February 1949
INDUSTRIAL AND ENGINEERING CHEMISTRY
and above where radiative level C is encountered more frequently. When massive shielding is necessary, as in a laboratory where chemical operations are performed routinely on gamma-activity, heavy floor loading must be provided. The frequency with which a given operation is met is important in determining when compromise measures become inadequate. Thus an ideal situation could be derived for handling the radiative problem a t level D from two extreme situations: a completely versatile, automatic, pushbutton, maintenance-free laboratory shielded on all sides, or bare space in which ideal facilities for each experiment could be built. Both are economically impractical, unnecessary, and a t variance with the requirement that there should be the minimum interference to the conduct of work. Therefore, the practical laboratory should have some features based upon both philosophies, and many facilities will be a mixture of each. Many specific examples of these points are presented in other papers of this symposium. SUMMARY
The critical factors with respect to contamination and radiation which must be established and reconciled for each laboratory facility are, for contamination, (1) the quantity, a, for different phases of laboratory operation based on the indicator most sensitive to contamination interference, (2) the upper limit for total activity and anticipated material losses based on the specific techniques being used, and the contamination potential based on both normal operation and the total sample, (3) the proportion of space needed for each activity level, and (4)the cost in time, money, and interference to the program to provide adr-
231
quate protection in the event of a mishap. All work must be planned so that both the probability risk and the consequence of a wrong guess are acceptable. The critical factors that must be established from the standpoint of radiation protection are: upper limits for the time and intensity of exposure encountered at each phase of the operation; these in turn set an upper limit to the total activity permissible with a given type and energy of radiation. If actual numbers cannot be applied to each of these limits, one should make appropriate exploratory measurements. On the basis of these data one should then examine the procedures and techniques, making alterations where indicated. The most hazardous aspects of every part in the procedure or phase of operation should be found and these points monitored with appropriate radiation-detecting devices. Particular attention should be paid to the exposure received by the hands, because they usually approach most closely to the radiation source. One concludes that in the operatioil of radiochemical Tacilities, two degrees of freedom, manipulative and procedural, are a t least partially lost, owing to the contamination and radiation parameters. Below 1 me., this need reflect only minor changes in existing laboratory design, but major changes in exist'ing laboratory practice. Above 1 me., one must specify more rigidly not only what kind and how much activity will be met, but t'he methods by which the work will be conducted. The laboratory may then be designed to meet these limits, leaving for special consideration problems that fall outside the specifications. RECEIVED August 28, 1948. Based on work performed under Contract W35-058-eng-71 for the Atomic Energy Project a t O a k Ridge National Laboratory.
Radiobiochemical laboratories WILLIAM P. NORRIS, Argonne National Laboratory, Chicago, I l l .
R adiobiocheniical laboratories, with few exceptions, may be considered, because of the nature of the work, to be concerned with levels of radioactivity not exceeding 10 mc. On a functional basis the operations involved may he considered to fall into five general categories: preparation of active materials in a form suitable for biological investigation, administration of active materials, care and housing of biological specimens containing radioactivity, preparation of samples for radioactivity measurements, and measurement of radioactivity. Ideally these operations should he carried out in separate rooms. While precautions are required to handle as much as 10 mc. of
radioactivity, protection against external exposure from sources of this magnitude may be achieved without a great expenditure of effort in most cases. A much more difficult problem is that of avoiding radioactive contamination, especially in working with animals where radioactive metabolic by-products are being eliminated. It seems advisable, therefore, to consider the installation ofwell-ventilatedisolation areas for specimens which are eliminating appreciable quantities of radioactivity. Other considerations include general laboratory ventilation, special hood facilities, surfaces which can be readily decontaminated, and construction to eliminate areas difficult to keep clean.
T
active materials in a form suitable for biological investigations, (2) administration of active materials, (3) care and housing of biological specimens containing radioactivity, (4) chemical manipulations, isolation of compounds, and preparation of samples for radioactivity measurements, and (5) measurements of radioactivity. Ideally these operations should be conducted in separate rooms equipped to require no exchange of equipment. This is desirable in order to produce reasonably clear-cut definitions of the possibilities of radioactive contamination in any single area and t o minimize the chance of cross contamination.
