Preliminary tests indicate the chelating agent triethylenetetraminehexaacetic acid (TTHA) is as effective as diethylenetriaminepentaacetic acid (DTPA) in plutonium removal. TTHA appears to be even more effective than DTPA when the agents are administered orally. The range of toxicity and the optimum dosage levels of TTHA have not yet been clearly defined. Two additional chelating agents, aminoethylcyclohexyldiaminepentaacetic acid (ACHDPA) and aminoethoxycyclohexylaminetetraacetic acid (ACHTA), although structurally similar to DTPA, were considerably less effective than DTPA in plutonium removal.