The Health Risk Assessment Unit at the Minnesota Department of Health has started a full review of three trimethylbenzene (TMB) isomers (1,2,3-trimethylbenzene; 1,2,4-trimethylbenzene; and 1,3,5-trimethylbenzene). TMB isomers are produced during petroleum refining and production of a component of gasoline. TMB isomers are also used in the production of solvents and are ingredients in paints, dyes, cleaning agents, and automotive fluids.
The review will consider if the existing Health Risk Values (HRL) for the three trimethylbenzene compounds in groundwater are adequately protective. This review is particularly significant because trimethylbenzene compounds are commonly detected in soil and groundwater at petroleum release sites, such as leaking underground storage tank (LUST) sites.
MDH previously developed water guidance for 1,2,4- and 1,3,5-trimethylbenzene. Re-evaluation of these contaminants in 2017 resulted in a recommendation for full review.