Pesticide residue refers to the pesticides that may remain on or in food after they are applied to food crops. The maximum allowable levels of these residues in foods are often stipulated by regulatory bodies in many countries. Regulations such as pre-harvest intervals also often prevent harvest of crop or livestock products if recently treated in order to allow residue concentrations to decrease over time to safe levels before harvest.
Exposure of the general population to these residues most commonly occurs through consumption of treated food sources, or being in close contact to areas treated with pesticides such as farms or lawns.
Many of these chemical residues, especially derivatives of chlorinated pesticides, exhibit bioaccumulation which could build up to harmful levels in the body as well as in the environment . Persistent chemicals can be magnified through the food chain and have been detected in products ranging from meat, poultry, and fish, to vegetable oils, nuts, and various fruits and vegetables.
Each country adopts their own agricultural policies and Maximum Residue Limits (MRL) and Acceptable Daily Intake (ADI). The level of food additive usage varies by country because forms of agriculture are different in regions according to their geographical or climatical factors.
Pre-harvest intervals are also set to require a crop or livestock product not be harvested before a certain period after application in order to allow the pesticide residue to decrease below maximum residue limits or other tolerance levels. Likewise, restricted entry intervals are the amount of time to allow residue concentrations to decrease before a worker can reenter an area where pesticides have been applied without protective equipment.
Many pesticides achieve their intended use of killing pests by disrupting the nervous system. Due to similarities in brain biochemistry among many different organisms, there is much speculation that these chemicals can have a negative impact on humans as well. There are epidemiological studies that show positive correlations between exposure to pesticides through occupational hazard, which tends to be significantly higher than that ingested by the general population through food, and the occurrence of certain cancers. Although most of the general population may not exposed to large portion of pesticides, many of the pesticide residues that are attached tend to be lipophilic and can bio-accumulate in the body.
According to the American Cancer Society there is no evidence that pesticide residues increase the risk of people getting cancer.Pesticide exposure cannot be studied in placebo controlled trials as this would be unethical. A definitive cause effect relationship therefore cannot be established. The ACA advises washing fruit and vegetables before eating to remove both pesticide residue and other undesirable contaminants.
Pesticide residues in food
Pesticides are used to protect crops against insects, weeds, fungi and other pests.
Pesticides are potentially toxic to humans and can have both acute and chronic health effects, depending on the quantity and ways in which a person is exposed.
Some of the older, cheaper pesticides can remain for years in soil and water. These chemicals have been banned from agricultural use in developed countries, but they are still used in many developing countries.
People who face the greatest health risks from exposure to pesticides are those who come into contact with them at work, in their home or garden.
Pesticides play a significant role in food production. They protect or increase yields and the number of times per year a crop can be grown on the same land. This is particularly important in countries that face food shortages.
To protect food consumers from adverse effects of pesticides, WHO reviews evidence and develops internationally-accepted maximum residue limits.
There are more than 1000 pesticides used around the world to ensure food is not damaged or destroyed by pests. Each pesticide has different properties and toxicological effects.
Many of the older, cheaper (off-patent) pesticides, such as dichlorodiphenyltrichloroethane (DDT) and lindane, can remain for years in soil and water. These chemicals have been banned by countries who signed the 2001 Stockholm Convention – an international treaty that aims to eliminate or restrict the production and use of persistent organic pollutants.
The toxicity of a pesticide depends on its function and other factors. For example, insecticides tend to be more toxic to humans than herbicides. The same chemical can have different effects at different doses (how much of the chemical a person is exposed to). It can also depend on the route by which the exposure occurs (such as swallowing, inhaling, or direct contact with the skin).
None of the pesticides that are authorized for use on food in international trade today are genotoxic (damaging to DNA, which can cause mutations or cancer). Adverse effects from these pesticides occur only above a certain safe level of exposure. When people come into contact with large quantities of pesticide, this may cause acute poisoning or long-term health effects, including cancer and adverse effects on reproduction.
Pesticides are among the leading causes of death by self-poisoning, in particular in low- and middle-income countries.
As they are intrinsically toxic and deliberately spread in the environment, the production, distribution, and use of pesticides require strict regulation and control. Regular monitoring of residues in food and the environment is also required.
WHO has two objectives in relation to pesticides:
to ban pesticides that are most toxic to humans, as well as pesticides that remain for the longest time in the environment.
to protect public health by setting maximum limits for pesticide residues in food and water.
Who is at risk?
The most at-risk population are people who are directly exposed to pesticides. This includes agricultural workers who apply pesticides, and other people in the immediate area during and right after pesticides are spread.
The general population – who are not in the area where pesticides are used – is exposed to significantly lower levels of pesticide residues through food and water.
Prevention and control
Nobody should be exposed to unsafe amounts of pesticide.
People spreading pesticide on crops, in homes, or in gardens should be adequately protected. People not directly involved in the spread of pesticides should stay away from the area during and just after a spread.
Food that is sold or donated (such as food aid) should comply with pesticide regulations, in particular with maximum residue limits. People who grow their own food should, when using pesticides, follow instructions for use and protect themselves by wearing gloves and face masks as necessary.
