Pesticide residue legislations challenge international ...

84 I cereal technology 02/2020

Peer revIew Pesticide testing / MRL / rice trade

AbstractThe diversity of maximum residue levels (MRLs) for plant protection products among the countries worldwide challenges the international food trade. This article describes this diversity and its impacts on the rice supply chain based on the practical experience of an international inspection and analytical company and pesticide testing of 2,592 samples in 2019. Economic impacts of MRLs are illustrated with the example of Basmati rice imports into the EU, where Indian rice exporters lost estimated revenues of over 200 million USD from January 1st 2018 to August 31st 2019 due to a drop in the MRL for tricyclazole from 1 to 0.01 mg/kg. The article furthermore describes that certain substances in food are frequently interpreted as residues from agricultural practices and fall under the EU MRL regulation for pesticides, although they might be - and frequently are - of natural origin or are contaminants not related to agrochemical applications. Examples are high concentrations of the natural plant hormone indole-3-acetic acid in cereal seeds, accumulation of bromide by Brazil nuts, phthalimide and mepiquat generated during food processing involving heat, chlorate from chlorinated water, and nicotine, diethyl-meta-toluamide (DEET) and icaridin from the hands of workers during harvesting and further handling of the crop. Phosphonate can be introduced into the food by agricultural applications of the fungicide fosetyl or plant strengthening phosphonate salts. But it can be also of natural origin, as microorganisms produce the chemical in biogeochemical phosphorous cycles in various environments. Problems arise not only, when these chemicals exceed the legal MRLs. For organic food they are often interpreted as indicators of forbidden pesticide applications and in infant food they frequently exceed the stringent default MRL of 0.01 mg/kg of the EU. Regarding the occurrence of phthalimide and phosphonate results from the analysis of 3,210 tea and spice samples and 1,417 further food samples are presented, which were obtained in the period of 2017 to 2019.

Pesticide residue legislations challenge international trade of food and feed Werner Nader, Michelle Maier, Marco Miebach and Gabriel Linder

1. Introduction

Internationally, food safety legislations are diverse and the economic impacts of this diversity have been studied in detail by Bremmers et al. (2011) on the example of meat exports to the USA and the European Union. Melo et al. (2014) describe the burden of regulations and standards on exporting countries with Chilean fruit exports as an example.

García Martinez and Poole (2004) focused on the market barriers created by diverse fresh produce safety standards of the European retail chains on developing Mediterranean exporting countries.

In 2005, the EU implemented harmonized MRLs for plant protection products (Regulation (EC) No 396/2005) followed by stringent enforcement and reporting in the RASFF (Rapid Alert System for Food

cereal technology 02/2020 I 85

Pesticide testing / MRL / rice trade Peer reviewPeer revIew Pesticide testing / MRL / rice trade

and Feed), when limits are exceeded. The USA fol-lowed with the tolerance levels of the Environmen-tal Protection Agency (EPA) in the Code of Federal Regulations, Title 40, Chapter I, Subchapter E, Part 180 (Electronic Code of Federal Regulations, 2020, 40 CFR 180) and their enforcement in food imports by detentions without physical examination (DWPE) of the Food and Drug Authority (FDA). Australia and New Zealand set up MRLs in schedule 20 of the Food Standards Code and Japan with various regu-lations of the Ministry of Health, Labour and Wel-fare. Many countries like Saudi Arabia adapted the Codex Alimentarius MRLs and appended MRLs for additional pesticides (Saudi Food and Drug Admin-istration, 2019, SFDA.FD 382:2019). Pesticides, for which no MRLs have been defined, should not be present and a default MRL of 0.01 mg/kg applies within the EU and zero tolerance in the USA. In ad-dition, these MRLs are undergoing permanent re-visions depending on safety evaluations and deci-sions made by the national food control authorities (European Food Safety Authority (EFSA), 2008).

Rice is the most important staple food of mankind and traded in large quantities over national bor-ders. The international diversity of these MRLs, the dynamics of MRL definitions and the consequential economic impacts on the trade, will be described in the following, taking Basmati rice as an example.

Even more diverse is the interpretation of pesti-cides in food from ecological agriculture, where res-idues are tolerated differently by the control bodies of the EU member states (Forschungsinstitut für bi-ologischen Landbau (FiBL), 2013). These differences will be described below including the tolerance lev-els defined by the National Organic Program (NOP) of the USA.

In addition to this international diversity in food legislations several substances commonly found in food are interpreted as residues of pesticides or their corresponding metabolites in the EU and are regulated by MRLs, although they might be of nat-ural origin or contaminate the food independent-ly of agricultural applications. But even if they do

not exceed the legal MRLs and are of no health con-cern, trade with organic and infant food will be af-fected, because these substances are interpreted as residues from forbidden agricultural applications. A position paper of a German quality circle of lab-oratories in the field of pesticide and contaminant analysis (relana®, 2019) summarizes some of these contaminants in food and feed samples. This knowl-edge is primarily based on the practical experience of the trade and analytical laboratories and rarely substantiated by scientific studies, which are pub-lished in the public domain, which is the case e.g. for mepiquat (Yuan et al., 2017) and nicotine (Ro-manotto et al., 2018). In the following, the article will describe several of these cases with a special focus on phosphonate, where recent literature pro-vides scientific evidence that this compound is gen-erated by microorganisms and occurs ubiquitous-ly in significant concentrations in the environment (Pasek et al., 2014).

2. Source of results

This article is based in part on the practical expe-rience and analytical results obtained during pre-shipment inspections of various food products pri-or to export to the EU, USA and Australia, primar-ily outside of the EU. Results from the analyses of 2,592 rice samples in 2019 and 3,210 tea and spice samples from 2017 to 2019 were evaluated in an an-onymized form. Furthermore 1,417 samples of var-ious food products were analysed from 2017 and 2019 for the fungicide fosetyl and its metabolite phosphonate. Results are primarily based on analy-ses by the QuEChERS method (Anastassiades et al., 2003) adapted to these matrices. Due to their high-ly highly polar characteristics fosetyl-aluminum and phosphonate were analysed by a special method re-cently published by Anastassiades et al. (2019).

