Substances of Very High Concern (SVHC) are chemicals that may have serious effects on human health or the environment. These include substances that are carcinogenic, mutagenic, or toxic for reproduction (CMRs), as well as those that are persistent, bioaccumulative, and toxic (PBT), or very persistent and very bioaccumulative (vPvB). Identifying and regulating SVHCs is a crucial aspect of REACH in reducing cancer risks.