Are mineral spirits considered petroleum derivatives and therefore excluded from the CERCLA definition of hazardous substance?
In most cases, yes. CERCLA section 101(14) specifically excludes petroleum from the definition of hazardous substance, consequently petroleum releases are not subject to CERCLA reporting and liability provisions. The petroleum exclusion includes "crude oil or any fraction" of petroleum unless the fraction is specifically listed or designated under the statute.
Mineral spirits, also known as Stoddard solvent, naphtha, or white spirits, are usually derived from refined petroleum distillates from the light end of crude oil but could possibly be derived from coal. Mineral spirits that are distilled from petroleum are considered petroleum for the purpose of CERCLA section 101(14) and, therefore, are excluded from the definition of hazardous substance.
Mineral spirits often contain substances, such as toluene, that are CERCLA hazardous substances. If these substances are present naturally or are added to petroleum-derived mineral spirits in the normal refining process, then they would be excluded as petroleum. However, hazardous substances added to mineral spirits outside the refining process, or that increase in concentration solely as a result of contamination during use, are not part of the "petroleum" and, thus, are not excluded from CERCLA regulation. In such cases, EPA may respond to releases of the added substance, but not the mineral spirits.
There are circumstances in which mineral spirits could be regulated as a hazardous substance. For instance, coal-derived mineral spirits would not qualify for the petroleum exclusion and potentially could be regulated as a hazardous substance. In addition, the exclusion would not apply if the mineral spirits were "specifically listed or designated" under one of the statutory provisions cited in section 101(14) of CERCLA.