Influence of blood storage after in vitro exposure on the yield of micronuclei observed in human lymphocytes.

In a cooperative study, four laboratories evaluated the micronucleus test in irradiated and non-irradiated lymphocytes with respect to time of storage, the difference between X-ray and gamma exposure and inter-observer variance. The results were compared with parallel studies on dicentric aberrations. No significant differences between laboratories, with respect to storage time or between gamma and X-irradiation were observed for micronuclei and dicentrics using analysis of variance. However, micronuclei are not suitable for an assessment of exposure inhomogeneity because of a significant overdispersion already in controls and homogeneously irradiated samples.