Substances that are poisonous, or harmful, to living organisms. Some of these substances can be produced by living cells or organisms and cause disease when introduced into another organism. Some, not all, spiders, insects, snakes, and fungi produce substances at the molecular level that are harmful to other living organisms. These are referred to as biotoxins.
Other toxins are inorganic, rather than biological, and can derive from industrial, technological, and even agricultural (such as pesticides and fertilizers) sources. These toxins affect the health of air, water, and soil systems, which in turn affect the health of the living organisms that live in or near these systems.
