Publications & Documents

A clear, efficient, and modern regulatory framework for pesticides is essential for addressing their impacts on human health and the environment, supporting a life-cycle approach to their management, and ensuring crop protection and a sustainable agricultural industry. This report identifies the gaps, barriers, implementation flaws and inefficiencies that affect the regulatory framework of pesticides in Mexico. It takes stock of the regulatory framework and recent reforms, and identifies both the areas that pose the greatest challenge for the effective regulation of pesticides and those where regulation – or lack of it – in pesticides most affects policy objectives and economic activity. These challenges and practices are assessed in view of OECD principles and country experiences, and recommendations are provided to support better regulation efforts. The report finds that Mexico would benefit from adopting a comprehensive, mutually-agreed policy strategy for pesticides, recognising that pesticide management is a shared responsibility across national and local governments, the pesticide industry, pesticide users, as well as the general public.

A Defined Approach (DA) consists of a selection of information sources (e.g in silico predictions, in chemico, in vitro data) used in a specific combination, and resulting data are interpreted using a fixed data interpretation procedure (DIP) (e.g. a mathematical, rule-based model). DAs use methods in combination and are intended to overcome some limitations of the individual, stand-alone methods. The first three DAs included in this Guideline use combinations of OECD validated in chemico and in vitro test data, in some cases along with in silico information, to come to a rules-based conclusion on potential dermal sensitisation hazard. The DAs included in this Guideline have shown to either provide the same level of information or be more informative than the murine Local Lymph Node Assay (LLNA; OECD TG 429) for hazard identification (i.e. sensitiser versus non-sensitiser). In addition, two of the DAs provide information for sensitisation potency categorisation that is equivalent to the potency categorisation information provided by the LLNA.

The RTgill-W1 cell line assay describes a 24-well plate format fish cell line acute toxicity test using the permanent cell line from rainbow trout (Oncorhynchus mykiss) gill, RTgill-W1. After 24 h of exposure to the test chemical, cell viability is assessed based on three fluorescent cell viability indicator dyes, measured on the same set of cells. Resazurin enters the cells in its non-fluorescent form and is converted to the fluorescent product, resorufin, by mitochondrial, microsomal or cytoplasmic oxidoreductases. A reduction in the fluorescence of resorufin indicates a decline in cellular metabolic activity, including disruption of mitochondrial membranes. The data are expressed as the percent cell viability of unexposed control values versus the test chemical concentration. The resulting concentration-response curves serve to determine the effective concentrations causing 50% loss in cell viability, i.e. the EC50 value. The test is designed to (i) predict fish acute toxicity in product testing; (ii) range-finding and pre-screening before conducting a full fish acute or other fish-based toxicity test; (iii) generation of toxicity information to be used for hazard assessment in combination with other lines of evidences (e.g., Quantitative Structure Activity Relationships (QSAR), weight of evidence (WoE)) within Integrated Testing Strategy (ITS)/Integrated Approach to Testing and Assessment (IATA).

Crop field trials are conducted to determine the magnitude of the pesticide residue in or on raw agricultural commodities, including feed items, and should be designed to reflect pesticide use patterns that lead to the highest possible residues. Objectives of crop field trials are to: (1) quantify the expected range of residue(s) in crop commodities following treatment according to the proposed or established good agricultural practice; (2) determine, when appropriate, the rate of decline of the residue(s) of plant protection product(s) on commodities of interest; (3) determine residue values such as the 'Supervised Trial Median Residue' and 'Highest Residue' for conducting dietary risk assessment; and (4) derive maximum residue limits (MRLs).  This Test Guideline requires one sample from treated plots at each sampling interval for crops that have eight or more crop field trials. The test substance(s) should be stored under appropriate conditions for the study duration and applied soon after preparation or mixing. Test substance applications should not be made in strong wind, during rain or when rainfall is expected shortly after application. For all applications, the application rate should be expressed in terms of amount of product and/or active ingredient per unit area. At the end of each crop field trial, the (stored) samples are analysed for residue level (expressed for example in mg/kg).

The EASZY assay is a mechanism-based in vivo screening assay designed to detect endocrine active chemicals acting as agonist through estrogen receptors (ERs), by inducing the expression of the green fluorescent protein (GFP) driven by the cyp19a1b promoter. The EASZY assay allows for the detection of estrogenic activity of chemicals on transgenic tg(cyp19a1b:GFP) Zebrafish embryos exposed for 96 hours during the embryonic stages of development. At the end of the experiment, the fluorescence of each newly hatched eleutheroembryo is measured using fluorescence microscope. Because the skull of early developmental stages of zebrafish is transparent, GFP is observed, imaged and quantified in vivo. The intensity of fluorescence is then quantified using image analysis software.

This Performance-Based Test Guideline (PBTG) describes in vitro assays, which provide the methodology of Stably Transfected Transactivation to detect Estrogen Receptor Agonists and Antagonists (ER TA assays). It comprises mechanistically and functionally similar test methods for the identification of estrogen receptor agonists and antagonists and should facilitate the development of new similar or modified test methods. The two reference test methods that provide the basis for this PBTG are: the Stably Transfected TA (STTA) assay using the (h) ERα-HeLa-9903 cell line, derived from a human cervical tumor, and the BG1Luc ER TA assay using the BG1Luc-4E2 cell line, derived from a human ovarian adenocarcinoma. The cell lines used in these assays express ER and have been stably transfected with an ER responsive luciferase reporter gene. The assays are used to identify chemicals that activate (i.e. act as agonists) and also suppress (i.e. act as antagonists) ER- dependent transcription. ER are activated following ligand binding, after which the receptor-ligand complex binds to specific DNA response elements and transactivates the reporter gene, resulting in increased cellular expression of a marker enzyme (e.g. luciferase in luciferase based systems). The enzyme then transforms the substrate to a bioluminescent product that can be quantitatively measured with a luminometer. These test methods are being proposed for screening and prioritisation purposes, but also provide mechanistic information that can be used in a weight of evidence approach.

Skin phototoxicity (photoirritation) is defined as an acute toxic response elicited by topically or systemically administered photoreactive chemicals after the exposure of the skin to environmental light. The in vitro reconstructed human epidermis phototoxicity test (RhE PT) is used to identify the phototoxic potential of a test chemical after topical application in reconstructed human epidermis (RhE) tissues in the presence and absence of simulated sunlight. Phototoxicity potential is evaluated by the relative reduction in viability of cells exposed to the test chemical in the presence as compared to the absence of simulated sunlight. Chemicals identified as positive in this test may be phototoxic in vivo following topical application to the skin, eyes, and other external light-exposed epithelia.

IUCLID (International Uniform Chemical Information Database) is a software application designed to record, store, maintain and exchange data on chemicals. It is a key software application for both regulatory bodies and the chemical industry where it is used in the implementation of various regulatory programmes. IUCLID can be customised and configured to manage chemical data in different contexts and is a platform employing globally harmonised data elements pertinent to chemicals. It is continuously updated to provide greater customisation, extension and integration with other tools. This second edition provides the latest updates on IUCLID features and processes, including visual 'working' contexts for the preparation and management of data according to regulatory contexts or data processes, possibilities for data entry in multiple languages, and a matrix view of the use of IUCLID in OECD countries.