FACTORS INFLUENCING THE BIOLOGICAL FATE AND PERSISTENCE OF RADIOACTIVE FALL- OUT

Technical Report · Thu Jan 01 04:00:00 EST 1959

OSTI ID:4154255

Lindberg, R G; Romney, E M; Olafson, J H; Larson, K H

A study was made of the biological fate and persistence of radioactive fall-out relative to the physical characteristics of fall-out contamination, which varied with distance from Ground Zero (GZ). Special attention was given to the type of fall-out contamination on forage plants as representative of the internal emitters available to animals grazing in fall-out-contanninated areas. Data indicated that the activity associated with the plant samples collected from areas within the various fall-out patterns was predominantly the result of external contamination by radioactive fall-out particles less than 44 mu in diameter. The degree of plant contamination was a function of the mechanical distribution of the particles less than 44 mu in size within a distance of 100 miles from GZ, which was in turn influenced by such conditions of weapon detonation as tower height and meteorology. The radioactive fall-out material on plant foliage was persistent, as evidenced by the activity remaining on leaves after washing in Versene and 0.1N HCl solutions and after mechanical shaking brought about by severe windstorms. An average of 21.6 per cent of the contamination on washed leaves was soluble in 0.1N HCl, which suggests that a sirailar percentage of the fall-out material ingested by grazing animals would go into solution in the digestive tract. The tissue burdens of mixed fission products in animals sampled from fall-out-contaminated environments tended to decrease with distance from GZ in a manner similar to the degree of plant contamination. Rowever, the beta activity per unit weight of femur tended to remain fairly constant io a distance of 140 miles from GZ. The thyroid showed a greater tissue burden of radioiodine at 60 miles than at either 12 or 140 miles from GZ. The relative decrease of total beta radiation in tissues of native animals serially sampled from the same fall-outcontaminated environment in most cases did not markedly deviate from the theoretical beta radioactive decay rate of mixed fission products (t/sup -1.2/). The beta activity per unit weight of femur, however, gradually increased until 3 days postshot and then decreased. The thyroid activity continued to rise throughout the 15-day sampling period. I/ sup 133/ is believed to contribute largely to the thyroid burden during the first 3 days following the detonation. In all cases, animals with high activity in the gastrointestinal contents also had relatively high tissue burdens, whereas animals with low activity in the gastrointestinal tract had low tissue burdens. This suggested that ingestion was the principal source of fission products accumulated in tissues. The data further indicated that, in a population of animals grazing in a fall-out-contaminated environment, a rapid equilibrium between the absorbed activity and that passing through the gut may have been established within the first 2 days following fall-out. Data suggested that inhalation was a negligible path of uptake of fission products derived from weapons testing during, and for 12 hr immediately following, fall-out contamination. The accumulation of fission products by grazing animals was related to particle size, and, because the plant acted as a selective collector for very small fall-out particles, the intake of radioactive bcmb debris by animals during grazing tended to be similar over a great distance and appeared to be independent of total residual fall-out. The amount of any specific fission product present in the envirorment is dependent in part upon the physical and chemical behavior of its parent during fall-out particle formation. Therefore, the amount of any specific isotope at any particular location within the fall-out pattern will be highly variable, and the occurrence of areas in which the biological accumulation of that isotope is high may be anticipated. (auth)

• Research Organization: California. Univ., Los Angeles. School of Medicine
• NSA Number: NSA-14-023892
• OSTI ID: 4154255
• Report Number(s): WT-1177
• Country of Publication: United States
• Language: English

Related Subjects

ANIMALS
ATMOSPHERE
BETA DECAY
BETA DETECTION
BIOLOGY
BIOLOGY AND MEDICINE
BONES
CONTAMINATION
DECAY
DISTRIBUTION
EDTA
EMISSION
ENVIRONMENT
FALLOUT
FISSION PRODUCTS
FOOD
HYDROCHLORIC ACID
INTESTINE
IODINE 131
LEVELS
LUNGS
METABOLISM
METEOROLOGY
NUCLEAR EXPLOSIONS
PARTICLES
PERFORMANCE
PLANT CELLS
PLANTS
QUANTITATIVE ANALYSIS
RADIOACTIVITY
SAMPLING
SOILS
SOLUBILITY
SOLVENT EXTRACTION
STOMACH
THYROID
TISSUES
VARIATIONS
VOLUME