3. Global diversity of MRL regulations – example rice

Rice is the most important food commodity feed-ing nearly half of the world population and being traded on a global scale in large quantities over the



boarders. The EU has defined maximum limits for residues of 495 plant protection products in rice (EU pesticide data base, 2020), Japan 313 (The Ja-pan Food Chemical Research Foundation, 2020), Australia/New Zealand 173 (Australia New Zealand Food Standards Code, 2020), the US 140 (Bryant Christie Inc., 2020) and Saudi Arabia 59 (Saudi Food and Drug Administration, 2019). With the exception of Saudi Arabia residues of chemicals without a MRL are not permitted. For these zero tolerance applies in the USA and a default MRL of 0.01 mg/kg is set in the EU. In Saudi Arabia pesticides, which are not in-cluded in the national MRL list, are judged based on either EU or US MRL definitions.

Table 1 comprises the top 40 pesticides detected by analyses of 2,592 rice samples in 2019 with the number of findings above the limit of quantifica-tion and the average and maximum concentrations. Furthermore listed are the corresponding MRLs in the EU (previous, current and anticipated), USA, Aus-tralia New Zealand and Japan. The fungicides tebu-conazole, tricyclazole, isoprothiolane, propiconazole

and carbendazim, which are mainly applied against the fungal rice blast, and the insecticides imidaclo-prid, buprofezin, chlorpyrifos and thiamethoxam were found in over 10% of the samples each (fig-ure 1). Carbendazim is normally not applied in the paddy fields and is most probably the metabolite of thiophanate-methyl. The MRLs defined for these chemicals differ significantly between the coun-tries. Rice with high residue levels of isoprothiolane and tebuconazole is perfectly fine for the EU mar-ket while triggering import alerts in the USA. On the other hand high levels of tricyclazole and buprofe-zin might cause a rapid alert in the EU RASFF, but the rice can be imported without problems into the US. Japan and Australia New Zealand tolerate car-bendazim residues of 1 and 2 mg/kg respectively, whereas the default limit applies in the EU and zero tolerance in the USA.

MRLs are not only diverse, but also subject to con-tinuous changes depending on human and environ-mental safety evaluations. Changes of MRLs for 9 of the top 40 pesticides, which have been implemented

Fig. 1: Top 9 fungicides and insecticides occuring as residues in rice. Top, fungicides: (a) tebuconazole, (b) tricyclazole, (c) isoprothiolane, (d) propiconazole and (e) thiophanat-methyl (mostly detected by its metabolite carbendazim). Bottom, insecticides: (f) imidacloprid, (g) bu-profezin, (h) chlorpyrifos-ethyl and (i) thiomethoxam.

Gra

phic

: Wer

ner N

ader

202

0


Pesticide testing / MRL / rice trade Peer reviewPeer revIew Pesticide testing / MRL / rice tradeSo

urce

: Wer

ner N

ader

/ G

raph

ic: c

t 202

0

Table 1: Top 40 Pesticide findings in 2,592 rice samples analysed in 2019 and MRLs in the EU (past, current and anticipated), the USA, Australia New Zealand and Japan.Chemical Findings Maximum Average MRL (mg/kg)

Number mg/kg mg/kg EU past (brown rice)

EU current/anticipated (brown rice)

USA Australia NZ Japan (brown rice)

Tebuconazol 583 0.670 0.031 1.5 1.5 zero tol. 0.2 0.1

Imidacloprid 461 0.190 0.020 1.5 (0.01) * zero tol. 0.1

Tricyclazole 366 0.250 0.042 1 0.01 3 3

Isoprothiolane 364 0.980 0.091 5 6 zero tol. 10

Propiconazole 342 0.230 0.016 1.5 (0.01) * 7 0.1 0.1

Buprofezin 300 0.120 0.020 0.5 0.01 1.5 0.1 0.5

Chlorpyrifos (-ethyl) 294 0.650 0.027 0.5 (0.01) * zero tol. 0.1 0.1

Carbendazim 279 0.076 0.013 0.01 0.01 zero tol. 2** 1

Thiamethoxam 267 0.110 0.023 0.01 0.01 6 0.01 0.3

Difenoconazole 185 0.260 0.015 3 3 7 0.01 0.1

Azoxystrobin 170 0.480 0.021 5 5 5 0.1 0.2

Triazophos 115 0.085 0.013 0.02 0.02 zero tol.

Acetamiprid 108 0.083 0.015 0.01 0.01 zero tol. 0.1

Malathion 107 59.800 1.610 8 (0.01) * 8 8 0.1

Profenofos 79 0.057 0.010 0.01 0.01 zero 0.02

Trifloxystrobin 75 0.260 0.017 5 5 3.5 0.1 3

Carbofuran 66 0.006 0.001 0.01 0.01 0.2 0.2 0.1

Clothianidin 65 0.028 0.006 0.5 (0.01) * 0.01 1

Piperonyl butoxide 64 0.940 0.065 synergist, no MRL set 20 20 24

Acephate 59 0.200 0.018 0.01 0.01 zero tol.

Quinclorac 56 0.075 0.011 5 5 5 5 5

4-Bromo-2-Chlorophenol 52 0.150 0.012 profenofos metabolite, no MRL set

Hexaconazole 37 0.028 0.008 0.01 0.01 zero tol.

Fenobucarb 36 0.065 0.009 0.01 0.01 zero tol. 1

Pirimiphos-methyl 36 0.270 0.013 0.5 0.5 zero tol. 10 / 2 / 1 *** 0.2

Fipronil 33 0.054 0.007 0.01 0.01 0.04 0.01 0.01

Diphenylamine 32 0.058 0.021 0.1 0.1 zero tol.

Flubendiamide 23 0.140 0.031 0.2 0.2 0.5 0.1

Methamidophos 23 0.034 0.011 0.01 0.01 zero tol.

Dichlorvos 22 0.120 0.032 0.01 0.01 zero tol. 5.00 0.2

Cyhalothrin. lambda 20 0.042 0.015 0.01 0.2 1 0.01 0.5

Dithiocarbamates 18 0.050 0.011 0.1 0.1 indiv. 0.5 0.3

Flutriafol 18 0.037 0.012 1.5 1.5 zero tol. 0.02

2,4-D 16 0.018 0.007 0.1 0.1 0.5 0.2 0.1

Cyproconazole 16 0.063 0.034 0.1 0.1 zero tol. 0.01 0.1

Cypermethrin 14 0.110 0.029 2 2 1.5 1 0.9

Diethyltoluamide 14 0.035 0.011 biocide, no MRL set zero tol.

