[20-year morpholoogical findings in the study of medical aftereffects of the Chernobyl accident].

Presented are the results of morphological studies of radiation sickness, congenital malformations and malignant tumors which have developed in Chemobyl victims. Until now consequences of the accident remain a subject of practical and research medicine. Scope of relevant topical problems the pathologists will have to investigate in the future is discussed.

Radiation-related mortality among offspring of atomic bomb survivors: a half-century of follow-up.

Our objective was to examine whether parental exposure to atomic bomb radiation has led to increased cancer and/or noncancer mortality rates among the offspring. We studied 41,010 subjects born from May 1946 through December 1984 (i.e., conceived between 1 month and 38 years after the bombings) and surviving for at least 1 year. One or both parents were in Hiroshima or Nagasaki at the time of the bombings and childbirth. We analyzed mortality data from 1946 to 1999 using the Japanese family registry system by Cox regression model and examined the effects of paternal and maternal irradiation with adjustment for city, sex, year of birth and parental age at childbirth. During follow-up, 314 cancer deaths and 1,125 noncancer disease deaths occurred. The mean age of living subjects was 45.7 years. Median doses were 143 mSv for 12,722 exposed fathers and 132 mSv for 7,726 exposed mothers. Cancer and noncancer mortality rates were no higher for subjects with exposed parents (5+ mSv or unknown dose) than for reference subjects (0-4 mSv), and mortality did not increase with increasing dose. For subjects with both parents exposed, the adjusted hazard ratios were 1.16 [95% confidence interval (CI) 0.92-1.46] for noncancer and 0.96 (95% CI 0.59-1.55) for cancer. This was true of deaths occurring both before and after 20 years of age. However, because of uncertainty due to the small number of deaths and relatively young ages of subjects, we cannot rule out an increase in disease mortality at this time.

Genetic analysis of the cause of gastroschisis in the HLG mouse strain.

An inbred mouse strain HLG shows a high incidence of gastroschisis after X-ray exposure to the zygotes. About 11% of the fetuses display this malformation after irradiation with 1 Gy. The C57BL-strain does not show the increased frequency of gastroschisis after radiation-exposure to the zygotes. The genetic background of this malformation was investigated in a backcross of HLG x C57BL females to HLG males. The pregnant HLG x C57BL females were irradiated in a stage in which the (HLG x C57BL) x HLG [BC1] embryos were in the 1-cell stage. The frequency of gastroschisis in the BC1 generation was compared with a genetic model of a single recessive mutation with 11% penetrance. This frequency does not fit a single-locus inheritance. The number of loci involved was estimated to be about two or three. HLG mouse strain may be a valuable animal model in the study of polygenic traits.

Pregnancy outcome in Finland after the Chernobyl accident.

The explosion at the Chernobyl nuclear power plant caused radioactive fallout in Finland in April-May 1986. The fallout was unevenly distributed geographically, and, accordingly, the country was divided into 3 fallout zones. Whole-body radioactivity measurements of randomly chosen persons showed that the regional differences prevailed throughout the following 2 years. Data for legal abortions, registered congenital malformations as well as preterm births and stillbirths of malformed children were collected. The corresponding expected figures were obtained from statistics from 1984 and 1985. No differences in the expected/observed rates of the above parameters were detected.

PIP: The effects of the 1986 Chernobyl accident on Finland are reported. Legal abortions, registered congenital malformations, preterm births, and stillbirths showed no differences in observed vs. expected rates after the accident. The limitations are that the population base is small, the detection system is incomplete, no reliable data are available on early abortions, and germinal mutations were not presently analyzed. Measurement of radiocesium (Cs 134 and 137) was accomplished by the Research Institute for Social Security with a stratified random sample of 380 people. 5 fallout zones differentiated groups, which were then collapsed into 3 groups. Regional differences in levels persisted into 1988. The Finnish Register of Congenital Malformations provided the compulsory data on congenital malformations. The 3 groups (children born before the accident in 1984-85, in the latter half of 1986, and in 1987) were analyzed in the 3 zones during 2 study periods (August-December 1986 and January-December 1987). Monthly analysis of induced abortions showed no increase following the accident. There was a slight decrease in births between January and March 1987, which is believed to be related to anxiety reinforced by public advice. There were no differences between expected and observed congenital defects in the 2 study periods. Preterm and stillbirths followed a similar pattern. The analysis showed no association between the temporal and spatial variations in radioactivity and variable incidence of congenital malformations.

[Lethal developmental defects in the offspring of a population living in a territory with traces of radioactivity]. / Letal'nye poroki razvitiia u potomstvo naseleniia, prozhivaiushchego na territorii radioaktivnogo sleda.

The paper is concerned with the materials of a study of long-term effects of irradiation at small doses of a limited population, taking by way of example lethal developmental defects in descendants. In 1957 a radioactive trace was formed as a result of an explosion of a tank with highly active radiochemical by-products. The population in this area was exposed to irradiation. Mortality from lethal developmental defects in the descendants was analyzed. The data obtained have shown that the effect on the gonads of external irradiation at doses of 0.1-0.5 Sv (33,500 persons) revealed no statistically significant variations in the mortality of the descendants from developmental defects as compared to the controls.