Chemical Health Hazards Research Articles

Chemical health hazards and toxicity of environmental pollutants on humans, animals and others: An overview

Toxicology, rooted in ancient civilizations and evolving through pivotal historical figures like Paracelsus and Alice Hamilton, has become a multidisciplinary field encompassing various branches such as pharmacology, medical, forensic, and environmental toxicology. This exploration embarks on a journey through time and science, unravelling the intricate interplay between chemicals, pollutants, and their profound impacts on human, animal, and environmental well-being. Spanning from ancient practices like the use of hemlock in Greek capital punishment to modern-day concerns surrounding industrial chemicals and pesticides, the review delves into the mechanisms by which toxins disrupt biochemical pathways and induce organ dysfunctions. From heavy metals and pesticides persistent effects on the nervous and reproductive systems to the carcinogenic properties of polychlorinated biphenyls (PCBs), hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), and volatile organic compounds (VOCs). The review highlights the diverse range of toxicants and their widespread impact on human health. Additionally, the review underscores the importance of proactive measures to mitigate exposure to harmful substances, advocating for the development of antidotes, bioremediation techniques, and stricter environmental regulations. By addressing the urgent need for comprehensive strategies to combat toxicological hazards, this review aims to contribute to ongoing efforts to safeguard public health and environmental sustainability in the face of evolving chemical threats.

Lessons From the Household Humidifier Disinfectant Tragedy (HHDT) With Focus on the Chemical Poisoning Surveillance System: Review and Recommendation.

Lessons learned from the Household Humidifier Disinfectant Tragedy (HHDT) in Korea, which poisoned thousands of citizens over a period of years, necessitated an examination of national poison prevention and surveillance systems. The objectives of this study are to identify essential changes needed in chemical poisoning prevention regulations and surveillance systems for effective poison control by comparing recent trends in international poison control center (PCC) operations, and to delineate the critical elements for establishing a state-of-the-art poison control surveillance system in Korea based on recent advances in PCCs with toxicovigilance. A comprehensive review of Korea's regulatory and surveillance systems for chemical health hazards, with a focus on household products under the HHDT, was conducted. A review of toxicovigilance systems in major countries shows that creating an effective national PCC requires key elements: a centralized database of toxic substances and poisoning cases, mandatory or voluntary reporting of poisoning cases, real-time alerts, collaboration among health organizations, and targeted follow-up of poisoned individuals. Significant deficiencies in Korea's legislation, toxicological data management, and poisoning surveillance systems, explained the inadequate response of the Korean government to the HHDT for nearly 17 years until the end of 2011. Based on a review of PCC toxicovigilance systems in major countries, a national framework with five core components is recommended for establishing a modern comprehensive Korea PCC system with toxicovigilance capacity. The core components include establishment of a centralized database of toxic substances information and clinical poisoning cases, implementation of mandatory or permissive reporting of poisoning cases, real-time alert mechanisms, collaborative systems among health-related organizations, and clinical follow-up of poisoned sub-groups. A rationale and framework for a state-of-the-art national Korean PCC with toxicovigilance is justified and offered. This proposed system could assist neighboring countries in establishing their own sophisticated, globally integrated PCC networks.

Causes of Countermeasures Against Serious Accidents Caused by Health Hazards of Chemical Substances, Based on Cases of Occupational Accidents in Japan

