Cell-cycle and ploidy analysis in bone marrow and liver cells of rats after long-term consumption of irradiated wheat.

Rats were fed for 4 or 90 days either with 70% freshly irradiated wheat (0.25, 0.75 or 2.25 kGy) and 30% complementary feed or with a control diet. None of the parameters examined (food consumption, body weight, haematological analysis, histopathological inspection of thymus, lung, liver, spleen and kidney, DNA analysis of bone marrow cells and nuclei from liver cells by flow cytometry) showed any statistically significant association with the feeding regimen. Minor changes in ploidy of liver cells and cell cycling of bone marrow cells were detectable (wheat-irradiation dose-dependent increase in G2/M-phase bone marrow cells up to 0.6%, decrease of 8C nuclei up to 1.1% in liver cells). From the pattern of alterations observed in our study, radiolytic by-products of wheat irradiation with a spindle poison-like activity can be excluded. Polyploid cells do not accumulate within the 90-day feeding period. The minor effects on cell cycle and ploidy observed are qualitatively comparable with the effects seen after food restriction in animal studies. It is suggested that an altered composition of fatty acids (the components of wheat most sensitive to irradiation) is responsible for these marginal effects. Our findings may explain the earlier findings of Bhaskaram and Sadasivan (American Journal of Clinical Nutrition 1975, 28, 130-135) who reported an increase in the number of polyploid cells in the lymphocytes of malnourished children fed irradiated wheat. The most likely mechanisms for such an effect are adaptive, constitutively regulated processes, similar to those which respond to food restriction. It is concluded that the consumption of irradiated wheat does not, therefore, pose any health risk to humans.