Question # 173

173. A covered facility uses a mixture in its processing operations and knows only that the mixture contains less than 99.9 percent of four listed toxic chemicals (combined). How should it report?
The facility should proportion the amount of chemicals so that their total percentage equals 99.9 percent, since each one cannot physically be present at 99.9 percent. The percentage could be divided equally among the four, unless the facility has some basis for proportioning them differently.