Toxicology is a scientific discipline, overlapping with biology, chemistry, pharmacology, and medicine, that involves the study of the adverse effects of chemical substances on living organisms and the practice of diagnosing and treating exposures to toxins and toxicants. The relationship between dose and its effects on the exposed organism is of high significance in toxicology. Factors that influence chemical toxicity include the dosage, duration of exposure (whether it is acute or chronic), route of exposure, species, age, sex, and environment. Toxicologists are experts on poisons and poisoning. There is a movement for evidence-based toxicology as part of the larger movement towards evidence-based practices. Toxicology is currently contributing to the field of cancer research, since some toxins can be used as drugs for killing tumor cells. One prime example of this is ribosome-inactivating proteins, tested in the treatment of leukemia. The word toxicology () is a neoclassical compound from Neo-Latin, first attested c. 1799, from the combining forms toxico- + -logy, which in turn come from the Ancient Greek words τοξικός toxikos, "poisonous", and λόγος logos, "subject matter").
History
Unlike many civilizations, records of Egyptian knowledge and use of poisons can only be dated back to approximately 300 BC. However, it is believed that the earliest known Egyptian pharaoh, Menes, studied the properties of poisonous plants and venoms, according to early records. The Egyptians are also thought to have come into knowledge about elements such as antimony, copper, crude arsenic, lead, opium, and mandrake (among others) which are mentioned in papyri. They carefully documented venomous snakes and scorpions, their effects, and treatments, using controlled herbal poisons in medicine, and are also thought to have been the first to master distillation and extract poison from apricot kernels. The Kalpasthāna is a section of the Suśrutasaṃhitā, an ancient Sanskrit medical compendium composed before c. 300 CE, with portions possibly dating to the fourth century BCE.It is devoted to the study of plant and animal poisons, including their classification, identification, and treatment. The Kalpasthāna was influential on many later Sanskrit medical works and was translated into Arabic and other languages, influencing South East Asia, the Middle East, Tibet and eventually Europe. Dioscorides, a Greek physician in the court of the Roman emperor Nero, made an early attempt to classify plants according to their toxic and therapeutic effect. A work attributed to the 10th century author Ibn Wahshiyya called the Book on Poisons describes various toxic substances and poisonous recipes that can be made using magic. In the 12th century, Jewish physician Maimonides wrote Kitāb al-Sumūm wa-l-Mutaḥarriz min al-Adwiya al-Qattāla ("Book on Poisons and the One Who Guards Against Deadly Drugs"), which discussed the treatment of poisoning. A 14th century Kannada poetic work attributed to the Jain prince Mangarasa, Khagendra Mani Darpana, describes several poisonous plants.
The late medieval philosopher Pietro d'Abano compiled a treatise on venoms and poisons drawing on earlier Greek sources, particularly works attributed to Dioscorides such as On Venoms and On Poisons. This work reflects an early engagement with Greek scientific traditions and has been viewed as a precursor to the later revival of Greek science associated with the Renaissance. The 16th-century Swiss physician Paracelsus is considered "the father" of modern toxicology, based on his rigorous approach to understanding the effects of substances on the body. He is credited with the classic toxicology maxim, "Alle Dinge sind Gift und nichts ist ohne Gift; allein die Dosis macht, dass ein Ding kein Gift ist." which translates as, "All things are poisonous and nothing is without poison; only the dose makes a thing not poisonous." This is often condensed to: "The dose makes the poison" or in Latin "Sola dosis facit venenum". Mathieu Orfila is also considered the modern father of toxicology, having given the subject its first formal treatment in 1813 in his Traité des poisons, also called Toxicologie générale. In 1850, Jean Stas became the first person to successfully isolate plant poisons from human tissue. This allowed him to identify the use of nicotine as a poison in the Bocarmé murder case, providing the evidence needed to convict the Belgian Count Hippolyte Visart de Bocarmé of killing his brother-in-law.
In the modern era, regulatory oversight of toxicology has shifted to specialized governmental and international bodies, including the U.S. Food and Drug Administration (FDA), the Environmental Protection Agency (EPA), and the World Health Organization (WHO), which enforce standardized protocols to assess chemical risks in food, drugs, and the environment. Building on Paracelsus's foundational dose-response principle, these agencies guide evidence-based safety evaluations through tiered toxicity studies and data interpretation. The FDA's Redbook 2000 exemplifies this continued evolution, serving as a pivotal guidance document for toxicological principles in assessing food additives and ingredients, ensuring public health protections aligned with contemporary scientific rigor.
Basic principles The goal of toxicity assessment is to identify adverse effects of a substance. Adverse effects depend on two main factors: i) routes of exposure (oral, inhalation, or dermal) and ii) dose (duration and concentration of exposure). To explore dose, substances are tested in both acute and chronic models. Generally, different sets of experiments are conducted to determine whether a substance causes cancer and to examine other forms of toxicity. Factors that influence chemical toxicity:
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