Dinotefuran 12 0.150 0.035 8 8 9 0.02 2

Phorate-sulfoxide 10 0.023 0.008 0.02 0.02 zero tol. 0.1

Thiophanate-methyl 10 0.018 0.005 0.01 0.01 zero tol.

* MRL change anticipated for 2020 | ** MRL defined for the husked rice | *** MRL of 10 for rice, 2 for husked and 1 for the polished rice



over the last 4 years or are anticipated in the EU, are shown in table 1. Only in two cases the MRL increased (isoprothiolane, from 5 to 6 mg/kg and lambda cyhalothrin, from 0.01 to 0.2 mg/kg), for all others the MRL was lowered or will be lowered to the default level of 0.01 mg/kg on short term.

4. Economic impacts of MRLs on the rice trade – example Basmati rice

Frequent MRL changes cause disturbances for interna-tional trade and the development of Basmati rice im-ports into the EU in figure 2 during the last 10 years is a good example. In 2010 isoprothiolane was de-tected in Indian Basmati rice, but was not included in the EU MRL list and therefore the default limit of 0.01 mg/kg applied (The Economic Times, 2010, Na-der et al., 2014). It was also not included in the ana-lytical scope of the laboratories, until the QuEChERS method (Anastassiades et al., 2003) was adapted to rice in 2010 and the pesticide showed up in the GC-

MS (gas chromatography with a mass spectrometer detector). As a consequence, Indian Basmati imports dropped by 22% or 47,613 metric tons (mt) in the fis-cal year of 2010/2011 with imports from Pakistan sub-stituting this volume (figure 2). Assuming an average price of 800 US Dollar (USD) per mt of cargo Basmati rice the financial loss for the Indian rice exporters can be estimated to 38 million USD. After an EFSA evalu-ation of the chemical, revealing no food safety con-cerns, the MRL was set to 5 mg/kg in July 2012 and In-dian Basmati imports increased by 105,442 mt or 60% in the fiscal year 2011/2012, whereas Pakistani im-ports dropped by 88,285 mt during the same period.

Till 2017 the MRL for tricyclazole in rice was 1 mg/kg, but was lowered to 0.01 mg/kg for all Basmati im-ports after January 1st, 2018, because the fungicide failed the EU wide approval. As a consequence Indi-an Basmati rice imports declined and volumes were to a large extent substituted by Pakistani Basmati (figure 2).

Fig. 2: Imports of Basmati cargo rice from India and Pakistan into the EU (Source: issued import certificates - communication of EU Mem-ber States, Rice News Today, 2020)

Source: Werner Nader / Graphic: ct 2020



The accumulating Basmati rice import volumes into the EU and the market shares of India and Pakistan in the period from January 13th, 2017 and August 26th, 2019 are shown in figure 3 a and b, respective-ly. In the three months before the deadline of the MRL change, January 1st, 2018, imports of Basma-ti from India increased significantly, flattened im-mediately thereafter and were then to a great por-tion substituted by imports from Pakistan (figure 3 a). The average market share of Indian Basmati de-creased from 73% during 2017 to 28% for the peri-od from 01.01.2018 to 26.08.2019. The total Basma-ti import volume into the EU was 635,243 mt during this latter period. Assuming the same market share for Indian rice exporters as in 2017 their loss in rev-enue due to the drop of the MRL for tricyclazole is estimated to 232 million USD at a price of 800 USD per mt.

But also for Pakistani rice exporters there is trouble ahead, as the MRL for chlorpyrifos-ethyl (figure 1 h), commonly detected in their rice, will drop in Octo-ber 2020 from 0.5 to 0.01 mg/kg, after it had been increased from 0.05 to 0.5 mg/kg just in 2018. Also the MRLs of four other pesticides common for rice will drop to default soon. Propiconazole is now ille-gal in the EU and the use of imidacloprid, clothian-din and malathion (table 1) is restricted to green-houses only due to risks for bees (imidacloprid and clothiandin) and birds (malathion).

Tricyclazole also affected Indian Basmati exports to the USA, which dropped in the fiscal year 2012/2013 due to residues of this fungicide, but recovered af-ter the import tolerance was increased from 0.01 to 3 mg/kg in 2014 (Nader et al., 2014).

5. Diversity of tolerance levels for pesticide residues in organic products

Under the current EU regulation (EC) No 834/2007 and the repealing regulation (EU) No 2018/848, which will apply from January 1st, 2021, only plant protection agents are permitted for organic pro-duction, which have been authorised in accordance with Regulation (EC) No 1107/2009 and have been assessed and found to be compatible with the ob-jectives and principles of organic production. Cur-rently these products are listed in annex II of the implementation regulation (EC) No 889/2008 and do not include synthetic chemicals, with some ex-ceptions for traps and dispensers. Due to their vast applications synthetic plant protection agents be-came ubiquitous and might occur in traces in or-ganic products by cross contaminations, e.g. due to drifts from neighbouring conventional farms. The current and the new EU regulation do not de-fine tolerance levels and leave the interpretation of residues to the private sector and national con-trol authorities. Limits are set by Italian law and in Belgium by the regional government of Wallonia

Fig. 3: Basmati rice imports into the EU from 13.01.2017 till 26.08.2019. Accumulated revenue (a) and market shares of Indian and Pakista-ni Basmati (b) (Source: issued import certificates - communication of EU Member States, Rice News Today, 2020).

Sour

ce: W

erne

r Nad

er /

Gra

phic

: ct 2

020

Sour

ce: W

erne

r Nad

er /

Gra

phic

: ct 2

020



(Forschungsinstitut für biologischen Landbau (Fi-BL), 2013). In Germany, the Association of Organ-ic Processors, Wholesalers and Retailers defines an orientation value of 0.01 mg per kg of the prima-ry product (Bundesverband Naturkost Naturwaren e.V. (BNN), 2012). Processing affecting the pesticide concentration has to be considered and residue lev-els have to be calculated back to the original prod-uct. Up to two synthetic plant protection products are tolerated as residues in concentrations at the orientation value. A measurement uncertainty of 50 % (relative, EU Commission, SANTE, 2019) can be considered, if the laboratory value exceeds 0.01 mg/kg. In other member states like the Netherlands the national control bodies for organic agriculture do

not even tolerate traces of residues, also not in pro-cessed food. In the USA pesticide residues in organ-ic products are tolerated up to a level of 5% of the corresponding MRL (40 CFR Part 180, see above) under title 7 of the Code of Federal Regulations, section 205.671 (7 CFR § 205.671). This means that pesticides with high MRLs are tolerated in high con-centrations also in organic products, e.g. 1 mg/kg glyphosate in organic soya beans due to the MRL of 20 mg/kg.

