Attempts were made to evaluate 709 children (324 boys and 385 girls) who had been exposed long-term to different doses of radiation during and after the Chernobyl accident and had moved to Israel between 1990 and 1994. Upon arrival, all of them underwent a check-up for most common clinical disorders and were then divided into three groups according to their residences (distance from the reactor) and the level of irradiation exposure: no radiation, <5 Ci/m2, and >5 Ci/m2, respectively. Blood serum analyses for total carotenoids, retinol, alpha-tocopherol and oxidized conjugated dienes in 262 of the children showed increased HPLC levels of conjugated dienes, indicating increased levels of oxidation of in vivo blood lipids in children from the contaminated areas. The levels were higher in girls than in boys. Some 57 boys and 42 girls were given a basal diet with a diurnal supplementation of 40 mg natural 9-cis and all-trans equal isomer mixture beta-carotene in a capsulated powder form of the alga Dunaliella bardawil, for a period of 3 months. Blood serum analyses were regularly conducted before supplementation to determine the baseline effect of radiation exposure to the children, after 1 and 3 months of natural beta-carotene supplementation. After supplementation, the levels of the oxidized conjugated dienes decreased in the children's sera without any significant changes in the level of total carotenoids, retinol or alpha-tocopherol. Other common blood biochemicals were within the normal range for all tests and no statistical differences before or after supplementation of beta-carotene were noted. High pressure liquid chromatography (HPLC) analyses for carotenoids in the blood detected mainly oxycarotenoids, and to a lesser extent, all-trans beta-carotene, alpha-carotene, but not 9-cis beta-carotene. The results suggest that irradiation increases the susceptibility of lipids to oxidation in the Chernobyl children and that natural beta-carotene may act as an in vivo lipophilic antioxidant or radioprotector.

beta-carotene and other carotenoids are reported to be potent free radical quenchers, singlet oxygen scavengers, and lipid antioxidants. Whole-body irradiation is known to cause an immunosuppression effect in mammals through the possible initiation and production of reactive oxygen species. We decided to test the possible antioxidative effect against whole-body irradiation of a natural beta-carotene, composed of equal amounts of the all-trans and 9-cis isomers, obtained from the unicellular alga Dunaliella bardawil. Rats were fed on ground commercial food enriched with natural beta-carotene (50 mg/kg diet). On completion of 1 week with beta-carotene, the rats were exposed to a single dose of 4 Gy whole-body irradiation, after which their livers and blood were removed for beta-carotene and retinol analysis in comparison with control livers of animals irradiated or not, or supplemented with beta-carotene after irradiation. A normal increase in body weight with no ill effects was noted in the groups of rats whose diet was supplemented by beta-carotene before and after irradiation, compared with the reduction in the specific growth rate in the group of rats irradiated without beta-carotene. Liver beta-carotene and retinol decreased significantly after irradiation compared with the rats which were not irradiated. This decrease was not shown in rats fed beta-carotene prior to irradiation, and the effect of irradiation was partially cured by supplementation with beta-carotene after irradiation. High-pressure liquid chromatography (HPLC) analysis of the irradiated animals showed a selective decline in 9-cis beta-carotene and in retinol over all-trans beta-carotene and retinyl-esters. These results suggest that 9-cis beta-carotene and retinol protect in vivo against the cellular damage by free radicals induced after whole-body irradiation.