The full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThis guidance on the assessment of dermal absorption has been developed to assist notifiers, users of test facilities and Member State authorities on critical aspects related to the setting of dermal absorption values to be used in risk assessments of active substances in Plant Protection Products (PPPs). It is based on the 'scientific opinion on the science behind the revision of the guidance document on dermal absorption' issued in 2011 by the EFSA Panel on Plant Protection Products and their Residues (PPR). The guidance refers to the EFSA PPR opinion in many instances. In addition, the first version of this guidance, issued in 2012 by the EFSA PPR Panel, has been revised in 2017 on the basis of new available data on human in vitro dermal absorption for PPPs and wherever clarifications were needed. Basic details of experimental design, available in the respective test guidelines and accompanying guidance for the conduct of studies, have not been addressed but recommendations specific to performing and interpreting dermal absorption studies with PPPs are given. Issues discussed include a brief description of the skin and its properties affecting dermal absorption. To facilitate use of the guidance, flow charts are included. Guidance is also provided, for example, when there are no data on dermal absorption for the product under evaluation. Elements for a tiered approach are presented including use of default values, data on closely related products, in vitro studies with human skin (regarded to provide the best estimate), data from experimental animals (rats) in vitro and in vivo, and the so called 'triple pack' approach. Various elements of study design and reporting that reduce experimental variation and aid consistent interpretation are presented. A proposal for reporting data for assessment reports is also provided. The issue of nanoparticles in PPPs is not addressed. Data from volunteer studies have not been discussed since their use is not allowed in EU for risk assessment of PPPs.

The RISK21 integrated evaluation strategy is a problem formulation-based exposure-driven risk assessment roadmap that takes advantage of existing information to graphically represent the intersection of exposure and toxicity data on a highly visual matrix. This paper describes in detail the process for using the roadmap and matrix. The purpose of this methodology is to optimize the use of prior information and testing resources (animals, time, facilities, and personnel) to efficiently and transparently reach a risk and/or safety determination. Based on the particular problem, exposure and toxicity data should have sufficient precision to make such a decision. Estimates of exposure and toxicity, bounded by variability and/or uncertainty, are plotted on the X-and Y-axes of the RISK21 matrix, respectively. The resulting intersection is a highly visual representation of estimated risk. Decisions can then be made to increase precision in the exposure or toxicity estimates or declare that the available information is sufficient. RISK21 represents a step forward in the goal to introduce new methodologies into 21st century risk assessment. Indeed, because of its transparent and visual process, RISK21 has the potential to widen the scope of risk communication beyond those with technical expertise.

The Health and Environmental Sciences Institute (HESI)-coordinated Risk Assessment in the 21st Century (RISK21) project was initiated to develop a scientific, transparent, and efficient approach to the evolving world of human health risk assessment, and involved over 120 participants from 12 countries, 15 government institutions, 20 universities, 2 non-governmental organizations, and 12 corporations. This paper provides a brief overview of the tiered RISK21 framework called the roadmap and risk visualization matrix, and articulates the core principles derived by RISK21 participants that guided its development. Subsequent papers describe the roadmap and matrix in greater detail. RISK21 principles include focusing on problem formulation, utilizing existing information, starting with exposure assessment (rather than toxicity), and using a tiered process for data development. Bringing estimates of exposure and toxicity together on a two-dimensional matrix provides a clear rendition of human safety and risk. The value of the roadmap is its capacity to chronicle the stepwise acquisition of scientific information and display it in a clear and concise fashion. Furthermore, the tiered approach and transparent display of information will contribute to greater efficiencies by calling for data only as needed (enough precision to make a decision), thus conserving animals and other resources.

The long-term risks of pesticides to wildlife in the EU currently are assessed by comparing the lowest no-observed-effect concentration (NOEC) determined from the suite of endpoints measured in existing avian and mammalian laboratory reproduction tests with estimated exposure concentrations by calculating Toxicity to Exposure Ratios (TERs). Regulatory authorities experience difficulties when assessing long-term risks because of the lack of accepted methods to improve the ecological realism of exposure and toxicity estimates and understand risks at a population level. This paper describes an approach for interpreting existing avian and mammalian toxicity test data that divides breeding cycles into several discrete phases and identifies specific test endpoints as indicators of direct pesticide effects possible at each phase. Based on the distribution of breeding initiation dates for a species of concern and the dates of pesticide applications, this approach compares the phase-specific toxicity endpoint with the expected pesticide exposure levels during each of the breeding phases. The fate of each breeding attempt is determined through a series of decision points. The cumulative reproductive response of individuals in a breeding population based on this decision framework provides a means of examining the estimated risks over the course of the breeding season and deriving an overall metric of the impact of the pesticide on reproduction. Research needed to further improve the approach is discussed.

Assessment of the acute systemic oral, dermal, and inhalation toxicities, skin and eye irritancy, and skin sensitisation potential of chemicals is required under regulatory schemes worldwide. In vivo studies conducted to assess these endpoints can sometimes be associated with substantial adverse effects in the test animals, and their use should always be scientifically justified. It has been argued that while information obtained from such acute tests provides data needed to meet classification and labelling regulations, it is of limited value for hazard and risk assessments. Inconsistent application of in vitro replacements, protocol requirements across regions, and bridging principles also contribute to unnecessary and redundant animal testing. Assessment of data from acute oral and dermal toxicity testing demonstrates that acute dermal testing rarely provides value for hazard assessment purposes when an acute oral study has been conducted. Options to waive requirements for acute oral and inhalation toxicity testing should be employed to avoid unnecessary in vivo studies. In vitro irritation models should receive wider adoption and be used to meet regulatory needs. Global requirements for sensitisation testing need continued harmonisation for both substance and mixture assessments. This paper highlights where alternative approaches or elimination of tests can reduce and refine animal use for acute toxicity requirements.