Consumers can further limit their intake of pesticide residues by peeling or washing fruit and vegetables, which also reduces other foodborne hazards, such as harmful bacteria.
Background: Pistachio is one of the main nutrients, not only as a strategic crop but also as a main type of nut, in Iranians’ food cycle. The aim of this study was to measure the relative safety of Iranian pistachio based on the standard pesticide’s residue limits, which should be monitored and assessed in the cultivation of pistachio in order to confirm its public health.
Results: Identified pesticides included Fenitrothion, Carbaryl and Diazinon. Detectable pesticide’s residue existed in 10% (5 samples) of the samples .Conclusion: All the results were compared with the Iran’s National Standards and the European Maximum Residue Limits. As compared to the acceptable daily intake, the calculated daily intake of each pesticide was much lower than the standard level, which could not cause any public health problem.
to the increasing growth of the world population and importance of health issues, demand for healthy food has increased. Pesticides are the most important chemicals consciously used by people to preserve agricultural commodity. Residues of pesticides in crops may have harmful effects on consumer, classified into acute and chronic effects .Thus, specification of pesticides’ residue in farming crops and comparing the residues with the maximum residue limit (MRL) is necessary in the agriculture industry . MRL is the index for the maximum concentration of pesticides allowed in food, farming products and animal food.It also refers to the duration in which edibles may be preserved without posing a danger to human health. This is why MRL standards have been agreed on as controlling criteria of pesticides in crops. Pistachio nuts, Pistacia vera L., are grown for economic purposes in countries such as Turkey and USA. The Iran is also one of the major producers and exporters of pistachio nuts in the world. Pistachio is considered as a rich source of antioxidant compounds such as phytoestrogens and also as a strategic cropfor export . There is no database on the residue level of pesticides in the pistachio nuts in Iran. Although many scientists have analyzed the pesticide’s residue level in various foods, the analysis of pesticides in nuts has been carried out only infew studies. Therefore, determining the pesticide’s residue in this crop is essential for consumers, producers and the national supervisory authorities. The main aim of this study was to assess the relative safety of Iranian pistachio based on the standard pesticides residue limits and the potential health risk to local inhabitants.
EU‐coordinated programme (EUCP)
To allow the assessment of representative consumer exposure to pesticide residues by food commodity, the same pattern of commodities is monitored for the presence of pesticides residues in 3‐year cycles. Regarding the 2017 EUCP, results were compared with the ones of 2014 for those commodities sampled in both years.
In 2017 EUCP, 12 food products were considered: oranges, pears, kiwi fruits, cauliflowers, onions, carrots, potatoes, beans (dried), rye grain, husked rice grain, poultry fat and sheep fat. Kiwi fruits, onions and dried beans were included in the programme for the first time, so no comparison with results of 2014 was possible for these three food products. The samples taken were analysed for 171 pesticides; 149 of those in food of plant origin, 8 in food of animal origin and 14 in both food of plant and animal origin.
Of the 11,158 samples analysed in these food commodities:
7,236 or 64.9% were found to be without quantifiable levels of residues (residues < LOQ).
3,743 or 33.5% contained one or more pesticide residues in concentrations below or equal to the legally permitted maximum residue levels (MRLs).
179 or 1.6% contained residue concentrations exceeding the legally permitted MRLs. Among these, 80 or 0.7% of the total samples were considered non‐compliant, when also considering the measurement uncertainty.
For products of plant origin, the highest MRL exceedance rates were identified for pesticide residues found in rice and pears followed by dried beans, carrots, rye, kiwi fruits, potatoes, oranges, cauliflower and onions.
Of the 28 MRL exceedances reported for pears in 2017, 4 of them were originated from third countries, the rest being of EU origin. Noteworthy MRL exceedances were reported for chlormequat, ethephon, chlorpyrifos and propiconazole.
For rice, MRL exceedances were recorded in 48 samples, 28 of which originated from South‐East Asia, most of them from India (21). Twenty‐three of the MRL exceedances in rice were reported for carbendazim (RD).1 Among the 39 pesticides with residue levels at or above the LOQ, the ones most frequently quantified were isoprothiolane (quantified in 12.1% of the tested samples) and bromide ion (quantified in 10.1% of the tested samples).
Pesticides not approved in the EU should not be found in samples grown in the EU. However, these can be used in third countries as long as they do not exceed the legal limit when entering the EU market. Among commodities of plant origin, the following non‐EU‐approved pesticides were found in samples produced in the EU: dieldrin (RD), parathion‐methyl (RD), and procymidone (RD) in carrots, dicloran in onions, fenthion (RD), methidathion and profenofos in oranges, permethrin in pears, clothianidin in potatoes, biphenyl and carbendazim (RD) in dried beans, carbendazim (RD), permethrin and dichlorvos in rice and permethrin in rye. Whereas, in samples originating from third countries, the following pesticides exceeded the legal limits: methidathion in kiwi fruits, chlorfenapyr, methidathion and profenofos in oranges, carbaryl and diazinon in dried beans, acephate, carbendazim (RD), hexaconazole, methamidophos and triazophos, in rice.
