CFR › Title 40 › Part 421 › §421.540 CFR §421.5Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy linkRemoval allowances pursuant to 40 CFR 403.7(a) may be granted for the toxic metals limited in 40 CFR part 421 when used as indicator pollutants.