Man's industrial activity causes the accumulation of chemical pollution in soil and sediments. Thanks to the ability of soil and sediments to stop the spread of toxic chemical substances, the direct consequences of their harmful effect can be avoided. However, changes in the physico-chemical features of soil or sediments may cause a sudden spread of chemical pollution. The coincidence of events leading to the spread of harmful substances, accumulated in soil and sediments, threatening health, the economy and the stability of the ecosystem, in termed a chemical time-bomb. It is, as shown in results obtained by international research teams, a looming threat to mankind.