6. Potential misinterpretation of substances in food as pesticide residues

6.1. Indole-3-acetic acid –natural plant hor-mone or synthetic growth regulator from agri-cultural applications?

Indole-3-acetic acid (Figure 4) is the most promi-nent plant hormone belonging to the group of aux-ins. It promotes length growth and root initiation. Synthetic indole-3-acetic acid is used as a plant growth regulator to cause rooting of cuttings of plants, e.g. as a power dip on ornamental cuttings. Based on unclear toxicological data and indications of teratogenic effects in animal studies its use in the EU is not approved. Natural concentrations be-tween 0.01 and 0.1 in vegetative plant tissues (Ep-stein and Ludwig-Müller, 1993) were considered by the EFSA during the definition of a MRL of 0.1 mg/kg. But results from an earlier study by Bandurski and Schulze (1977) were not taken into account,

Fig. 4: Natural plant hormone (auxin) indole-3-acetic acid

Fig. 5: The fungicide fosetyl-aluminum (a) and its metabolite phosphonate (oxidation state +4, b). Furthermore 2 other oxidation states in the biogeochemical cycle of phosphorous, phosphinate (oxidation state +1, c) and phosphate (oxidation state +5, d) (Pasek et al., 2014).

Gra

phic

: Wer

ner N

ader

202

0

Gra

phic

: Wer

ner N

ader

202

0



which revealed much higher concentrations in cere-al seeds. In rice kernels the plant hormone was de-tected in concentrations of 1.7 for free and 2.7 mg/kg for total indole-3-acetic acid. Maize kernels even contained up to 78.5 mg/kg of the total plant hor-mone. It might be speculated that the seeds store these high amounts of auxin to stimulate rapid length growth of the stem during germination. Ce-reals therefore fail the EU MRL regulation by nature.

6.2. Phosphonate

Numerous chemicals are included in the EU MRL list, which are considered to be metabolites gener-ated by degradation of plant protection products, e.g. tetrahydrophthalimid, which can be clearly at-tributed to the fungicide captan. The MRL is then

based on the sum of captan and tetrahydrophthal-imid, expressed as captan. But many chemicals can be also compounds naturally occurring in environ-ment, by-products of food processing or environ-mental contaminants rather than residues from pesticide applications.

Fosetyl-aluminum (figure 5 a) is a fungicide and phosphonate (or phosphite) its metabolite (figure 5 b). MRLs in the EU are therefore defined for the sum of fosetyl, phosphonic acid and their salts, ex-pressed as fosetyl. This definition also includes po-tassium and disodium phosphonate, which are ap-proved for a variety of applications. Due to the low toxicity of these compounds MRLs between 2 (e.g. for cereals) and 500 mg/kg (e.g. for tree nuts) have been defined in the EU for plant products. EU reg-

Sour

ce: W

erne

r Nad

er /

Gra

phic

: ct 2

020

Table 2: Results of phosphonate analysis at Eurofins Global Control, 1,360 samples, 2017 to 2020. Further 57 samp-les of other products like millet, cacao, lineseed etc. are not listed, as neither fosetyl or phosmet nor phosphonate were detected in them.

ProductTotal samples

testedfosetyl phosphonate EU MRL > MRL

positive positive average maximumsample number % mg/kg %

Rice 522 0 10.2% 1.10 11.00 2 1%

Lentil 318 0 14.5% 1.96 18.70 2 2.2%

Apple 130 0 32.3% 0.86 5.00 150 0%

Chickpea 103 0 39.8% 0.62 4.00 2 3.9%

Bean 77 0 28.6% 5.55 34.50 2 10.4%

Banana 48 0 33.3% 0.41 0.68 2 0%

Quinoa 36 0 11.1% 0.57 3.30 2 5.6%

Wheat 34 0 11.8% 0.71 1.30 2 0%

Pea 33 0 12.1% 0.60 0.64 2 0%

Maize 16 0 25% 0.24 0.33 2 0%

Grapefruit 12 0 25% 1.07 1.60 75 0%

Grape 6 3 50% 1.73 2.70 100 0%

Broccoli 6 2 50% 16.97 28.70 10 33.3%

Almond 4 0 75% 3.54 6.20 500 0%

Pistachio 4 0 75% 4.05 6.90 500 0%

Ginger 3 0 66.7% 0.37 0.37 400 0%

Avocado 2 2 100% 21.75 41.90 50 0%

Cranberry 2 0 50% 0.58 0.91 2 0%

Mango 2 0 50% 0.89 0.89 2 0%

Fennel 1 0 100% 0.69 0.69 400 0%

Pear 1 0 100% 2.60 2.60 150 0%



ulation (EU) 2016/127 defines a limit of 0.01 mg/kg for residues of most pesticides in infant food and phosphonate falls under this limit.

For organic products, the BNN released a fact sheet on phosphonic acid, potassium phosphonate and fosetyl-Al (Bundesverband Naturkost Naturwaren, 2017). When fosetyl is not detected in the sample, BNN considers applications of potassium phospho-nate as the most probable source of phosphonate residues. Potassium phosphonate is applied as a plant strengthener against fungal infections, partic-ularly in grapes, which is not permitted in the EU for organic production since 2013. An orientation value of 0.05 mg/kg at the limit of quantification of most laboratories was defined by the BNN, above which the unauthorized use of plant strengtheners or fer-tilizers should be investigated at farm level. The BNN fact sheet argues against a natural occurrence of phosphonate in the environment in significant concentrations based on expert opinions, which re-fer to the rapid oxidation of phosphonate to phos-phate under aerobic conditions (Hofmann, 2012).

Table 2 summarizes the results from testing of 1,417 samples of different foodstuff from 2017 to 2019. Fosetyl was detected in 7 samples (broccoli, avoca-do and grape juice), but phosphonate in 259 or 18% of all samples. For pulses (lentils, chickpeas, peas and beans) 23% of the samples contained phos-phonate with an average concen-tration of 2.2 mg/kg and a maxi-mum of 34.5 mg/kg (beans). For cereals (rice, wheat, quinoa and maize) 21.6% of all samples were tested positive for phosphonate with an average concentration of 0.66 mg/kg and a maximum of 11 mg/kg (rice). The EU MRL for the sum of fosetyl and its metabo-lite phosphonate was exceeded in 4.1% of the samples of pulses, 1% of rice and 5.6% of quinoa. All 259 samples would have failed the 0.01 mg/kg limit set for in-fant food.

