exceptions. Mean leukocyte and erythrocyte counts of D. microps from NTS are significantly (P<.05) depressed when compared to control animals. In addition, packed cell volumes were significantly (P<.01) reduced in D. merrtami from NTS. Mean relative leukocyte differential counts (Table 6) are comparable for the two populations with one exception. Neutrophils are significantly depressed (P<.01) in D. mterops from NTS. There have been many laboratory studies on the effects of Pu on the hemopoietic system of mammals. These studies, summarized in Wick (1967), have pointed out that Pu causes destruction of bone marrow, anemia, and leukopenia. Depressed levels of lymphocytes were reported by Paglia (1968) in a natural population of D. microps from a Pu-contaminated area of NTS. To determine if Pu body burdens were related to blood cell reductions in rodents of Area 11, NTS, correlation coefficients were determined for blood cell counts and Pu body burdens. Significant depressions is some leukocyte counts were correlated with elevated Pu carcass burdens. In Fig. 2, relative lymphocyte counts were plotted against Pu carcass burdens of D. mtcrops and a least squares fit for the power curve plotted. Relative lymphocyte counts were negatively correlated (P<.01) to Pu carcass burdens. In Fig. 3, in a similar manner, lymphocytes were negatively correlated (P<.01) with Pu carcass burdens in P, longimembris. In Fig. 4, leukocyte counts were negatively correlated (P<.01) with Pu carcass burdens in D. merrtam. Although these results are preliminary, and based on small sample sizes, levels of Pu in carcasses of some rodent species in Area 11, NTS, appear to be related to depressed leukocyte counts on a statistical basis. There is no evidence at this time that these depressions are of a deleterious nature. Additional data from examination of animals with high Pu body burdens is needed. animals. We plan to evaluate blood cell formation in the bone marrow of these By comparing blood cell counts in bone marrow with peripheral blood cell counts, one can determine if depressed peripheral counts are caused by a block in the synthesis of certain cells or a reduction in the number of circu- lating cells. FUTURE PLANS In addition to proposed initial investigation of nuclear event sites and surveillance of safety shot areas, we recommend continued and concentrated study in one safety shot area (Area 11) with the following specific objectives: 1. 2. Census, collection, and radioanalysis of small vertebrates with emphasis on the higher activity strata. Study and analysis of trophic relationships including analysis of Pu and Am in major food sources of trophic categories. 210