Glyphosate in Fruits and Vegetables – as Present as in the Media?

Report from a day in the lab

Dr. Florian Hägele

 

Glyphosate – hardly another pesticide receives as much media coverage and is so heatedly discussed. Glyphosate has been used worldwide for more than 40 years in enormous amounts in different pesticides to fight against weeds. But what is the outlook for our food? Is this expansive use of glyphosate also reflected in the contamination of our fruits and vegetables? Analyses of a total of 17,222 samples of conventionally and organically produced fruits and vegetables conducted by CVUA Stuttgart from 2010 to 2019 shed light on the situation.

 

Photo: Fruits and vegetables.

 

What is glyphosate?

Glyphosate, with the chemical name N-(Phosphonomethyl)glycine, is used worldwide in agriculture and gardens as an herbicidal substance to combat weeds among cultivated crops and plants. Glyphosate is currently still authorized for use in both Germany and the European Union (EU) as a plant protector substance for the combating of weeds. It is absorbed into green plant parts and spreads throughout the entire plant. Since it is not a selective herbicide, the application of glyphosate leads to the complete destruction of all plants, so it cannot be used during the growth phase of crops. Outside the EU, however, genetically modified, glyphosate resistant crops are grown that make the application of glyphosate during the growth period possible. Aside from the application of glyphosate as an herbicide, it is also used in cultures such as cereals, lentils or beans for desiccation (pre-harvest treatment for the purpose of speeding up the ripening process). Glyphosate has been criticized, however, because the substance has disadvantageous effects on the environment and, from the viewpoint of the International Agency for Cancer Research (IARC), it is classified as “likely carcinogenic” for humans. Other organizations and officials such as the Federal Institute for Risk Assessment (BfR) and the European Food Safety Authority (EFSA) have come to the conclusion, however, that no health risk exists if glyphosate is used properly. [1]

 

How is glyphosate detected in food?

Glyphosate belongs to a group of very polar pesticides that are determined with help from the so-called QuPPE (Quick Polar Pesticides) method. Glyphosate is hereby extracted from the crushed and homogenized test material with acidified methanol and is both qualitatively and quantitatively determined using liquid chromatography and mass spectrometry coupling (LC-MS/MS). Using this method, our laboratory can achieve a limit of determination for fruits and vegetables of 0.02 mg/kg of sample and a limit of detection of 0.007 mg/kg, depending on the matrix. The QuPPe method thus enables the reliable detection of even small residue amounts of glyphosate in our fruits and vegetables.


This method is being used in many laboratories worldwide and is currently in the process of being standardized. At the same time, the method is being continuously developed in order to detect additional substances and sample types. The main degradation product of glyphosate, aminomethyl phosphonic acid (AMPA), for example, can also be determined with help from the QuPPE method. There is currently a trial being conducted with so-called ion chromatography with mass spectrometry-coupling (IC-MS/MS), with which our lab will be able to achieve even lower limits of determination of glyphosate.

 

Are there limits of determination for glyphosate in foods?

Regulation (EC) No. 396/2005 regulates EU-wide authorized maximum residue levels (MRLs) for pesticide residues in or on food and feed of plant and animal-based origins. Residue maximums are always based on a combination of each substance and fruit or vegetable culture, and take consideration of the particular method of application.


The glyphosate MRL for most types of fruits and vegetables is established at the lower analytical limit of determination (usually 0.1 mg/kg). There are some exceptions, however, where the allowable MRL is higher. These include, in particular, potatoes (0.5 mg/kg), cereals such as wheat and rye (10 mg/kg), barley and oat (20 mg/kg), oil seeds such as linseeds, rap, and mustard seeds (10 mg/kg), soy beans and sunflower seeds (20 mg/kg), legumes such as beans (2.0 mg/kg), lentils, peas, and lupines (10 mg/kg) and herbal teas (2.0 mg/kg).
There are no MRLs for AMPA, the degradation product of glyphosate.

