Scientific Opinion of the PPR Panel on the follow-up of the findings of the External Scientific Report 'Literature review of epidemiological studies linking exposure to pesticides and health effects'

A Th2-type immune response and low-grade systemic inflammatory reaction as potential immunotoxic effects in intensive agriculture farmers exposed to pesticides

Pesticides are chemicals widely used in agriculture to keep crops healthy and prevent them from being destroyed by pests, thus contributing to a sustainable food and feed production. However, long-term exposure to these compounds may be harmful to human health as they can affect the function of various organs systems, including the immune system. There is growing evidence that pesticides may increase the risk of developing immune-based diseases and inflammation. This study assessed whether greenhouse farmers occupationally exposed to pesticides presented alterations in immunoregulatory proteins, used as surrogate biomarkers of immune function. The study population consisted of 175 greenhouse workers occupationally exposed to pesticides and 91 non-exposed controls. Serum levels of 27 cytokines, chemokines and growth factors were measured using a magnetic bead-based immunoassay in a subpopulation of 111 greenhouse workers and 79 non-exposed controls. Since analytical determinations were performed in two periods of the same crop season with different use of pesticides (period of high and low pesticide exposure), linear mixed models for repeated measures were used to optimize statistical inference. The increase in IL-13, IL-4 and IL-6 observed in greenhouse workers compared to controls, and in the period of high exposure to pesticides relative to that of low exposure, suggest an altered Th1/Th2 balance towards the Th2 response. This finding points to a type-2 inflammation commonly presented as allergic inflammation, which has often been reported in farm-workers and in which pesticide exposure is considered a risk factor. Furthermore, the increase in IL-1β and VEGF, mediators of inflammation and angiogenesis, may suggest a low-grade systemic inflammation that might underlie chronic pathological conditions linked to pesticide exposure.

Scientific Committee guidance on appraising and integrating evidence from epidemiological studies for use in EFSA's scientific assessments

EFSA requested its Scientific Committee to prepare a guidance document on appraising and integrating evidence from epidemiological studies for use in EFSA's scientific assessments. The guidance document provides an introduction to epidemiological studies and illustrates the typical biases, which may be present in different epidemiological study designs. It then describes key epidemiological concepts relevant for evidence appraisal. This includes brief explanations for measures of association, exposure assessment, statistical inference, systematic error and effect modification. The guidance then describes the concept of external validity and the principles of appraising epidemiological studies. The customisation of the study appraisal process is explained including tailoring of tools for assessing the risk of bias (RoB). Several examples of appraising experimental and observational studies using a RoB tool are annexed to the document to illustrate the application of the approach. The latter part of this guidance focuses on different steps of evidence integration, first within and then across different streams of evidence. With respect to risk characterisation, the guidance considers how evidence from human epidemiological studies can be used in dose-response modelling with several different options being presented. Finally, the guidance addresses the application of uncertainty factors in risk characterisation when using evidence from human epidemiological studies.

Pesticide residues in agricultural end-products and risk assessment for consumers in North China

This study investigated pesticide residues in market-sold vegetables and fruits in Hebei Province, China, over 5 years (2018-2022). A modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) method was applied to gas chromatography with triple-quadrupole mass spectrometer (GC-MS/MS). The analytical methods were validated with respect to matrix effect (ME), recovery rate (78.9~105.5%), limit of quantitation (LOQ, 2.93~9.73 μg/kg), and linear correlation coefficient (0.9982~0.9997). Residues of 10 pesticides in 12 categories of vegetable and fruit were detected. 31.9% of the samples were detected pesticide residues; 15.5% of samples were detected multi-component pesticide residues. Twenty-seven positive detections of pesticide residues exceeded the corresponding maximum residue limit (MRL), accounting for 2.33%. The most types of pesticide residues were detected in cherry, with the number of 7. Procymidone was the most detected pesticide, and it was detected in 8 categories of samples. The hazard index (HI) of omethoate was the highest and the procymidone was the lowest. The HI of all the vegetables and fruits were less than 100%. The effects of pesticide residues are within an acceptable range for human. Adequate attention and further monitoring are still needed.

Application of AOPs to assist regulatory assessment of chemical risks - Case studies, needs and recommendations

While human regulatory risk assessment (RA) still largely relies on animal studies, new approach methodologies (NAMs) based on in vitro, in silico or non-mammalian alternative models are increasingly used to evaluate chemical hazards. Moreover, human epidemiological studies with biomarkers of effect (BoE) also play an invaluable role in identifying health effects associated with chemical exposures. To move towards the next generation risk assessment (NGRA), it is therefore crucial to establish bridges between NAMs and standard approaches, and to establish processes for increasing mechanistically-based biological plausibility in human studies. The Adverse Outcome Pathway (AOP) framework constitutes an important tool to address these needs but, despite a significant increase in knowledge and awareness, the use of AOPs in chemical RA remains limited. The objective of this paper is to address issues related to using AOPs in a regulatory context from various perspectives as it was discussed in a workshop organized within the European Union partnerships HBM4EU and PARC in spring 2022. The paper presents examples where the AOP framework has been proven useful for the human RA process, particularly in hazard prioritization and characterization, in integrated approaches to testing and assessment (IATA), and in the identification and validation of BoE in epidemiological studies. Nevertheless, several limitations were identified that hinder the optimal usability and acceptance of AOPs by the regulatory community including the lack of quantitative information on response-response relationships and of efficient ways to map chemical data (exposure and toxicity) onto AOPs. The paper summarizes suggestions, ongoing initiatives and third-party tools that may help to overcome these obstacles and thus assure better implementation of AOPs in the NGRA.

