A study using juvenile swine as test animals was performed to measure the gastrointestinal absorption of arsenic from two soil samples from El Paso County, Texas (Test Material 1 and Test Material 2). The relative bioavailability of arsenic was assessed by comparing the absorption of arsenic from the test materials to that of a reference material (sodium arsenate). The arsenic concentrations of Test Material 1 and Test Material 2 were 74 ppm and 73 ppm, respectively. Groups of five swine were given oral doses of sodium arsenate or a test material twice a day for 15 days. The amount of arsenic absorbed by each animal was evaluated by measuring the amount of arsenic excreted in the urine (as measured on days 8, 11, and 14). The urinary excretion fraction (UEF) (the ratio of the amount excreted per 24 hours divided by the dose given per 24 hours) was calculated for sodium arsenate and the test materials using linear regression analysis.