Organophosphorus compounds (OPs) are a large and diverse class of chemicals mainly used as pesticides and chemical weapons. People may be exposed to OPs in several occasions, which can produce several distinct neurotoxic effects depending on the dose, frequency of exposure, type of OP, and the host factors that influence susceptibility and sensitivity. These neurotoxic effects are mainly due to the interaction with enzyme targets involved in toxicological or detoxication pathways. In this work, the toxicological relevance of known OPs targets is reviewed. The main enzyme targets of OPs have been identified among the serine hydrolase protein family, some of them decades ago (e.g. AChE, BuChE, NTE and carboxylesterases), others more recently (e.g. lysophospholipase, arylformidase and KIA1363) and others which are not molecularly identified yet (e.g. phenylvalerate esterases). Members of this family are characterized by displaying serine hydrolase activity, containing a conserved serine hydrolase motif and having an alpha-beta hydrolase fold. Improvement in Xray-crystallography and in silico methods have generated new data of the interactions between OPs and esterases and have established new methods to study new inhibitors and reactivators of cholinesterases. Mass spectrometry for AChE, BChE and APH have characterized the active site serine adducts with OPs being useful to detect biomarkers of OPs exposure and inhibitory and postinhibitory reactions of esterases and OPs. The purpose of this review is focus specifically on the interaction of OP with esterases, mainly with type B-esterases, which are able to hydrolyze carboxylesters but inhibited by OPs by covalent phosphorylation on the serine or tyrosine residue in the active sites. Other related esterases in some cases with no-irreversible effect are also discussed. The understanding of the multiple molecular interactions is the basis we are proposing for a multi-target approach for understanding the organophosphorus toxicity.

Organophosphorus compounds (OPs) are a large and diverse class of chemicals that have been synthesized, since the XIX century for several purposes like chemical weapons, flame-retardants, ectoparasiticides and investigational new drugs, but mainly as agrochemicals in agriculture and indoor. Although the amount of OP pesticides being used is declining, especially in developed countries, OPs continue being one of the most important classes of insecticides and chemical warfare agents today due to its toxic effects on the enzyme acetylcholinesterase (AChE). Existing research on the toxicological effects of OPs is extensive, however, there is a lack of knowledge on the long-term effects of low levels of OPs and their exactly pathways of toxicity. Recent data prove that other molecular targets than AChE could be targeted by OPs, triggering these effects. Here these data are reviewed and it is highlighted that the current uses of OPs are producing several neurotoxic effects. It is also shown that, to protect people from possible uses and misuses of OPs, more regulations on OPs are needed. Moreover, more mechanistic studies are needed to completely understand their toxicological interactions and mechanisms of action and to identify the whole group of enzymes that interact with them.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Italy, and co‐rapporteur Member State, France, for the pesticide active substance oxamyl and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of oxamyl as a nematicide on potato and tobacco (field use), on tomato (permanent greenhouse), on cucurbits (edible and inedible peel), pepper, aubergine and plants nurseries of the above‐mentioned crops on soil bed preparation (permanent greenhouse). The reliable end points, appropriate for use in regulatory risk assessment and the proposed MRLs, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

The conclusions of the EFSA following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Spain, and co‐rapporteur Member State, Greece, for the pesticide active substance phosmet and the assessment of applications for maximum residue levels (MRLs) are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of phosmet as an insecticide on citrus fruits, pome fruits, peaches/nectarines and potatoes (field uses). The reliable end points, appropriate for use in regulatory risk assessment, are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.

No abstract

The conclusions of the EFSA following the peer review of the initial risk assessment carried out by the competent authority of the rapporteur Member State, France, for the pesticide active substance acibenzolar-S-methyl are reported. The context of the peer review was that requested by the European Commission following the submission and evaluation of confirmatory information with regard to the endocrine disruption potential of the substance. The conclusions were reached on the basis of the evaluation of the representative uses of acibenzolar-S-methyl as a plant activator on pome fruit, tomato and tobacco. The reliable endpoints concluded as being appropriate for use in regulatory risk assessment, derived from the available studies and literature in the dossier peer reviewed, are presented. Assessments not finalised together with the missing information identified as being required by the regulatory framework are listed.

No abstract

The conclusions of the European Food Safety Authority (EFSA) following the peer review of the initial risk assessments carried out by the competent authorities of the rapporteur Member State, Austria, and co‐rapporteur Member State, Malta, for the pesticide active substance abamectin are reported. The context of the peer review was that required by Commission Implementing Regulation (EU) No 844/2012, as amended by Commission Implementing Regulation (EU) No 2018/1659. The conclusions were reached on the basis of the evaluation of the representative uses of abamectin as an insecticide and acaricide on tomato and strawberry. The reliable end points appropriate for use in regulatory risk assessment are presented. Missing information identified as being required by the regulatory framework is listed. Concerns are identified.