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


European Food Safety Authority
EFSA Journal
EFSA Journal 2013;11(2):3123 [30 pp.].

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

Reasoned Opinion
On request from
Question Number
20 février 2013
25 février 2013
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 isoxaflutole. In order to assess the occurrence of isoxaflutole residues in plants, processed commodities, rotational crops and livestock, EFSA considered the conclusions derived in the framework of Directive 91/414/EEC and 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. Although no apparent risk to consumers was identified, some information required by the regulatory framework was found to be missing. Hence, the consumer risk assessment is considered indicative only and one MRL proposal derived by EFSA still requires further consideration by risk managers.


Isoxaflutole was included in Annex I to Directive 91/414/EEC on 01 October 2003, 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 afore mentioned regulation. In order to collect the relevant pesticide residues data, EFSA asked The Netherlands, as the designated rapporteur Member State (RMS), to complete the Pesticide Residues Overview File (PROFile). The requested information was submitted to EFSA on 23 March 2009 and, after having considered several comments made by EFSA, the RMS provided on 11 December 2009 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 20 September 2012 a draft reasoned opinion that was circulated to Member State experts for consultation. Comments received by 23 November 2012 were considered for finalisation of this reasoned opinion. The following conclusions are derived.

The toxicological profile of isoxaflutole was evaluated in the framework of Directive 91/414/EEC, which resulted in an ADI of 0.02 mg/kg bw per d. An ARfD was not deemed necessary.

Primary crop metabolism of isoxaflutole was investigated in cereals following soil (pre-mergence) and foliar (early post-emergence) application in maize, hereby covering the cereals crop group. The relevant residue for enforcement and risk assessment in cereals is defined as the sum of isoxaflutole and its diketonitrile-metabolite, expressed as isoxaflutole. Considering that the use of isoxaflutole is also supported in poppy seed, an additional metabolism study is required in order to confirm the proposed residue definition for oilseed as well. An analytical method for enforcement of this residue definition with an LOQ of 0.02 mg/kg in commodities with high water, high oil, high acid and dry matter content is available.

Regarding the magnitude of residues, a sufficient number of supervised residues trials is available for maize (grain and forage), sweet corn and sugar cane, which allowed EFSA to estimate the expected residue concentrations in the relevant plant commodities and to derive appropriate MRLs. For poppy seed, no residues trials were available. EFSA was therefore not able to derive reliable MRL proposal and risk assessment values, and further residues trials are required.

As quantifiable residues of isoxaflutole are not expected in edible part of crops and total chronic exposure represents less than 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 isoxaflutole residues in rotational crops was already investigated during the peer review of isoxaflutole. 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 also apply to the GAPs of isoxaflutole supported in the framework of this review.

Based on the uses reported in the framework of this review, no significant intake was calculated for poultry, dairy ruminant, meat ruminants and pigs. Consequently, no MRLs in commodities of animal origin are required.

Chronic consumer exposure resulting from the authorised uses reported in the framework of this review was calculated using revision 2 of the EFSA PRIMo. For those commodities where data were insufficient to derive an MRL, EFSA considered the existing EU MRL for an indicative calculation. The highest chronic exposure was calculated for WHO Cluster diet B, representing 0.3 % 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 as ‘Recommended’ in the table are sufficiently supported by data and therefore proposed for inclusion in Annex II to the Regulation. The remaining MRL value listed in the table cannot be recommended for inclusion in Annex II because it requires further consideration by risk managers (see summary table footnotes for details). In particular, this existing EU MRL still needs to be confirmed by submission of the following data:

  • a metabolism study with post-emergence application in oilseeds;
  • a clarification of the Czech GAP on poppy seeds;
  • 4 residue trials complying with the northern GAP and 4 residue trials complying with the southern GAP on poppy seed;
  • storage stability data for isoxaflutole residues in high oil content commodities (depending on the storage conditions of the residues trials in poppy seeds).

If the above reported data gaps are not addressed in the future, Member States are recommended to withdraw or modify the relevant authorisations at national level.

Minor deficiencies were also identified in the assessment but these deficiencies are not expected to impact either on the validity of the MRLs derived or on the national authorisations. The following data are therefore considered desirable but not essential:

  • detailed information on the soil degradation study (investigating the isoxazole moiety).
Isoxaflutole, MRL review, Regulation (EC) No 396/2005, consumer risk assessment, oxazoles, herbicide, diketonitrile-isoxalutole
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