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As expected, the concentration of pesticide residues and the associatedrisk were especially high in unprocessed tomatoes stored for onlythree days, whereas storage and processing reduced the risk of adverseeffects considerably. The relatively rapid decay, with DT50 values of0.85–1.65 days,was most likely partly due to a combination of hydrolysisand microbial degradation, as none of the organophosphates areknown to be particularly volatile (British Crop Protection Council,2014). Chlorpyriphos, dimethoate and malathion all have documentedhydrolysis rates in the range of 0.5–6 days depending on pH (BritishCrop Protection Council, 2014), indicating that hydrolysis might be animportant degradation pathway under the humid storage conditions.In addition, all five organophosphates have reported half-lives in soilsof a few days, indicating that microbial degradation on the surface ofthe unwashed tomatoes could also be of importance (British CropProtection Council, 2014). The organophosphate half-lives in thisstudy are, however, in the very short end of literature values for environmentaldegradation, particularly considering the cool storage conditions,though degradation half-lives of chlorpyriphos residues in applesof b1 day have been reported (Knight and Hull, 1992). Hence, it cannotbe excluded that physical removal of the pesticides to the paper bagsthat the tomato sub samples were kept in during storage have playeda role in the decrease of the pesticides over time.Washing and peeling the tomatoes efficiently removed almost allchlorpyriphos and ethyl-parathion. This was expected, as these twoorganophosphates have log Kow values of 4.7 and 3.84, respectively,making them immobile in plant tissue and therefore located on theouter surface of the peel (British Crop Protection Council, 2014;Devine et al., 1993). Dimethoate, malathion and methyl-parathion,however, have log Kow values of 0.7, 2.75 and 3.0, making them xylemmobile. Dimethoate has, with its pKa of 2, also phloem-mobile properties(British Crop Protection Council, 2014; Devine et al., 1993). Thesethree organophosphates might therefore also end up in the tomatofruitsvia xylem or phloem transport from other parts of the plant,thereby being present in the tomato pulp in addition to the peel. Thisis most likely the main reason why washing and peeling removesthese three organophosphates less efficiently compared to chlorpyriphosand ethyl-parathion. A meta study investigating the reduction ofpesticide residue levels in fruit and vegetables found that washing onaverage reduced pesticide residues to 68% (CI95: 52–0.82) whereaspeeling on average reduced pesticide residues to 41% (CI95 :30–54%)(Keikotlhaile et al., 2010). The reductions found in the present studyfor dimethoate, malathion and methyl-parathion where washing andpeeling reduced the residues on day 3 to approximately 50% and 30%,fall well within the ranges found by Keikotlhaile et al. (2010).The cumulated chronic and acute risk of eating unprocessed tomatoeson day three was significant for both adults and children. This isdespite using the relatively low estimated daily intake of tomatoes inBolivia of 25 g/person/day, corresponding to 1/4 of a tomato per day(EFSA/FAO/WHO, 2011). As this number might well be a Bolivian average,it is our impression that the tomato consumption in the tomatogrowing areas of Bolivia is considerably higher, more likely resemblingthe 100–200 g/person/day typical for Caribbean countries and easternMediterranean countries (EFSA/FAO/WHO, 2011). Increasing thechronic consumption to more than 1/4 tomato per person per day,will also increase the chronic risk. In addition, it is important to emphasizethe fact that this study is confined to a small selection of pesticidesin only one food commodity. Other pesticides are also present in variousquantities in all cultivated commodities constituting a Bolivian diet. AVenezuelan study of organophosphate pesticide residues in six differentvegetables, though, found tomatoes to have the highest detection frequency(62.5%) (Quintero et al., 2008), making tomatoes an importantcrop to investigate. In addition to the pesticides measured as part ofthis study, tomato farmers reported the use of various other pesticides,of which the concentrations are unknown (Table A.1). A recent review,however, confirms the finding of for example pyrethroids, carbamatesand various fungicides in fruits and vegetables produced in low incomecountries (Syed et al., 2014). Some of these pesticides may give rise toadditional dose addition or synergistic or antagonistic effects. Carbamates,for example, have been reported on the list of pesticides usedin tomato crops in Bolivia (Table A.1). Since carbamates have the samemode of action as organophosphate pesticides, and in addition haveshown to synergize these (Laetz et al., 2009; Walker, 2009), thesecould contribute to a higher HI, thus yielding a higher risk. In Brazil,studies have shown that the cumulative intake of organophosphorusand carbamate pesticides by high consumers of fruits and vegetablesmay represent a health concern (up to 169% of the ARfD) (Caldas andJardim, 2012), hence, the problem seems to occur also outside Bolivia.Illegal pesticides were also found in Brazilian fruits and vegetables(Jardim and Caldas, 2012). In a total of 13,556 samples of 22 fruit andvegetable crops, rice, and beans analyzed within two Brazilian pesticideresidue monitoring programs between 2001 and 2010, 13.2% of thesamples revealed non-authorized active ingredient use (Jardim andCaldas, 2012). Most of the organophosphates found in the Bolivian tomatoesare all legal; however, ethyl-parathion is illegal in Bolivia andshould therefore not be found. In the present study, other illegal pesticidesfound included organochlorines. Even though the organochlorinesin general did not indicate a risk for adults, aldrin, dieldrin, endrin, andheptachlor are listed in Annex A of the Stockholmconvention, meaningthat most countries in theworld consider these chemicals so dangerousto humans and the environment that the chemicals should not be used(Stockholm Convention on Persistent Organic Pollutants, 2001). Heptachlor,which is classified as a possible carcinogen (WHO IARC, 2001),was detected in 85.2% of the Bolivian tomato samples, which is a veryhigh amount considering that Bolivia ratified the Stockholmconventionin 2003 and therefore has agreed not to produce or use these pesticidesfor any purpose since 2004. And though the organochlorines are persistentin the environment and the detected aldrin, dieldrin, endosulfan,endrin and metoxychlor therefore might be old residuescirculating in the environment, the high frequency of heptachlorcould indicate that it is still being used. A recent study showed considerableamounts of obsolete pesticides in the stocks in small holder farmhouses in Bolivia (Haj-Younes et al., 2015).A study of pesticide intoxications among Bolivian farmers from2002also showed that several banned and restricted pesticides such as aldrinand ethyl parathion were in use by more than 75% of farmers, and selfreported symptoms of pesticide intoxications by organophosphateswere common after pesticide handling (Jørs et al., 2006). Farmers
used very fewprotectivemeasures and had poor knowledge of the dangers
related to pesticides and the benefit of protective measures when
handling them (Jørs et al., 2006). Many low income countries have
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