 

Info Box

Maximum Residue Levels

Maximum residue levels (MRLs) are not toxicological endpoints or limit values. They are derived from residue investigations carried out under realistic conditions. The expected residues are then compared with toxicological limit values, in order to ensure that lifelong or a one-time intake of the substance does not pose a health risk.

 

Maximum residue levels regulate trade, and may not be exceeded. Food containing residues above the MRL is not marketable, so it may not be sold. Not every exceedance of an MRL poses a health risk, however. It is therefore important to make differentiated observations. [2]

 

To ensure implementation of EU guidelines regarding baby food, maximum residue levels for these foods are regulated via a national ordinance for dietary foods. The dietary regulation states that ready-to-eat foods for babies or young children may not contain more than 0.01 mg/kg of plant, pest, or storage control substances.

 

How many food samples have been analyzed for glyphosate by CVUA Stuttgart since 2010?

As the central laboratory for residues and contaminants in plant-based fruits and vegetables in Baden-Württemberg, CVUA Stuttgart monitors the presence of pesticides, including glyphosate, within the framework of its official food control program. A total of 17,222 samples of fruits and vegetables have been analyzed for residues of glyphosate from 2010 until the end of 2019. Of these, 14,571 fruit and vegetable samples had been conventionally, and 2,651 organically, cultivated. The selection of samples to be tested is oriented toward consumer shopping habits as well as the risk potential, thereby covering the whole spectrum of plant-based foods.

 

How does the residue situation for fruits and vegetables look?

Glyphosate residues above the limit of determination of 0.02 mg/kg were detected in only 78 of the 17,222 samples, with an overall rate of 0.45 %. Among these 78 cases were 72 samples from conventional cultivation and six from organic. The average quantity of glyphosate detected from all positive samples was 0.80 mg/kg, and the highest determined amount was 9.3 mg/kg in a sample of linseeds.

 
As expected, fewer organically produced fruits and vegetables were contaminated with glyphosate residues than conventionally produced products. Table 1 presents an overview of the findings in conventionally and organically produced foods.


Trace amounts of glyphosate were detected in 138 samples (0.80 %) above the limit of detection of 0.007 mg/kg.  It is possible in these cases to declare that glyphosate is present, but a precise determination of the residue amount is no longer analytically feasible due to the miniscule amounts. Most relevant for our little ones, however, is that none of the 132 analyzed baby food samples had any traces of glyphosate.


Only 27 of the 17,222 samples were found to contain glyphosate in amounts above the current, legal, EU-wide harmonized MRLs in, equivalent to a rate of just 0.16 %. As a result, these samples were reported for being in violation of food law. Three of the 27 violations were organically grown lentils. These samples were also judged to be fraudulent in terms of their claims of being “organic”.


Compared with other pesticides in our routine spectrum of over 750 substances, an overall detection rate of 0.45 % and violation rate of 0.16 % is extremely low. This is mainly due to the fact that glyphosate is normally only used for the purpose of removing weeds before the growing season for fruits and vegetables, thus leaving very few residues for the consumer. With the exception of desiccation in certain plant cultures or of genetically modified plants, glyphosate is usually no longer applied during the growing period. Since the process of desiccation is strongly regulated in this country [1] and hardly any GMO plants treated with glyphosate with the exception of GMO feed are imported to Germany, the comparably rare glyphosate findings in our analyzed samples were hardly surprising.

 

