-f- HW-80991 SUMMARY STATEMENT An evaluation of results obtained from the Hanford environmental surveillance program for 1963 indicates that most of the environmental radiation exposure for the majority of persons in the neighborhood of the Hanford project was due to natural sources and world-wide fallout rather than to Hanford operations. Of the low-level wastes released to the environment from the Hanford plants, neutron-induced radionuclides present in reactor cooling water discharged to the Columbia River continued to be the source of greatest potential exposure to the people in the environs. The primary mechanisms of exposure from this source are drinking water derived from the river and consumption of fish and waterfowl which inhabit the river. The city of Richland started using the Columbia River as a source of Sanitary water during 1963. In the 4 months following startup of the new plant in August, this source contributed a total exposure amounting to about 3% of the annual permissible limit for populations. _The gastrointestinal tract is the limiting organ for the mixture of nuclides present in drinking water pumped from the Columbia River. In Pasco and Kennewick, which are further downriver, the estimated exposures from drinking water were respectively about 5% and1% of the GI tract limit (population at large) for the full 12 months of 1963. The only persons who received radiation exposures attributable to Hanford that were greater than those resulting from the drinking water were the people that ate local fish or waterfowl or who regularly consumed produce from nearby farms irrigated with water pumped from the Columbia River below the reactors. The highly unlikely, but conceivable combination of circumstances that would result in the greatest exposure to an individual from the radio' nuclides released by the Hanford plants is postulated as; (1) the consumption of some 200 meals of locally caught fish during the year, (2) the consumption of meat, milk, fruit, and vegetables from irrigated farms of the Riverview district, and (3) the drinking of water from the Pasco system.

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