about 0.006 nCi/day. We note for consideration in the next section that their model specifies the Pu inhalation rate for man to be 5.5 times less than that for beef cattle, or in this case about 0.001 nCi/day. The model of Martin and Bloom allows us to calculate hypothetical 239Pu concentrations in muscle of grazing beef cattle resulting from inhalation and ingestion over time period t. It is of interest to compare these model estimates with those reported in Figure 3 for cattle that grazed Area 13. Using data in Martin and Bloom's Figure 2 and their equations 7.1,7 9, and 10 we obtained hypothetical 239py concentrations in muscle of 2.4 x 107© and 3.1 x 1077 nCi/g (wet weight) for soil concentrations (C.) of 0.55 and 0.07 nCi/g, respec- tively, for grazing time t = 176 days. On an ash weight basis, these muscle concentrations become approximately 6.5 x 10-5 and 8.2 x 10-6 nCi/g ash. The conversion from wet to ash weight was made my multiplying by the average ratio of received weight to ash weight (see footnotes 9 and 10) of calves and cows grazed in Area 13. This average + approximate SE was 27 + 6. From Figure 3, we see that these estimates of Pu concentrations are factors of about four and two larger than actually found in cattle muscle tissue in the inner and outer compounds, respectively. Of course, these computations do not constitute an adequate evaluation of Martin and Bloom's model since so few data are available. Also, the parameter estimate used in the model are not known with any accuracy. The equations of the model may also require modification. In Figure 3, the Pu concentrations for tissue samples are given on an ash weight basis. Due to the difficulty of obtaining a reproducible ash weight on tissue samples in the laboratory, it may be preferable to report results on a dry weight basis. Smith (1976) prefers wet weight to ash weight for cattle tissue samples due to high variability in percent ash reported by laboratories for similar tissues, but he does not consider the dry~-weight comparison. A problem with reporting on a wet weight basis is that samples tend to dry out, and different laboratories may use different handling procedures that affect the recorded wet weight. Lee et al. (1976) report on a rapid dissolution method for tissue sample analyses for reporting on a dry weight basis. Their procedure involves cutting the wet tissue (up to 250 grams) into small cubes followed by successive six-hour drying periods until a constant weight is obtained. This technique may allow the determination of reliable dry weights so that soil, vegetation, small mammals, and cattle tissue samples can be reported and compared on a dry weight basis. We hope to be able to statisti- cally examine this question of reporting on a wet, dry, or ash basis in the near future. Hypothetical 239pu Concentrations in Human Tissue An important goal of the NAEG program is to assess the potential health hazard to man from the plutonium present in the environs of NTS. Martin and Bloom (1976) have devised a plutonium transport and dose estimation model based on NTS studies that estimates inhalation and ingestion rates, organ burdens, accumulated doses, and dose commitments for a Standard Man assumed to live in and obtain most of his food from a Pu-contaminated area such as Area 13 at NTS. Using this model based on parameter values found in ICRP (International Committee on Radiological Protection) publications, they estimated that the 249