ABC of Safety in the Biological Sciences
Arsenic compounds are highly toxic by inhalation or ingestion and potentially carcinogenic when acquired in small doses and accumulated in the body over a period of time. Dimethylarsenic acid (cacodylic acid), as used commonly in electron microscopy in buffer solutions, releases arsenic slowly and is therefore less likely to cause acute arsenic poisoning.34
The action of acids on metals in the presence of arsenic forms arsine gas (a constituent of mustard gas). Some alloys such as ferrosilicon, which may be contaminated with arsenic, release arsine upon contact with water.
Approximately 120 mg of arsenic trioxide is lethal whilst the fatal dose for organic arsenicals, such as cacodylic acid, is 0.1 - 0.5 gm per kilogram of body weight. The exposure limit for arsine is 0.05 ppm (0.002 mg/m). Arsenic should be stored in a security cabinet and handled only under a fume hood to ensure that levels of exposure remain below the recommended threshold limit. Protective clothing should be worn.