hshawcross

Fruits and vegetables: the holy grail of health?

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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 washing is. I understand it helps, but is there any investigation, showing how much pesticides remain in fruits after washing?

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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, diarrhoea 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 effect of low concentrations monotonous pesticide exposure, and most certainly the prenatal development stage exposure is not accounted for duly, check what TDI means in black on white, it is one size fits all, 140kg male and 50kg female and <0.001kg foetus.

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Hope in the nearest future we will give up non-organic products full stop, or at least will reduce their amount significantlly. I am so sorry that a lot of people still don't want to accept the fact that we are being poisoned when eat supermarket food. When I talk to my friends and colleauges, most of them agree that organic is much healthier, but they continue to buy everything in ordinary supermarkets. I believe it is my task to promote healthy lifestyle and will continue to persuade them to switch to organic food. Join me in this task. Let's make this world better! :)

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On 6/7/2017 at 7:01 AM, alexherb said:

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, diarrhoea 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 effect of low concentrations monotonous pesticide exposure, and most certainly the prenatal development stage exposure is not accounted for duly, check what TDI means in black on white, it is one size fits all, 140kg male and 50kg female and <0.001kg foetus.

alexherb, certainly a good point on the gov calculate toxicity thresholds, to some human being 140 kg MRL can be increased twice although for the foetus it may be the irreversable brain damage below MRL.  

According to the source [1] "safety" limit is MRL (Maximum Residue Level). "MRLs are set at the highest level of pesticide that the relevant regulatory body would expect to find in that crop when it has been treated in line with good agricultural practice (GAP). When MRLs are set, effects of the residue on human health are also considered. The MRLs are set at a level where consumption of food containing that residue should not cause harm to consumers."  

This wording is too generic and in legal language is a nullity, it's way too vague to state they measure "harm to consumers" without the fully explicit print and conditions. Indeed, it may hide the fact that long term exposure is not accounted, moreover it can hide anything else. How can we trust such sources? 

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People! Don't read it! Carry on eating fruits and vegetables, although remember an excess - kills, moderation - saves! 

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One thought came to my mind, it maybe a bit weird, but it may be true. What if there was a huge conspiracy about healthy lifestyle? Someone decided to promote healthy lifestyle just to get more money. How? Look at all organic stuff, products are much more expensive than regular stuff. I understadn that producing organic food may be connected to higher expences, but I do not think it is always true and still it is always and always dearer. Also, I have concerns about all these harmful effects that you describe. I think humans would still live careless and relatively healthy life even if there wasn't such ubiquitous promotion of health. Someone found a humankind weakness - everyone wants to live longer. That's why people will believe any lier who will tell: this product is expensive, but it will make you live up to 100 years and you will be healthy during all your life.

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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. Each chemical applied on farmlands must be approved, there must be clear evidences of its harmlessness, even if it is natural. And vice versa, I'm confident there are a lot of 'natural' substances which are too toxic to be appled on crops and so on, check out Rotenone already banned despite it comes from seeds and plant roots as a source !

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