The international initiative titled: "Using Adverse Outcome Pathways (AOP) to address combined exposures to chemicals with relevant effect-biomarkers", was coordinated by the OECD's Working Parties on Exposure Assessment (WPEA) and Hazard Assessment (WPHA). It brought together over 90 experts from 25 countries to advance the regulatory and scientific use of effect biomarkers for assessing exposures to chemical mixtures and their associated biological and health-relevant effects. Effect biomarkers provide biologically integrated information that can complement traditional single-substance approaches by supporting the interpretation of combined chemical exposures and associated biological responses. While the official OECD Guidance targets primarily regulatory audiences, this article communicates the project's rationale and methodology to academic, industrial, and regulatory communities. Assessing chemical mixture exposures through effect biomarkers overcomes the limitations of traditional single-substance approaches that have guided regulatory frameworks for decades. Effect biomarkers, anchored in AOPs, offer biologically integrated assessments resulting from both known and unknown exposures integrating all exposure routes. Effect biomarkers are powerful in identifying biologically relevant responses, enabling targeted health assessments of vulnerable populations within human biomonitoring programs. This OECD project has produced a harmonised framework for deriving effect-based mixture threshold levels, applicable to both Occupational Biomonitoring Effect Levels (OBELs) for human health and Effect-Based Trigger values (EBTs) for environmental assessments. The framework establishes biologically anchored trigger values that help identify risks from exposures to complex chemical mixtures and can guide appropriate risk management measures. The derivation was guided by four core selection criteria and additional quality principles, ensuring biological relevance to regulatory-defined adversity, quantifiability, robustness, sensitivity, and interpretability for risk assessment. A four-tiered system (Tiers 0-3) reflects increasing toxicological and methodological certainty and relevance, with thresholds informing risk management decisions based on observed changes in biomarkers. Seven case studies demonstrate the framework's applicability across key hazard classes (genotoxicity/carcinogenicity, endocrine disruption, neurotoxicity, and reproductive toxicity), thus supporting harmonised group- and individual-level assessments and broader integration of effect biomarkers into occupational and environmental health assessments.

Inhalation is a major route of chemical exposure for both consumers and workers. Physiologically-based kinetic (PBK) modeling is a promising tool to understand the absorption, distribution, metabolism, and excretion (ADME) of inhaled chemicals and to predict systemic concentrations of chemicals in humans. New Approach Methodologies (NAMs) can help generate essential input parameters for PBK models. However, validated NAM-based test methods to assess uptake of inhaled chemicals are currently lacking. Reliable information on respiratory uptake is required to determine relevant exposure concentrations for evaluation of systemic effects using NAMs. This manuscript describes a project that aims to apply robust and reliable in vitro models to study cellular uptake, intracellular accumulation, absorption and systemic exposure of chemicals following inhalation. To evaluate the robustness and predictivity of different NAM-based barrier models, to examine appropriate in vitro to in vivo scaling strategies, and to assess sensitivity and uncertainty in the resulting PBK models, the project will focus on relatively data-rich chemicals, specifically per- and polyfluoroalkyl substances (PFAS). While some have been widely explored and others remain data-poor, the entire chemical family is of interest due to its health hazards. Therefore, the work combines experimental and modeling approaches by generating in vitro data on the respiratory uptake and benchmark this to existing human in vivo data, developing biokinetic models to better understand chemical fate within the test systems, and refining inhalation PBK models to improve estimates of systemic uptake. Read-Across (RAx) will be employed as data gap filling technique to infer on the apparent permeability of non-tested PFAS. Together, the in vitro and in silico results will inform and parameterize PBK models, ultimately enabling more reliable predictions of systemic availability. The project will deliver a workflow to combine in vitro and in silico methods to assess the uptake of inhaled substances, that could be modified and applied to other inhaled substances. Standardized in vitro models for respiratory uptake will improve the evaluation of inhalation as a route of exposure contributing to systemic effects, which is a key requirement for quantitative in vitro to in vivo extrapolation (qIVIVE) and supports the implementation of next-generation risk assessment (NGRA).

