Anthropogenic (man-made) sources of arsenic, like the natural sources, are mainly arsenic oxides and the associated anions. Man-made sources of arsenic, include wastes from mineral processing, swine and poultry farms. For example, many ores, especially sulfide minerals, are contaminated with arsenic, which is released in roasting (burning in air). In such processing, arsenide is converted to arsenic trioxide, which is volatile at high temperatures and is released into the atmosphere. Poultry and swine farms make heavy use of the organoarsenic compound roxarsone as an antibiotic in feed. Some wood is treated with copper arsenates as a preservative. The mechanisms by which these sources affect "downstream" living organisms remains uncertain but are probably diverse. One commonly cited pathway involves methylation.
The monomethylated acid, methanearsonic acid (CHAsO(OH)), is a precursor to fungicides (tradename Neoasozin) in the cultivation of rice and cotton.  Derivatives of phenylarsonic acid (CHAsO(OH)) are used as feed additives for livestock, including 4-hydroxy-3-nitrobenzenearsonic acid (3-NHPAA or Roxarsone), ureidophenylarsonic acid, and  p-arsanilic acid.  These applications are controversial as they introduce soluble forms of arsenic into the environment.