REACH, the European chemical regulation, is a substance-based law, though some substances as defined can include mixtures of either discrete or variable composition chemicals. Still, there is concern that mixtures of chemicals, sometimes called "chemical cocktails," could have greater toxicity than the sum of the toxicities for the individual chemicals. This paper by the three committees attempts to address this concern, though no new amendments to the REACH law were proposed at this time.
According to the press release, the main conclusions of this preliminary opinion are:
- Chemicals with common modes of action may act jointly to produce combined effects that are larger than the effects of each mixture component alone.
- For chemicals with different modes of action (i.e. acting independently), no robust evidence is available that exposure to a mixture of such substances is of health concern if each individual chemical is present at or below their no effect levels.
- For chemicals that interact, interactions (including antagonism, potentiation, synergies) usually occur at medium or high-dose levels (relative to the lowest effect levels). At low exposure levels they are either not occurring or toxicologically insignificant.