The purpose of this study was to summarize the typical and specific causes and risk reduction measures of serious accidents in Japan caused by chemical substances in terms of the 10 types of human health hazards in the UN GHS (Globally Harmonized System of Classification and Labelling of Chemicals) classification. The list of "Cases of Major Accidents Caused by Chemical Substances" published on the "Safety in the Workplace Website" of the Ministry of Health, Labor and Welfare (MHLW) was linked to the "Results of GHS Classification by the Government" of the National Institute of Technology and Evaluation (NITE). Analysis was conducted by health hazards in order to obtain reference examples of measures taken against health hazards in response to the revision of the law on autonomous chemical substance management in 2022. Using the text mining tool KH Coder ver. Three using cluster analysis, we grouped causes and measures among serious disasters by health hazard, illustrated co-occurrence networks, and extracted typical examples of each in a co-occurrence network. Representative causes of and measures against occupational accidents caused by health hazardous properties were summarized from the extracted typical cases. Although few occupational accidents were caused by the health hazards of chemicals, when all health hazards were classified into acute toxicity, acute health hazard, and chronic health hazard, contact was a clear cause for many of the acute toxicity and acute health hazards, such as corrosiveness and sensitization. However, many occupational accidents were caused by the physical hazardous aspects of the chemical substances or by the safety aspects of the workplace. Causes of occupational accidents due to health hazards included unsafe behavior and unsafe conditions, or lack of understanding of the physicochemical properties of a substance and specific reactions such as mixing or hydrolysis of the substance. Typical risk reduction measures for health hazards included equipment to prevent human contact with health hazardous substances, systems to control unsafe behavior, promoting understanding of chemical reactions, and providing information about chemicals to all persons involved in testing, research, and subcontract work. The data of occupational accident cases of "death or more than 4 days lost from work" were used. Most of the cases were related to acute health hazards, but relatively few to chronic health hazards, and few occupational accidents were caused by health hazards. Most of the occupational accidents were caused by health hazards due to the physical hazards of chemical substances and inadequate workplace safety. In light of the above, it is necessary in autonomous chemical substance management to first take risk reduction measures for workplace safety and chemical physical hazards, then to prevent contact with acute toxicity and acute health hazards such as corrosiveness and sensitization, and, lastly, to take risk reduction measures for chronic health hazards, using allowable concentrations and controlled concentrations as indices.

Plastic use for food and drinks and related knowledge, attitudes, and practices among a sample of Egyptians.

Plastic is extensively used in everyday life, particularly for food and beverage containers. The inappropriate use of these containers may lead to the leaching of various chemicals from plastic, such as bisphenol A, phthalate, and styrene, which cause numerous adverse health effects. This study aimed to assess the knowledge, attitudes, and practices toward using plastic for food and drinks among a sample of the Egyptian population. A questionnaire was designed based on scientific literature to assess sociodemographic data, knowledge, attitudes, and practices toward the use of plastic for food and drinks. A total of 639 participants were recruited by employing the convenience sampling technique. More than half of the participants (347, 54%) had poor knowledge scores. Personal experiences, social media, and web pages represented the most common knowledge sources. A comparison between plastic-related knowledge scores and the studied sociodemographic characteristics revealed statistically significant differences in age, gender, education, marital status, residence, working, and socioeconomic standard. A good attitude was reported by the majority (515, 80.6%) of participants. The majority (493, 77.2%) were occasional and frequent plastic users and the practice scores were significantly associated with age, education, residence, and socioeconomic standard. Higher educational level, gender (women), and rural residence were predictors of good participants knowledge, while lower socioeconomic status and urban residence were predictors of bad participants practice in a multivariate logistic regression analysis. The observed unsatisfactory knowledge and practice scores vs. the high attitude indicates a knowledge gap that can help direct future improvements. We call for public awareness programs about safe plastic use and the related health hazards of plastic chemicals. We also stress upon the urgent need for a collaboration between health authorities and the plastic and food industry to guarantee that information about proper plastic use is conveyed to consumers.

