arsenicals

Arsenicals are chemical compounds containing arsenic, including inorganic forms such as arsenite (As(III)) and arsenate (As(V)) and a range of organoarsenicals. They have historically been used in medicine, agriculture, and industry because of their biological activity, but many arsenicals are highly toxic. Regulation governs exposure, handling, and environmental release in many jurisdictions.

Classes and examples: Inorganic arsenicals include arsenite and arsenate compounds, arsenic trioxide and related oxides. Organoarsenicals are carbon-arsenic compounds such as arsanilic acid and roxarsone, which were used as feed additives. Arsenic-containing pigments (Paris green, Scheele’s green) and wood preservatives (chromated copper arsenate) have also been employed, with many uses restricted or banned due to safety concerns.

Medical and regulatory history: The arsenic-containing drug salvarsan (arsphenamine) treated syphilis in the early 1900s. Arsenic trioxide is currently used to treat acute promyelocytic leukemia (APL). In agriculture, organoarsenicals and inorganic arsenicals used as pesticides and preservatives have faced phase-outs or bans and ongoing substitutions for safer alternatives.

Toxicology and exposure: Arsenic compounds disrupt cellular energy metabolism and oxidative processes by binding to sulfhydryl groups. Inorganic arsenicals tend to be more toxic than many organoarsenicals. Chronic exposure is associated with skin lesions, cancers (skin, bladder, lung), cardiovascular and neurological effects; acute exposure can be fatal. Drinking-water guidelines typically aim for about 10 micrograms per liter.

Environment and regulation: Arsenic occurs naturally and is released by mining and smelting, as well as through agricultural use and improper disposal. Groundwater contamination is a major concern in several regions. Risk assessment and remediation strategies include monitoring, removal, stabilization, and treatment of contaminated media, with enforcement of permissible levels and safe-handling practices.