Health Effects of Pesticide Exposure in Latin American and the Caribbean Populations: A Scoping Review

BACKGROUND

Multiple epidemiological studies have shown that exposure to pesticides is associated with adverse health outcomes. However, the literature on pesticide-related health effects in the Latin American and the Caribbean (LAC) region, an area of intensive agricultural and residential pesticide use, is sparse. We conducted a scoping review to describe the current state of research on the health effects of pesticide exposure in LAC populations with the goal of identifying knowledge gaps and research capacity building needs.

METHODS

We searched PubMed and SciELO for epidemiological studies on pesticide exposure and human health in LAC populations published between January 2007 and December 2021. We identified 233 publications from 16 countries that met our inclusion criteria and grouped them by health outcome (genotoxicity, neurobehavioral outcomes, placental outcomes and teratogenicity, cancer, thyroid function, reproductive outcomes, birth outcomes and child growth, and others).

RESULTS

Most published studies were conducted in Brazil (37%, n = 88 ) and Mexico (20%, n = 46 ), were cross-sectional in design (72%, n = 167 ), and focused on farmworkers (45%, n = 105 ) or children (21%, n = 48 ). The most frequently studied health effects included genotoxicity (24%, n = 62 ) and neurobehavioral outcomes (21%, n = 54 ), and organophosphate (OP) pesticides were the most frequently examined (26%, n = 81 ). Forty-seven percent (n = 112 ) of the studies relied only on indirect pesticide exposure assessment methods. Exposure to OP pesticides, carbamates, or to multiple pesticide classes was consistently associated with markers of genotoxicity and adverse neurobehavioral outcomes, particularly among children and farmworkers.

DISCUSSION

Our scoping review provides some evidence that exposure to pesticides may adversely impact the health of LAC populations, but methodological limitations and inconsistencies undermine the strength of the conclusions. It is critical to increase capacity building, integrate research initiatives, and conduct more rigorous epidemiological studies in the region to address these limitations, better inform public health surveillance systems, and maximize the impact of research on public policies. https://doi.org/10.1289/EHP9934.

How Many Urine Samples Are Needed to Accurately Assess Exposure to Non-Persistent Chemicals? The Biomarker Reliability Assessment Tool (BRAT) for Scientists, Research Sponsors, and Risk Managers

In epidemiologic and exposure research, biomonitoring is often used as the basis for assessing human exposure to environmental chemicals. Studies frequently rely on a single urinary measurement per participant to assess exposure to non-persistent chemicals. However, there is a growing consensus that single urine samples may be insufficient for adequately estimating exposure. The question then arises: how many samples would be needed for optimal characterization of exposure? To help researchers answer this question, we developed a tool called the Biomarker Reliability Assessment Tool (BRAT). The BRAT is based on pharmacokinetic modeling simulations, is freely available, and is designed to help researchers determine the approximate number of urine samples needed to optimize exposure assessment. The BRAT performs Monte Carlo simulations of exposure to estimate internal levels and resulting urinary concentrations in individuals from a population based on user-specified inputs (e.g., biological half-life, within- and between-person variability in exposure). The BRAT evaluates—through linear regression and quantile classification—the precision/accuracy of the estimation of internal levels depending on the number of urine samples. This tool should guide researchers towards more robust biomonitoring and improved exposure classification in epidemiologic and exposure research, which should in turn improve the translation of that research into decision-making.

"Good Epidemiology Practice" Guidelines for Pesticide Exposure Assessment

Both toxicology and epidemiology are used to inform hazard and risk assessment in regulatory settings, particularly for pesticides. While toxicology studies involve controlled, quantifiable exposures that are often administered according to standardized protocols, estimating exposure in observational epidemiology studies is challenging, and there is no established guidance for doing so. However, there are several frameworks for evaluating the quality of published epidemiology studies. We previously developed a preliminary list of methodology and reporting standards for epidemiology studies, called Good Epidemiology Practice (GEP) guidelines, based on a critical review of standardized toxicology protocols and available frameworks for evaluating epidemiology study quality. We determined that exposure characterization is one of the most critical areas for which standards are needed. Here, we propose GEP guidelines for pesticide exposure assessment based on the source of exposure data (i.e., biomonitoring and environmental samples, questionnaire/interview/expert record review, and dietary exposures based on measurements of residues in food and food consumption). It is expected that these GEP guidelines will facilitate the conduct of higher-quality epidemiology studies that can be used as a basis for more scientifically sound regulatory risk assessment and policy making.

