202-207

[18] Ministry of Fisheries, Crops and Livestock (2004) Retrieved October 2016 from, http://pdf.usaid.gov/pdf_docs/Pnacy849.pdf 

[19] European Commission (2008) Annex II: pesticides - plant protection products referred to in Article 5(1). Retrieved October 2016 from, https://members.wto.org/crnattachments/2016/TBT/EEC/16_0337_01_e.pdf 

[20] The Expert Committee on Pesticide Residues in Food. (2015) Report on the Pesticide Residues Monitoring Programme for Quarter 1 2015. Retrieved October 2016 from, http://webarchive.nationalarchives.gov.uk/20151023155227/http://www.pesticides.gov.uk/Resources/CRD/PRiF/Documents/Results%20and%20Reports/2015/Q1%202015%20FINAL.pdf 

[21] Nandipati, S. & Litvan, I. (2016) Environmental exposures and Parkinson’s Disease. Int J Environ Res Public Health, 13(9), doi: 10.3390/ijerph13090881 [epub ahead of print]

[22] Johnson, ME. & Bobrovskaya, L. (2015) An update on the rotenone models of Parkinson's disease: their ability to reproduce the features of clinical disease and model gene-environment interactions. Neurotoxicity, 46, 101-16.

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It would be interesting to know how effective the washing is. I understand it helps, but is there any research, showing how much pesticides remain on fruits after washing?

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I always wondered how organic production can save their products from pests without pesticides? I bet they use something to circumvent  pesticide bans of organic regulations, and still have some substances in, that are 'not forbidden' and thus otherwise 'allowed', so nobody knows if such chemicals are harmless because no one will ever test against not banned substances.

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Just 1.9% of fruits and vegetables have level of pests above the safe level? But what is considered to be safe? When it does not cause nausea, diarrhea and so on? I think that this "UK’s Pesticides Residues Committee" hide the truth or just don't want to see that there is a long term monotonous exposure effect of low concentrations of pesticides not accounted for well but still very insidious. 

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What? 'natural' pests are ok? But 'natural' doesn't mean non-hazardous at all! There are a lot of poisons in nature. "The dose makes the poison" and there is no difference if substance is natural or synthetic. In the perfect world each chemical used on farmlands must be safety approved, there must be clear evidences of its harmlessness, even if it is natural. I'm sure there are a loads of 'natural' substances which are toxic but  still allowed to use as no one much cares today especially with so much synthetic poison used in fields as well as inhouse.

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