Arsenic has gained the reputation of being a lethal poison, used by wives of nobles to assassinate their spouse earning it the nickname the poison of kings and the king of poison. This was because its symptoms were very similar to natural sickness that it was difficult to detect one had been poisoned so people used it for its difficulty to trace but this was then, because now we have advanced in chemistry and can tell when one has been poisoned with arsenic and today, Arsenic which was known as a deadly element has been transformed to a life-saving medicine.
Arsenic is a silvery gray metaloid having the property of a metal and a non-metal and with the atomic number 33 and it was known and still known to be a poison in its pure form or as Arsenic trioxide which was used in times before modern forensic became a thing and a lot of people got away with murder. Victims of this poison usually would experience stomach pain, vomiting, and frailty for days or weeks while the poison is doing its job and these symptoms are similar to cholera or food poisoning.
The ability to get away with murder with Arsenic came to a halt in 1836 when forensic chemistry took a new direction with James Marsh developing the Marsh test which was the first reliable method to find arsenic in the tissue of victims. Arsenic can bind with other metals like copper, nickel and iron to form ore like Arsenopyrite. The binding with metals allow arsenic to be present in the earth crust causing it to be released with mining or other earth disturbing related activities into soils and water leading to groundwater contamination.
At a point, arsenic was found in a lot of compounds especially ones that had to do with beauty and decor. It was used as paint giving the Shayless green and Paris green color and this slowly poisoned the occupants of the houses the paints were used or people who purchased items with arsenic coating especially when the items were damped. It was also used in agriculture and pest control as it was used for everything insecticide or pest control.
With all its reputation, it would be difficult to believe that Arsenic can ever be used in medicine but it has been used for millennium such as in traditional Chinese medicine where Arsenic sulfide minerals (realgar) were used in small amounts to treat ailments. In 1700s, the Fowler solution which was a 1% arsenic tonic was prescribed for all type of health issues including eczema, asthma, arthritis and leukemia but not all were true and only a few people reported recovery but arsenic breakthrough in medicine came with the fight against syphilis.
Paul Ehrlich was able to find a drug that would target the disease and not hurt the patient and so he discovered Arsphenamine which was an arsenic based chemical that worked at attacking the syphilis bacteria and it worked becoming the first effective treatment against syphilis. While it was useful, it had its own downsides as its preparation was cumbersome and it was painful for patients who were to be treated and patients also had side effects. This was the standard treatment until the 1940s when penicillin replaced it.
In the 20th century, Arsenic trioxide was revised for treating Acute promyelocytic Leukemia (APL) which was a deadly subtype of leukemia. Scientist realized that Arsenic trioxide could cause the cancer cell to self-destruct so trials began and in the year 2000 it was approved as a treatment for APL. Arsenic is also used for other treatments including treating parasitic conditions but in all when doctors are treating with it, dose matters because a slight higher dose can change from being therapeutic to being lethal.
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FOR FURTHER READING
https://www.sciencedirect.com/topics/earth-and-planetary-sciences/arsenopyrite
https://pmc.ncbi.nlm.nih.gov/articles/PMC2693900/
https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1338725/full
https://pmc.ncbi.nlm.nih.gov/articles/PMC3179678/
https://cfpub.epa.gov/si/si_public_record_report.cfm?Lab=NHEERL&dirEntryId=341168
https://www.sciencedirect.com/topics/biochemistry-genetics-and-molecular-biology/arsphenamine
https://www.atamanchemicals.com/arsenic-trioxide_u26397/
https://www.mayoclinic.org/drugs-supplements/arsenic-trioxide-intravenous-route/description/drg-20062068
https://pmc.ncbi.nlm.nih.gov/articles/PMC5619256/