 Therefore, in order to extrapolate from miner to environmental exposures, it is necessary to be able to extrapolate from the effects of multiple traversals to the effects of single traversals of a particle.Due to the random distribution of particle tracks, the biological effects of an exact number (particularly one) of particles cannot practically be simulated in the laboratory using conventional broadbeam exposures.Microbeam techniques can overcome this limitation by delivering an exact number (one or more) of particles per cell nucleus.