- The agency responsible for establishing Recommended Exposure Limits (RELs) for hazardous substances in the workplace is NIOSH (National Institute for Occupational Safety and Health).

- NIOSH conducts research and provides guidance on occupational safety and health hazards.
- Its role includes recommending exposure limits that serve as guidelines to help employers and workers minimize health risks from hazardous substances.
- These RELs are non-enforceable recommendations, meaning they do not have the force of law but are designed to inform workplace safety standards.

- In contrast, OSHA (Occupational Safety and Health Administration) is the federal agency that sets and enforces permissible exposure limits (PELs), which are legally enforceable standards in the workplace.
- Although OSHA may use NIOSH’s RELs as a basis, its limits are regulatory.

- The EPA (Environmental Protection Agency) focuses on environmental protection and regulations outside of occupational settings, and the CDC (Centers for Disease Control and Prevention) is a broader public health agency that oversees NIOSH but does not directly issue RELs itself.

In summary:
- NIOSH: Establishes Recommended Exposure Limits (RELs) based on scientific research.
- OSHA: Enforces Permissible Exposure Limits (PELs), which are legally binding.
- EPA: Focuses on environmental exposures, not occupational exposure limits.
- CDC: Parent agency of NIOSH, does not set RELs directly.

Reference: Occupational Safety and Health Administration Handbook, Volume 2, Chapter 5, Page 112