Children are particularly vulnerable to environmental pollutants, making indoor air quality in schools a key health determinant. This study addresses regulatory gaps and the lack of standardized methods for assessing fungal contamination in Portuguese elementary schools, particularly regarding pathogenicity, toxigenicity, and antifungal resistance. Fungal contamination was assessed in 11 Portuguese elementary schools using surveys on building context and operation, active and passive air sampling, molecular detection of Aspergillus sections by qPCR, mycotoxin and azole resistance screening, and PM measurements. Results:Schools showed heterogeneous ventilation, with some relying on natural ventilation and others using mechanical systems. Airborne fungal contamination was dominated by respirable fractions, reaching 3.3 × 102 CFU m-3. Culture-based analyses revealed distinct fungal profiles, with Cladosporium sp. and Penicillium sp. frequently prevailing, while Aspergillus detection increased at higher incubation temperatures. Seasonal variability was observed, with contamination patterns differing between seasons. Rural and urban schools showed contrasting fungal distributions, with higher concentrations in rural schools, particularly in EDCs on DG18 at 27 °C (1.67 × 103 CFU/m2). Azole resistance screening detected resistant Aspergillus sections across environments. In gymnasiums, the Fumigati section represented 100% of sections detected on ITZ in filters and EDCs. In classrooms, Circumdati and Fumigati accounted for 100% of sections detected on ITZ in EDCs, while the Candidi section represented 100% in filters. The Fumigati section also grew on VOZ and POZ in EDCs. Mycotoxins, including ochratoxin A, mycophenolic acid and sterigmatocystin, were detected in 1.93% of dust samples. Particle concentrations occasionally exceeded reference thresholds in warm (47.1% PM2.5; 58.8% PM10) and cold seasons (47.4% PM2.5; 23.1% PM10). Regulatory thresholds did not prevent the detection of relevant fungal hazards, including Aspergillus species and azole-tolerant growth. These findings show that quantitative indicators alone may not capture exposure complexity, highlighting the need for complementary data, and the limitations in the current legal framework.

Human biomonitoring (HBM) complements air and surface measurements by integrating exposure from all routes and sources, strengthening occupational exposure assessment and control. In occupational settings, HBM can quantify exposure during routine work and nonroutine activities, evaluate controls, investigate incidents (potential overexposures), and support medical surveillance. To use HBM to its full potential, occupational health and safety professionals (OHPs) should adopt harmonized biomonitoring approaches reflecting best practice. This short communication presents the BASIC Guide series (Human Biomonitoring and Surveillance of Chemical Exposure in Occupational Settings), initiated by the International Society of Exposure Science Human Biomonitoring working group (ISES Europe HBM WG) as an integral part of the HBM Global Network. These chemical-specific practical documents operationalize the OECD (Organisation for Economic Co-operation and Development) occupational biomonitoring guidance, supporting the consistent implementation of exposure biomonitoring programs. Each BASIC Guide provides clear instructions on biomarker selection, sample handling, analytical methods, quality assurance, and result interpretation and communication. By translating international frameworks into actionable protocols, the BASIC Guides improve reproducibility and regulatory alignment in occupational HBM and enable more defensible exposure assessments worldwide.

Introduction Work environments are rapidly changing in Europe, with climate change, the transition to the circular economy, and expansion of work in green jobs among key factors. Research and interventions are urgently needed to promote worker health and well-being. The European Union (EU) INTERCAMBIO project is the first large-scale initiative to systematically assess mental and physical health effects of climate change and green transition-related occupational exposures through intervention-based research using a common methodological framework across multiple industries and countries. Methods INTERCAMBIO will 1) promote advanced research methods throughout the work; 2) evaluate occupational heat, cold, and solar ultraviolet radiation exposures and potential short- and long-term mental and physical health effects in observational studies; 3) evaluate impacts of specific workplace interventions in five key industries, namely outdoor construction, healthcare, public transit, renewable energy, and waste management/recycling; 4) model socio-economic impacts of interventions and develop a policy framework for social protection and decent green jobs; and 5) coordinate stakeholder engagement and develop a new health research agenda. Results Targeted multidisciplinary workplace interventions developed with co-creation methodology in a broad range of strategic, rapidly evolving industries will be evaluated, considering the multifaceted impact of climate change and the green transition on workers. Conclusion INTERCAMBIO will fill important data gaps and provide an evidence-base for protecting workers’ health. While INTERCAMBIO focuses on specific industries in the European context, further intervention-based research is also needed more broadly in industries worldwide.

