Summary of Section 1

• Drinking water contains a mixture of anions and cations which are monitored and managed to avoid adverse health or environmental effects.
• The toxicity of a chemical to a receptor can be illustrated by a dose-response curve.
• The LD₅₀ is the lethal dose responsible for killing 50% of the receptor population. The LC₅₀ is the analogous lethal concentration.
• Toxicological effects observed in the short-term are termed acute while chronic effects arise from prolonged exposure.
• The lethal dose low (LD_LO) is the lowest dose per unit of body weight of a chemical known to have produced death in a particular receptor.
• Tolerable daily intake or guideline values are often set for chemicals in drinking water.