Table 1: Overview of glyphosate findings in foods from conventional and organic cultivation (CVUA Stuttgart 2010–2019)
Food Category
No. of Samples
Samples w/ trace amounts < 0.02 mg/kg 1)
Samples w/ residues
>  0.02 mg/kg 2)
Samples >  MRL 3)
Organic Cultivation
Conventional Cultivation
Alcohol free drinks
227
2
-
-
-
Baked goods
17
-
-
1 (5.9 %)
-
Raw materials for making beer
20
-
-
-
-
Vegetables
7.270
54
-
1 (0.01 %)
1 (0.01 %)
Vegetable products
481
3
-
-
-
Cereal and cereal products
521
10
1 (0.2 %)
15 (2.9 %)
9 (1.7 %)
Spices
126
5
-
3 (2.4 %)
-
Legumes and oil seeds, nuts, soy products
473
13
3 (0.6 %)
37 (7.8 %)
15 (3.2 %)
Coffee
4
-
-
-
-
Potatoes and starchy plant parts
429
15
-
-
-
Nutritional supplements
19
-
-
-
-
Fruits
6.223
30
1 (0.02 %)
11 (0.2 %)
2 (0.03 %)
Fruit products
459
5
 
 
 
Mushroom and mushroom products
521
-
1 (0.2 %)
1 (0.2 %)
-
Baby food
132
-
-
-
-
Tea
86
-
-
3 (3.8 %)
-
Wine and wine products
214
1
-
-
-
TOTAL for all samples
17.222
138 (0.80 %)
6 (0.03 %)
72 (0.45 %)
27 (0.16 %)

1) Limit of Detection (LOD): smallest concentration that can be qualitatively determined

2) Limit of Quantification (LOQ): smallest concentration that can be quantitatively determined with necessary precision

3) MRL = Maximum Residue Level

 

The degradation product AMPA, for which there is no maximum quantity given in terms of fruits and vegetables, was seldom detectable, as in the case of glyphosate. AMPA was found in just 48 samples (average value: 0.088 mg/kg), whereby 46 samples were from the category of cultured mushrooms. This can be explained by the substrate, often straw, from which cultured mushrooms can absorb certain substances. If the cereal straw had been previously treated with glyphosate, residues of its degradation product AMPA could end up in the mushrooms.

 

Are there food groups that are more conspicuous than others?

Even though the frequency of findings in fruit and vegetables was altogether low, there are individual food groups, especially cereals and their products as well as legumes that have observable conspicuities regarding glyphosate (see Table 1).


Among cereals and cereal products 16 of the 521 analyzed samples (3 %) were determined to contain glyphosate residues > 0.02 mg/kg. Nine of the samples (1.7 %) exceeded the legally established MRLs for glyphosate (Table 2).  A high frequency of detection can be seen here in buckwheat (15 %) and millet (32 %), whereas wheat, spelt, oat and rye mainly stemming from Germany were not contaminated with glyphosate. Rice from traditional rice-growing countries was also inconspicuous in terms of glyphosate.

 

Table 2: Overview of glyphosate findings in cereals and cereal products (CVUA Stuttgart 2010–2019)
Type of Cereal
No. of Samples
Positive Samples > 0.02 mg/kg 1)
Samples >  MRL 2)
Min
(mg/kg)
Max
(mg/kg)
Average mg/kg
Buckwheat
47
7 (15 %)
6 (13 %)
0.024
2.8
0.96
Spelt
51
-
-
-
-
-
Barley
28
2 (7 %)
-
0.096
0.42
0.26
Oats
43
-
-
-
-
-
Millet
19
6 (32 %)
3 (16 %)
0.029
0.28
0.15
Rice
94
-
-
-
-
-
Rye
34
-
-
-
-
-
Wheat
116
-
-
-
-
-
Other (Quinoa, Maize, Green spelt, Cereal products, Emmer wheat, Amaranth)
89
1
-
0.068
0.068
0.068
TOTAL all samples
521
16 (3 %)
9 ( 2 %)
0.024
2.8
0.53

1) Limit of Quantification (LOQ): smallest concentration that can be quantitatively determined with necessary precision

2) MRL = Maximum Residue Level

 

From a total of 473 samples from the category legumes, oil seeds, nuts, and soy products, 40 samples (9 %) were positive for glyphosate in amounts > 0.02 mg/kg (see Table 3). Exceedances of the MRLs occurred in 15 samples (about 3 %). A high frequency of findings was observed in peanuts (13 %), chick peas (11 %), linseeds (21 %) and lentils (15 %). A violation rate of 9 % for lentils due to glyphosate is particularly relevant, where a total of 12 out of 128 lentils exceeded the MRL.