emagnification: A tool for estimating effect-size magnification and performing design calculations in epidemiological studies

Artificial effect-size magnification (ESM) may occur in underpowered studies, where effects are reported only because they or their associated p-values have passed some threshold. Ioannidis (2008, Epidemiology 19: 640-648) and Gelman and Carlin (2014, Perspectives on Psychological Science 9: 641-651) have suggested that the plausibility of findings for a specific study can be evaluated by computation of ESM, which requires statistical simulation. In this article, we present a new command called emagnification that allows straightforward implementation of such simulations in Stata. The commands automate these simulations for epidemiological studies and enable the user to assess ESM routinely for published studies using user-selected, study-specific inputs that are commonly reported in published literature. The intention of the command is to allow a wider community to use ESMs as a tool for evaluating the reliability of reported effect sizes and to put an observed statistically significant effect size into a fuller context with respect to potential implications for study conclusions.

Critical assessment and integration of separate lines of evidence for risk assessment of chemical mixtures

Humans are exposed to multiple chemicals on a daily basis instead of to just a single chemical, yet the majority of existing toxicity data comes from single-chemical exposure. Multiple factors must be considered such as the route, concentration, duration, and the timing of exposure when determining toxicity to the organism. The need for adequate model systems (in vivo, in vitro, in silico and mathematical) is paramount for better understanding of chemical mixture toxicity. Currently, shortcomings plague each model system as investigators struggle to find the appropriate balance of rigor, reproducibility and appropriateness in mixture toxicity studies. Significant questions exist when comparing single-to mixture-chemical toxicity concerning additivity, synergism, potentiation, or antagonism. Dose/concentration relevance is a major consideration and should be subthreshold for better accuracy in toxicity assessment. Previous work was limited by the technology and methodology of the time, but recent advances have resulted in significant progress in the study of mixture toxicology. Novel technologies have added insight to data obtained from in vivo studies for predictive toxicity testing. These include new in vitro models: omics-related tools, organs-on-a-chip and 3D cell culture, and in silico methods. Taken together, all these modern methodologies improve the understanding of the multiple toxicity pathways associated with adverse outcomes (e.g., adverse outcome pathways), thus allowing investigators to better predict risks linked to exposure to chemical mixtures. As technology and knowledge advance, our ability to harness and integrate separate streams of evidence regarding outcomes associated with chemical mixture exposure improves. As many national and international organizations are currently stressing, studies on chemical mixture toxicity are of primary importance.

Moving towards a holistic approach for human health risk assessment - Is the current approach fit for purpose?

It is recognised that new scientific improvements and their integration in risk assessment, as outlined in the National Academies of Sciences, Engineering and Medicine 2017 report, have the potential to improve human health risk assessments by enabling a mechanistic understanding of adverse effects and more accurate predictions of biological responses. Here, I discuss why such improvements are needed and can ease a paradigm shift in human health risk assessment. The current approach to human health risk assessment is limited by several elements: (1) the relevance of data is debatable, as they are largely based on in vivo animal models that are poorly predictive for complex endpoints, raise challenges with regard to interspecies extrapolations, and are seldom informative of the mechanism underlying the observed effects; (2) lack of flexibility in data requirements by regulators, which limits the uptake of new scientific developments in a timely manner; and (3) lack of data accessibility, which makes data integration difficult. However, mechanistic-based assessments are currently conducted for the identification of endocrine disruptors and are developed for addressing developmental neurotoxicity. Such assessments can serve as examples for changing the paradigm of risk assessment. There are several opportunities for improvement, such as: make regulatory standard requirements less prescriptive; enhance and use the opportunities for read-across; analyse and quantify uncertainties in order to benchmark new approach methods to the current system; better integrate screening methods early in regulatory assessments and decision-making; and develop more adverse outcome pathways in order to link new approach methods with the current approach and ultimately make it possible to base regulatory decisions on early key events of a toxicity pathway.

Revisiting Risk Governance of GM Plants: The Need to Consider New and Emerging Gene-Editing Techniques

New and emerging gene-editing techniques make it possible to target specific genes in species with greater speed and specificity than previously possible. Of major relevance for plant breeding, regulators and scientists are discussing how to regulate products developed using these gene-editing techniques. Such discussions include whether to adopt or adapt the current framework for GMO risk governance in evaluating the impacts of gene-edited plants, and derived products, on the environment, human and animal health and society. Product classification or definition is one of several aspects of the current framework being criticized. Further, knowledge gaps related to risk assessments of gene-edited organisms-for example of target and off-target effects of intervention in plant genomes-are also of concern. Resolving these and related aspects of the current framework will involve addressing many subjective, value-laden positions, for example how to specify protection goals through ecosystem service approaches. A process informed by responsible research and innovation practices, involving a broader community of people, organizations, experts, and interest groups, could help scientists, regulators, and other stakeholders address these complex, value-laden concerns related to gene-editing of plants with and for society.