La gestion des déchets au Québec repose sur la collecte sélective pour revaloriser les matières résiduelles et réduire l’enfouissement. Les travailleurs du secteur sont exposés aux bioaérosols contenant microorganismes et allergènes. Les risques sanitaires sont influencés par la nature des matières manipulées et les méthodes de travail employées. La manutention des déchets a déjà été mise en lien avec des inflammations respiratoires, des troubles digestifs, et des syndromes liés aux poussières organiques toxiques. L’objectif du projet visait à évaluer l’exposition des travailleurs aux microorganismes et d’en apprécier les risques pour la santé. Dans le cadre de ce projet, 28 camions ont été étudiés : 12 pour les déchets ultimes, 10 les matières recyclables et 6 les résidus organiques. Des prélèvements d’air ont été effectués au niveau des voies respiratoires des travailleurs lors d’une journée type, ainsi que dans l’habitacle. Les filtres ont été collectés et le nombre de jours d’utilisation documenté. L’analyse a combiné culture microbiologique, biologie moléculaire, tests de cytotoxicité, évaluation de la résistance aux antimicrobiens et mesures de performance des filtres. Des essais en laboratoire ont également examiné l’effet de l’usure et du colmatage des filtres sur la circulation d’air, la réémission microbienne et la prolifération. Ce projet a démontré que • Les travailleurs affectés à la collecte des déchets sont exposés à des concentrations de bactéries et d’endotoxines pouvant dépasser les recommandations. • Les éboueurs présentent les expositions les plus élevées en microorganismes cultivables. • Des mycètes du groupe Aspergillus (section Fumigati), potentiellement pathogènes, ont été détectés dans la zone respiratoire lors de la décharge au site d’enfouissement. • Les tests de cytotoxicité ont révélé un potentiel toxique des bioaérosols sur les cellules pulmonaires et hépatiques. • Dans les filtres de cabine, plusieurs microorganismes présentant des risques sanitaires (Aspergillus, E. coli, Enterobacter spp., Legionella spp.) ont été identifiés, avec des concentrations plus élevées dans les camions de matières organiques. • L’efficacité de filtration mesurée variait largement (1,3 à 42 % pour la taille de particule la plus pénétrante). • Aucun filtre n’offrait une efficacité élevée, et certains modèles présentaient une faible rétention microbienne associée à une filtration peu performante. Pour réduire l’exposition il est recommandé d’améliorer les méthodes de travail des éboueurs, notamment pour limiter le contact avec les matières organiques, d’installer des filtres d’habitacle plus performants et de renforcer les programmes d’entretien des cabines (remplacement des filtres, nettoyage des surfaces). Le présent rapport comprend le résumé de trois articles scientifiques qui abordent les résultats obtenus de cette étude.

With the global population rising, there is increasing demand for agricultural productivity, particularly for animal-derived proteins and products. This trend places additional pressure on natural resources and the workforce in the animal production sector. This study aims to address environmental and health factors influenced by animal production within the One Health framework, encompassing animal welfare, food security, food safety, workers health and climate change. In this context, three feedlots' farms and two dairies from the North of Portugal, representing the worst-case exposure scenario, were engaged in this study. Samples were collected using Electrostatic Dust Cloths (EDC) placed on farm surfaces and attached to work clothing (EDCT). Additional samples were obtained from feed, used bedding material, and surface swabs from feeders, drinkers, milking parlors, and frequently touched areas in social spaces (e.g., offices and changing rooms). Microbial characterization and azole-resistance screening were performed using diverse culture media, complemented by molecular assays (qPCR) targeting toxigenic fungal species. Thirty-eight mycotoxins were analyzed across the sampled matrices. This comprehensive approach identified critical sources of microbial and mycotoxin contamination: bedding material showed the highest bacterial contamination (TSA; 5.40 X 103 CFU.g-1), while swabs (MEA; 2.5 X 104 CFU.m-2 to 9.00 X 104 CFU.m-2) and feed (MEA; ranged from 1.33 X 102 CFU.g-1 to 8.00 X 102 CFU.g-1) exhibited the greatest fungal contamination. Feed was identified as the main source of mycotoxin exposure for both animals and workers, since all 16 feed samples tested positive for mycotoxin contamination. Results revealed widespread distribution of Aspergillus sp. across environmental matrices, highlighting the need for targeted interventions. Azole-resistance screening and mycotoxin profiling further emphasize the importance of implement targeted interventions to prevent, monitor, and remediate environmental contamination by fungi and mycotoxins across different contexts (food safety, animal health, public and occupational health) underscoring the value of a One Health approach.