In vitro testicular toxicity of environmentally relevant endocrine-disrupting chemicals: 2D vs. 3D models of prepubertal Leydig TM3 cells

The testis is a priority organ for developing alternative models to assess male reproductive health hazards of chemicals. This study characterized a 3D in vitro model of murine prepubertal Leydig TM3 cells with improved expression of steroidogenesis markers suitable for image-based screening of testicular toxicity. This 3D scaffold-free spheroid model was applied to explore the impact of prototypical endocrine-disrupting chemicals (EDCs) and environmental reprotoxicants (benzo[a]pyrene, 2- and 9-methylanthracenes, fluoranthene, triclosan, triclocarban, methoxychlor) on male reproductive health. The results were compared to the male reprotoxicity potential of EDCs assessed in a traditional monolayer (2D) culture. The testicular toxicity was dependent not only on the type of culture (2D vs. 3D models) but also on the duration of exposure. Benzo[a]pyrene and triclocarban were the most active compounds, eliciting cytotoxic effects in prepubertal Leydig cells at low micromolar concentrations, which might be a mechanism contributing to their male reprotoxicity.

Assessment of Awareness Regarding Health Hazards of Plastic Chemicals and their Warning Label among a Sample Population of Varanasi City: A Cross-sectional Study.

Background:Plastic containers are widely used to store and serve edibles. In the production of some types of plastic, chemicals such as bisphenol A (BPA) and bisphenol S (BPS) are used. These chemicals leach from the plastic containers into the edibles, get access into the biological systems, and cause a toxic impact on health.Aim:This cross-sectional survey was planned to assess the usage of food contact plastic and awareness regarding the health hazards of plastic chemicals and warning labels on plastic items among a sample population of Varanasi city.Materials and Methods:Data were collected by interviewing the 556 adult participants, using a prevalidated structured questionnaire. Chi-square test was used to test the association and P < 0.05 was considered as significant.Results:Most of the participants were found to be following routine practices during cooking and storage of edibles which may expose them to BPA and BPS through the gut. Although many participants were aware that plastic may contain some type of chemicals which may enter the human body and harm human health in some way, they lacked precise knowledge regarding warning label like “BPA free plastic” “plastic containing BPA” and “food grade plastic.” Furthermore, none of the participants could recognize the “resin identification codes” correctly.Conclusion:Most of the participants had only elementary awareness of health risk of plastic usage. A significant number of participants lacked crucial information that can help them to make healthy choices as a consumer and use safe alternatives of plastic.

Health Risk Assessment of Physical and Chemical Hazards in the Painting Area of a Manufacturing Company

Introduction: The work process of the Painting Area in a Manufacturing Company can pose a risk to physical and chemical health hazards for workers. Hazard analysis and identification, exposure assessment, and risk assessment are, therefore, needed to protect the health of workers from these health hazards, which can later be used as a basis to determine appropriate controls so as not to have a negative impact on workers’ health. The purpose of this study was to analyze the hazards and their impacts on workers’ health through hazard identification measures, exposure assessments, risk assessments and control recommendations. Methods: Health Risk Assessment of physical and chemical hazards in the Painting Area was undertaken using a semi-quantitative method by calculating a risk assessment matrix using the guidelines from IPIECA &amp; OGP in 2016. Results: Physical hazards were found in the form of lighting hazards, vibrations (arm vibration and whole body vibration), noise and heat pressure. Meanwhile, chemical hazards were found in the form of thinner vapor, solvent, NaNO3, H2SO4, NaOH, H3NSO4 and indoor air quality (CO, NO2, SO2, H2S). The results of the risk assessment matrix obtained 4 levels of risk hazards, consisting of 11.1% in the first priority, 50% in the second priority, 25.9% in the third priority and 12.9% in the condition that did not require immediate action. Conclusion: Physical and chemical health hazards were at 4 levels based on the calculation of risk control priorities. A hierarchy of risk control could be used to reduce the risk of health hazards.Keywords: health risk assessment, ipieca &amp; ogp 2016, painting area, risk assessment matrix

Evaluation of atrazine neurodevelopment toxicity in vitro-application of hESC-based neural differentiation model

