As explained in the academic book Chemical Exposure and Toxic Responses, "The relationship between the dose of a toxicant and the resulting effect is the most fundamental aspect of toxicology. Many believe, incorrectly, that some agents are toxic and others are harmless. In fact, determinations of safety and hazard must always be related to dose." Numerous studies have found that all substances (even water and oxygen) become poisonous at a certain dose, and natural substances are sometimes more harmful to people and the environment than the same doses of synthetic substances. Thus, a teaching guide published by the American Society for Microbiology states, "Many people are frightened by the use of synthetic chemicals on food crops because they have heard that these chemicals are 'toxic' and 'cancer causing,' but are all synthetic chemicals more harmful than substances people readily ingest, like coffee and soft drinks? No." For more details, click on the documentation link below.