Pathway Analyses PLUTONIUM CONCENTRATIONS IN THE INHALATION PATHWAY The contribution from the inhala~ in the air than expected from worldwide fallout and more than encountered in New York City during comparable tion pathway to plutonium concentra- periods. tion in urine, especially at Bikini, resuspension does significantly is very hard to quantify. contribute to inhalation’ of plutonium In addi- tion to the different activity levels These data indicate that at Bikini. We will show in a follow- from fallout in the air at Bikini and ing section that resuspension might New. York, reSuspension processes that also contribute to elevated plutonium contribute airborne plutonium at New levels in the ingestion pathway at York and Bikini are very difficult Bikini. to assess. Nevertheless, it is | Comparable data on plutonium con- important to assess these processes centrations in the air exist only for in estimating the cumulative exposure the periods of May 29 to June 2, to plutonium from inhalation. 1970,° and May 1972.? Bennett? has recently concluded that sampling period, plutonium from resuspended fallout During the 1970 239,240 Pu levels in .surface air were determined at five at New York presently contributes locations on Bikini Island and ranged 0.3% and will ultimately contribute from 60 to 540 aci/m>.° intake equal to 0.5% of the intake cencentration at four sites on the that occurs during the original island of Eneu (in Bikini Atoll) was deposition of the fallout debris. only 40 aCi/m> during a comparable Data of one of the authors * show that period. ° the soil plutonium levels on Bikini function of latitude are the average Island are, on the average, higher plutonium concentrations at ground than plutonium levels from fallout level at air sampling stations of the deposited in the United States.” HASL sampling network, Visual observations indicate that The mean air Plotted in Fig. l as a June 1970.8 taken during The concentration-— the formation of dust clouds or the latitude profile is simply a con- resuspension of surface materials by tinuous curve drawn through the people or vehicles at Bikini is availabie data points. slight, even during very long dry spells. However, the available From this curve, the average fallout-plutonium concentration aerosol data show that some locations expected in ground-level air at the on Bikini Island have more plutonium latitude of Bikini Island (11°, 37' 9010223