Atrazine is one of the widely used herbicides in the world and most of the current researches on atrazine neurodevelopment toxicity have focused on rodents or zebrafish models in vivo, resulting in relatively high cost, time consumption, and lower translational value to identify its hazard for the developing brain. Major international initiatives have pushed forward to convert the traditional animal-based developmental toxicity tests to in vitro assays using human cells to detect and predict chemical health hazards. In this study, we presented a human neural differentiation model based on human embryonic stem cells (hESC) that can be used to test toxicity at different stages of neural differentiation in vitro. hESC were differentiated into neural stem cells (NSC) and then terminally differentiated towards mixed neurons and glial cells for 21 days. Cell survival, proliferation, cell cycle, apoptosis, and gene expression levels were examined. Our results demonstrated that atrazine inhibited the proliferation of hESC and NSC, and showed different toxic sensitivity on these two kinds of cells. Also, atrazine blocked the NSC cell cycle G1 phase via down-regulating CCND1, CDK2, and CDK4, with no obvious effect on apoptosis. In addition, atrazine curbed EB spontaneous differentiation and NSC-induced neurons and glia cells differentiation. Atrazine altered genes expression levels of PAX6, TUBB3, NCAM1, GFAP, TH, NR4A1, and GRIA1. From the data we obtained, we recognized that the dopaminergic system was not the only target of atrazine neurotoxicity, glutamatergic neurons and astrocytes were also adversely affected.

Emergency First Aid Training Awareness in Occupational Health at Mol Pakistan Oil and Gas Company

There are a number of issues and risk factors which can affect the health of workers in every occupation. As an employee and occupational health nurse, I also observed some issues in my organization. I was assigned a project to be conducted as a part of my course, I selected the “Emergency First Aid Training Awareness in occupational health” for my project. During my assessment I observed that there are many issues related to occupational health, like physical health hazards, chemical health hazards and biological health hazards. But foremost of them was lack of knowledge of occupational workers regarding emergency first aid care. I assessed the knowledge of workers by developing a questionnaire. Most of them were unaware about first aid at a work place. I arranged different sessions for the workers to trained them regarding first aid provision in their work place. I used different teaching aids like poster presentations, showing videos clips and demonstration. I also used the concept of “Orem’s self-care theory” in my project. The results of my implementation of sessions and demonstration were effective. The employees demonstrated good skills of first aid at the end of my project.

Bio Ceramics: New Material from Mangrove Bark

Mangroves are salt-tolerant plants of tropical and subtropical intertidal regions of the world. The specific regions where these plants occur are termed as 'mangrove ecosystem'. They are having an ecological role as primary producers. In future there is a need to find out natural compounds to come over against chemical compounds. As these compounds reported to have carcinogenic effects. An attempt was made to find out largest sources of plants, the mangroves. They are facing various types of stresses; they are rich in several secondary metabolites. So, some mangrove barks are tested as a new source as a bio ceramic material by using bone marrow mesenchymal stem cells (BMMSCs). From the study it is revealed that among all tested barks, prop root bark of Rhizophora mucronata shows higher biocompatibility for cell adhesion. Thus, this study will enlighten the use of natural products to replaces chemical health hazards for ceramic material as ecofriendly materials.

Occupational Health and Safety Hazards in Rice Farming in Ghana

The paper explored specific hazards prevalent in rice farming in Ghana. Ten respondents, including rice irrigation scheme managers, extension officers and rice farmers, were interviewed and observed in a qualitative study. The deductive thematic analysis was use to analyse the transcribed interview data and themes were organised on the semantic level. It emerged that rice farmers in Ghana were exposed to myriad of biological, ergonomic, physical and chemical health and safety hazards. These hazards have enormous health and safety implications for the farmers, if preventive measures are not put in place. The need for appropriate personal protective equipment and protective wears are high recommended given that most of the hazards identified are inherent in the rice farming process. Keywords: Health and safety hazards, Rice farm workers, production agriculture, biological hazards, ergonomic hazards DOI: 10.7176/EJBM/12-21-10 Publication date: July 31 st 2020

Knowledge, attitude and practice related to chemical hazards and personal protective equipment among particleboard workers in Ethiopia: a cross-sectional study

