Propylene glycol n-butyl ether (PnB; CAS# 5131-66-8 or 29387-86-8) has been used as a coupling agent and solvent in domestic and commercial cleaning solutions such as degreasers and hard surface cleaners. Within the scope of HERA applications, PnB finds use in various hard surface cleaners.
The HERA risk assessment has shown that the use of PnB in HERA applications results in environmental risk characterization ratios well below one, indicating no concern, for all environmental compartments. For human health, a margin of exposure of more than 300,000 has been calculated for the total aggregate consumer exposure. This MOE has been considered very large, large enough to account for the inherent uncertainty and variability of the database and inter and intra-species extrapolations.
The outcome of this HERA risk assessment which focuses on the specific uses of PnB in household cleaning products is fully consistent with that of the OECD high production volume chemical review which looked at all global uses of the category of propylene glycol ethers in general and PnB in particular. The SIDS initial assessment report (SIAR) concluded that propylene glycol ethers are considered of low priority for further work. The available data for all category members including PnB indicate that their aquatic and mammalian toxicity is low.