Pesticide Residues in Table Grapes (Jan – Oct, 2012)

Ein Bericht aus unserem Laboralltag

Kathi Hacker, Ellen Scherbaum

Analytical Background

Table grapes are very popular in Germany and are on offer most of the year. The majority of table grapes on the German market originate abroad; however, in the last few years an increasing number of local grapes are also being marketed in autumn, from September to October.

From the budding of the plants through to the harvest, grapes are exposed to pests and illnesses. Pesticides are therefore commonly employed in commercial cultivation to protect the grapes from pests and to safeguard the harvest. In previous years, however, analyses of table grapes have detected pesticide residues in exceedance of the maximum residue limit (MRL) for pesticides. Therefore, within the scope of the official food control program, table grapes were also analyzed in 2012, including an increased number of samples from local cultivation.

Summary

Table grapes from conventional cultivation

Up to the time of reporting a total of 90 samples of conventionally produced table grapes from various countries were analyzed at CVUA Stuttgart for approximately 600 different pesticides. Among these were 24 samples (27%) from Germany. Pesticide residues were detected in 88 of the 90 (98%) table grapes from conventional cultivation (98% in 2011; 96% in 2010; 100% in 2009).

• Samples from foreign soil: Two samples from Turkey and one from South Africa were found to contain pesticides exceeding the MRL. From the 64 samples originating from foreign countries, the rate of MRL violations was 5% in 2012 (1% in 2011; 6% in 2010; 6% in 2009).
• Local samples: The local samples were primarily obtained from small producers or direct marketers; 22 of the 24 analyzed grapes came from Baden-Württemberg. Violations of the MRL were detected in 5 of the 24 local samples, two of which were from Rheinland-Pfalz. This corresponds to a rate of 21% (16% in 2011; 15% in 2010; 76% in 2009).
• Gratifying results: None of the 90 samples contained active substances over the acute reference dose (ARfD) established for small children (in 2009 an exceedance of the ARfD was found in 5 of the 145 analyzed samples). Therefore, none of the samples were classified as a health concern.
• Investigations showed that 89% of the grapes contained several different substances (multiple residues) per sample. On average one grape sample contained 7.3 different substances, with an average quantity of 0.45 mg pesticides/kg grapes. (Values in 2011 were 6.3 substances and 0.55 mg/kg; 2010: 5.5 substances and 0.52 mg/kg; 2009: 5.9 substances and 0.62 mg/kg).
• In 10 (42%) of the samples from local cultivation substances were detected that are not authorized in Germany for use in table grapes. These included the substances captan (1x), dimethomorph (4x), dithianon (4x), folpet (5x), indoxacarb (1x), iprovalicarb (2x) und spiroxamin (1x). It is suspected that in some of the cases so-called wine grapes (used for making wine) were redesignated as table grapes (those eaten directly). The resulting MRL violations occurred because table grapes have stricter limits on pesticides than wine grapes, both in quantity and type. Nevertheless, in 2012 no samples of local grapes were found with pesticides that are completely forbidden in Germany, for all foods.

Table grapes from organic cultivation

Up to the time of reporting a total of 26 samples of organically produced table grapes from various countries were analyzed (2 of which were grown in Germany). No residues of chemical/synthetic pesticides were detected in 15 of the analyzed grape samples. In the remaining 11 samples only traces of residues were found. Of these, 7 contained residues of the insecticide spinosad, which is authorized for use in organic cultivation under the EU regulation for organic farming.

With regard to pesticides, all of the inspected organic table grapes fulfilled the requirements for organic cultivation.

Conclusion and Evaluation

The results of the investigations show that conventionally produced table grapes were among the fruits with higher levels of contamination from pesticides this year as well. As many as 98% of the analyzed table grape samples contained pesticide residues. The number of samples in violation of the MRL rose again in comparison to the previous year, reaching the same high level as in 2010 (9% in 2012, 3% in 2011, 9% in 2010). The acute reference dose (see Info Box) determined for small children was not exceeded in any cases. Thus, no samples were categorized as a health concern.

All of the five locally produced grape samples that violated the MRL contained substances in quantities greater than 0.01 mg/kg; moreover, these pesticides are unauthorized in Germany for use in table grapes (violation of the authorized indications code). These included 4 cases of folpet and 1 case of captan. Grapes that are treated with pesticides containing folpet may not be marketed as table grapes for direct consumption. The percentage of samples exceeding the MRL, as well as the number of locally produced grape samples with residues of unauthorized pesticides has increased again this year, and is still unacceptable. The official food inspections will therefore be accordingly intensified in the following season.

All of the 26 organically produced table grape samples were in line with the EU regulations for organic farming.

Detailed Results for Table Grapes from Conventional Cultivation

Illustration 1 depicts the current situation regarding residues detected in the 90 samples of table grapes from conventional cultivation. A total of 98% of the conventionally produced table grapes analyzed during this reporting period contained residues of at least one substance; only two were residue-free.

Illustration 1: Pesticide residues in table grapes from conventional cultivation (CVUA Stuttgart, 2012); R = Residues; MRL = Maximum residue limit according to EU Regulation Nr. 396/2005.

