260. How does a facility determine the threshold for reporting of a listed toxic chemical (such as chromium) in a solid piece of steel which it processes?
Since steel is a mixture (and not a compound), the processing threshold determination is made based on the total amount of each toxic chemical present in the steel. If the toxic chemical is present in a known concentration, the amount present can be calculated by multiplying the weight of the steel by the weight percent of the listed toxic chemical (see 40 CFR Section 372.30(b)(3)). The threshold for processing chromium is 25,000 pounds.