Laura Maria Padovani

Do human lymphocytes exposed to the fallout of the Chernobyl accident exhibit an adaptive response? 2. Challenge with bleomycin

The present study concerns the possible adaptive response, induced in vivo by a continuous exposure to ionizing radiations, to a challenge treatment with the radiomimetic glycopeptide bleomycin (BLM). Lymphocytes from children contaminated as a consequence of Chernobyl accident were treated for the last 5 h of culture with 2.5 micrograms/ml BLM. The induced chromosome damage was significantly lower than that found with the same treatment in lymphocytes from control children. This hyposensitivity to BLM was still present if, 1 h after the addition of the drug, inhibitors of the enzymes involved in DNA repair, such as 3-aminobenzamide (2 mM), or aphidicolin (0.4 microM) or 3-dideoxythymidine (5 mM) were added to the cultures. The resistance to BLM in lymphocytes from contaminated children seems to be related to a mechanism upstream in respect to the activities of enzymes involved in the DNA repair and specifically linked to the action of this drug. This is consistent with the different response found when the cells were challenged with ionizing radiation in vitro, as reported in the accompanying paper (L. Padovani, L. et al. (1995) Mutation Res., this issue).

Cytogenetic study in lymphocytes from children exposed to ionizing radiation after the Chernobyl accident

The present study concerns the monitoring of children from the Byelorussian, Ukrainian and Russian republics exposed to the fall-out of the Chernobyl accident. Cytogenetic analyses have been performed on 41 children coming from different areas and exhibiting varying amounts of 137Cs internal contamination, as evaluated by whole-body counter (WBC) analysis. On a total of 28,670 metaphases scored, radiation-induced chromosome damage is still present, although at a very low frequency. Due to the very low fraction of dicentrics, because of the time elapsed from the accident and the relatively low doses of exposure, radiobiological dosimetry is not possible for these children. However, considering that the WBC data indicate that the children are still exposed to 137Cs contamination, the observed occurrence of stable chromosome rearrangements and breaks may represent the persisting effect of continuous low doses of radiation. The present study also indicates that the parallel use of internal contamination dosimetry and cytogenetics could be usefully employed to monitor individual exposure to radiation and to define further management measures.

Cytogenetic effects in lymphocytes from children exposed to radiation fall-out after the Chernobyl accident

In a previous paper we reported that a group of children exposed to ionizing radiation following the Chernobyl accident exhibited an appreciable number of chromosome breaks and rearrangements reflecting the persistence of a radiation-induced damage. The results suggested that the children were still exposed to radioactive contamination through consumer foodstuff and life styles. In the present paper, 31 exposed children have been considered together with a control group of 11 children with the aim to confirm previous results. All children underwent whole-body counter (WBC) measures and conventional cytogenetic analysis. The frequency of chromosome aberrations detected by conventional cytogenetics in the group of children chronically exposed to low doses of ionizing radiation resulted in significant differences with respect to the control group. The present work suggests that, for these groups of children, even if the frequency of aberrations is very low and the observation of statistically significant differences is consequently a problem, a persistently abnormal cytogenetic picture is still present several years after the accident.

Do human lymphocytes exposed to the fallout of the Chernobyl accident exhibit an adaptive response? III. Challenge with bleomycin in lymphocytes from children hit by the initial acute dose of ionizing radiation.

In the present paper, we report data on the possible adaptive response, induced in vivo by exposure to ionizing radiation to a challenge treatment with the radiomimetic glycopeptide bleomycin (BLM). Lymphocytes from children living in Pripjat at the time of the Chernobyl accident, and thus hit by the initial acute dose of ionizing radiation, were treated for the last 5 h of culture with 0.004 U/ml BLM. Significantly lower chromosome damage was found only in lymphocytes from children who, independently of the initial acute exposure to ionizing radiation, still showed a 137Cs internal contamination, due to persistent continuous exposure to low doses of radiation. The present results indicate that past exposure to acute high dose of ionizing radiation does not interfere with resistance to BLM which is related to internal contamination.

Health status and internal radiocontamination assessment in children exposed to the fallout of the Chernobyl accident

Abstract The Chernobyl fallout caused release of radioisotope contaminants in a very large area that includes Belarus, the Ukraine, and the Russian Federation. In this study, the authors monitored the health status and level of internal contamination in 422 children who resided in the aforementioned areas and who were ≤ 10 y of age at the time of the accident. The children came to Italy for a 1-mo period between 1991 and 1992. During this time, the children underwent pediatric checkups and biochemical, immunological, and thyroid analyses. All children underwent whole-body counter measurements, and urine radiotoxicological analysis was performed for 224 of them. The 24 children evacuated from Pripiat, a village very close to the Chernobyl reactor site, were selected for cytogenetic analysis. All of these children continue to have a detectable internal contamination of caesium radioisotopes. This condition is likely the result of ground and foodstuff contamination in the various areas. The children did not evidence overt pathologies related to ionizing radiation. However, minor alterations in immunological and thyroid parameters were observed in the group of the evacuated children. Traditional cytogenetic dosimetry was not possible, but the occurrence of acentric fragments was observed—indicating a persistent effect of continuous exposure to low doses of radiation.

Cytogenetic study on children living in Southern Urals contaminated areas (nuclear incidents 1948–1967)

As a result of the activities of the first Soviet plutonium production reactor, large territories of the Southern Urals were exposed to radioactive contamination. Three different incidents occurring between 1948 and 1967 lead to major exposure. A total of 280,000 people residing on the contaminated territories were exposed both to external and internal contamination particularly due to the long-lived radionuclides 137Cs and 90Sr. The highest doses were received by 28,000 people living on the Techa riverside villages. In the present paper 15 presumably exposed children coming from the Muslyumovo village on the Techa river have been analyzed using conventional cytogenetic procedure in order to assess a radiation-induced damage. The data obtained have been compared to a group of matched unexposed controls. The results show a statistical difference between the two cohorts which suggests a possible residual contamination representing a continuous hazard for the new generations.

The Cyclops Islands

On the eastern coast of Sicily, below the Aetna volcano, there is a tiny archipelago, a marine protected area, where the legend of Ulysses is still alive