Given the vast number of chemicals in the stream of commerce today, it is not feasible to provide health-based exposure limits for all of them. Establishing safe exposure levels for constituents of concern (COCs) involves an enormous amount of time, resources, and stakeholder considerations. The effort to develop technically defensive regulations is often unjustified for uncommon COCs or chemicals that are not suspected of posing human health risks (drinking water COCs are regulated at the federal level per the 1996 Safe Drinking Water Act and also can be regulated at the state level).
Ultimately, establishing regulations balances the frequency of occurrence (size of population potentially impacted), time and cost constraints, and level of human health risk. While all of these factors are contemplated when establishing regulations, the degree of human health risk is the most important factor to consider. Unfortunately, human health risk is often the most difficult to understand and time-consuming to establish.