Substitution as a method of reducing the effects of hazardous substances and materials has been laid down in order no. 540 of the Ministry of Labour concerning substances and materials. This says that “it is not allowed to use a substance or material which may be hazardous to or otherwise reduce safety or health if it can be replaced by a nonhazardous, less hazardous, or less irritant substance or material.” The purpose of a substitution is in all cases to remove or reduce effects from substances and materials which are hazardous to health. Substitution is the removal from the working process of the substance or material which gives rise to considerations of substitution. The common starting point on all levels is that in a given working process a substance or material is used which, by means of substitution, is removed from the working process.