Many construction materials contain substances that are classified as dangerous according to European chemicals legislation. A number of dangerous substances have already been banned for various reasons. For example, PCB and PCP were banned after causing significant health problems for building users as a result of being released from construction materials into indoor air. Both heavy metals and organic substances such as wood preservatives have been found to leach out of construction products, a finding that is associated with the undesirable input of these substances into water, soil and ground water. Other dangerous substances include reaction products such as prepolymers, for example, which only fully develop into a final reaction product through the action of atmospheric oxygen or curing agents, for example. In these cases, it is necessary to demonstrate that the dangerous substances will not leach out or be released in gaseous form, or that the levels which are in fact emitted do not pose any serious health concerns. The authoritative basis for assessment of the environmental or health implications of emissions is essentially provided by national legislation such as the Chemicals Prohibition Regulation or pertinent environmental laws.
