Formation of arsenite in lead arsenate or calcium arsenate mixtures

Lead and calcium arsenates have been used as insecticides in the past with various adjuvants added to increase their effectiveness. Adverse health effects have been reported in industrial situations where these materials were formulated, and packaged, and occasionally used. Reduction of arsenate has been demonstrated to occur when mixtures of lime, lime sulfur, sulfur, and casein were added to lead or calcium arsenate. The formation of soluble arsenite increased with time after the formulations were dry mixed. Levels of soluble arsenite declined in aqueous suspension after 1 day but increased again after 2 months. Total arsenite varied from 0.6 to 2.4% of the arsenic present 253 days after formulation.