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This is the complete lecture note for EHS 401 Environmental Toxicology. You can read it online below, open it in the full viewer, or download the PDF for offline study. It pairs with the course's video lectures, so you can read and watch together.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS EHS 401 Environmental Toxicology Series 1 Foundations and Principles of Environmental Toxicology Part 1 Introduction to Toxicology • 1.1 Definition of Toxicology and Environmental Toxicology • 1.2 Scope and Relevance of Toxicology in Environmental Health • 1.3 Key Terminologies: Toxicodynamics, Toxicokinetics, LD50, LC50, Dose Response Part 2 Classification and Types of Toxicology • 2.1 Medical Toxicology • 2.2 Environmental Toxicology • 2.3 Forensic Toxicology • 2.4 Other Branches (e.g., Industrial, Food, Ecotoxicology) Part 3 Principles of Toxicology in Public Health • 3.1 Importance of Toxicology in Environmental Health Care • 3.2 Role of Toxicology in Policy and Regulation • 3.3 Standards and Health Implications Part 4 Dose Response and Toxicological Concepts • 4.1 Concept of LD and LC • 4.2 Dose Response Curves • 4.3 Probit Analysis Basics
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Introduction Environmental toxicology provides the foundation for understanding how chemicals and other toxic substances interact with living systems and the environment. Every day, humans are exposed to a variety of agents through air, water, food, and occupational activities. Some of these exposures are harmless, while others can cause significant harm to cells, organs, and entire ecosystems. This Series sets the stage for your learning journey by introducing the essential principles and concepts that underpin the study of toxicology, helping you to appreciate its relevance in safeguarding public and environmental health. The aim of this Series is to equip you with a clear understanding of the basic principles of toxicology, including its definitions, classifications, and importance in public health. It intends to build a strong conceptual foundation that will support your learning in subsequent Series. We shall commence this Series by exploring the meaning of toxicology and environmental toxicology, together with key terms such as toxicodynamics, toxicokinetics, LD50, LC50, and dose response. Next, we will examine the classification and types of toxicology, highlighting the distinctions between medical, environmental, and forensic branches. Following that, we will consider the principles of toxicology in public health, focusing on its importance in policy, regulation, and health standards. Finally, we will wrap up by discussing dose response concepts, including LD and LC, dose response curves, and the basics of probit analysis. This sequential flow will provide you with a solid grounding in the principles and foundations of environmental toxicology. Series Learning Outcomes Upon completing this Series, you should be able to: • define toxicology and environmental toxicology, including key terms such as toxicodynamics, toxicokinetics, LD50, LC50, and dose response, • explain the scope and relevance of toxicology in environmental health care, • classify the different types of toxicology, including medical, environmental, forensic, and other specialised branches, • outline the principles of toxicology in public health, with emphasis on policy, regulation, and health standards, analyse dose response relationships by interpreting LD and LC concepts, dose response curves, and the basics of probit analysis.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Part 1 Introduction To Toxicology 1.1 Definition of Toxicology and Environmental Toxicology Toxicology is the scientific study of the adverse effects of chemical, physical, or biological agents on living organisms and the environment. It examines how these agents cause harm, the conditions under which harm occurs, and the mechanisms involved. Environmental toxicology is a branch of toxicology that focuses specifically on the effects of toxic substances on ecosystems, wildlife, and human populations through environmental exposure. To put it simply, toxicology helps us answer questions such as: What makes a substance harmful? How much exposure is too much? Fill in the blank: Toxicology is the study of the ______ effects of agents on living organisms.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 1.2 Scope and Relevance of Toxicology in Environmental Health The scope of toxicology is broad, covering medical, environmental, forensic, industrial, and food toxicology. Its relevance lies in protecting public health by identifying harmful substances, setting exposure limits, and guiding policies for safe environments. For example, toxicology informs regulations on pesticide use, air quality standards, and permissible levels of heavy metals in drinking water. Environmental health relies heavily on toxicology to evaluate risks, prevent poisoning, and design interventions. Without toxicology, it would be difficult to determine whether pollutants in air, water, or soil are safe or hazardous. Fill in the blank: Toxicology helps establish ______ limits for substances to protect public health. Box 1.1: Selected Applications of Toxicology in Environmental Health Toxicology plays a critical role in protecting both human health and the natural environment by providing the scientific data necessary to manage chemical risks. Key applications include: • Setting Safe Exposure Limits: Establishing threshold values, such as Acceptable Daily Intake (ADI) or Occupational Exposure Limits (OELs), to ensure that chemical levels in air, water, or food do not cause adverse health effects. • Evaluating Risks of Industrial Pollutants: Assessing the toxicity and persistence of industrial by-products (like heavy metals or PFAS) to understand their impact on local ecosystems and downstream populations. • Guiding Public Health Interventions: Informing medical and governmental responses to contamination events, such as advising on fish consumption or identifying the source of a local disease cluster. • Supporting Environmental Regulations: Providing the evidence base for laws and standards, such as the Clean Air Act or REACH, which restrict the use of hazardous substances to prevent long-term environmental degradation. 1.3 Key Terminologies: Toxicodynamics, Toxicokinetics, LD50, LC50, Dose Response Toxicodynamics refers to the study of the effects of toxic substances on biological targets, such as cells, tissues, or organs. It explains what the toxicant does to the body. Toxicokinetics is the study of how the body absorbs, distributes, metabolises, and eliminates toxic substances. It explains what the body does to the toxicant. LD50 (Lethal Dose 50) is the dose of a substance that kills 50 percent of a test population, usually animals, under controlled conditions. LC50 (Lethal Concentration 50) is the concentration of a substance in air or water that kills 50 percent of a test population. Both are measures of toxicity and are used to compare the relative danger of substances.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Dose response describes the relationship between the amount of exposure to a toxicant and the severity of the effect. It is often represented by a curve showing how increasing doses lead to increasing effects. Fill in the blank: The term that describes what the body does to a toxicant is ______.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS Pilot questions 1 1. Which branch of toxicology focuses on the effects of toxic substances on ecosystems and human populations? 2. What is the main role of toxicology in environmental health? 3. Define toxicodynamics in one sentence. 4. What does LD50 measure? 5. Fill in the blank: The relationship between exposure amount and effect severity is called ______. Part 2 Classification And Types Of Toxicology 2.1 Medical Toxicology Medical toxicology is the branch of toxicology concerned with diagnosing, managing, and preventing poisoning in humans. It focuses on the clinical aspects of toxic exposure, including drug overdoses, adverse drug reactions, and poisoning from household or industrial chemicals. Medical toxicologists often work in hospitals, emergency departments, and poison control centres. Fill in the blank: Medical toxicology is primarily concerned with the ______ aspects of toxic exposure.
LA-NET | ONLINE LEARNING VIDEO PLATFORM FOR POST-SECONDARY & HIGHER INSTITUTION STUDENTS 2.2 Environmental Toxicology Environmental toxicology examines the effects of toxic substances on ecosystems, wildlife, and human populations through environmental exposure. It investigates pollutants in air, water, and soil, and assesses their impact on biodiversity and public health. For example, studies on pesticide residues in rivers or heavy metals in soil fall under this branch. Fill in the blank: Environmental toxicology focuses on the effects of toxic substances on ______ and human populations.
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