HE problems encountered in biochemical investigations provide opportunities for the use of a wide variety of radioactive elements with an equally wide variety of biological materials. Except in cases where large amounts of the radioactive isotope are used purposely to produce radiation effects, the quantity of radioactivity administered to the organism is ordinarily kept a t a n absolute minimum compatible with analytical sensitivity and accuracy, to ensure the least possible opportunity for the production of metabolic abnormalities. Therefore, it should be possible to carry out the majority of biological investigations, even with animals as large as dogs, without requiring more than 10 to 20 me. of radioactivity distributed throughout the experiment. Biochemical laboratories thus tend to fall within the range of semihot to low level installations, although these terms are fairly ambiguous. On a functional basis the operations involved may be oonsidered to fall into five general categories: (1) the preparation of
GENERAL CONSTRUCTION
Any area exposed to radioactive contamination should be constructed of materials which are nonporous and readily decontaminated. Of the materials considered, glass and stainless
232
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
steel seem to be the best; stainless steel is generally superior because of its durability and ease of fabrication. Asphalt tile or rubber tile has been favored as floor covering. Experience indicates that these materials tend to flow and seal the cracks between the tile and that removal and replacement of contaminated tile are not prohibitive. Asphalt tile may be laid on layers of tar and paper. Care should be taken to keep all suifaces free of pipes and other rough objects to facilitate cleaning and to eliminate all remote areas difficult to clean. PREPARATIOX O F MATERIALS
The preparation of active materials for administration to biological specimens may involve either organic chemical syntheS I S or the preparation of inorganic compounds. In either case the task may require withdrawals from stock solutions containing considerably more than the amount of radioactivity required for the experiment. These operations should be done in rooms especially designed for the work. Considerations of the problems involved are presented by Garden ( 1 ) and Rice (x?). ADMINISTRATION OF MATERIALS
The problems unique to biological experimentation arise in the administration of radioactive materials and in the care and housing of the radioactive specimens after injection. In cases where one R ishes to administer linomn quantities of radioactivity directly into the organism-for example, the intravenous injection of solutions-the possibilities for contamination are considerable. For this work one should be providcd with a room bufficiently large to accommodate the expel iinenters, the animals, and the radioactive solution. This room, in addition t o being provided with smooth, decontaininable surfaces, should be equipped with a modified stainless steel hood to be used for containing both the radioactive solution and the animal to he injected. This hood should be dejigned to provide simultaneous access on a t least tv,o sides and it should allow the workers to maintain glass surfaces betxyeen the operations and the exposed portions of the body, particularly the face, a t all times. This room for administration of radioactive materials should be as close as possible to the area which will be used to house the radioactive animals. CARE AND HOUSING OF SPECIMESS
To some extent the treatment of biological material after injection will depend on the metabolic behavior of the radioactive element or compound. Studie. \+ith isotopic tracers show, in general, that most metabolic reactions proceed with great speed and that excretion of the isotope frequently bcgins almost immediately. I n some cases, as with radiocarbon, the radioacti7Te material may be eliminated as a gas. The results of some experiments Kith certain coinpounds containing iadiocarbon have caused investigators to believe that elimination of CI4O2 begins before the hypodermic needle is withdrawn. I n almost every case, biochemical and radiochemical studies show that the excretion of radioactive isotopes is maximal during
Vol. 41, No. 2
the first few hours to 2 days aft,er administration and dccroascs steadily thereafter. Therefore, if possible, it is advisable to provide some means of isolating the radioactive organisms, particularly animals, during the first few days after injection or until the quantity of eliminated radioactivity is no longer a hazard. I n many cases complete isolation becomes a difficult proposition where t,he subject material must be maintained a t critical environmental conditions. It is probable t,hat,there is no general solution for all types of living material. Quarters for radioactive animals, like laboratories, should be made of smooth decontaminable surfaces. The entirc room should be water-tight and equipped with lorn pressure st,cam and hot water conncctions for n-ashing purposcs. Each room should have a drain in the floor, and, if the activity levels are high enough, the drain pipes should be connected t o a hot drain. Cages for animals should be constructed entirely of stainless steel. Experience in this laborat,ory indicates that it is preferable, as well as more economical t o use stainless steel rather than other metals, since stainless steel withstands cleaning and decontamination much more effectively. The procedure for the decontamination of cages may vary with the isotope; however, if t,he laboratory is using many cages, a tank or tanks are needed for immersing the cages in appropriate decontaminating solut,ions. This t>reatmentmay then be folloived by application of hot water and steam for furt,her decontamination and sterilization. While workers in biological fields must remain aware of the desirability of keeping exposures to ionizing radiations within the limits of 0.1 roentgen unit per day, it appears that t,he most difficult, problem at hand is that of avoiding excessive radioactive contamination. (Rccent considcrat,ions by tho Nat,ional Committee on Radiat,ion Protection indicate that 0.3 roentgen per week may be more acceptable as the permissihle level for totalbody irradiation.) Special emphasis should be placed on thc iiecossity of proiriding smooth and easily cleaned surfaces and adoquat,o air supply. Because of the hazards of contamination from organisms metabolizing radioactive materials, every effort should be made t o effect a complete separation of the quarters for maintaining such Organisms. MANIPULATIONS AND MEASUKERIENTS
Laboratories for chemical manipulations with biological materials do not differ appreciably from the laboratories dcsigncd for strictly chemical manipulations with loiv levels of radioactivity discussed by Swartout ( 3 ) . Indeed, much of the work with microorganisms and relatively immobile specimens, such as plants, may be done using these same tcchniqurs and considcrations. LITERATURE CITED
(1) Garden, N . B., Isn.EXG.Cmm., 41, 237 (1948). (2) Rice, C . N., Ibid., 41, 244 (1948). (3) Swartout, J. A., I b i d . , 41, 233 (1948).
RECEIVED M a y 10, 1948. Based on work performed under Contract
7V-31-
109-eng-38 for t h e Atomic Energy Project a t Argonne Kational Laboratory.
