MISCELLANEOUS PUBLICATION NO. 10 65, U.S. DEPARTMENT OF AGRICULTURE 



Radioactive Substances 



Radioactive substances, which are possible con- 

 taminants of air, water, and soil, may be pro- 

 duced by several sources. Radioactive wastes re- 

 sulting from mining and refining radioactive 

 minerals such as uranium and thorium may wash 

 into streams. There may be accidental or unau- 

 thorized releases of radioactive isotopes from 

 power reactors or from research laboratories. 

 There is atmospheric fallout from testing nuclear 

 weapons. This has diminished with the existence 

 of the test ban treaty involving the United States, 

 the U.S.S.R., and Great Britain. Unfortunately, 

 all nations having nuclear capability are not mem- 

 bers of this treaty and therefore do not adhere to 

 the ban. Potential for radioactive contamination 

 under nuclear war staggers the imagination. 



Agriculture and forestry contribute but very 

 little to either actual or potential contamination 

 from radioactivity — some phosphate rocks used 

 for fertilizer production contain very low levels 

 of radioactive uranium and thorium. Agriculture 

 has experienced minor adverse effects from this 

 source of contamination. During the spring of 

 1966, milk was confiscated in Nevada because of 

 an unduly high level of iodine-131 in the area as 

 a result of accidental venting during and follow- 

 ing an underground weapons test. Potential dam- 

 age to agriculture from radioactive fallout could 

 be serious under unrestricted testing of nuclear 

 weapons. Under nuclear warfare, the situation 

 would be catastrophic. 



Much information has been attained through 

 research on the behavior of radionuclides in soils, 

 plants, and animals. Attention was especially fo- 

 cused on the behavior of strontium-90. This iso- 

 tope justifies serious concern because of its rela- 

 tively long half-life and its chemical behavior so 

 analogous to that of calcium in soils, plants, bones, 

 and milk. 



Engineering research has designed equipment 

 to decontaminate soil that has been surface-coated 

 with radioactive fallout. One procedure involves 

 skimming off the contaminated surface, and an- 

 other involves burying the surface by plowing 

 deeply — 2 feet — and adding a chemical root in- 

 hibitor to the buried layer. 



There is need of much better information on the 

 duration and effects of retained fallout particles 



on plants to improve validity of prediction of radi- 

 ation doses to plants and animals. There must be 

 much better techniques in terms of effectiveness, 

 cost, and rapidity of operation for decontami- 

 nating forage, food plants, and soils. Research 

 should ascertain the possibilities for specific ge- 

 netic lines of feed and food plants that have the 

 physiological capability to exclude radioactive 

 elements. 



Agriculture should support a relatively modest 

 program of research on measures counteractive 

 to radioactive wastes. If ever the unfortunate time 

 arrives when such information is urgently needed, 

 it will be too late to start. 



Chemical Air Pollutants 



Airborne chemical contaminants include such 

 substances as sulfur dioxide, fluorine, carbon mo- 

 noxide, ozone, nitrogen oxides, peroxyacetylni- 

 trate, sundry hydrocarbons, and just plain smoke. 

 Thirty million tons of sulfur dioxide are spewed 

 into the atmosphere over the United States every 

 year from smelters, use of fossil fuels for heat and 

 power, and burning refuse. Seventy-five million 

 tons of the other chemical contaminants are emit- 

 ted into our atmosphere by exhausts from internal 

 combustion engines, industrial mills, refuse burn- 

 ing, home heating, forest fires, and agricultural 

 burning. 



Crop plants, ornamentals, and trees are sub- 

 jected to chronic injury in and near every metro- 

 politan area. Livestock have been afflicted with 

 fluorosis near certain industries, such as steel, alu- 

 minum, and phosphate mills. In southern Califor- 

 nia acute injury is widespread. About 14,000 square 

 miles in that State are now afflicted with airborne 

 toxicants (82). 1 Losses to agriculture and forestry 

 in the United States because of the flood of these 

 noxious chemicals into the atmosphere are esti- 

 mated as exceeding $500 million annually (88, p. 

 V-137). 



Agricultural endeavor makes a small local con- 

 tribution to chemical air pollution in the form of 

 hydrocarbons and smoke emitted from burning 

 crop residues in fields. Major forest fires produce 

 tremendous quantities of smoke. Fires in our for- 

 ests produce upwards of 500,000 tons of hydro- 



1 Italic numbers in parentheses refer to Literature 

 Cited, p. 108. 