Six hundred seventy two samples were from organ-ic agriculture. Of these 71 or 10.6 % exceeded the BNN orientation value. In contrast to the BNN the European Organic Certifiers Council sets the lim-it for further investigations at 0.2 mg/kg (EOCC, 2018). Even considering this higher limit still 50 or 7.8% of the samples would fail.

But recent scientific data reveal that phosphonate is also produced by microorganisms, might occur ubiqui-tously in the environment in significant concentra-tions and can therefore be of natural origin also in the food. Pasek et al. (2014) analysed water from var-ious lakes and rivers in Florida and found phospho-nate and phosphinate (figure 5 c) in 28 of 32 samples in significant concentrations of up to 0.46 mg / l or 33% of the total dissolved phosphorus compounds. Further studies reveal that micro-organisms produce organic and inorganic phosphonates continuously by reduction of phosphate within biogeochemical phos-phorous cycles (Han et al., 2013, van Mooy et al, 2015). The phosphate (figure 5 d) is regenerated by oxidation of phosphonate either by assimilatory or dissimilatory processes. Figueroa and Coates (2017) provided evidence that the bacteria catalysing these cyclic processes occur ubiquitously.

A study by Varadarajan et al. (2002) furthermore in-dicates that plants might accumulate phosphonate, which could explain the high concentrations ob-

Fig. 6: The fumigation gases methylbromide (a) and phosphane (b)

Gra

phic

: Wer

ner N

ader

202

0



served for certain products in table 2. Plants take up phosphate via so-called Pi transporters, which do not differentiate between phosphate and phosphonate. In contrast to phosphate phosphonate cannot be metabolized and will therefore ac-cumulate.

Significant concentrations of phos-phonate were found in rice, which is grown submerged under anaero-bic conditions in the root area with a low redox potential. Even higher phosphonate concentrations than in rice are observed in pulses. The cause of these high concentrations has to be further investigated and both agricultural applications of phosphonate salts or accumulation of phosphonate produced by mi-cro-organisms naturally seem feasible at present. Pasek et al. (2014) reported particularly high con-centrations of phosphonate in anaerobic waters, which could be also the case in the water flooded paddy fields. Van Mooy et al. (2015) reported that nitrogen-fixing cyanobacteria in the oligotrophic surface ocean play a critical role in the reduction of phosphate to organic and inorganic phospho-nate. Legumes live in symbiosis with nitrogen-fixing bacteria. The BNN fact sheet considers convention-al phosphorous fertilizer as a potential source of phosphonate, but excludes the ground rock phos-phate authorized for organic farming as a source. We detected phosphonate in concentrations of 0.2 mg/kg in a biodynamic fertilizer prepared from cow and sheep manure, which can be also of microbi-al origin, e.g. from the anaerobic microflora in the foregut of the ruminants.

6.3. Bromide and phosphane, residues from fumigation

Fumigation with methyl bromide or phosphane (fig-ure 6 a and b) is a common procedure to protect food and feed against insect infestations. These

chemicals have in common that they either rapid-ly dilute into the atmosphere or decay to chemicals, which also occur naturally in the environment, in particular bromide and phosphorous compounds.

The MRL for inorganic bromide in the EU is 50 mg/kg. According to BNN bromide concentrations above 5 mg/kg indicate fumigation with the chem-ical and the source of this high value should be in-vestigated. But both the EU regulation and the BNN guideline do not consider that certain plants might naturally accumulate bromide from the soil in high concentrations. Furr et al. (1979) reported bromide concentrations of 87 mg/kg in Brazil nuts. These high concentrations were confirmed in a study per-formed by the food laboratory Wiertz-Eggert-Jöris-sen GmbH (today part of the Eurofins group) on be-half of the trade association Warenverein e.V. in Hamburg. Samples of Brazil nuts were directly ob-tained from the Peruvian rain forest and concen-trations of 40 to 190 mg/kg bromide were detected (Warenverein Hamburg, letter, 2015). As a conse-quence a MRL of 200 mg/kg for Brazil nuts was de-fined in the German national regulation for residues in food (Rückstandshöchstmengenverordnung, RH-

Fig. 7: Mepiquat-chloride (a) and phthalimide (b), potentially generated during food processing. Phthalimide is produced under heat from phthalic anhydride (c) and pri-mary amines, but can be also a metabolite of the fungicide folpet (d) or the insectici-de phosmet (e).

Gra

phic

: Wer

ner N

ader

202

0



MVO) which is still valid and contradicts the MRL of 50 mg/kg defined under EU regulation (EC) No 395/2005.

Recently trace amounts of phosphane below 0.005 mg/kg in rice were interpreted as an indication of fumigation, which is not permitted for organ-ic products (Stiftung Warentest, 2018). But also a natural origin of phosphane should be taken into consideration, as recent literature indicates its for-mation by methanogenic bacteria under anaerobic conditions (Cao et al., 2017).

6.4. Mepiquat and phthalimide – chemicals potentially produced during food processing

During processing of food products certain chem-icals can be formed, which are possibly misinter-preted as pesticide residues. Mepiquat (figure 7 a) is a plant growth regulator, which is applied in agri-culture to control stem growth, in particular in ce-reals and some oils seeds. It is approved in the EU with MRLs of 3 and 4 mg/kg for certain cereals and up to 40 mg/kg for certain oil seeds, but not al-lowed in organic agriculture. During roasting of cof-fee the chemical is generated by chemical reac-tions involving the Maillard reaction and a further N-methylation in concentrations above the MRL for coffee, 0.2 mg/kg. It is also produced during baking and

pan frying of potatoes and vegetables and might exceed the MRLs of 0.02 mg/kg defined for these foods (Yuan et al., 2017).

The fungicide folpet (figure 7 d) is used broadly for the cultivation of grapes, tomatoes and hops. During analysis the chemical frequently decays to phthalimide (figure 7 b) in the injection system of the gas chromatograph. In order to prevent an un-derestimation of its content the EU defined the MRL on the basis of the sum of folpet and phthalimide.

