Question # 175

175. A covered facility receives a mixture from a supplier who only provides the lower bound concentration of a Section 313 listed toxic chemical in the mixture (e.g., more than two percent toluene). Should the covered facility use this information in threshold determinations for the listed toxic chemical?
The facility should subtract out the percentage of any other known components of the mixture to determine what a reasonable ‘maximum’ percentage of toluene could be (e.g., if the mixture contains 80 percent water then toluene can be no more than 20 percent). The facility then should use the midpoint of the ‘minimum’ and ‘maximum’ percentages in order to determine the pounds of toluene to apply toward the threshold. If no other information is available, the facility should assume that the ‘maximum’ is 100 percent.