The Directive seeks to limit the chance of hazardous substances possibly leaching out and polluting the environment during end-of-life recycling or disposal in landfills. The electronics industry is most affected by the restriction on lead, as it is a key component in electronic component packaging (pins), solders and solder pastes. While the term "lead-free" is sometimes used to describe RoHS, the real requirement for manufacturers is to design and ship products that are not only lead-free but fully RoHS compliant, meaning they do not contain more than the allowances of any of the hazardous substances named in the directive.

The hazardous substances and the proposed maximum concentrations levels are: