Bone cancer from radium: canine dose response explains data for mice and humans.

Analysis of lifetime studies of 243 beagles with skeletal burdens of radium-226 shows that the distribution of bone cancers clusters about a linear function of the logarithms of radiation dose rate to the skeleton and time from exposure until death. Similar relations displaced by species-dependent response ratios also provide satisfactory descriptions of the reported data on deaths from primary bone cancers in people and mice exposed to radium-226. The median cumulative doses (or times) leading to death from bone tumors are 2.9 times larger for dogs than for mice and 3.6 times larger for people than for dogs. These response ratios are well correlated with the normal life expectancies. The cumulative radiation dose required to give significant risk of bone cancer is found to be much less at lower dose rates than at higher rates, but the time required for the tumors to be manifested is longer. At low dose rates, this time exceeds the normal life-span and appears as a practical threshold, which for bone cancer is estimated to occur at an average cumulative radiation dose to the skeleton of about 50 to 110 rads for the three species.

Physical factors affecting the mutagenicity of fly ash from a coal-fired power plant.

The two finest, most respirable coal fly ash fractions collected from the smokestack of a power plant were more mutagenic than two coarser fractions. Mutagenicity was evaluated in the histidine-requiring bacterial strains TA 1538, TA 98, and TA 100 of Salmonella typhimurium. Ash samples collected from the hoppers of an electrostatic precipitator in the plant were not mutagenic. The mutagens in coal fly ash were resistant to x-ray or ultraviolet irradiation, possibly as a result of stabilization by fly ash surfaces. All mutagenic activity is lost with heating to 350 degrees C.

Safety of airway gene transfer with Ad2/CFTR2: aerosol administration in the nonhuman primate.

In this study, the safety and efficacy of aerosol delivery to non-human primates of an adenoviral vector encoding the cystic fibrosis transmembrane conductance regulator protein (CFTR) were evaluated. The technique of concurrent flow spirometry was used to determine the deposited dose of Ad2/CFTR-2, which ranged from 3 to 8 x 10(10) I.U. Transgene DNA was detected by the polymerase chain reaction (PCR) in lung tissue from all treated animals, and human CFTR mRNA was detected on days 3, 7, and 21 post-exposure. The treatment was well tolerated, with no evidence of respiratory distress. Histologic changes in the lungs from Ad2/CFTR-2-treated animals were mild and, overall, indistinguishable from animals exposed to aerosolized vehicle. One vector-treated animal demonstrated an increase in lavage lymphocyte numbers 3 days after treatment and another had an abnormal chest radiograph 14 days after treatment. A third vector-treated animal had histologic evidence of a bronchointerstitial pneumonia 7 days after aerosol treatment that resolved by day 21. This study demonstrated that Ad2/CFTR-2 can effectively be delivered to the lungs of nonhuman primates and result in minimal adverse effects.

Factors influencing the deposition of inhaled particles.

Because the initial deposition pattern of inhaled particles of various toxic agents determines their future clearance and insult to tissue, respiratory tract deposition is important in assessing the potential toxicity of inhaled aerosols. Factors influencing the deposition of inhaled particles can be classified into three main areas: (1) the physics of aerosols, (2) the anatomy of the respiratory tract and (3) the airflow patterns in the lung airways. In the physics of aerosols, the forces acting on a particle and its physical and chemical properties, such as particle size or size distribution, density, shape, hygroscopic or hydrophobic character, and chemical reactions of the particle will affect the deposition. With respect to the anatomy of the respiratory tract, important parameters are the diameters, the lengths, and the branching angles of airway segments, which determine the deposition. Physiological factors include airflow and breathing patterns, which influence particle deposition. Various lung models used in predicting particle deposition are reviewed and discussed. The air-way structures of various animal species are compared, showing the unique structure of the human lung compared to the animal species under study. Regional deposition data in man and dog are reviewed. Recent deposition data for small rodents are presented, showing regional difference in deposition with the right apical lobe having the highest relative deposition.

Skeletal uptake and lifetime retention of 90Sr and 226Ra in beagles.

Skeletal uptake and retention of graded doses of ingested or injected 90Sr and injected 226Ra have been studied in 863 beagles; measurements of skeletal burden were made up to a maximum lifetime of 18.5 years. Doses ranged from 0 in 162 controls to levels that markedly reduced life span. Skeletal uptake of the administered doses averaged 2 to 2.3% for 90Sr fed to 388 beagles from midgestation to age 540 days, 33 to 35% for 45 dogs that were given single intravenous injections of 90Sr at age 540 days, and 37 to 45% for 226Ra given in eight fortnightly intravenous injections to 253 dogs from age 435 to 540 days. Skeletal retention was evaluated from the time when uptake ended until death, which occurred, on the average, at 14 to 14.5 years for the lower levels. Simple two-parameter power functions of the form SB(t) = at-b, with SB the skeletal burden, t the time after beginning of intake, and a and b fitted parameters, but corrected for radioactive decay, were used to describe the whole-skeleton retention of deposited 90Sr or 226Ra, as well as in 17 skeletal subgroups. The negative logarithmic slope, b, of these power functions for whole skeleton was about the same for both 90Sr and 226Ra, with an average value of 0.30 +/- 0.05 SD, indicating a common clearance mechanism. The lifetime average cumulative absorbed dose to irradiated skeleton varied from 0.38 to 107 Gy for beta rays in the 90Sr studies and from 0.94 to 167 Gy for alpha particles in the 226Ra studies. Daily dose rates to the skeleton for singly injected 90Sr fell rapidly after injection and declined to about 10% of the peak values late in life. Rates declined more slowly to 40-50% of peak values in other treatment groups. The time-weighted average dose rate for fed 90Sr and injected 226Ra was a robust measure that declined only about 20% late in life compared to peak values. The lifetime average dose rate varied from 0.08 to 133 mGy day-1 for the 90Sr studies and from 0.21 to 162 mGy day-1 for the 226Ra studies. Lifetime doses to mandible and cervical vertebrae for the intermediate dose levels of fed 90Sr were calculated to be about 40% higher than the skeletal average.

Impaired cell proliferation in mice that persists across at least two generations after paternal irradiation.

Irradiation of male F0 mice 6 to 7 weeks prior to mating causes significant changes in the proliferation of F1 and F2 embryonic cells. These changes are revealed as a competitive cell proliferation disadvantage in chimera assays when the affected embryo is paired with a normal embryo in an aggregation chimera. This effect has been observed previously to be transmitted to F1 embryos for absorbed doses from 0.01 to 1.0 Gy; 0.01 Gy is about 100-fold lower than detectable using conventional germline mutation assays. However, until now there has been no reported cross-generation heritability. We now report that this competitive cell proliferation disadvantage persists without degradation in the F2 generation of embryos when F0 males received 1.0 Gy from gamma irradiation 6 and 7 weeks prior to conception of F1 males.

Embryonic effects transmitted by male mice irradiated with 512 MeV/u 56Fe nuclei.

High-energy, high-charge nuclei may contribute substantially to the yearly equivalent dose in space flight from galactic cosmic radiation (GCR) at solar minimum. The largest single heavy-ion component is 56Fe. We used the mouse embryo chimera assay to test 512 MeV/u 56Fe nuclei for effects on the rate of proliferation of embryonic cells transmitted by sperm from irradiated mice. Male CD1 mice were acutely irradiated with 0.01, 0.05 or 0.1 Gy (LET, 184 keV/micron; fluence, 3.5 x 10(4)-3.3 x 10(5) nuclei/cm2; average dose rate, 0.02 Gy/min) at the Lawrence Berkeley Laboratory BEVATRON/BEVALAC Facility in Berkeley, CA. Irradiated males were bred weekly for 7 weeks to nonirradiated females and their four-cell embryos were paired with control embryos, forming aggregation chimeras. After 30-35 h of culture, chimeras were dissociated to obtain "proliferation ratios" (number of cells contributed by the embryo from the irradiated male/total number of cells in the chimera). Significant dose-dependent decreases in proliferation ratios were obtained across all three dose groups for postirradiation week 2 (P < 0.05 to P < 0.003). The 0.01- and 0.05-Gy dose groups also produced significant decreases in proliferation ratios for postirradiation week 1 (P < 0.05 to P < 0.01) and the 0.05-Gy dose group produced significant decreases in proliferation ratios for postirradiation week 6 (P < 0.05). Postirradiation weeks 1, 2 and 6 correspond to irradiation of epididymal sperm, testicular spermatids and spermatogonia, respectively. We calculate that only about 5% of sperm in the 0.1-Gy, 2.5% in the 0.05-Gy and 0.5% in the 0.01-Gy dose groups sustained direct hits from 56Fe nuclei. However, up to 47% of sperm during postirradiation weeks 1 and 2 transmitted proliferation ratios that were at or below one standard deviation from control mean proliferation ratios. Morphometry on sectioned testes showed a significant log-linear dose response for cell killing of type B spermatogonia, which are the most radiosensitive stage of spermatogenesis and which would have been tested as mature sperm during postirradiation week 6. We conclude that amplification from secondary radiation produced in the mouse and/or from diffusible chemical products arising from hit sperm and adjacent cells contributed to the high incidence of transmitted effects on proliferation of embryonic cells.

Paternally inherited effects of gamma radiation on mouse preimplantation development detected by the chimera assay.

It has previously been shown that type B spermatogonia in male mice treated with 0.05 Gy of X rays undergo an alteration expressed by progeny embryos as a cellular proliferation disadvantage in a chimera assay. We wished to obtain information on the assay's detection limit to ionizing radiation and on the radiosensitive target in male germ cells. Male mice were briefly irradiated with 137Cs gamma rays at nominal absorbed doses of 0.0, 0.0015, 0.005, 0.010, or 0.05 Gy and then mated for the next 8 weeks to untreated females. Four-cell embryos from treated males (experimental embryos) were paired with FITC-labeled embryos from untreated males (control embryos) to form aggregation chimeras. The chimeras were cultured for 30-40 h and examined under phase-contrast and UV illumination for the number of unlabeled cells (from the experimental embryo) and total chimera cell number, which were then expressed as "proliferation ratios" (No. unlabeled cells/total chimera cell No.). Significant decreases in proliferation ratios were observed at postirradiation weeks 4, 6, and 7 for the 0.01-Gy dose group and at weeks 5-6 for the 0.05-Gy dose group. In addition, significantly lower ratios were observed with early and mid four-cell embryos, but not with late four-cell embryos. These results suggest that mouse male germ cells express a radiosensitive target(s) whose detection limit by the assay lies at an absorbed dose between 0.005 and 0.010 Gy for brief gamma irradiation and whose effect on embryonic cell proliferation might decay by the second cleavage.

Bone sarcoma characteristics and distribution in beagles fed strontium-90.

A total of 66 primary bone sarcomas were diagnosed in 47 beagles; 43 of these dogs were part of the 403 beagles fed 90Sr and 4 were part of the 162 controls. Multiple primary bone sarcomas were found in 15 of the 47 beagles (32%). The incidence of multiple primary bone sarcoma was restricted to the two highest dose groups, except for a single control dog which developed two bone sarcomas. A threshold-like radiation dose response was observed; no sarcomas were observed in the lowest three dose groups, but the number of primary bone sarcomas increased rapidly in the higher dose groups. Of the 66 primary sarcomas, 49 were osteosarcomas (74%). As the dose increased, the proportion of osteosarcomas increased sharply, 4/10 (40%), 26/29 (90%), and 16/18 (89%), in the three highest dose groups. Thirteen of the bone sarcomas of other types occurred in males, and 4 in females, whereas 21 osteosarcomas occurred in males, and 28 in females. The ratio of bone sarcomas of the appendicular skeleton to those in the axial skeleton was 40:26, with osteosarcomas occurring more often in the appendicular than the axial skeleton (32:17), whereas nonosteogenic tumors showed no predilection (8:9). A statistical study of the distribution of bone sarcomas among 16 separate bone groups showed a correlation only with the distribution of cancellous bone volume-to-surface ratio and not with either skeletal mass distribution or dose distribution. The highest occurrence of sarcomas was in the humeri, femora, and mandible, and no occurrence in the coccygeal vertebrae, paws, or sternum. It is postulated that the distribution of bone sarcomas reflects a critical combination of the osteosarcoma precursor cell population, their cell division rate, and the radiation dose absorbed by these cells.

Bone sarcoma characteristics and distribution in beagles injected with radium-226.

A total of 155 primary bone sarcomas were found in 131 of the 246 beagles injected with 226Ra and 5 primary bone sarcomas were found in 4 of the 158 unexposed controls. Of these 155 bone sarcomas, 146 (94%) were osteosarcomas and 9 were non-osteosarcomas. An additional 31 primary bone sarcomas (28 osteosarcomas) developed in 44 dogs terminated from the main study because of limb amputation for bone sarcoma. Non-osteosarcomas predominated in both the controls and the second lowest of six logarithmically increasing dose levels (there were no bone sarcomas in the lowest dose group). Osteosarcomas predominated at the higher dose levels, and incidence tended to increase as dose increased. The 146 osteosarcomas were distributed quite evenly between males and females (72:74). Of the 9 non-osteosarcomas, 6 occurred in males and 3 in females. The ratio of bone sarcomas of the appendicular skeleton to those in the axial skeleton was 110:45, with osteosarcomas occurring more often in the appendicular skeleton (108:38). Cases of multiple primary bone sarcomas in dogs injected with 226Ra were found only in the four highest dose groups. Amputations were performed on 44 of the 96 dogs (94 injected and 2 unexposed) that developed appendicular bone sarcomas. A statistical study of the distribution of bone sarcomas among 16 separate bone groups showed a statistically significant correlation to cancellous skeletal surface, but the variability among bone groups was too large for this relationship to be of real predictive value. It is postulated that the distribution of bone sarcomas reflects primarily the relative cell division rates in the bone groups and secondarily the radiation dose distribution, with the highest occurrence of bone sarcoma in the humeri, pelvis, femora and tibiae/fibular tarsal, and no occurrence in the coccygeal vertebrae, sternum, forepaws or hindpaws.

Interspecies scaling of risk for radiation-induced bone cancer.

The induction of bone cancer in mice, dogs and humans, due to protracted alpha-irradiation from skeletal burdens of radium, was found to be represented by a single dose-rate/time/response function, when time was normalized with respect to species natural life-span. In the absence of other causes of death, the median time to death from bone cancer after 226Ra intake is given by tm* = 790-d*-0.29, based on the dog data, with -d* the time-weighted average absorbed dose rate in cGy/mLSF to skeleton and where time is measured as milli-life-span-fraction. On the basis of life-span scaling of the time dimension, data on cancer induction from studies with laboratory animals can be scaled to estimate human risks in a three-step process involving a three-dimensional analysis. The overall cancer risk distribution is shown to be a mountain-like surface rising from a Euclidean plane formed by the dose rate and survival time co-ordinates. At lower dose rates the time required for cancer induction may exceed the natural life-span yielding a quasi-threshold for cancer risk. For intakes of 226Ra in young adults this quasi-threshold is predicted to occur at a cumulative life-time alpha-radiation dose to the skeleton of about 1 Gy.

Cellular reprogramming in the F3 mouse with paternal F0 radiation history.

PURPOSE: In the mouse, paternal F0 acute irradiation of Type B spermatogonia produces biological effects in offspring, including altered signalling kinase activities and protein levels. It was hypothesized that these effects represented cellular reprogramming that would alter the response of somatic cells in these offspring to an acute ionizing radiation exposure. MATERIALS AND METHODS: Nineteen-day-old third generation (F3) CD1 mice with and without an acute 1.0 Gy paternal F0 radiation history each received an acute dose of 1.0 Gy from attenuated 137C n-rays. Kidney PKC and MAPK activities, and p53 protein levels were evaluated immediately following F3 irradiation. The same endpoints and DNA damage were evaluated in kidney-derived fibroblast primary cell cultures 3 weeks post-irradiation. RESULTS: Kidneys had significantly decreased PKC and MAPK activities and p53 protein levels related to F0 irradiation and increased PKC and MAPK activities following F3 irradiation irrespective of F0 radiation history. Kidney-derived fibroblasts had significant changes or strong trends for all selected endpoints based upon cross-interaction of F0 radiation history with F3 irradiation. Comet assays demonstrated significantly increased DNA damage in fibroblasts related to F0 irradiation and increased DNA damage following F3 irradiation. However, significantly decreased F3 irradiation damage was demonstrated based upon cross-interaction of F0 radiation. CONCLUSIONS: The data suggest that irradiation of paternal F0 Type B spermatogonia resulted in cellular reprogramming causing offspring with this radiation history to have altered responses to acute somatic n-irradiation.

Development of partition coefficients, Vmax and Km values, and allometric relationships.

A knowledge of the methods used to obtain partition coefficients, Vmax, and Km values, and the use of allometric relationships is essential to understanding their role in physiologically based pharmacokinetic (PBPK) models. Vial equilibration methods for obtaining the partition coefficients of volatile and nonvolatile compounds were presented using the results from studies with p-chlorobenzotrifluoride (PCBTF) and isofenphos, respectively. Partition coefficients for volatile and nonvolatile compounds from published studies were included. Several published in vivo inhalation (gas uptake) studies and in vitro enzyme studies were presented to demonstrate several methods for obtaining Vmax and Km values. Allometric equations used in PBPK models for body weight scaling of respiration and cardiac rates between species were presented along with equations for within species body weight scaling of Vmax.

