Gamma Radiation Sterilization of Ponderosa Pine and Birch Sapwood


  • Christine V. Sharman
  • Roger S. Smith


The sterilizing effects of gamma radiation on microbiologically contaminated ponderosa pine and birch sapwood (beams and cubes) conditioned to moisture contents ranging from 0.5% to 150% were examined.

The lethal radiation dosage required depended on the moisture content of the wood and also, perhaps, on the initial concentration of microorganisms within the wood. Fungi were more sensitive to radiation than bacteria, but a radiation dose between 1 and 5 M rads was sufficient to kill all microorganisms in 3/4-inch cubes of both woods. Smaller radiation dosages were required to sterilize wood at either very low or very high moisture contents than at intermediate moisture contents. Both woods had similar lethal dosage requirements for sterilization.

Seven fungal species isolated after a radiation dosage of 5 X 105 rads were found to be Fungi Imperfecti. Following gamma irradiation of wood samples, there was no evidence of an aftereffect modifying the growth of microorganisms in the wood.


American Society for Testing Materials. 1961. Standard method of testing wood preservatives by laboratory soil-block cultures. A.S.T.M. Designation D-1413-61, Philadelphia, Pa.nBarton, George M. 1966. Chemical and physical effects of radiation on wood. Internal Report, Can. Dept. Forest. Rural Develop., Forest Prod. Lab., Vancouver, B. C.nBellamy, W. D., and E. J. Lawton. 1954. Problems in using high-voltage electrons for sterilization. Nucleonics, 12(4): 54-57.nBors, J., and H. Glubrecht. 1967. Untersuchungen über die strahlen-resistenze holzzerstörender pilze. Holzforschung, 21(5): 129-135.nDaniels, M., G. Scholes, and J. Weiss. 1953. ‘After-effect’ in aqueous solutions of deoxyribonucleic acid irradiated with X-rays. Nature, 171(4365): 1153-1154.nDavis, R. J., U. L. Sheldon, and S. I. Auerbach. 1956. Lethal effects of gamma radiation upon segments of a natural microbial population. J. Bact., 72: 505-510.nFranz, N. 1963. Exploratory experiments on the possible use of radioactive waste materials in wood industries. Forest Prod. J., 13(3): 94-96.nFriedin, A. S. 1958. Deistvie radioaktivnogo izlucheniya na fiziko-mekhanicheskie svoistva drevesiny. Mekh. Obrab. Drev., 7(9): 13-15.nGlegg, R. E. 1957. The influence of oxygen and water on the after-effect in cellulose degradation by gamma-rays. Radiat. Res., 6: 469-473.nGlegg, R. E. and Z. I. Kertesz. 1956. After-effect in the degradation of cellulose and pectin by gamma rays. Science, 124: 893-894.nIsenberg, Irving H. 1951. Pulpwoods of United States and Canada. Inst. Pap. Chem., Appleton, Wis.nIizuka, Hiroshi, and Hitoshi Ito. 1968. Effect of gamma radiation on the microflora of rice. Cereal Chem., 45(5): 503-511.nJackson, M. E., J. C. Corey, L. R. Frederick, and J. C. Picker, Jr. 1967. Gamma irradiation and the microbial population of soils at two water contents. Proc. Soil Sci. Soc. Am., 31 (4): 491-494.nJohnson, L. F., and T. S. Osborne. 1964. Survival of fungi in soil exposed to gamma radiation. Can. J. Bot., 42(1): 105-113.nKashkina, G. B., and Yu, D. Abaturov. 1967. Vyzhivanie pochvennykh mikroorganizmov pri obluchenii pochvy gamma-Iuchami. Radio-biologiya, 7(2): 263-266.nKenaga, D. L., and E. B. Cowling. 1959. Effect of gamma radiation on ponderosa pine. Forest Prod. J., 9(3): 112-116.nMcLaren, A. D., R. A. Luse, and J. J. Skujins. 1962. Sterilization of soil by irradiation and some further observations on soil enzyme activity. Proc. Soil Sci. Soc. Am., 26: 371-377.nMcLaren, A. D., L. Reshetko, and W. Huber. 1957. Sterilization of soil by irradiation with an electron beam and some observations on soil enzyme activity. Soil Sci., 83: 497-502.nPan, Huo-Ping, B. E. Proctor, S. A. Goldblith, H. M. Morgan, and R. Z. Naar. 1959. The influence of high energy radiation on cotton. Part I. The properties of raw cotton sliver lap, yarn, and fabric irradiated under various conditions. Textile Res. J., 29: 415-421.nPaszner, L. 1968. Effect of inter- and intra-crystalline swelling on cellulose degradation by gamma rays. Svensk Papp-Tidn., 71(22): 822-828.nPopenoe, H., and C. F. Eno. 1962. The effect of gamma radiation on the microbial population of the soil. Proc. Soil Sci. Soc. Am., 26: 124-127.nSkou, J. P. 1969. The effect of temperature on the growth and survival of Aureobasidium pullulans and of the radulasporic stage of Guignardia fulvida and of Sydowia polyspora. Friesia, 9(1-2): 226-236.nSmith, D. M., and R. Y. Mixer. 1959. The effect of lignin on the degradation of wood by gamma irradiation. Radiat. Res., 11: 776-780.nSmith, R. S. 1968. Effect of moisture content on the sterilization of wood, under vacuum, by propylene and ethylene oxides. Can. J. Bot., 46(3): 299-303.nStotzky, G., and J. L. Mortenson. 1959. Effect of gamma radiation on growth and metabolism of micro-organisms in organic soil. Proc. Soil Sci. Soc. Am., 23: 125-127.nSykes, G. 1965. Disinfection and sterilization theory and practice. E. and F. N. Spon Ltd., London.n






Research Contributions