Which federal agency uses RQ to define hazardous substances?

The correct answer is that the federal agency which uses Reportable Quantities (RQ) to define hazardous substances is the Environmental Protection Agency (EPA).

The concept of RQ is significant in environmental management and public health as it sets thresholds for the amount of specific hazardous substances that, if released into the environment, must be reported to the relevant authorities. The RQ values are determined by the EPA, which provides guidelines for the reporting and assessment of hazardous substances under various regulations, particularly the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), commonly known as Superfund.

This framework enables the EPA to monitor and respond to hazardous substance releases, ensuring public safety and environmental protection. The definitions and regulations that stem from the EPA's authority assist states and local governments in addressing hazardous waste issues effectively.

The other agencies listed have their own roles and responsibilities concerning workplace safety, transportation of hazardous materials, and health risks but do not define hazardous substances using RQs. For example, OSHA is primarily concerned with worker safety and health regulations, while the Department of Transportation focuses on the safe transport of goods, including hazardous materials, but does not allocate RQ definitions. The Agency for Toxic Substances and Disease Registry is involved in health-related assessments of toxic substances but does