BackgroundWork in the wood industry is often associated with exposure to wood dust and formaldehyde. The aims of this study were to describe the Knowledge, Attitude and Practice (KAP) concerning chemical health hazards among particleboard workers and to compare the KAP among temporary and permanent workers.MethodsA cross-sectional study design was used to collect data by structured questionnaires in two particleboard factories in Ethiopia. A total of 159 workers and 13 management personnel participated in this study. Both closed-ended and open-ended questions were included in the interviews. Chi-square tests, T tests and correlation analyses were used for categorical and continuous data. Total knowledge score (range 0–8) was calculated as the sum score of 8 items weighing one point each. Multiple linear regression was applied to estimate the impact of employment status on total knowledge score adjusted for level of education. Content analysis was applied to analyse collected data from open-ended questions.ResultsThe mean age of the respondents was 28 (SD = 6) years and on average they had 3.7 [3] years of service. The permanent workers were older than the temporary workers (29 vs 26 years, p = 0.001), and a considerably high fraction of the permanent workers had vocational education (90%) compared to the temporary workers (11%). Permanent workers had higher proportion of response on knowledge of 10 of 12 topics regarding chemical hazards and attitudes on 6 of 11 of these topics than temporary workers. Permanent workers had higher knowledge scores (3.7) compared to temporary workers (1.3) (p < 0.001), also after adjusting for education (p = 0.011). Permanent workers were provided with personal protective equipment (PPE) while temporary workers were not. The qualitative data helps to understand the workers and administrative personnel attitude and thinking regarding chemical hazards and PPE.ConclusionsThe findings revealed that permanent workers have higher proportion of positive response on knowledge and attitude towards chemical health hazards than temporary workers. However, practice in use of PPE depended on access to PPE. Few temporary workers were provided with PPE.

Development of a Screening Method for Health Hazard Ranking and Scoring of Chemicals Using the Mahalanobis–Taguchi System

For efficient management of chemicals, it is necessary to preferentially select hazardous chemicals as being high-priority through a screening method. Over the past 20 years, chemical ranking and scoring (CRS) methods have been applied in many countries; however, these CRS methods have a few limitations. Most of the existing methods only use some of the variables to calculate the hazard of chemicals or use the most conservative score without consideration of the correlation between chemical toxicities. This evaluation could underestimate or overestimate the real health hazard of the chemicals. To overcome the limitations of these methods, we developed a new CRS method using the Mahalanobis–Taguchi System (MTS). The MTS, which conducts multivariate analysis, produced chemical rankings that took into accounts the correlation between variables related to chemical health hazards. Also, the proportion of chemicals managed by the Korea Chemicals Control Act that were given a high rating appeared to be higher when the MTS was used, compared to the existing methods. These results indicated that the new method evaluated the health hazards of chemicals more accurately, and we expect that the MTS method could be applied to a greater range of chemicals than the existing CRS methods.

Composition and chemical health hazards of the most common electronic cigarette liquids in nine European countries

Background: The aim of the present study was to identify the composition and reported chemical health hazards of the most common electronic cigarette liquids (e-liquids) in nine European Union (EU) Member States (MS) prior to adoption of the Tobacco Product Directive (TPD).Materials and methods: Within the Horizon2020, EUREST-PLUS study, 122 of the most commonly sold e-liquids in 9 EU MS were randomly selected and purchased. A quantitative and qualitative chemical analysis was performed using a previously validated based gas chromatography–mass spectrometry and liquid chromatography–mass spectrometry method. The most commonly detected compounds were then divided according to the Danger Globally Harmonized System of Classification and Labelling of Chemicals (GHS) and Warning GHS codes.Results: Within our qualitative analysis, 171 different compounds were detected. Discrepancies in measured versus reported nicotine concentration were identified. Forty-one (85.4%) of the most commonly detected compounds were registered with Warning GHS codes, 11 with Danger GHS codes and 9 with both codes. Of the total number of the detected compounds, 293 were attributable to fruits flavor, followed by tobacco flavor (204), nonalcoholic drinks (n = 64), desserts–sweets (n = 50), menthol – mint (n = 42) and alcohol (n = 39). Menthol which is classified as a strong irritant to skin and eye was the most frequently detected compound.Conclusion: A large plethora of compounds with varying warning codes was identified in e-cigarette samples. The systematic monitoring and chemical evaluation of e-liquids are warranted, so as to ensure consumer protection.

