THH - Toxicology and Human Health Module Overview
Toxicology and Human Health
Impacts of the environment on human health can be as obvious as the air you can see like London's Great Smog of 1952 or as invisible as the mercury-contaminated water of Japan's Minamata Bay, but all have can profound and devastating consequences. A disease rarely has a single cause and effect relationship with environmental exposure; it is always a reflection of exposure, tolerance, and the biological status of the organism. Toxins can enter the human body in a variety of routes, like their types, sources and therefore the effects can also vary. Human diseases can be infectious or noninfectious but are very often a reflection of the environment and health status of the individual. Finally, since hazards to human health can be found where we live, work, and play, risk analysis, a system of evaluation, was developed to protect us from potential environmental dangers.
Essential Questions
- What are the types and characteristics of major groups of pollutants in environmental toxicology?
- Why is there controversy and concern about synthetic organic compounds such as dioxin?
- What is the dose-response concept and how does it relate to LD-50, TD-50, LC-50, ED-50, ecological gradients, and tolerance?
- How do the processes of bioaccumulation and biomagnification work and why are they important in toxicology?
- What is the importance of the threshold effect of environmental toxins?
- What is the process of risk assessment in toxicology and how can it be used to evaluate the risk to human health and life?
- What controversial issues can develop with the use of risk assessment?
- What is the Precautionary Principle and how does it apply to environmental health?
Key Terms
- Epidemiologist- the study of the cause of human disease and associated patterns
- Pandemic- global or large area spread of an infectious disease
- Precautionary Principle- when an activity or material poses potential threats to human health or the environment, precautionary measures should always be taken
- Risk Assessment- The process of determining potential negative environmental health effects to people following exposure to toxic substances- 4 main parts: 1-identification 2- dose-response assessment 3- exposure assessment 4- risk characterization
- Dose-response- the principle that the effect of a chemical on an individual depends on the dose (or concentration) of that chemical
- Lethal Dose 50 (LD-50)- a dose that is toxic to 50% of the population
- Bioaccumulation- the tendency for some materials to accumulate in biologic tissues, notably in fat
- Biomagnification (or biological magnification)- the tendency for some substances to bioaccumulate (at nontoxic levels) and are found at much higher concentrations as it moves up the food chain often with deleterious effects (i.e. DDT and mercury)
- Toxicology- science focused on the study of toxins and their effect on a living organism
- Acute- short term disease or exposure to a substance
- Chronic- long term disease or exposure to a substance
- Latent- present or potential to develop but not evident or active
- Epidemic- the locally-focused rapid spread of infectious disease
- Zoonosis- an infectious disease that can be spread between different species of animals, notably between humans and other animals (i.e. rabies)
- Tolerance- ability to withstand stresses or exposure to a toxic substance
- Synergism- cooperative action of different substances, when combined the effect, is far greater than the sum of each separately
- Toxic- harmful, deadly, or poisonous
- Threshold- point in a system at which a change occurs, in toxicology any points below, do not show any effects or evidence of exposure
- Ecologic gradient- a change in the relative abundance of a species or group of species along a distant line or over an area
RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.