Final answer:
A toxic substance is a chemical that can cause harm to humans or the environment. Environmental health risks are categorized into chemical, physical, biological, and ergonomic hazards. Environmental toxicology studies the harmful effects of environmental contaminants.
Step-by-step explanation:
Defining Toxic Substance
A toxic substance is defined as any chemical or compound that can cause harm when inhaled, ingested, or comes into contact with skin. Toxicity can vary widely, from mildly irritating substances to those that can be fatal, even in small quantities.
Typical Categories of Environmental Health Risks
Environmental health risks can generally be categorized into chemical, physical, biological, and ergonomic hazards. Knowing these categories helps to assess and manage risks effectively in various environments.
Evaluating Environmental Health
To define environmental health, one would consider it as the branch of public health concerned with all aspects of the natural and built environment affecting human health. Environmental toxicology, meanwhile, is a field of science that studies the harmful effects of various environmental contaminants on living organisms, which include chemicals, radiation, and some natural substances.