OFFICTAL USE ONLY V. RESIDUAL ACTIVITY IN PACIFIC OCEAN During February-May, 1955, a survey was. made by the Health and Safety Laboratory of the U. S. Atomic Energy Commission and the Office of Naval Research (Operation Troll) of the Pacific Ocean extending from the Marshall Islands westward across the Pacific, northward to Japan, then west to San Francisco. The Chart represents data on activity found in sea water and plankton. Table Forty-two shows some representative data on activity versus depth of water sample. 10 Tables Forty-three and Forty-four show representative data for marine life. LO Below is a summary of some of their conclusions: 1. Seam water and plankton samples show the existence of widespread lJow~level activity in the Pacific Ocean. Water activity ranged from 0-570 d/min/liter and plankton from 3-140 d/min/g wet weight. 2. There is some concentration of the activity in the main current streams, such as the North Equatorial Current. The highest activity was off the coast of Luzon, averaging 190 d/min/liter down to 600 m (April 1, 1955). 3. Analyses of fish indicate no activity approaching the maximum permissible level for foods. The highest activity in tuna fish was 3.5 d/min/g ash, less than 1 percent of the permissible level .* 4. Measurements of plankton activity offer a sensitive indication of activity in the acean. * Based on 1/10 mpc. of that for atomic energy workers. OFFICIAL USE ONLY