Woodworkers are exposed to several potentially harmful agents, including microorganisms that grow in the wood. The most common fungal species in woodworking environments are Aspergillus, Penicillium, and Cladosporium spp. with occupational exposure to Aspergillus spp. posing a significant respiratory risk. This study aimed to assess exposure to Aspergillus spp. in two Portuguese woodworking environments and to perform a thorough analysis of Aspergillus fumigatus complex isolates collected from 13 DIY stores and 6 Carpentries in Lisbon Metropolitan Area. Sampling combined active and passive methods to assess microbial contamination. Aspergillus fumigatus isolates were analysed for their antifungal susceptibility, resistant mechanisms, mycotoxins production and cytotoxic potential in lung (A459) and liver (HepG2) cell lines. The MAS-100 presented Aspergillus sections Aspergilli and Flavi with the highest prevalence in DIY stores and Carpentries, respectively. A total of 1185 Aspergillus spp. were recovered, 270 identified as Aspergillus fumigatus sensu stricto growing at 37°C. None of those isolates was resistant to azoles, 99.07% of them produced gliotoxin and 39.9% of them produced cytotoxic effects in at least one cell line. This study comprehended a multi-approach that considered not only sampling methods but also the laboratory assays to be applied in the Aspergillus section Fumigati isolates recovered from two different woodworking environments, allowing a complete and robust analysis of this specific environment and species. Overall, the findings indicate that woodworkers are exposed to A. fumigatus isolates with relevant pathogenic traits, despite the absence of azole resistance, underscoring the need for continued environmental and occupational monitoring.

Abstract The 2025 Annual Report of the Advisory Group on Biomarkers of Effect (AGoB) details the group's establishment, objectives, and activities in supporting EFSA's development of guidance on biomarkers of effect (BoEs) in regulatory risk assessment. The report outlines AGoB's collaborative efforts, meeting summaries, scientific advice and plans for future work.

Human biomonitoring (HBM) plays a critical role in assessing human exposure to chemicals and their potential health impacts. The REACH (Registration, Evaluation, Authorisation, and Restriction of Chemicals) Regulation aims to protect both the general population and workers from the risks posed by chemicals. HBM provides valuable data to support risk assessment and regulatory decisions on chemicals and chemical's use. However, despite the acknowledged potential, the current REACH guidance provides only limited and non-binding recommendations for the use of HBM in regulatory processes. Therefore, the systematic integration of HBM into the REACH regulatory framework remains limited. Several key factors contribute to this limitation: an over-reliance on traditional exposure modelling in risk assessment, the absence of enforcement mechanisms for its application by registrants and regulators and the lack of harmonized biomonitoring limit values, even though standardized approaches for deriving biomarker-based no-effect level (DNELbiomarker) are available. Additional barriers include restricted data availability, as HBM data are classified as medical information and subject to strict data protection regulations. REACH will benefit from a more systematic use of HBM data. Several solutions and calls for action are presented here to advance the use of HBM in REACH regulations.

Introduction Cadmium is a metal that poses significant health risks, particularly in occupational environments where exposure can happen. The main objective of this scoping review is to review the cadmium exposure levels in the different occupational settings in the European Union (EU), considering the regulatory measures currently in place. The secondary objectives, depending on the availability of data, are (a) to identify the occupational settings where higher exposure levels occur, (b) to identify any geographical and temporal differences and trends within the EU and (c) to identify the most relevant co-exposures reported.Methods and analysis A scoping review will be conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews reporting guidelines. Studies reporting quantitative occupational data on cadmium exposure obtained through human biomonitoring and/or air monitoring will be included. A descriptive analysis of the findings will be performed.Ethics and dissemination This protocol for a scoping review does not require ethical approval as it is based on secondary data. The dissemination plan of the scoping review includes its publication in a scientific journal of reference, as it is expected that it will provide important knowledge to support ongoing and future occupational health interventions in the EU, at the technical and regulatory levels.Registration This study is registered at the Open Science Framework (OSF), 7 April osf.f2w3h.

