WASTES IN RELATION TO AGRICULTURE AND FORESTRY 



19 



a long half-life of 30 years and may collect in 

 muscle tissue. Cesium-137 is bound very tightly by 

 clay particles in soil, which lowers its probability 

 of entering into plants providing food and feed 

 for livestock. 



Phosphate rock used for making phosphatic fer- 

 tilizers sometimes contains traces of uranium-238. 

 Although uranium is not readily absorbed by 

 plants, radioactive decay of uranium-238 gives, 

 among other products, radium-226, radon-222, 

 lead-210, and polonium-210. These elements may be 

 absorbed by plants, or settle as dust onto plant tis- 

 sue. At present, radioactivity from phosphatic 

 fertilizers is not a significant threat, but it may 

 bear watching. 



Tobacco leaves are reported to contain the pecu- 

 liar capacity to accumulate polonium-210 at an ap- 

 preciable level. This level varies with location, 

 culture, type of tobacco, and curing methods. Polo- 

 nium-210 volatilizes at the temperature of tobacco 

 combustion, and may be inhaled into the lungs by 

 smokers. Thus, it has been suspected of being one 

 of the factors causing lung cancer that is asso- 

 ciated with smoking. This potential effect of polo- 

 nium-210 in tobacco is still a debated question. 

 Many scientists consider its level to be too low in 

 tobacco to constitute a hazard to smokers. 



Radioactive contaminants in farm products may 

 cause economic losses to farmers. During the spring 

 of 1966, milk was confiscated on a dairy in Nevada 

 because of an unduly high level of iodine-131 in 

 the area as a result of accidental venting during 

 and following an underground weapons test. 

 Dairymen in central Minnesota considered using 

 stored feed instead of pastures during the summer 

 of 1962, when worldwide fallout from nuclear test- 

 ing reached its highest level. The estimated direct 

 cost of this action in one small area would have 

 been $9,000 a day. 



Knowledge of the behavior of fallout in soils is 

 adequate to permit a rough prediction of amounts 

 of fallout radionuclides that will bo taken up by 

 plants and to recommend remedial measure?. 

 Keeping plant uptake at a safe level will be ex- 

 pensive. Recent studies indicate that the fallout 

 must be physically separated from plant root-. 

 Even for shallow-rooted crops, burying contami- 

 nated surface soil 25 inches deep did not prevent 

 nificant amounts of uptake by the plants. A 

 physical or chemical barrier was required to be 



placed between the roots and the radioactive con- 

 taminants. However, for plants that are directly 

 contaminated with fallout, factors affecting the 

 residence time of particles on plant surfaces are 

 inadequately known. This seriously hampers pre- 

 diction of levels of forage and milk contamination 

 during periods with moderate-to-heavy fallout. 



The adverse effects of radioactive contaminants 

 on the agricultural economy at the present time are 

 small. But if the world should resort to use of 

 nuclear weapons to settle international disputes, 

 the degree of radioactive contamination of our 

 soils, water, crops, and livestock that could take 

 place staggers the imagination. Adequate prepara- 

 tions for civil defense require that all possible 

 techniques for counteracting the adverse effects of 

 nuclear fallout on agriculture be developed. 



Chemical Air Pollutants 



People like clean air. But public concern over 

 polluted air is not new. During the reign of Ed- 

 ward II (1307-27), England put a man to the 

 torture ostensibly for filling the air with a "pesti- 

 lential odor" from the burning of sulphurous "sea" 

 coal. In 1661, John Evelyn, one of the founders of 

 the Royal Society, published the first really sci- 

 entific paper on sources, effects, and problems in 

 control of air pollution in London. The problem 

 has snowballed. Technical advancement which 

 abets air pollution outruns that which abates it. 



As shown by the city of Pittsburgh, good prog- 

 ress can be made in stopping the emission of 

 appalling levels of industrial smoke. Yet. smoke 

 along with carbon monoxide, sulfur oxides, hydro- 

 carbons, nitrogen oxides, and other s md 

 vapors emanating from municipal and industrial 

 activity continues to increasingly burden our at- 

 mosphere. Some of these gases react in sunlight to 

 produce still other toxic consl ituents such as oz 

 and peroxyacetylnitrate. Agriculture and forestry 

 are ad\ ersely affected. 



Internal combustion engines used in transporta- 

 tion in the United States pour out 75 million I 

 a year of carbon monoxide, hydrocarbons, nitroj 

 oxides, and lead compounds into the air. 



Central-station generation of electricity belches 

 L6 million tons of air pollutants a year, largely 

 made up of sulfur oxides. 



Industry contributes about 23 million tons of air 

 pollutants per year that involve a whole array of 