In 492 out of 3,210 samples of tea and spices ana-lysed by Eurofins Global Control phthalimide was detected in concentrations above the LOQ (0.01 mg/kg) with a maximum of 0.63 mg/kg. None of the samples contained folpet. The insecticide phosmet (figure 7 e), another potential source of phthalim-ide, was detected in only 2 samples. Phthalimide can be prepared by heating of phthalic anhydride (figure 7 c) with ammonia or primary amines. This process might also occur during food processing under heat (drying of tea and herbs, milling of spice etc.). Phthalic anhydride and its precursor phthal-ic acid are used in many technical products and oc-cur ubiquitously in dusts. In food it finds its reaction partner in the primary amines of the amino acids. The food laboratory Labor Friedle GmbH detected phthalic anhydride in many different food samples

Fig. 8: Chemicals in food frequently caused by cross contaminations: chlorate (a), N,N-Diethyl-meta-toluamide (b), icaridin (c) and nicotine (d)

Graphic: Werner Nader 2020



and could even demonstrate a positive correlation between the phthalimide and phthalic anhydride concentrations (relana, 2016).

Similarly to phosphonate phthalimide rarely ex-ceeds the MRLs of the EU. But problems might arise, when it is detected in organic food. Therefore the BNN recommends applying the orientation value only, when folpet or phosmet are also detected in the sample (Bundesverband Naturkost Naturwaren, 2016).

6.5. Chlorate, diethyl-meta-toluamide, icaridin and nicotine

Salts of chlorate (figure 8 a) have been used as non-selective herbicides and are banned in the EU. A de-fault MRL of 0.01 mg/kg applies. But the chemical can also be generated as a side product in chlorinat-ed water by disproportionation of chlorine to chlo-ride and chlorate. Since chlorinated drinking wa-ter is a standard in many countries, chlorate can be detected in many food products above the default MRL. This even includes rice, which has been pol-ished under a mist of water to achieve a silky shine of the kernels. Due to the frequent occurrence of chlorate the EU plans to define MRLs above the cur-rent default limit ranging from 0.05 mg/kg for cere-als to 0.7 mg/kg for leaf vegetables, herbs etc. (EU Commission, SANTE 10684-2015 rev. 8). Residues of disinfectants like chlorate and quarternary ammo-nium compounds (e.g. didecyldimethylammonium chloride and benzalkonium chloride) in food will be-come even more frequent due to the vast applica-tions of these chemicals during the COVID-19 pan-demic.

Diethyl-meta-toluamide (DEET) and icaridin (figure 8 b and c) are common insect repellents, classified as bi-ocides by EU legislation and not covered by regulation (EC) No 396/2005 with defined MRLs. Until recently they fell under § 1 (4) Nr. 2 b of the German regulation for maximum limits of residues (RHMVO, Bundesministeri-um für Justiz und Verbraucherschutz, 2020) with a de-fault MRL of 0.01 mg/kg. This limit has been deleted. The chemicals occur primarily in plant products, which

are harvested or processed by hand, e.g. pine nut kernels, berries, wild mushrooms, herbs and spic-es. DEET was detected above 0.01 mg/kg in 33 out of the 3,210 samples of tea and spices, which are mentioned above. The EU plans to set reference val-ues between 0.05 to 1 mg/kg for internal trade with certain products.

Nicotine (figure 8 d) has been used as a natural in-secticide and is banned in the EU with a MRL of 0.01 mg/kg for most products. But it might occur in food by cross contaminations, e.g. from hands of smok-ing workers or from air and dust from neighbouring tobacco fields, as was recently shown by Romanot-to et al. (2019) for Indian tea gardens. According-ly the EU defined higher transition MRLs up to 0.6 mg/kg for tea, wild mushrooms, certain herbs and spices, until the causes of these contents have been clarified.

7. Resume

Imports of Basmati rice from India and Pakistan in-to the EU and the USA are good examples for the impacts of pesticide MRLs on the trade and rev-enue losses for exporters can be significant, as is shown above. In particular, for farmers in these re-mote source countries it is difficult to adapt to per-manent changes in MRLs as was shown for the EU with isoprothiolane, tricyclazole, buprofezin, chlor-pyrifos-ethyl, propiconazole, imidacloprid, clothian-din and malathion. In the USA, zero tolerance was repealed for tricyclazole, buprofezin and difecona-zole, but persists for tebuconazole and isoprothi-olane. In addition farmers and exporters have to watch developments in other major markets for Basmati rice, the Gulf States, the Iran, Canada and Australia.

Not only for the layman it is difficult to understand, why a product like rice with residues of tricyclazole and buprofezin slightly above 0.01 mg/kg cannot be commercialized in the EU, but is perfect for the US mar-ket in even 100 fold higher concentrations. Tebucon-azole and isoprothiolane cause problems in the USA, but are totally fine for the EU in high concentrations.



Global trade with food and feed products would ben-efit from the harmonization of MRLs on a global scale and regulation (EC) No 396/2005 is a good example, as it brought the different residue limits of the member states into line for the common market. But even de-spite this harmonization discrepancies persist within the EU, e.g. for bromide in Brazil nuts with an EU MRL of 50 mg/kg and a German MRL of 200 mg/kg. Insect re-pellents are not considered pesticides under EU law while until recently they fell under the German national MRL regulation with a default limit of 0.01 mg/kg.

Discrepancies are even higher for pesticide tolerance lev-els in organic products and also occur among the mem-ber states of the common EU market. The new organ-ic regulation (EU) No 2018/848 and its predecessor (EC) No 834/2007 do not define tolerance levels and leave this to the national control authorities and private sector. The current discrepancy of zero tolerance in the Nether-lands and other EU countries in contrast to the German orientation value will persist and traders are treated dif-ferently by the control bodies depending into what coun-try they import.

Bromide in Brazil nuts, indole-3-acetic acid in cereals and phthalimide and mepiquat in heat treated food are good examples that the MRL definitions by EU law still require further revisions based on scientific evidence, which is al-ready in the public domain. Similarly the control bodies for organic agriculture have to accept that in most cases the presence of these substances is natural, adventitious or technically unavoidable.

The presence of phosphonate in a variety of food re-quires further investigations, as recent scientific da-ta reveal that the compound is found in significant concentrations in various environments, might occur ubiquitously in the environment and is an interme-diate in a biogeochemical phosphorous cycle driv-en by microorganisms. High concentrations in cer-tain crops like rice and pulses (table 2) might be ex-plained with the efficient uptake of the substance by plant Pi transporters (Varadarajan et al., 2002). Notwithstanding agricultural applications are most probable in many instances and have to be always considered.

