Review of the existing maximum residue levels for chloridazon according to Article 12 of Regulation (EC) No 396/2005


European Food Safety Authority
EFSA Journal
EFSA Journal 2015;13(9):4226 [52 pp.].
Reasoned Opinion
On request from
European Commission
Question Number
28 August 2015
3 September 2015
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 chloridazon. In order to assess the occurrence of chloridazon 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. 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 almost all MRL proposals derived by EFSA still require further consideration by risk managers.


Chloridazon was included in Annex I to Directive 91/414/EEC on 1 January 2009 by Commission Directive 2008/41/EC, and has been deemed to be approved under Regulation (EC) No 1107/2009, in accordance with Commission Implementing Regulation (EU) No 540/2011, as amended by Commission Implementing Regulation (EU) No 541/2011. As the active substance was approved after the entry into force of Regulation (EC) No 396/2005 on 2 September 2008, EFSA is required to provide a reasoned opinion on the review of the existing MRLs for that active substance in compliance with Article 12(1) of the aforementioned regulation. In order to collect the relevant pesticide residues data, EFSA asked Germany, as the designated rapporteur Member State (RMS), to complete the Pesticide Residues Overview File (PROFile) and to prepare a supporting evaluation report. The PROFile and evaluation report provided by the RMS were made available to the Member States. A request for additional information was addressed to the Member States in the framework of a completeness check period which was initiated by EFSA on 22 December 2014 and finalised on 23 February 2015. After having considered all the information provided, EFSA prepared a completeness check report which was made available to Member States on 26 March 2015.

Based on the conclusions derived by EFSA in the framework of Directive 91/414/EEC, and the additional information provided by the RMS and Member States, EFSA prepared in June 2015 a draft reasoned opinion, which was circulated to Member States for consultation via a written procedure. Comments received by 30 June 2015 were considered during the finalisation of this reasoned opinion. The following conclusions are derived.

The metabolism of chloridazon has been investigated in primary crops (sugar beet) and rotational crops (leafy, roots and cereals). Similar metabolic patterns were observed in these studies. Moreover, hydrolysis studies demonstrated that chloridazon and its main metabolite chloridazon-desphenyl (also called metabolite B) were stable under processing by pasteurisation, baking/brewing/boiling and sterilisation. Consequently, the residue definition for monitoring is proposed as the sum of chloridazon and chloridazon-desphenyl, expressed as chloridazon. A validated analytical method for enforcement of the proposed residue definition in plant commodities is available. The risk assessment residue definition was proposed as the sum of chloridazon, chloridazon-desphenyl, and their conjugates, expressed as chloridazon. These residue definitions cover all the authorised GAPs reported in this review (root and leafy crops) but would not be applicable to other crop groups.

The available residue trials allowed EFSA assessing the magnitude of residues resulting from the authorised GAPs reported in this review. However, results of field rotational crops studies indicated that a significant uptake of residues in leafy crops and in wheat straw cannot be avoided. For these crops, EFSA therefore assessed the impact of proposing 3 different plant-back intervals. For all leafy crops that can be grown in rotation (even when GAPs are not authorised), different MRL proposals were derived depending on the plant-back interval, while for roots crops the MRLs derived from the primary crop use always cover the negligible uptake from rotational crops. However, all the MRL proposals other than sugar beet roots were derived on a tentative basis due to uncertainties regarding residues levels in primary crops and rotational crops. Based on available data on sugar beet and red beet (roots and tops), tentative conversion factors were derived for root and leafy crops. Furthermore, residue transfer from sugar beet to white sugar has also been investigated, indicating that transfer from raw sugar beet to white sugar does not occur.

Chloridazon is authorised for use on sugar and fodder beets that might be fed to livestock. The metabolism of chloridazon and chloridazon-desphenyl was investigated separately, both in goats and laying hens. As metabolic pathways are expected to be similar in ruminants and pigs, the results of the goat metabolism study could be extrapolated to swine. From these studies, it was agreed that chloridazon-desphenyl was the only relevant compound in livestock commodities. The presence of chloridazon is not expected in livestock commodities. Therefore, EFSA proposed to proceed with a common residue definition for monitoring and risk assessment being “chloridazon-desphenyl, expressed as chloridazon”. A validated analytical method for enforcement of the proposed residue definition is available. In the absence of a reliable feeding study for ruminants, EFSA considered the results of the metabolism studies to derive MRLs and risk assessment values in livestock commodities. Different calculations were performed according to the respective dietary burdens resulting from the 3 different risk mitigation options.

Chronic consumer exposure resulting from this assessment was calculated using revision 2 of the EFSA PRIMo. These calculations included residues from the authorised GAP reported in this review and the potential uptake of chloridazon residues in crops that may be grown in rotation. EFSA evaluated the 3 different scenarios corresponding to the 3 proposed risk mitigation options. The highest chronic exposure was calculated for British toddler, representing 7.2 % of the ADI in scenario 1 (PBI 30 days), 6.1 % of the ADI in scenario 2 (PBI 120 days) and 6.4 % of the ADI in scenario 3 (PBI 365 days). Acute exposure calculations were not carried out because an ARfD was not deemed necessary for this active substance.

chloridazon, MRL review, Regulation (EC) No 396/2005, consumer risk assessment, pyridazinone, herbicide, 5-amino-4-chloro-3(2H)-pyridazinone
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