The term<unk> " is often used colloquially to describe any harmful substance—particularly corrosive substances, carcinogens, mutagens, teratogens and harmful pollutants, and to exaggerate the dangers of chemicals. Paracelsus (1493–1541), the father of toxicology, once wrote: "Everything is<unk> , there is<unk>  in everything. Only the dose makes a thing not a<unk> " (see median lethal dose). The term<unk> " is also used in a figurative sense: "His brother's presence<unk> ed the atmosphere at the party". The law defines<unk> " more strictly. Substances not legally required to carry the label<unk> " can also cause a medical condition of<unk> ing. Some<unk> s are also toxins, which is any<unk>  produced by animals, vegetables or bacteria, such as the bacterial proteins that cause tetanus and botulism. A distinction between the two terms is not always observed, even among scientists. The derivative forms "toxic" and<unk> ous" are synonymous. Animal<unk> s delivered subcutaneously (e.g., by sting or bite) are also called venom. In normal usage, a<unk> ous organism is one that is harmful to consume, but a venomous organism uses venom to kill its prey or defend itself while still alive. A single organism can be both<unk> ous and venomous, but that is rare. All living things produce substances to protect them from getting eaten, so the term<unk> " is usually only used for substances which are<unk> ous to humans, while substances that mainly are<unk> ous to a common pathogen to the organism and humans are considered antibiotics. Bacteria are for example a common adversary for Penicillium chrysogenum mold and humans, and since the mold's<unk>  only targets bacteria humans may use it for getting rid of bacteria in their bodies. Human antimicrobial peptides which are toxic to viruses, fungi, bacteria and cancerous cells are considered a part of the immune system. In nuclear physics, a<unk>  is a substance that obstructs or inhibits a nuclear reaction. For an example, see nuclear<unk> . Environmentally hazardous substances are not necessarily<unk> s, and vice versa. For example, food-industry wastewater—which may contain potato juice or milk—can be hazardous to the ecosystems of streams and rivers by consuming oxygen and causing eutrophication, but is nonhazardous to humans and not classified as a<unk> . Biologically speaking, any substance, if given in large enough amounts, is<unk> ous and can cause death. For instance, several kilograms worth of water would constitute a lethal dose. Many substances used as medications—such as fentanyl—have an only one order of magnitude greater than the ED50. An alternative classification distinguishes between lethal substances that provide a therapeutic value and those that do not.
Poison
Tin poisoning
Xenointoxication
Mushroom poisoning
Secondary poisoning
Cyanide poisoning
Chinese alchemical elixir poisoning
Theobromine poisoning