Old Usage of Arsenic

Some arsenic compounds are used in the manufacture of everything from wallpaper to ceramics. Arsenic in the 1800s was commonly used in the form of copper arsenite, a green compound that was used as a pigment to color wallpaper and paint.  This caused a lot of health problems. As mold and bacteria fed on the wallpaper and paint, they released trimethylarsine, C₃H₉As, which became airborne and inhaled. This would lead to arsenic poisoning and in some cases, death. It was substituted by copper carbonate by the end of the 1800s as the primary green pigment.

Of course, arsenic is most often thought of in terms of its toxicity and it is used as a weed killer and rat poison. Intentional arsenic poisoning is now pretty much the stuff of old murder mysteries. Originally arsenious oxide was administered in small doses over a period of time, precipitating death accompanied by symptoms reminiscent of pneumonia. Today the arsenic remaining in the body can be detected during autopsy so this is not (happily) a very effective way to dispatch people undetected.

Since Arsenic is toxic to most organisms, it is praised as an herbicide, and pesticide. For example, copper arsenate, Cu3(AsO4)2

, mixed with chromium is a pesticide used to treat wood. As of 2004, CCA, chromium copper arsenate, has been put into restricted use by the EPA. In the 1900s copper acetoarsenite, or Paris Green, was used as an insecticide and fungicide in many agricultural farmland. Agent blue is one of the herbicides used during the Vietnam War by the US to destroy Vietnam rice farm. It is a blend of cacodylic acid, (CH3)2AsO2H, and sodium cacodylic, an arsenic salt.