OBJECTIVE--To evaluate the outcome of pregnancy in Finnish women after the accident at the Chernobyl nuclear power plant on 26 April 1986. DESIGN--Geographic and temporal cohort study. SETTING--Finland divided into three zones according to amount of radioactive fallout. SUBJECTS--All children who were exposed to radiation during their fetal development. Children born before any effects of the accident could be postulated--that is, between 1 January 1984 and 30 June 1986--served as controls. INTERVENTIONS--Children were divided into three temporal groups: controls, children who were expected to be born in August to December 1986, and children who were expected to be born in February to December 1987. They were also divided, separately, into three groups according to the three geographic zones. END POINT--Incidence of congenital malformations, preterm births, and perinatal deaths. MEASUREMENTS AND MAIN RESULTS--There were no significant differences in the incidence of malformations or perinatal deaths among the three temporal and three geographic groups. A significant increase in preterm births occurred among children who were exposed to radiation during the first trimester whose mothers lived in zones 2 and 3, where the external dose rate and estimated surface activity of caesium-137 were highest. CONCLUSIONS--The results suggest that the amount of radioactive fallout that Finnish people were exposed to after the accident at Chernobyl was not high enough to cause fetal damage in children born at term. The higher incidence of premature births among malformed children in the most heavily polluted areas, however, remains unexplained.
Comment In: BMJ. 1989 May 20;298(6684):13842502266
Our objective was to explore whether the radiation fallout in Finland after the accident at the Chernobyl nuclear power plant in April 1986 led to an increased incidence of trisomy 21. In this geographic and temporal cohort study, the country was divided into three zones according to the amounts of radioactive fallout and internal radiation caused by two cesium isotopes. The 518 cytologically verified cases of trisomy 21 were divided into a control group (conceived before the accident), and a study group of children whose expected dates of birth were in the post-accident years 1987-1988, i.e., pregnancies commenced after May 1986. The cases were also divided into three subgroups according to the zones of radiation. There were no significant differences in prevalence of trisomy 21 between the control and study groups nor between the three zones in spite of the significant differences in the levels of radiation and in the body burden that prevailed throughout the study period. Power estimates showed that in the two zones of lower radiation, an increase of 0.5% in the prevalence would have been detected with a power of 0.85, and in the somewhat smaller zone of the highest radiation, with a power of 0.70. The study lends no further support to the view that the low radiation fallout in western Europe would have been causally associated with trisomy 21.
The chromosome dicentric aberrations in the lymphocytes and levels of antibodies to human thyroid microsomal antigen in the serum of the children lived in the area of Bryansk Province suffered from the Chernobyl accident was examined. Correlation between those tests was not estimated: the autoantibodies were revealed in group with dicentrics and without those in 4.0% and 4.5% of cases correspondingly. Antimicrosomal antibodies were revealed more frequently (5.0%) and in higher titers in the children from the more polluted Bryansk Province than in those from Kaluga Province (3.1%). These data can testify about the role of inside radiation of thyroid gland in appearance of autoimmune thyroiditis signs.
The callus culture of Nicotiana tabacum L. was obtained from the plants chronically irradiated in 10 km zone of Chernobyl Atomic Power Station. The tobacco plants in 10 km zone of Chernobyl during the vegetation period exposed to irradiation with the average dose rate of 0.36 mA/kg (5 mP/h). The total absorbed dose was approximately 0,31 Gy. The morphogenetic analysis of this culture shows a considerable decrease of regeneration index and callus weight.
The fallout from the Chernobyl reactor resulted in radioactive fall-out in eastern Sweden leading to a ground radiation intensity of between 2 and 500 microR h-1 above the 10-15 microR h-1 background, an average external cumulative dose of about 3-4 mSv (0.3-0.4 rem) to about 1 million people, or about 3500 man-Sv (350,000 man-rem) over 50 years, or 70 man-Sv per year with a maximum dose to a few individuals of 40 mSv. The corresponding figures reported for civilians around Chernobyl is 8.6 million man-rem in 1986 and 29 million man-rem over 50 years, or 600,000 man-rem (equivalent to about 6000 man-Sv) per year. If Swedish doses are averaged over the whole population, the average is about 1 mSv or 10,000 man-Sv, or 200 man-Sv per year. The thyroid uptake of 131I is approximately 0.1-0.2 kBq (0.005 microCi) and the total body uptake of 137Cs, 1 kBq (0.03 microCi), resulting in an approximate internal dose of 0.02 mSv. If a linear dose-response curve is assumed, an increase of the normal cancer mortality incidence in the million Swedes affected by 3500 man-Sv per 50 years from 200,000 to about 200,070 can be assumed. Corresponding figures for all of Sweden are 8,000,000 inhabitants, 7000 man-Sv, 1,720,000 normal cancer deaths, and 1,720,140 expected cancer deaths. Corresponding figures reported for the population outside the 30 km evacuation zone around Chernobyl are 300,000 man-Sv, and an increase from 6,800,000 cancer deaths per 50 years to 6,806,000 cancer deaths.
The objective of the European Childhood Leukaemia-Lymphoma Incidence Study (ECLIS) is to investigate trends in incidence rates of childhood leukaemia and lymphoma in Europe, in relation to the exposure to radiation which resulted from the accident at the Chernobyl nuclear power plant in April 1986. In this first report, the incidence of leukaemia in children aged 0-14 is presented from cancer registries in 20 European countries for the period 1980-1988. Risk of leukaemia in 1987-1988 (8-32 months post-accident) relative to that before 1986, is compared with estimated average dose of radiation received by the population in 30 geographic areas. The observed changes in incidence do not relate to exposure. The period of follow-up is so far rather brief, and the study is planned to continue for at least 10 years.