 

Table 3: Overview of glyphosate findings in legumes, oil seeds, nuts, and soy products (CVUA Stuttgart 2010–2019)
Food Category
No. of Samples
Positive Samples > 0.02 mg/kg 1)
Samples >  MRL 2)
Min
(mg/kg)
Max
(mg/kg)
Average mg/kg
Bean
88
5 (6 %)
1 (1 %)
0.23
4.2
1.3
Peanut
24
3 (13 %)
1 (4 %)
0.059
0.11
0.077
Chick pea
19
2 (11 %)
-
0.26
1.2
0.7
Flax seed
29
6 (21 %)
-
0.20
9.3
2.0
Lentil
128
19 (15 %)
12 (9 %)
0.048
4.1
1.3
Oil seed
12
1 (8 %)
1 (8 %)
1.1
1.1
1.1
Soy bean
52
1 (2 %)
-
0.89
0.890
0.89
Sunflower seed
17
1 (6 %)
-
0.51
0.510
0.51
Sweet lupine
2
-
-
-
-
-
Pinto bean
11
1 (9 %)
-
1.67
1.670
1.7
Walnut
17
1 (6 %)
-
0.092
0.092
0.092
Other (Cashew nut, Chia seed, Sweet chestnut, Pea, Hanf seed, Hazelnut, Coconut, Pumpkikn seed, Almond, Poppy seed, Mung bean, Brazil nut, Pecan, Pistacio, Rapeseed, Sesame)
74
-
-
-
-
-
TOTAL all samples
473
40 (9 %)
15 (3 %)
0.048
9.3
1.3

1) Limit of Quantification (LOQ): smallest concentration that can be quantitatively determined with necessary precision

2) MRL = Maximum Residue Level

 

The reason for the comparatively high rate of findings and/or violations in cereals and cereal products as well as legumes is the so-called desiccation in field cultivation. Desiccation is a procedure performed in agriculture in which crops such as cereals or legumes are treated with desiccants (often glyphosate) to speed up the ripening process. The plant is purposefully killed off and, at the same time, the fruits ripen fully, and are easily harvested. Since this procedure occurs shortly before the harvest, higher levels of glyphosate residues can result in the end product. Desiccation is strictly regulated in Germany and is only permitted in certain situations [1].

 

Although desiccation is sometimes used with potatoes, the residue situation in this product group is insignificant. Of the 429 analyzed potatoes, none of the samples contained glyphosate residues in amounts over the limit of determination or the MRL. Quantities above the limit of detection were detected in just 15 potato samples, but these were only in trace amounts.

 

Are there differences among countries as to levels of glyphosate contamination among fruits and vegetables?

The fruits and vegetables analyzed in the time frame from 2010 to 2019 came from 99 different countries around the globe. Nevertheless, the largest proportion of samples (about 64 %) were grown in Germany (6,108 samples) and other EU countries (4,992). Of all the 11,100 samples from EU countries, just 15 contained glyphosate residues (0.1 %) and two exceeded the MRL (0.02 %), which presents a very positive picture. In contrast, fruits and vegetables from third countries or unknown origins were significantly more often contaminated with glyphosate and had amounts exceeding the legal MRLs (see Table 4). In addition, foods produced in the EU with positive glyphosate findings had, on average, significantly lower amounts than those grown outside the EU (Table 4). One cause could be differences in the practices of applying glyphosate in third countries.

 

In terms of the regional distribution of glyphosate findings, however, it is important to note that, in contrast to fruits and vegetables, no obligatory disclosure regarding the country of origin is necessary for cereals, legumes and processed goods such as flour. An exact allocation to a particular agricultural country is not always possible, especially with buckwheat, millet and lentil samples that were often contaminated with glyphosate. It cannot be ruled out, therefore, that some of these samples had been grown in an EU country or in Germany.

