Applications of Toxicology

Applications of Toxicology

A Brief History of Toxicology

Much of the early history of toxicology has been lost and in much that has survived toxicology is of almost incidental importance in manuscripts dealing primarily with medicine. Some, however, deal more specifically with toxic action or with the use of poisons for judicial execution, suicide or political assassination. Regardless of the paucity of the early record, and given the need for people to avoid toxic animals and plants, toxicology must rank as one of the oldest practical sciences. The Egyptian papyrus, Ebers, dating from about 1500 BC, must rank as the earliest surviving pharmacopeia, and the surviving medical works of Hippocrates, Aristotle, and Theophrastus published during the period 400 to 250 BC all include some mention of poisons. The early Greek poet Nicander treats, in two poetic works, animal toxins (Therica) and antidotes to plant and animal toxins (Alexipharmica). The earliest surviving attempt to classify plants according to their toxic and therapeutic effects is that of Dioscorides, a Greek employed by the Roman emperor Nero about AD 50.

There appear to have been few advances in either medicine or toxicology between the time of Galen (AD 131–200) and Paracelsus (1493–1541). It was the latter who, despite frequent confusion between fact and mysticism, laid the groundwork for the later development of modern toxicology by recognizing the importance of the dose response relationship. His famous statement—“All substances are poisons; there is none that is not a poison. The right dose differentiates a poison and a remedy”—succinctly summarizes that concept. His belief in the value of experimentation was also a break with earlier tradition. There were some important developments during the eighteenth century. Probably the best known is the publication of Ramazini’s Diseases of Workers in 1700, which led to his recognition as the father of occupational medicine. The correlation between the occupation of chimney sweeps and scrotal cancer by Percival Pott in 1775 is almost as well known, although it was foreshadowed by Hill’s correlation of nasal cancer and snuff use in 1761.

It is clear, however, that since the 1960s toxicology has entered a phase of rapid development and has changed from a science that was largely descriptive to one in which the importance of mechanisms of toxic action is generally recognized. Since the 1970s, with increased emphasis on the use of the techniques of molecular biology, the pace of change has increased even further, and significant advances have been made in many areas, including chemical carcinogenesis and xenobiotic metabolism, among many others.

 Relationship to Other Sciences

Toxicology is highly eclectic science and human activity drawing from, and contribut ing to, a broad spectrum of other sciences and human activities. At one end of the spectrum are those sciences that contribute their methods and philosophical concepts to serve the needs of toxicologists, either in research or in the application of toxicology to human affairs. At the other end of the spectrum are those sciences to which toxicology contributes. In the first group chemistry, biochemistry, pathology, physiology, epidemiology, immunology, ecology, and biomathematics have long been important while molecular biology has, in the last two or three decades, contributed to dramatic advances in toxicology. In the group of sciences to which toxicology contributes significantly are such aspects of medicine as forensic medicine, clinical toxicology, pharmacy and pharmacology, public health, and industrial hygiene. Toxicology also contributes in an important way to veterinary medicine, and to such aspects of agriculture as the development and safe use of agricultural chemicals. The contributions of toxicology to environmental studies has become increasingly important in recent years.

Clearly, toxicology is preeminently an applied science, dedicated to the enhancement of the quality of life and the protection of the environment. It is also much more. Frequently the perturbation of normal life processes by toxic chemicals enables us to learn more about the life processes themselves. The use of dinitrophenol and other uncoupling agents to study oxidative phosphorylation and the use of α-amanitin to study RNA polymerases are but two of many examples. The field of toxicology has expanded enormously in recent decades, both in numbers of toxicologists and in accumulated knowledge. This expansion has brought a change from a primarily descriptive science to one which utilizes an extensive range of methodology to study the mechanisms involved in toxic events.

Applied Toxicology.

This includes the various aspects of toxicology as they apply in the field or the development of new methodology or new selective toxicants for early application in the field setting.

1. Clinical toxicology: It is the diagnosis and treatment of human poisoning.

2. Veterinary toxicology: is the diagnosis and treatment of poisoning in animals other than humans, particularly livestock and companion animals, but not excluding feral species. Other important concerns of veterinary toxicology are the possible transmission of toxins to the human population in meat, fish, milk, and other foodstuffs and the care and ethical treatment of experimental animals.

3. Forensic toxicology: concerns the medicolegal aspects, including detection of poisons in clinical and other samples. Forensic Toxicology Applications

While there are many uses for forensic toxicology testing, the most familiar one to most people is likely to be drug and alcohol testing. This type of testing is commonly performed in the transportation industry and in workplaces. Another use is for drug overdoses, whether these are intended or accidental. People who drive with a blood alcohol concentration over the accepted legal limit can also be assessed through toxicology testing. Another application of forensic toxicology relates to sexual assault that involves the use of drugs. Various drugs are used today for the purposes of rendering the victim unable to fight the attacker, who then proceeds to sexually assault the victim. Through toxicology testing, a victim can find out what drug was given and can then be treated accordingly.

There are a lot of substances and poisons in our world – many of which impact how we function in work and society. For some people, these substances can influence their death. Fortunately, forensic toxicology testing allows forensic scientists to identify substances and determine a pattern of use. In this way, a forensic toxicologist can provide closure on the 'what if' of a person's drug habits or perhaps some mystery surrounding their death.

4. Environmental toxicology: is concerned with the movement of toxicants and their metabolites and degradation products in the environment and in food chains and with the effect of such contaminants on individuals and, especially, populations. Because of the large number of industrial chemicals and possibilities for exposure, as well as the mosaic of overlapping laws that govern such exposure, this area of applied toxicology is well developed.

5. Industrial toxicology: is a specific area of environmental toxicology that deals with the work environment and constitutes a significant part of industrial hygiene.