The diversity and frequent changes of MRLs as well as the misinterpretation of substances suppos-edly resulting from the application of agrochemi-cals have serious implications on the internation-al trade. It is therefore important to permanently question these MRL definitions and to revise them in a flexible and swift manner, not only to avoid fi-nancial losses, but also frustrations about rules, which might lose sight of the major goals – food safety and authenticity.

Authors:Dr. Werner Nader1, Michelle Maier1, Dr. Marco Miebach2 and Gabriel Linder1

1 Eurofins Global Control GmbH, Am Neuländer Gewerbepark 8, 21079 Hamburg, Germany2 Eurofins Dr. Specht Express GmbH, Am Neuländer Gewerbepark 2, 21079 Hamburg, Germany

DOI: 10.23789/1869-2303-2020-2-84

References

Anastassiades M., Lehotay S.J., Stajnbaher D. and Schenck F.J. (2003): Fast and easy multiresidue method employing acetonitrile extraction/parti-tioning and dispersive solid-phase extraction for the determination of pesticide residues in produce. Journal of AOAC International 86(2), 412-431Anastassiades M., Kolberg, D. I., Eichhorn E., Ben-kenstein A., Wachtler A.-K., Zechmann S., Mack D., Wildgrube C., Barth A., Sigalov I., Görlich S., Dörk D. and Cerchia G. (2019): Quick method for the analy-sis of numerous highly polar pesticides in foods of plant origin via LC MS/MS involving simultaneous extraction with methanol (QuPPe Method). EU Ref-erence Laboratory for Pesticides requiring Single Residue Methods, https://www.eurl-pesticides.eu/userfiles/file/EurlSRM/meth_QuPPe-PO_EurlSRM.pdf. Last checked March 28, 2020Australia New Zealand Food Standards Code, Sched-ule 20 (2020): Maximum residue limits. https://www.legislation.gov.au/Details/F2020C00200. Last checked March 28, 2020



Bandurski R.S. and Schulze A. (1977): Concentration of indole-3-acetic acid and its derivatives in plants. Plant Physiology 60, 211-213Bremmers H., van der Meulen B, Wijnands J. and Poppe K. (2011): A legal-economic analysis of in-ternational diversity in food safety legislation: con-tent and impact. European Food and Feed Law Re-view 1, 41-50Bryant Christie Inc.: Pesticide MRLS. https://www.bryantchristie.com/BCGlobal-Subscriptions/Pesti-cide-MRLs. Last checked March 28, 2020 Bundesministerium für Justiz und Verbrauch-erschutz (2020): Verordnung über Höchstmen-gen an Rückständen von Pf lanzenschutz- und Schädlingsbekämpfungsmitteln, Düngemitteln und sonstigen Mitteln in oder auf Lebensmitteln, RHMV. http://www.gesetze-im-internet.de/rhmv_1994/. Last checked March 28, 2020 Bundesverband Naturkost Naturwaren e.V., BNN (2012): BNN Orientation Value for pesticides- a guideline to evaluate pesticide residues in organic products. https://n-bnn.de/sites/default/dateien/BNN-Orientierungswert_EN_09042019.pdf. Last checked March 28, 2020Bundesverband Naturkost Naturwaren e.V., BNN (2016): Interpretation guide for phthalimid detec-tion in organic products. https://n-bnn.de/sites/default/dateien/bilder/Downloads/interpretation_guide_Phthalimid_English.pdf. Last checked March 28, 2020Bundesverband Naturkost Naturwaren e.V., BNN (2017): Fact sheet phosphonic acid, potassium phos-phonate (potassium salt of phosphonic acid) and fo-setyl-aluminum. https://n-bnn.de/sites/default/dateien/bilder/Downloads/FactSheet_phosphon-ic_acid_en_Mai_2017.pdf. Last checked March 28, 2020Cao J., Zhang C., Rong H., Zhao M., Wei W. and Zhao L. (2017): Study on effects of electron donors on phosphine production from anaerobic activated sludge. Water 9 (563); doi:10.3390/w9080563 Commission Regulation (EC) No. 889/2008 of 5 September 2008 laying down detailed rules for the implementation of Council Regulation (EC) No 834/2007 on organic production and labelling of or-ganic products with regard to organic production,

labelling and control. Official Journal of the Europe-an Union L250, 1–83Commission delegated Regulation (EU) 2016/127 as regards the specific compositional and information requirements for infant formula and follow-on for-mula and as regards requirements on information relating to infant and young child feeding. Official Journal of the European Union L25, 1–29Council Regulation (EC) No 834/2007 of 28 June 2007 on organic production and labelling of or-ganic products and repealing Regulation (EEC) No 2092/91834/2007. Official Journal of the European Union L189, 1–23Electronic Code of Federal Regulations (2020): Tol-erances and exemptions for pesticide chemical resi-dues in food. Title 40, Chapter I, Subchapter E, Part 180. https://www.ecfr.gov/cgi-bin/text-idx?tpl=/ecfrbrowse/Title40/40cfr180_main_02.tpl. Last checked March 28, 2020EOCC Factsheet on Phosphonic Acid. https://eocc.nu/wp-content/uploads/2019/04/EOCC-Factsheet-Fosetyl-Phosphonic-Acid.pdf. Last checked March 28, 2020Epstein E., and Ludwig-Müller J. (1993): Indole-3-butyric acid in plants: occurrence, synthesis, me-tabolism and transport. Physiologia Plantarum 88, 382-389EU pesticide data base (2020). https://ec.europa.eu/food/plant/pesticides/eu-pesticides-database/public/?event=homepage&language=EN. Last checked May 13, 2020European Commission document SANTE/12682/2019: Method Validation & Quality Control Procedures for Pesticide Residues Analysis in Food & Feed. https://ec.europa.eu/food/sites/food/files/plant/docs/pesticides_mrl_guidelines_wrkdoc_2019-12682.pdf. Last checked March 28, 2020European Commission document SANTE 10684-2015 rev. 8 (2018): Draft Commission Regulation (EU) …/… of XXX amending Annex III to Regulation (EC) No 396/2005 of the European Parliament and of the Council as regards maximum residue levels for chlorate in or on certain products. https://www.meyerscience.com/images/publikationen/SANTE-10684-2015-Rueckstandsh%C3%B6chstgehalt_Chlorat.pdf. Last checked March 28, 2020