Regarding commodities of animal origin (i.e. poultry fat and sheep fat), the most frequently quantified pesticides were fat‐soluble persistent organic pollutants (dichlorodiphenyltrichloroethane (DDT) (RD) and hexachlorobenzene). Although the persistent organic pollutants (POPs) are prohibited at international level under the Stockholm convention (UNEP, 2001), they are still found in the environment mainly due to their persistence. Apart from an MRL exceedance identified for lindane in one sample of sheep fat, no exceedances were reported in samples of animal origin.
EU‐coordinated and national programmes (EUCP + NP)
The overall EU pesticide monitoring programmes for 2017 incorporate the results of both the EUCP and national programmes, as implemented by the 28 Member States, Iceland and Norway.
The reporting countries analysed 88,247 samples for 801 pesticides. On average, 229 pesticides were analysed per sample. Most of the samples (56,718, 64.3% of the total) originated from the reporting countries (EU, Iceland and Norway); 25,409 samples (28.8%) were from products imported from third countries. The origin of the products was unknown for 6,120 samples (6.9%).
Overall, 95.9% of the samples analysed (EUCP and national programmes) fell within the legal limits (84,627 samples),2 i.e. the measured levels did not exceed the MRLs permitted in EU legislation. In 4.1% of the samples, the residue levels exceeded the MRLs (3,620 samples). Considering the measurement uncertainty, 2.5% of the samples (2,221 samples) exceeded the legal limits (non‐compliance) triggering legal or administrative actions. 54.1% of the samples tested did not contain quantifiable residue levels (residue levels were below the LOQ) and 41.8% contained quantified residues below the MRLs.
In 2017, the MRL exceedance rate was 4.1% vs 3.8% in 2016. This difference between 2016 and 2017 can be explained to a certain extent by the increased number of enforcement samples taken in 2017, which was more than twice the number taken in 2016 (10,677 enforcement samples in 2017, or 12.1% of total samples vs 4,173 samples in 2016, or 4.9% of total samples). This demonstrates the importance and effect the targeted controls can have on detecting MRL exceedances.
Residues in unprocessed food products were not quantified in 51.7% of the samples; 44% of them contained quantified residues within the legal limits and 4.3% exceeded the MRLs. Processed products had a higher rate of samples without quantified residues (71.4%) and a lower occurrence of quantified residues (25.9%) as well as a lower MRL exceedance rate (2.7%).
Samples from third countries had a higher MRL exceedance rate (7.6%) and a higher non‐compliance rate (5.5%) compared to food produced in the EU, which had MRL exceedance rate of 2.6% and non‐compliance rate of 1.3%.
Regulation (EC) No 669/2009 on import controls covered 76,789 consignments of products imported to the EU; 10,089 of these consignments were selected for laboratory analyses of which 304 (3.0%) were considered non‐compliant with the MRLs in place.
Reporting countries analysed 1,546 samples of baby food. In 94.6% of the samples, quantifiable residues were not reported (residues were below the LOQ), whereas 84 samples (5.4%) contained quantifiable residues at or above the LOQ. Twenty‐three of these samples (1.5% of samples) exceeded the MRL of 0.01 mg/kg applicable for baby food.3 Residues of glyphosate and persistent environmental contaminants were not found above the limit of quantification in any of the baby food samples analysed. The most frequently measured residues were chlorates, copper, dodine, mercury and spinosad. However, chlorates, copper and mercury residues may also originate from different sources, so their presence is not necessarily linked to the use of pesticides (e.g. food processing by‐products, natural occurring substances, environmental contaminants, etc.).
Overall, 5,806 samples of organic food (excluding baby food samples) were sampled; 5,010 samples (86.3%) did not contain quantifiable residues, whereas 711 samples (12.2%) contained residues within legal limits; most of these samples contained only residues of substances that do not necessarily come from a pesticide use (e.g. naturally occurring substances and persistent organic pollutants). The MRLs were exceeded in 1.5% of the organic samples analysed (85 samples), of which 0.7% (38 samples) were non‐compliant.
Most of the animal origin products analysed were free of quantifiable residues (8,475 samples out of 9,682, 87.5%) while 1,207 samples (12.5%) were found to contain one or several pesticides in quantified concentrations. MRL exceedances were identified in 102 samples (1.1%) of which 66 samples (0.8%) were non‐compliant considering the measurement uncertainty. In 2016, the MRL exceedance rate was 1.9%, mainly due to chlorate residues in milk.4
Multiple residues (i.e. more than one pesticide in the same sample) were reported in 24,292 samples (27.5%). The frequency of multiple residues in unprocessed products (29%) was higher than in processed products (12.0%). In unprocessed products, the highest frequency of multiple residues was found in currants (black, red and white) (71.7% of samples), blackberries (69.3%), limes (65.2%), lemons (63.3%), sweet cherries (62.5%), strawberries (61.7%) and lamb’s lettuce/corn salads (61.0%). These commodities coincide with findings from previous years.