Inherited effects from irradiated mouse immature oocytes detected in aggregation embryo chimeras.

Data obtained using the mouse-preimplantation-embryo-chimera assay are presented that show a transmitted effect following low-dose irradiation of immature oocytes in vivo. Six-week-old female mice were irradiated using 137Cs-gamma-rays (0.05 Gy, 0.15 Gy, and unexposed controls). At 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12 weeks post exposure, the mice were mated and aggregation chimeras made from the 4-cell embryos. Three independent experiments have now been carried out, all showing a significant embryonic cell-proliferation disadvantage of the embryos obtained from the females treated 7 weeks previously, i.e., embryos from oocytes that were immature at the time of radiation exposure. No effect was detected at 1-6 weeks when embryos were obtained from maturing oocytes. Also, the effect was not seen at 8, 9, 10, 11, and 12 weeks post exposure. The implications of these results are discussed in the light of previous studies on mouse oocytes.

Transmitted proliferation disadvantage from mouse oocytes labeled in vivo with [3H]thymidine: radiosensitive target considerations.

This study was conducted to test the hypothesis that a nuclear target is involved in the embryonic cell proliferation disadvantage transmitted by irradiated mouse oocytes and detected by the chimera assay. In this assay, the cells from the irradiated embryo exhibit a competitive cell proliferation disadvantage when they are challenged by direct cell-cell contact with cells from a normal embryo in an aggregation chimera. Here, six pregnant CD-1 mice received a total of 1.85 TBq tritiated thymidine (TdR) delivered by multiple intraperitoneal injections during days 13-15 postconception. Six more pregnant mice were sham-injected to provide control embryos. Sixty randomly selected female progeny were mated at 47 days of age and their 4-cell embryos tested in the chimera assay. The mean proliferation ratio (PR, number of cells from the experimental embryo divided by total cell number of the chimera) for experimental chimeras was 0.45 +/- 0.02 SE (n = 43), which was significantly less than the mean PR of 0.49 +/- 0.01 SE (n = 47; p = 0.02) for control chimeras. This entire experiment was repeated, with similar results. A comparison for TdR confined to the nucleus (i.e., mean beta-ray range is only 0.7 microm) with the relationship for uniform irradiation by 137Cs gamma-rays demonstrates that these two very different modes of dose delivery produce essentially identical PRs. These results in vivo suggest a nuclear DNA target for embryonic cell proliferation disadvantage consistent with our previous findings in vitro.

Radiosensitive target in the early mouse embryo exposed to very low doses of ionizing radiation.

We exposed mouse preimplantation embryos in vitro to either tritiated water (HTO) or tritiated thymidine (TdR) to determine whether the radiosensitive target was nuclear or extranuclear for embryonic cell proliferation disadvantage in the mouse embryo chimera assay. 8-cell embryos were incubated in either HTO or TdR for 2 h and paired with non-irradiated control embryos to form chimeras. Chimeras were cultured for an average of 20.2 h to allow for 2-3 cell cycles and then partially dissociated to obtain the number of progeny cells contributed by the two partner embryos for each chimera. These values were expressed as a "proliferation ratio" (number of cells from the irradiated embryo: total number of cells in the chimera). A ratio significantly less than 0.50 indicates that the experimental embryo expressed an embryonic cell proliferation disadvantage, which is the endpoint of this assay. The activity concentrations of HTO and TdR were adjusted so that both would deliver comparable mean absorbed nuclear doses during the combined initial 2-h irradiation incubation and subsequent 20.2 h chimera incubation periods. Although nuclear doses were comparable under these conditions, the extranuclear dose delivered by the uniformly distributed HTO was about 100 times greater than the extranuclear dose delivered by TdR for each given nuclear dose. Consequently, obtaining mean TdR proliferation ratios < or = mean HTO proliferation ratios would be evidence for a nuclear target while obtaining mean HTO proliferation ratios < mean TdR proliferation ratios would be evidence for an extranuclear target. TdR consistently produced lower mean proliferation ratios over a range of doses from 0.14 Gy to 0.43 Gy. Therefore, we conclude that the radiosensitive target for this endpoint is nuclear.

