For as long as there have been targets that needed to be removed quietly, there have been poisoners. For centuries, poison has often been the favored tool for political assassinations in a number of societies. The Romans and Persians were both said to have had special children who were slowly fed increasing doses of a lethal poison. Eventually, the child would exhibit the desired side effects of being immune to the poison and being so saturated with it that even their sweat or saliva was poisonous. There are many naturally occurring poisons, with hemlock and nightshade being examples, but more ?civilized? poisoners have one chemical of preference. That chemical is arsenic.

Arsenic poisoning is often a slow, time-consuming process that leads to an equally slow, painful death. Arsenic poisoning is, according to one serial poisoner who fancied herself a philosopher, an ?art form and a precise science.? Controlled doses, preferably starting with small amounts that increase over time, are ideal to avoid the body's drug metabolism from rejecting it. Too strong a dose and the body simply forces the poison out with minimal side effects, which was what happened to Napoleon Bonaparte. This was, according to popular lore, also the case with one of the earlier victims of serial poisoner Belle Gunness. Too little and the body's drug tolerance kicks in, preventing any real effects from emerging. It is often a delicate balance between dosage and ?schedule? that allows the venom to be so effective.

Arsenic is considered the near-perfect poison because it is virtually undetectable by the senses and most of the symptoms can easily be attributed to an ulcer or heart condition. Stomach pains, particularly around the bowel region, are among the signs of high concentration doses. Mild headaches, dizziness, and hotheadedness have been observed as symptoms of lower dosages. Since arsenic was usually administered over time, the compounding symptoms often served to make it appear as if the person died of illness. The later, more obvious effects were also highly similar to cholera, which earned it favor as the poison of choice for the ruling classes of Renaissance Italy. Notable victims of that time were several political enemies of the Borgia family and Francesco I de Medici of Tuscany.

Interestingly enough, arsenic in its purest form is hardly lethal. It can cause mild discomfort and headaches, but is only lethal in exceptional cases. The real threat of arsenic poisoning comes when arsenic is mixed with other compounds, which usually start a sort of drug interaction when introduced to the body. In most cases, arsenic combined with oxygen is significantly more fatal than pure arsenic, with arsenic trioxide being among the most potent. Long-term ingestion or arsenic through liquids, particularly water or tea, are also more effective than the pure form of the chemical. Mixing it with drinks also makes it much harder to detect without proper testing.

Not all arsenic poisoning is intentional, however. Groundwater in several places can be easily contaminated by arsenic. Recently, Bangladesh has had to deal with this problem due to well tapping into contaminated underground water sources in the 1970s. In the past, arsenic was also a component in a variety of colors used by artists, notably emerald green. The neurological problems of Vincent Van Gogh have sometimes been attributed to long-term arsenic, lead, and mercury exposure that were supposedly found in the paints he used.