 

Table 4: Glyphosate residues in fruits and vegetables by country of origin (CVUA Stuttgart 2010–2019)
 
Domestic Samples
Samples from other EU Countries
Samples from Third Countries
Samples from Unknown Origin *)
Total No. Samples
No. Samples
6,108
4,992
4,212
1,910
17,222
Samples w/ Residues
8 (0.13 %)
7 (0.14 %)
28 (0.66 %)
35 (1.8 %)
78 (0.45 %)
Samples >  MRL
1 (0.02 %)
1 (0.02 %)
12 (0.28 %)
13 (0.68 %)
27 (0.16 %)
Ave. Amount of Glyphosate in Positive Samples (mg/kg)
0.35
0.27
1.2
0.74
0.80

*) In contrast to fruits and vegetables, disclosure of the origin is not required for cereals, legumes and processed goods.

 

How is the acute toxicity of the glyphosate detected in fruits and vegetables judged?

For the assessment of likely acute, toxic risk from a short exposure, the amount of residues ingested by the consumption of a contaminated food is compared to the so-called Acute Reference Dose (ARfD) derived by the European Food Safety Authority (EFSA). An ARfD value of 0.5 mg/kg bodyweight has been established for glyphosate. Based on our analyses, none of the determined quantities posed an acute health risk from glyphosate.

 

Comprehensive toxicological information on glyphosate can be found in the published toxicological assessment of the Federal Institute for Risk Assessment (BfR) [3].

 

Info Box

Acute Reference Dose (ARfD)

For the evaluation of pesticides that have a high, acute toxicity and that can cause health damage after just a single or short-term intake, the Acceptable Daily Intake (ADI) value is only appropriate to a limited extent. Since the ADI is derived from long-term studies, it is possibly inadequate as a measure of acute risk from residues in food. Therefore, in addition to the ADI value, a further exposure limit has been established, the so-called acute reference dose (ARfD). The World Health Organization defined the ARfD as the amount of a substance one can consume over the period of one day or in one meal without resulting in any discernible health risk. Other than for the ADI, the ARfD value is not determined for every pesticide, but only for such substances that, when taken in sufficient quantities, could damage one’s health even after just one exposure.

 

EU Pesticides database

EFSA calculation model Pesticide Residue Intake Model “PRIMo” – revision 3.1

 

Summary

Glyphosate in food – highly contaminated or hardly noticeable? The analyses conducted by CVUA Stuttgart show an overall positive picture. In an analytical time frame of 10 years, during which over 17,000 fruit and vegetable samples were analyzed for residues of glyphosate, only 78 samples were determined with quantifiable amounts, a rate of 0.45 %. Especially good news for parents is that none of the baby food samples were detected with glyphosate residues. Only 27 samples contained glyphosate amounts exceeding the respective, legal, EU-wide harmonized MRLs, which accounts for a violation rate of just 0.16 %. Compared to other pesticides in our routine analytical spectrum of more than 750 substances, this presents an overall, extremely low value. There is a tendency towards more frequent determinations of glyphosate in certain food groups, however, including lentils, linseeds, buckwheat and millet in the cereals and cereal products category, as well as in legumes.  Based on our findings, however, there was no acute health risk from glyphosate.

 

Even though we seldom find glyphosate residues in fruits and vegetables despite its widespread application in agriculture, CVUA Stuttgart will continue to intensively test food for glyphosate residues in the future.

 

Photo Credit

CVUA Stuttgart, Andrea Karst, pesticide laboratory

 

References

[1] Federal Ministry for Nutrition and Agriculture (BMEL) – Questions and Answers to Glyphosate

[2] Federal Office of Consumer Protection and Food Safety (BVL) Brochure „Pflanzenschutzmittel – sorgfältig geprüft, verantwortungsbewusst zugelassen“, November 2009

[3] Federal Institute for Risk Assessment (BfR)

 

Translated by: Catherine Leiblein

 

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Report published on 19.05.2020 12:04:27