- 68 impluntation of’ the embryo, severe muldevelopment was observed in all children; a high proportion of whom lived for many years. A much smaller portion of.malformed children were born when the mother was irradiated during the last three months of pregnancy. With regard to the possibility that fetuses and infants are receiving higher doses of irradiation presumably from ingested radionuclides, the report of the United Nations Scientific Committee on the Effects of Atomic Radiation for 1969 contains the following statement: "The results of _ extensive and comprehensive surveys carried out in a number of countries have contributed considerably to our knowledge of the levels of long-lived radionuclides in man and food chains in those countries as well as to our understanding of the many and complex processes involved in the transfer of radioactivity to the human body. Although the estimates of the doses ascertained do not differ significantly from the previous ones the Committee now has increaséd confidence that they are representative of the doses to which humans have been committed, at least for those populations in the countries and areas from which the results of measurements are available." It is possible to approximate radiation exposures to the fetus from atmospheric fallout. Also, fetuses are known to be affected by radiation at doses lower than those which would cause damage to an adult. Basic re- search must be continued on both animals and, where possible, man to learn the effects of ionizing radiation on reproductive capacity. The results of animal experiments clearly indicate the complexity involved in determining whether a given system does or does not play a primary role in the response