Background Climate change is emerging as a major global health crisis, escalating occupational hazards across all sectors and exacerbating social inequalities. Workers, especially those in outdoor, informal, and precarious employment are increasingly exposed to multiple hazards, leading to adverse physical and mental health outcomes, productivity losses, and premature death. Objective This commentary aims to underscore the need to integrate occupational health into climate mitigation and adaptation strategies. Methods Drawing on current evidence and policy frameworks, this manuscript outlines strategic priorities and practical measures to strengthen the role of occupational health systems in climate resilience. Results Key points include heat action plans, expanded social protections, improved surveillance and early warning systems, and investment in climate-resilient workplace innovations. It also calls for cross-sectoral collaboration between health, labour, and environment sectors and highlights the urgent need for intervention studies to identify effective, evidence-based OSH strategies. Significance Integrating occupational health into climate policies will help protect vulnerable worker populations, strengthen public health resilience, and promote sustainable economic outcomes in times of climate crisis. Collaboration between occupational and public health systems is essential to ensure no worker is left behind in the climate response. Impact This commentary addresses the critical but often overlooked intersection of occupational health and climate mitigation and adaptation. Its original contribution is explicitly positioning the OSH not merely as recipient of adaptation policy but as cross-sectoral catalyst for mitigation and resilience. It offers a timely discussion regarding integrating worker protection into climate strategies. By focusing on vulnerable populations particularly those in informal and outdoor work it aligns with global development and climate goals. The proposed actions aim to address a major gap in current climate-health responses, ensuring more equitable and resilient outcomes for workers in Europe and worldwide.

Several studies have reported the incidence of fungi and mycotoxins in coffee beans; however, there are few reports related to occupational exposure to these agents at coffee dry milling industries. The aim of this review was to identify and to analyze studies assessing occupational exposure to fungi and mycotoxins in coffee industries. Therefore, a systematic literature search was conducted using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) methodology and focusing on the assessment of occupational exposure to fungi and mycotoxins in the coffee industry. In these papers, different environmental matrices were considered in evaluating occupational exposure, but the most used matrix was airborne dust (four of the five studies). Airborne fungi were sampled using active (four of the five studies) and passive sampling. Only the most recent of the studies (2022) identified microorganisms by their genera and species, and only two groups of mycotoxins were analyzed in the studies considered, namely, Ochratoxin A and Aflatoxins. None of the studies reported data on both fungi and mycotoxins. The fungal genera identified in these occupational environments included Cladosporium, Paecilomyces, Aspergillus, Penicillium, and other genera. Among the mycotoxins, only aflatoxins and ochratoxin A were investigated. Occupational exposure to these biological agents may lead to several health effects. Fungal spores and fragments can cause respiratory diseases such as asthma, allergic rhinitis, bronchitis, and hypersensitivity pneumonitis. Additionally, the mycotoxins studied—particularly Aflatoxins and Ochratoxin A—are associated with serious toxicological effects. Coexposure to both fungi and mycotoxins may enhance health risks and should be carefully considered in occupational risk assessments. Considering the possible effects related to exposure to fungi and mycotoxins and the number of workers involved in this type of industry in the world, more studies should be developed. This is the first review to systematically consolidate data on occupational exposure to both fungi and mycotoxins specifically within the coffee industry, highlighting existing knowledge gaps and the need for targeted risk assessments in coffee-producing settings.

[This corrects the article DOI: 10.3389/fpubh.2025.1536836.].

Human biomonitoring (HBM) provides an integrated chemical exposures assessment considering all routes and sources of exposure. The accurate interpretation and comparability of biomarkers of exposure and effect depend on harmonized, quality-assured sampling, processing, and analysis. Currently, the lack of broadly accepted guidance on minimum information required for collecting and reporting HBM data, hinders comparability between studies. Furthermore, it prevents HBM from reaching its full potential as a reliable approach for assessing and managing the risks of human exposure to chemicals.The European Chapter of the International Society of Exposure Science HBM Working Group (ISES Europe HBM working group) has established a global human biomonitoring community network (HBM Global Network) to develop a guidance to define the minimum information to be collected and reported in HBM, called the “Minimum Information Requirements for Human Biomonitoring (MIR-HBM)”. This work builds on previous efforts to harmonize HBM worldwide.The MIR-HBM guidance covers all phases of HBM from the design phase to the effective communication of results. By carefully defining MIR for all phases, researchers and health professionals can make their HBM studies and programs are robust, reproducible, and meaningful. Acceptance and implementation of MIR-HBM Guidelines in both the general population and occupational fields would improve the interpretability and regulatory utility of HBM data. While implementation challenges remain—such as varying local capacities, and ethical and legal differences at the national levels, this initiative represents an important step toward harmonizing HBM practice and supports an ongoing dialogue among policymakers, legal experts, and scientists to effectively address these challenges. Leveraging the data and insights from HBM, policymakers can develop more effective strategies to protect public health and ensure safer working environments.