Mouse immature oocytes irradiated in vivo at 14-days of age and evaluated for transmitted effects using the aggregation embryo chimera assay.

A previous study using the mouse-preimplantation-embryo-chimera assay demonstrated a reproducible transmitted effect (proliferation disadvantage observed in early embryos) from females irradiated as 49-day-old adults using 0.15 Gy of gamma rays and then mated seven weeks later, i.e., embryos were from oocytes that were immature at time of irradiation. Because mouse immature oocytes are known to be much more radiosensitive to cell killing in juveniles than in adults, a follow-on study was performed here using 14-day-old juvenile mice. In contrast to adults, the exposure of juveniles to 0.15 Gy of gamma rays did not result in a detectable transmitted proliferation disadvantage when animals were mated 7 or 12 weeks later. This observation is discussed in light of previous studies on mouse immature oocytes and embryo chimeras.

In vitro fertilization rate of mouse oocytes with spermatozoa from the F1 offspring of males irradiated with 1.0 Gy 137Cs gamma-rays.

Previous studies suggest that the spermatozoa from acutely irradiated male mice exhibit a reduced fertilization rate in vitro with the maximum decrease occurring for spermatozoa produced 6 weeks after irradiation (Y. Matsuda et al., Mutation Res. 142 (1985) 59-63). We have found that spermatozoa from unirradiated F1 males conceived 6 weeks after paternal F0 irradiation also exhibit a significantly reduced fertilization rate in vitro. After acute 137Cs gamma-irradiation yielding an absorbed dose of 1.0 Gy, adult CD1 F0 male mice were mated at weekly intervals with unirradiated female CD1 mice. Unirradiated adult males from F1 litters conceived 5 and 6 weeks after paternal F0 irradiation were allowed to mature. Their epididymal spermatozoa were evaluated for in vitro fertilization rates using oocytes from unirradiated 8-12-week-old CD1 females. The mean fertilization rate for spermatozoa from F1 males conceived 5 weeks after paternal F0 irradiation (80.74 +/- 15.74 SD %, n = 5) did not differ significantly from the control fertilization rate (89.40 +/- 10.94 SD %, n = 8). However, the fertilization rate for spermatozoa from F1 males conceived 6 weeks after paternal F0 irradiation (56.14 +/- 21.93 SD %, n = 5) was significantly less than the fertilization rate for control spermatozoa (p < 0.006) or for that of the F1 males conceived 5 weeks after paternal F0 irradiation (p < 0.04). These data suggest that spermatozoa obtained 6 weeks after paternal F0 irradiation can transmit a decrease in fertilization rate to the F1 generation males as well as exhibit decreased fertilization rate themselves when tested directly in vitro.

Time and dose-response study of the effects of vanadate in rats: changes in blood cells, serum enzymes, protein, cholesterol, glucose, calcium, and inorganic phosphate.

A daily dosage of vanadate (0.9 mgV/kg) injected subcutaneously for 16 days to adult rats produced significant changes in blood cells and serum elements. The hematological changes included an increase in white blood cell count at two days after the last injection. At five days, red blood cell count (RBC), hemoglobin, and packed cell volume (PCV) were low. At 12 days, there were reductions in RBC, hemoglobin, PCV, and lymphocyte counts and an increase in polymorphonuclear cell (PMN) counts. At 25 days, RBC, hemoglobin, and PCV were still low. At 40 days, the only change was a reduction in RBC. Changes in the serum at two days posttreatment were a reduction in lactic dehydrogenase activity (LDH), alkaline phosphatase activity (AP), calcium, albumin, and total protein and an increase in cholesterol. At five days, glutamic-oxalacetic transaminase (GOT), lactic dehydrogenase (LDH), inorganic phosphate, and total protein were low and calcium was high. At 12 days, GOT, glutamic-pyruvic transaminase (GPT), and LDH were reduced, and the levels of calcium and cholesterol were elevated. At 25 days, there was a reduction in GPT and LDH and an increase in glucose, calcium, and albumin. At 40 days, the levels of GOT, LDH, AP, and inorganic phosphate were still low. Vanadate at lower dosage levels (0.3-0.6 mg V/kg per day for 16 days) also produced significant changes in blood cellular and serum elements but at lesser degrees of severity. These findings show that the exposure of rats repeatedly to low levels of Vanadate caused anemia, elevation in blood cholesterol levels, and a reduction in serum enzymes activities.