Biosolids used on crops must meet which EPA regulation?

• A. 40 CFR part 260
• B. 40 CFR part 136
• C. 40 CFR part 503
• D. 40 CFR part 60

Answer: (C)

Biosolids applied to cropland are regulated under the EPA rule that governs their processing, testing, and land application. This regulation is 40 CFR Part 503, which sets pollutant limits for metals, requires pathogen reduction, and mandates practices to control vector attraction and manage application rates, timing, and site restrictions. It also establishes monitoring, recordkeeping, and reporting requirements to ensure safe use and disposal of biosolids. Other regulatory parts cover different topics—for example, Part 260 deals with hazardous waste management, Part 136 outlines approved analytical methods, and Part 60 sets air emission standards—so they do not govern how biosolids are used on crops.