Much in Use, Seldom Present – Residues from Glyphosate in Cereals

Report from a day in the lab

Ellen Scherbaum, Anne Wolheim, Diana Kolberg and Cristin Wildgrube // Translated by Catherine Leiblein

 

In the years 2010 and 2012 CVUA Stuttgart analyzed 127 samples of cereals, ground cereal products and cereal products for the presence of the herbicide Glyphosate. With sales of 15,000 tons of plant protection preparations in Germany per year, Glyphosate is among the most commonly used herbicide.

 

Of the 127 samples analyzed only 2 (1.6 %) were found with residues under the allowable MRL (maximum residue limit). Both samples were produced conventionally and came from Germany. None of the organically, and just 1.6 % of the conventionally, produced cereals and their products were found to have residues of Glyphosate; in both cases the amount of residues detected were well under the valid MRL.

 

Background

Cereals

photograph of a grain field.The term cereal (or grain) encompasses various species of agriculturally grown cultivated plants; they belong to the botanic family of grasses. The most important types of grains are rye, wheat, barley, millet, oat, corn and rice. For thousands of years grains have played a significant role in the feeding of mankind, both as a raw food material and as the main ingredient in bread, a main food staple. Grains are especially important among agricultural products because a minimum of production expenditure can yield a maximum of nutrient rich food.
Hardly any food is as versatile as grain with its various methods of preparation. One thinks firstly of the many types of bread, from German rye breads to Turkish flatbreads, but also of risotto or pilau from rice, polenta from corn, or couscous from millet. Cereals are an indispensable part of a balanced diet; 100 gr. of wheat, for example, contains 11.4 gr. protein, 70.2 gr. carbohydrates, and 2 gr. fat, in addition to ample fiber, potassium, phosphorus, magnesium and vitamins B1, B2, B6 and A. Grains play a large roll as a basic food stuff for people around the world and is an important factor in the state of global nutrition. In 2010 approximately 2,431 million tons of grain, including rice, was harvested worldwide [1].

 

Table 1: Worldwide Cereal Produktion, in tons
Cereal type
World production (t)
Production in Germany (t)

Corn

844,405,181

4,072,900

Wheat

650,881,002

24,106,700

Rice

672,015,587

-

Barley

123,477,192

10,412,100

Millet

84,930,562

-

Oats

19,600,935

600,300

Rye

12,328,178

2,903,470

Total

2,431,745,337

42,095,470

 

Glyphosate

Glyphosate is a non-selective leaf herbicide with the chemical name N-(Phosphonomethyl)-glycine and the molecular formula C3H8NO5P. Glyphosate is a main component in many wide-band herbicides. The substance first came on the market as an active substance in the herbicide “Roundup”. Glyphosate is an herbicide that works systemically. That means it is absorbed by the plant and distributed via the roots and vascular tissue.

The mechanism by which this herbicide works is via the inhibition of the enzyme 5-enolpyruvoyl-shikimate-3-phosphate systructural formular of glyphosate.nthase (EPSPS) involved in the metabolic pathway of shikimic acid. It hinders the synthesis of EPSPS and thereby the synthesis of aromatic amino acids in the plant. Investigations into the use of Glyphosate have shown, on the one hand, good biodegradation, low warm-blooded toxicity, little soilactivity, and no accumulation. On the other hand, however, an increase in fusarian root fungus infestation has been reported, as well as a hindrance to the accumulation of rhizobia bacteria, which negatively affects the plant’s availability of nitrogen [2].

Ill. 1: Chemical Structure of  Glyphosate
 

 

Glyphosate (in the product Roundup) has been used in farming since 1974, with the purpose of killing off weeds or competing plants from fields before the sowing of cultivated plant seeds (preventive herbicide).


Roundup only has an effect on the green parts of the plants, not on the roots. This makes it possible to fight against weeds and to sow a new crop in the same step of production; germination and growth won’t be negatively influenced. Roundup is often sold together with genetically modified seeds, but is also used in conventional monocultures.


In addition, Glyphosate is used in a so-called “desiccation” agricultural procedure where a portion of the cultivated plants are removed in order to speed up the ripening of the seeds or to bring the timing of the ripening of all the plants on one farm in sync, in order to streamline the machine-driven harvesting [3, 4]. This can be problematic if the plants are harvested too soon after the application of Glyphosate, without observing the necessary waiting period.
German domestic sales of Glyphosate containing plant protection preparations were set at 15,000 tons for 2010 (Federal Office of Consumer Protection and Food Safety, BVL).


The BVL homepage provides information regarding the toxicological effects of Glyphosate containing herbicide formulas. These effects, however, are not related to the substance Glyphosate itself, but rather to specific secondary substances called polyethoxylated tallow amine (POEA), which are present in only some Glyphosate containing formulas. Further information regarding this topic, as well as the herbicide approval process can be found on the BVL homepage: www.bvl.bund.de (press release from 1 June 2010). Currently, the presence of Glyphosate in the urine of humans and animals is being discussed in the media.


Extensive information on the risk assessment and approval of the herbicide substance Glyphosate was also published in the context of a short inquiry put to members of parliament and the governmental Green Party on 27 Sept. 2011 (Lower House - printed matter 17/7168) [5].

 

Legal Issues

The MRLs for Glyphosate in cereals were established via EU Regulation Nr. 396/2005, article 18, paragraph 1b, and are listed in Appendix 1. The following chart contains examples of MRLs for Glyphosate.

Table 2: Maximum Residue Limits for Glyphosate (mg/kg)
Cereal type
Max. Limit for Glyphosate (mg/kg)

Barley

20

Buckwheat (Amaranth, Quinoa)

0,1*

Corn

1

Millet (Italian Foxtail Millet, Teff)

0,1*

Oats

20

Rice

0,1*

Rye

10

Sorghum

20

Wheat (Spelt, Triticale )

10

Other

0,1*

* No application, limits are set as appropriate

 

Analytical Results

A total of 127 samples of cereals and cereal products were analyzed for residues of Glyphosate in 2010 and 2012. Residues were detected in only two of the 127 samples (1.6 %). The highest amount of Glyphosate residue detected was in a sample of rye crispbread, at 0.26 mg/kg. The second detection came from a sample of millet, with a residue amount of 0.086 mg/kg Glyphosate. Among these 127 analytical samples were 37 from organic production, none of which contained any Glyphosate residues.

 

diagramme.

Ill 2:  Percentage of samples with and without Glyphosate residues and number of samples from organic production.

 

Of the 127 cereal and cereal product samples 78 came from Germany. The two samples that were detected with residues (crispbread and millet; see above) were among these. Despite the common application of Glyphosate, only 2 out of 127 cereal samples were found with residues. All samples from organic production were free of Glyphosate residues

 

diagramme.

Ill 3:     Countries of origin for the analyzed samples.

 

Despite frequent use of Glyphosate, residues were found only in 2 cereal samples out of 127. None of the organic samples showed residues of Glyphosate.

 

Literature

[1] http://www.wissen.de/thema/getreide (German)
[2] Glyphosate (wikipedia.org)
[3] Sikkation (wikipedia.org) (German)
[4] www.roundup.de (German)
[5] http://dipbt.bundestag.de/dip21/btd/17/071/1707168.pdf (German)

 

Picture

Getreide, Wilhelmine Wulff,Pixelio.de, 593205.

 

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Report published on 27.09.2012 11:35:47