Computational approaches to chemical hazard assessment

SummaryComputational prediction of toxicity has reached new heights as a result of decades of growth in the magnitude and diversity of biological data. Public packages for statistics and machine learning make model creation faster. New theory in machine learning and cheminformatics enables integration of chemical structure, toxicogenomics, simulated and physical data in the prediction of chemical health hazards, and other toxicological information. Our earlier publications have characterized a toxicological dataset of unprecedented scale resulting from the European REACH legislation (Registration Evaluation Authorisation and Restriction of Chemicals). These publications dove into potential use cases for regulatory data and some models for exploiting this data. This article analyzes the options for the identification and categorization of chemicals, moves on to the derivation of descriptive features for chemicals, discusses different kinds of targets modeled in computational toxicology, and ends with a high-level perspective of the algorithms used to create computational toxicology models.

The formal electronic recycling industry: Challenges and opportunities in occupational and environmental health research

BackgroundE-waste includes electrical and electronic equipment discarded as waste without intent of reuse. Informal e-waste recycling, typically done in smaller, unorganized businesses, can expose workers and communities to serious chemical health hazards. It is unclear if formalization into larger, better-controlled electronics recycling (e-recycling) facilities solves environmental and occupational health problems. ObjectivesTo systematically review the literature on occupational and environmental health hazards of formal e-recycling facilities and discuss challenges and opportunities to strengthen research in this area. MethodsWe identified 37 publications from 4 electronic databases (PubMed, Web of Science, Environmental Index, NIOSHTIC-2) specific to chemical exposures in formal e-recycling facilities. DiscussionEnvironmental and occupational exposures depend on the degree of formalization of the facilities but further reduction is needed. Reported worker exposures to metals were often higher than recommended occupational guidelines. Levels of brominated flame-retardants in worker's inhaled air and biological samples were higher than those from reference groups. Air, dust, and soil concentrations of metals, brominated flame-retardants, dioxins, furans, polycyclic-aromatic hydrocarbons, or polychlorinated biphenyls found inside or near the facilities were generally higher than reference locations, suggesting transport into the environment. Children of a recycler had blood lead levels higher than public health recommended guidelines. ConclusionsWith mounting e-waste, more workers, their family members, and communities could experience unhealthful exposures to metals and other chemicals. We identified research needs to further assess exposures, health, and improve controls. The long-term solution is manufacturing of electronics without harmful substances and easy-to-disassemble components.

Occupational hazards awareness and preventive practices among students of a dental institution in South India

Background: Dentists are constantly exposed to numerous occupational health risks. These can cause the appearance of numerous infirmities, which further develop and intensify with time. Objective: To assess the level of awareness of occupational hazards and preventive practices among the dental students in dental college and hospital. Materials and Methods: The study was conducted at a dental institution in South India using self-administered questionnaires. All the students attending the second-year bachelor of dental surgery (BDS) and Internship of the college were included in the study. Total number of participants included was 160 comprising 82 second year BDS and 78 internship students of the institution. The self-administered questionnaire also included questions on baseline characteristic information such as gender, age, and years of study. Data were analyzed using SPSS, version 15.0. Results: The most prevalent preventive measure reported by the participants was the use of facemask (99.4%), wearing gloves on a routine basis (98.1%), and changing gloves between the patients (96.2%). Majority (84.4%) of the study participants were vaccinated against Hepatitis B. Only 57.5% study participants had regular exposure to dental amalgam, and 43.8% feel stress while working in clinic or laboratory. Overall, internship students score for better awareness and preventive practices; this was found to be statistically significant (Table 1). Clinical practices were better among the internship group of participants as compared to second-year BDS students. Conclusion: Majority of the study participants were aware of the biological, chemical, and physical health hazards associated with dentistry but incapable to follow preventive measures in daily routine. The number of years of study and clinical hours spent improves the knowledge and practices of occupational hazard awareness and preventive practices among dental professionals.

