Hydrogen arsenate and dihydrogen arsenate predominate in aqueous solution near neutral pH. The toxic compounds in arsenic are arsenate and arsenite. Arsenate and phosphate salts behave very similarly. In the glyceraldehyde 3-phosphate dehydrogenase reaction arsenate attacks the enzyme-bound thioester. It can remove copper, cobalt, cadmium, arsenate, and organic solvents. Arsenate can replace phosphate in many reactions. Lead arsenate is used in insecticides and herbicides. This is due to the strong chemical likeness of arsenate and phosphate. PO (phosphate), AsO (arsenate), and VO (vanadate). Under oxidative environmental conditions some bacteria use arsenite as fuel, which they oxidize to arsenate. Secondary weathering incrustations of erythrite, hydrated cobalt arsenate, are common. One is when arsenate is reduced to arsenite which adsorbs to iron oxides less strongly. Some varieties of cobalt violet are made with cobalt arsenate. The first cobalt violet, the intensely red-violet cobalt arsenate, was highly toxic. As from wood that had been treated with chromated copper arsenate.