Table 1 gives an overview of the results from the residue analyses. From the 90 samples of conventionally produced table grapes 8 were in violation of the MRL.  Of these 8 samples, 5 were local products, 2 came from Turkey, and one was from South Africa. The guilty substances found in the locally produced grapes included captan (1x), cyazofamid (1x) and folpet (4x). While the substance captan is not permitted in Germany for either table- or wine grapes, the substance folpet is authorized for use only on wine grapes. The substance cyazofamid is permitted for table grapes in Germany. Though the EU-established maximum limits for captan und cyazofamid are the same for table- and wine grapes (0.02 mg/kg and 0.5 mg/kg respectively), this is not so for folpet. The maximum limit for this substance is significantly lower for table grapes (0.02 mg/kg) than for wine grapes (5 mg/kg).

A positive note is that in the reporting year of 2012 not a single sample was found with residues over the acute reference dose determined for small children. Therefore, none of the samples were categorized as being a health concern.

MRL = Maximum limit according to EU Regulation Nr. 396/2005; *Data pool too small for calculating averages. **The comparability of these data with each other is limited in that the number of countries investigated in the various years was inconsistent.

^&Since there is no specific MRL established for the substance DDAC in the EU Regulation Nr. 396/2005, the general MRL of 0.01 mg/kg is valid, in accordance with Article 18, Paragraph 1b of the EU Regulation Nr. 396/2005. Meanwhile, the EU has assigned a value of 0.5 mg/kg for DDAC (didecyldimethylammonium chloride); this value was not exceeded in the current samples. Contamination from DDAC can occur in various ways, e.g. via application as a pesticide or through cross-contamination, because it is also authorized for use as a disinfectant. Because it is often difficult to identify the source of DDAC residues, the assigned value of 0.5 mg/kg provides businesses as well as food controllers a transitional measure for managing the marketing of products with a quantity of < 0.5 mg/kg of benzalkonium chloride (BAC). This low level is assumed to be safe for one’s health. For more information, see the Internet article Residues of Quarternary Ammonium Compounds (QAC) in Fruits and Vegetables – Origin and Findings

Unauthorized Substances

In addition to controlling for the observance of the legal maximum residue limits, locally cultivated products in which residues are detected are also analyzed for the presence of substances not permitted in Germany (see Info Box „Authorized Indications“). In 2012 all of the five samples of locally produced table grapes that violated the MRL were also found to contain folpet (4X) and captan (1X) in quantities > 0.01 mg/kg. These substances are not authorized for use in Germany, and therefore are in violation of the authorized indications code. A further five local samples that did not exceed the MRL were, nevertheless, also in violation of the code. Residues of the active substances dimethomorph (4x), dithianon (4x), folpet (1x), indoxacarb (1x), iprovalicarb (2x) und spiroxamine (1x) were detected (see Table 2)..

Multiple Pesticides

As presented in Table 1, 89% of the conventionally produced table grapes were found to contain more than one substance per sample (multiple residues). Illustration 2 shows that the frequency distribution is very wide, ranging from 0 to a high of 23 substances detected in one sample. In 2012 analyses revealed an average number of 7.3 substances per sample. The average quantity per pesticide was 0.45 mg/kg. As seen in Table 3, the grapes analyzed in 2012 were found on average to contain a higher number of different substances per sample, but a lower quantity of each pesticide in comparison to previous years.

Illustration 2: Frequency distribution of multiple residues in table grapes from conventional cultivation (CVUAS Jan. - Oct., 2012). All values above the LOQ (limit of quantification) were used.

The existence, form and quantity of these multiple residues indicates the employment of so-called combination preparations (using several substances) as well as myriad different preparations used to protect plants from illnesses and pests. Because authorization of particular substances may change, expire or be added to, the spectrum of substances is in constant flux. In order to maintain an accurate picture of the status of food contamination via official food control it is especially important that new analytical methods are continuously developed so that new substances can be detected.

As Table 4 shows, the locally produced table grapes were less contaminated with pesticide residues than those from Asia and South America (0.39 mg/kg vs. 0.90 and 0.51 respectively). Only the grapes from Africa were minimally contaminated. Grapes from Turkey contained an average of 16.4 substances per sample, and presented the highest level of pesticide content, at 2.0 mg/kg.

Spectrum of Active Ingredients

Among the conventionally produced table grapes analyzed this year, a total of 81 different substances were detected. When one compares these data with those of previous years, the higher differentiation can have various causes, although the previous discussion of the ever-expanding spectrum of substances and their accompanying regulations, as well as the further development of analytical methods, all make a significant contribution. Equally significant are such aspects as land of origin and time of year. An overview of the 50 most commonly detected substances from the spectrum of active ingredients is presented in Table 5. Fungal disease poses a serious problem for grape production, which is reflected in the spectrum of active ingredients: the most frequently detected residues were those of fungicides.

* = Total parameter; F = Fungicide; I = Insecticide; A = Acaricide; G = Growth regulator

Photo Credits:

Süß und saftig an der Rebe (“Sweet and Juicy on the Vine”), Marianne J., Pixelio.de, Image-ID=603575.

Artikel erstmals erschienen am 31.01.2013