Effectuality of Cleaning Workers' Training and Cleaning Enterprises' Chemical Health Hazard Risk Profiling.

BackgroundGoal-oriented communication of risk of hazards is necessary in order to reduce risk of workers' exposure to chemicals. Adequate training of workers and enterprise priority setting are essential elements. Cleaning enterprises have many challenges and the existing paradigms influence the risk levels of these enterprises.MethodsInformation on organization and enterprises' prioritization in training programs was gathered from cleaning enterprises. A measure of enterprises' conceptual level of importance of chemical health hazards and a model for working out the risk index (RI) indicating enterprises' conceptual risk level was established and used to categorize the enterprises.ResultsIn 72.3% of cases, training takes place concurrently with task performances and in 67.4% experienced workers conduct the trainings. There is disparity between employers' opinion on competence level of the workers and reality. Lower conceptual level of importance was observed for cleaning enterprises of different sizes compared with regional safety delegates and occupational hygienists. Risk index values show no difference in risk level between small and large enterprises.ConclusionTraining of cleaning workers lacks the prerequisite for suitability and effectiveness to counter risks of chemical health hazards. There is dereliction of duty by management in the sector resulting in a lack of competence among the cleaning workers. Instituting acceptable easily attainable safety competence level for cleaners will conduce to risk reduction, and enforcement of attainment of the competence level would be a positive step.

製品評価技術基盤機構「化学物質評価の促進に係る有害性等調査に関する業務」の概要紹介

製品評価技術基盤機構「化学物質評価の促進に係る有害性等調査に関する業務」の概要紹介

A Unified Probabilistic Framework for Dose-Response Assessment of Human Health Effects.

BackgroundWhen chemical health hazards have been identified, probabilistic dose–response assessment (“hazard characterization”) quantifies uncertainty and/or variability in toxicity as a function of human exposure. Existing probabilistic approaches differ for different types of endpoints or modes-of-action, lacking a unifying framework.ObjectivesWe developed a unified framework for probabilistic dose–response assessment.MethodsWe established a framework based on four principles: a) individual and population dose responses are distinct; b) dose–response relationships for all (including quantal) endpoints can be recast as relating to an underlying continuous measure of response at the individual level; c) for effects relevant to humans, “effect metrics” can be specified to define “toxicologically equivalent” sizes for this underlying individual response; and d) dose–response assessment requires making adjustments and accounting for uncertainty and variability. We then derived a step-by-step probabilistic approach for dose–response assessment of animal toxicology data similar to how nonprobabilistic reference doses are derived, illustrating the approach with example non-cancer and cancer datasets.ResultsProbabilistically derived exposure limits are based on estimating a “target human dose” (HDMI), which requires risk management–informed choices for the magnitude (M) of individual effect being protected against, the remaining incidence (I) of individuals with effects ≥ M in the population, and the percent confidence. In the example datasets, probabilistically derived 90% confidence intervals for HDMI values span a 40- to 60-fold range, where I = 1% of the population experiences ≥ M = 1%–10% effect sizes.ConclusionsAlthough some implementation challenges remain, this unified probabilistic framework can provide substantially more complete and transparent characterization of chemical hazards and support better-informed risk management decisions.CitationChiu WA, Slob W. 2015. A unified probabilistic framework for dose–response assessment of human health effects. Environ Health Perspect 123:1241–1254; http://dx.doi.org/10.1289/ehp.1409385