The poultry industry poses a global health risk due to microbial contamination. Also, particulate matter (PM) may act as a vehicle for microbial dissemination. Understanding PM dynamics in poultry production environments is crucial for evaluating occupational exposure to airborne pathogens. This study aims to quantify PM contamination and assess occupational exposure to airborne bacteria in poultry pavilions (PP) throughout different stages of the production cycle. Air samples from indoor (n=47) and outdoor (n=20) PP were collected across various stages of the growth cycle (empty pavilion- sanitary control, 1st, 2nd, and 3rd weeks). For bacteria characterization the impactor MAS-100 was set to 100 L/min for 5 minutes and culture-based methods were performed. PM size fractions (PM0.5, PM1, PM2.5, PM5, and PM10) were measured using a Lighthouse Handheld Particle Counter at a flow rate of 2.83 L/min during 5 min. The highest bacterial loads and PM contamination occurred during the 3rd week, indicating a link between PM and the dissemination of airborne bacteria. PM10 and PM5 were dominant throughout the production cycle, highlighting their potential role in carrying pathogens to workers' respiratory systems. These findings emphasize the need to monitor PM and microbiological contamination in poultry farms to reduce worker health hazards.

Aim:We estimated the average direct cost per Acute Coronary Syndromes (ACS) in-patient episodes by diagnosis, namely ST-elevation myocardial infarction (STEMI), non-ST elevation myocardial infarction (NSTEMI), unstable angina (UA), and undetermined AMI (Acute Myocardial Infarction). We also analyzed the changes in direct costs over time between 2002 and 2022, and the total direct economic burden of ACS hospitalizations for the Portuguese National Health Service (NHS). Methods:We used the Portuguese Registry of Acute Coronary Syndromes (61,440 ACS hospitalizations), a cohort of people with ACS, recruited and followed from first hospitalization. A direct cost analysis was conducted. As resources, we considered health professional working hours, non-medical resources used during in-patient stays, laboratory and diagnostic tests, interventional cardiology procedures, pharmaceuticals, hospitalization-related complications, rehabilitation services, and death costs. A multivariate analysis was performed to identify the main cost determinants. Results:The average cost per ACS patient from 2002 to 2022 was 6,280.79 €. A significantly higher average cost was observed among patients diagnosed with STEMI of 3,853.26€ (95% confidence interval [CI] 3,690.87 to 4,015.65€), among NSTEMI patients of 1,308.91 € (95% CI 1,173.52 € to 1,444.30 €), and among patients who died during the hospitalization of 12,017.64€ (95% CI 11,232.21 € to 12,803.08 €). Over time, cost trends fluctuated, increasing until 2011 and then gradually decreasing until 2022, apart from 2020. Considering the total universe of 294,307 ACS-hospitalizations, the Portuguese NHS incurred a direct economic burden of 1,831 million euros over the complete period, with total annual costs averaging 87,203,851 €, representing on average 0.93% of the NHS annual health expenditure. Conclusion:ACS represent a significant direct cost and economic burden for the NHS.

Derivation of occupational biomonitoring levels (OBLs) is needed to effectively utilize biomonitoring for assessing exposures to chemical substances, and consequently, implement risk reduction measures to reduce health risks among workers. OBLs are the appropriate option for chemical substances that can be absorbed through the skin. This methodology for derivation of OBLs has been developed in collaboration with scientific and regulatory experts from more than 40 institutes in 15 countries within the Organization for Economic Cooperation and Development (OECD) framework. This manuscript provides a summary of the guidance on derivation of OBLs destined for scientists, risk assessors, and regulators who are tasked with establishing OBLs for regulatory purposes and implementing occupational biomonitoring programs. The derivation methodology follows a tiered approach based on the strength of evidence and quality of the data that we have labeled level of confidence. The tiered approach serves as a practical framework in occupational health risk assessment and management. We distinguish between four OBL levels depending on the strength of scientific evidence and confidence level: health-based derivation of OBL based on robust epidemiological data showing causal exposure-health effect relationship and Provisional OBL (POBL) based on robust toxicological animal data showing dose-response relationship as well as two assessment values which are not health based: reference levels in the general population (Reference OBL or (ROBL)), and Technical achievable OBL or (TOBL). Four case studies illustrating the derivation methods for OBLs and POBLs are also provided. Using this state-of-the-art approach (OECD guidance document no. 370) will lead to a harmonized derivation of OBLs and subsequently to evidence-based risk management measures.