To estimate the contribution of consequences of collision of small-size space objects (SOs) into the current near-Earth space (NES) contamination level, the situation forecasting since 1990 to 2012 was carried out. The forecasting has been fulfilled in two stages. At the first stage on the mentioned time interval the evolution of altitude distributions of various-size objects has been constructed without allowance for mutual collisions. At the second modeling stage these results were used as initial data for determining characteristics of objects larger than 1 mm in size taking into account mutual collisions of SOs larger than 1 cm in size. During situation forecasting the fragmentation model was used, whose parameters were updated based on available experimental data. For catalogued objects the forecasted and real data agree well enough. For smaller-size objects the results occurred to be unexpected. They testify to very strong effect of mutual collisions on NES contamination by particles of size from 1 mm to 5.0 cm. As compared to the SDPA model data for 2010 (without allowance for mutual collisions), the estimates of a number of objects of mentioned size occurred to be greater an order of magnitude. The conclusion was drawn from modeling materials that the so-called cascade effect transmuted from a hypothesis to reality.