Reasoned opinion on the review of the existing maximum residue levels (MRLs) for mesosulfuron according to Article 12 of Regulation (EC) No 396/2005


European Food Safety Authority
EFSA Journal
EFSA Journal 2012;10(11):2976 [27 pp.].

EFSA wishes to thank the rapporteur Member State France for the preparatory work on this scientific output.

Reasoned Opinion
On request from
Question Number
22 November 2012
26 November 2012
European Food Safety Authority (EFSA), Parma, Italy
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According to Article 12 of Regulation (EC) No 396/2005, the European Food Safety Authority (EFSA) has reviewed the Maximum Residue Levels (MRLs) currently established at European level for the pesticide active substance mesosulfuron. In order to assess the occurrence of mesosulfuron residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC as well as the European authorisations reported by Member States (incl. the supporting residues data). Based on the assessment of the available data, MRL proposals were derived and a consumer risk assessment was carried out. No information required by the regulatory framework was found to be missing and no risk to consumers was identified.


Mesosulfuron was included in Annex I to Directive 91/414/EEC on 01 April 2004, which is before the entry into force of Regulation (EC) No 396/2005 on 02 September 2008. EFSA is therefore required to provide a reasoned opinion on the review of the existing MRLs for that active substance in compliance with Article 12(2) of the aforementioned regulation. In order to collect the relevant pesticide residues data, EFSA asked France, as the designated rapporteur Member State (RMS), to complete the Pesticide Residues Overview File (PROFile). The requested information was submitted to EFSA on 24 April 2009 and, after having considered several comments made by EFSA, the RMS provided on 06 January 2010 a revised PROFile.

Based on the conclusions derived in the framework of Directive 91/414/EEC and the additional information provided by the RMS, EFSA issued on 07 August 2012 a draft reasoned opinion that was circulated to Member States’ experts for consultation. Comments received by 12 October 2012 were considered for finalisation of this reasoned opinion. The following conclusions are derived.

Although the approval under Directive 91/414/EEC referred to mesosulfuron, this substance is currently only available on the market under its variant called mesosulfuron-methyl, which is considered to be the actual active substance. The following conclusions therefore refer to mesosulfuron-methyl instead of mesosulfuron.

The toxicological profile of mesosulfuron-methyl was evaluated in the framework of Directive 91/414/EEC, which resulted in an ADI of 1.0 mg/kg bw per d which was established for mesosulfuron. An ARfD was not deemed necessary.

Primary crop metabolism of mesosulfuron-methyl was investigated following early foliar application in wheat. Only one crop category has been covered (cereals) which is insufficient to propose a general residue definition for all commodities of plant origin. The relevant residue for enforcement and risk assessment in cereals is therefore defined as mesosulfuron-methyl. An analytical method for enforcement of this residue definition with an LOQ of 0.01 mg/kg in dry commodities is available.

Regarding the magnitude of residues, a sufficient number of supervised residue trials is available for the GAPs reported by the RMS, which allowed EFSA to estimate the expected residue concentrations in the relevant plant commodities and to derive MRLs and risk assessment values.

As residues of mesosulfuron-methyl are not expected in treated crops and the chronic exposure does not exceed 10 % of the ADI, there is no need to investigate the effect of industrial and/or household processing. Specific processing factors for enforcement of processed commodities are therefore not proposed.

Occurrence of mesosulfuron-methyl residues in rotational crops was investigated during the peer review of mesosulfuron. It was concluded that metabolic patterns in primary and succeeding crops are similar and that significant residues in rotational crops are not expected. These conclusions are applicable to the GAPs supported in the framework of this review.

The dietary burden was calculated for different groups of livestock, based on the uses reported by the RMS. The results of the calculation indicate that no significant intakes for livestock are expected; the setting of MRLs in commodities of animal origin is therefore not necessary. Nevertheless the nature of mesosulfuron-methyl residues in commodities of animal origin was investigated in lactating cows and laying hens. Based on the results of the metabolism studies, EFSA concludes that the residue in animal commodities may be defined as mesosulfuron-methyl however this would only be necessary if the livestock dietary burden were to be increased in the future. Validated analytical methods for enforcement of the proposed residue definition are not available.

Chronic consumer exposure resulting from the authorised uses reported in the framework of this review was calculated using revision 2 of the EFSA PRIMo. The highest chronic exposure was calculated for Danish children, representing 0.01 % of the ADI. Acute exposure calculations were not carried out because an ARfD was not deemed necessary for this active substance.

Based on the above assessment, EFSA does not recommend inclusion of this active substance in Annex IV to Regulation (EC) No 396/2005. MRL recommendations were derived in compliance with the decision tree reported in Appendix D of the reasoned opinion (see summary table). All MRL values listed in the table are sufficiently supported by data and therefore proposed for inclusion in Annex II to the Regulation.

mesosulfuron-methyl, MRL review, Regulation (EC) No 396/2005, consumer risk assessment, sulfonylurea, herbicide.
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