European Food Safety Authority (2008): Opinion of the Scientific Panel on Plant Protection prod-ucts and their Residues to evaluate the suitability of existing methodologies and, if appropriate, the identification of new approaches to assess cumula-tive and synergistic risks from pesticides to human health with a view to set MRLs for those pesticides in the frame of Regulation (EC) 396/2005. The EFSA Journal 704, 1-84. Figueroa I.A. and Coates J.D. (2017): Microbial phos-phite oxidation and its potential role in the global phosphorus and carbon cycles. Advances in Applied Microbiology, 98, 93-115Forschungsinstitut für biologischen Landbau (FiBL) (2013): Guideline for handling pesticide residues in Czech organic production, final report. https://orgprints.org/34119/1/speiser-etal-2013-Residue_guideline_June_2013.pdf. Last checked March 28, 2020Furr A.K., MacDaniels L.H., St.John L.E., Gutenmann W.H., Pakkala I.S. and Lisk D.J. (1979) Elemental composition of tree nuts. Bulletin of Environmental Contamination and Toxicology 21, 392–396García Martinez M. and Poole N. (2004): The devel-opment of private fresh produce safety standards: implications for developing Mediterranean export-ing countries. Food Policy 29, 229–255 Han C., Geng J. Ren H. Gao S., Xie X. and Wang X. (2013): Phosphite in sedimentary interstitial wa-ter of lake Taihu, a large eutrophic shallow lake in China. Environmental Science & Technology 47(11), 5679-5685, https://doi.org/10.1021/es305297yHofmann U. (2012): Kann Kalium-Phosphonat als mineralisch, natürlich vorkommend angesehen werden? Expert opinion for the Bund Ökologis-che Lebensmittelwirtschaft e.V. (BÖLW). https://www.yumpu.com/de/document/view/6035875/gu-tachten-bund-okologische-lebensmittelwirtschaft. Last checked March 28, 2020Melo O., Engler A., Nahuehual L., Cofre G. and Bar-rena J. (2014): Do sanitary, phytosanitary, and qual-ity-related standards affect international trade? Ev-idence from Chilean fruit exports. World Develop-ment 54, 350-359Nader W.F., Grote A.-K. and Cuevas Montilla E. (2014): Impacts of food safety and authenticity is-

sues on the rice trade. Pages 159 – 176 in: Rice Pro-cessing – The Comprehensive Guide to Global Tech-nology and Innovative Products (J. Sontag, editor). Erling Verlag, GermanyPasek M. A., Sampson J. M. and Atlas Z. (2014). Re-dox chemistry in the phosphorus biogeochemi-cal cycle. Proceedings of the National Academy of Sciences of the United States of America, 111(43), 15468-15473.Regulation (EC) No 396/2005 of the European Par-liament and of the Council of 23 February 2005 on maximum residue levels of pesticides in or on food and feed of plant and animal origin and amending Council Directive 91/414/EEC, Official Journal of the European Union L70, 1–16Regulation (EC) No 1107/2009 of the European Par-liament and of the Council of 21 October 2009 con-cerning the placing of plant protection products on the market and repealing Council Directives 79/117/EEC and 91/414/EEC. Official Journal of the Europe-an Union L309, 1–49Regulation (EU) 2018/848 of the European Parlia-ment and of the Council of 30 May 2018 on organ-ic production and labelling of organic products and repealing Council Regulation (EC) No 834/2007. Of-ficial Journal of the European Union L150, 1–95relana (2016): Phthalimid: metabolite of folpet or unavoidable artifact. Position paper No. 16-03, ver-sion 2016/07/22 https://www.relana-online.de/wp-content/uploads/2016/07/PP_16-03_Folpet-PI_vers20160722.pdf. Last checked March 28, 2020relana (2019): Sources of contamination of sam-ples for analysis. Position paper No. 19-01, ver-sion 2019/04/12 https://www.relana-online.de/wp-content/uploads/2019/04/relana-pos.-paper-19-01-Sources-of-Contaminations-20190412-final.pdf. Last checked May 13, 2020 Rice News Today (2020): Latest stats on export of brown (cargo) Basmati rice. http://ricenewstoday.com/?page_id=248. Last checked May 13, 2020Romanotto A., Hofmann A., Gassert K., Heidorn T. and Speer K. (2018): Tabakanbau als Quelle einer Nikotinbelastung indischer Tees. Lebensmittelche-mie 72, 143-144Saudi Food and Drug Administration (2019): Maxi-mum limits of pesticide residues in agricultural and



food products. Document SFDA.FD 382:2019 Stif-tung Warentest e.V. Berlin (2018): Auf der Suche nach Spitzenqualität. Zeitschrift Test 9, 10-18The Economic Times, Mumbai (2010): Basmati ex-porters to haul European testing lab to court for ‘biased’ report. https://economictimes.indiatimes.com/news/economy/foreign-trade/basmati-ex-porters-to-haul-european-testing-lab-to-court-for-biased-report/articleshow/6108527.cms. Last checked May 13, 2020The Japan Food Chemical Research Foundation (2020): Maximum Residue Limits (MRLs) List of Ag-ricultural Chemicals in Foods, http://db.ffcr.or.jp/front/. Last checked March 28, 2020Van Mooy B.A.S., Krupke A., Dyhrman S.T., Fredricks H.F., Frischkorn K.R., Ossolinski J.E., Repeta D. J., Rouco M., Seewald J. D. and Sylva S. P. (2015): Ma-jor role of planktonic phosphate reduction in the marine phosphorus redox cycle. Science 348 (6236), 783-735 Varadarajan D.K., Karthikeyan A.S., Matilda P.D. and Raghothama K.G. (2002): Phosphite, an analog of phosphate, suppresses the coordinated expression of genes under phosphate starvation. Plant Physiol-ogy 129, 1232-1240Warenverein der Hamburger Börse e.V., letter dat-ed January 15th, 2015: Bromid in ParanüssenYuan Y., Tarres A., Bessaire, T., Rademacher, W., Stadler, R.H. and Delatour, T. (2017): Heat-induced formation of mepiquat by decarboxylation of pipec-olic acid and its betaine derivative. Part 2: Natural formation in cooked vegetables and selected food products. Food Chemistry 228, 99-105

Pesticide residue legislations challenge international ...

Documents

Transcript of Pesticide residue legislations challenge international ...