Response: OSHA's HCS applies to hazardous chemicals known to be present in the workplace in such a manner that employees may be exposed under normal conditions of use or in a foreseeable emergency (see 29 CFR 1910.1200(b)(2)). However, the HCS does not apply to [a]ny hazardous waste as such term is defined by the Solid Waste Disposal Act, as amended by the Resource Conservation and Recovery Act of 1976, as amended (42 U.S.C. 6901 et seq.), when subject to regulations issued under that Act by the Environmental Protection Agency (see 29 CFR 1910.1200(b)(6)(i)).

The RCRA defines “hazardous waste” as solid waste, or combination of solid wastes, which because of its quantity, concentration, or physical, chemical, or infectious characteristics may (A) cause, or significantly contribute to an increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness; or (B) pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, or disposed of, or otherwise managed (42 U.S.C. 6903(5)). “Solid waste” is defined under the RCRA as garbage, refuse, sludge, and other discarded material (42 U.S.C. 6903(27)).

EPA's regulations implementing RCRA provide that certain solid wastes are not hazardous wastes, including [d]rilling fluids, produced waters, and other wastes associated with the exploration, development, or production of crude oil, natural gas or geothermal energy (40 CFR 261.4(b)(5)). EPA also issued guidance in October 2002 explaining that while gas exploration and production (E&P) wastes (e.g., flowback or produced waters) are exempt from RCRA Subtitle C hazardous waste regulations, these waste types may fall under the control of state regulations, RCRA Subtitle D solid waste regulations, and other federal regulations. See Exemption of Oil and Gas Production Wastes from Federal Hazardous Waste Regulations (EPA 530-K-01-004), available at: http://www.epa.gov/epawaste/nonhaz/industrial/special/oil/oil-gas.pdf* [This document is apparently withdrawn. June 2016 updates to the RCRA now require pretreatment per 40 CFR Part 435¹

When waste does not meet the definition of “hazardous waste” under the RCRA regulations, it is covered by the HCS if it meets the standard’s definition of “hazardous chemical” and if it does not fall under any of the other HCS exemptions. The HCS defines “hazardous chemical” as any chemical which is classified as a physical hazard or health hazard, a simple asphyxiant, or combustible dust, pyrophoric gas, or hazard not otherwise classified (29 CFR 1910.1200(c)). The HCS requires employers to provide employees with effective information and training on hazardous chemicals in their work area (see 29 CFR 1910.1200(h)(1)-(3)). Among the training an employer must provide is training on the physical, health, simple asphyxiation, combustible dust, pyrophoric gas hazards, and hazards not otherwise classified, and the measures employees can take to protect themselves from these hazards (see 29 CFR 1910.1200(h)(3)(ii)-(iii)).

You also mentioned that truck drivers who haul drilling wastes from gas extraction well sites are concerned about potential exposure to radioactive materials. Ionizing radiation is exempt from the HCS (see 29 CFR 1910.1200(b)(6)(xi)).  However, employers with employees working in a radiation area must comply with OSHA's Ionizing Radiation standard, 29 CFR 1910.1096, including instructing workers on precautions to minimize exposure (see 1910.1096(i)(2)).

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OSHA has developed additional resources regarding the identification and control of other health hazards encountered in the oil and gas production and hydraulic fracturing processes. These resources include: OSHA Hazard Information Bulletin: Potential Health Hazards Associated with Handling Pipe used in Oil and Gas Production (available at: https://www.osha.gov/dts/hib/hib_data/hib19890126.html) and Hydraulic Fracturing and Flowback Hazards Other than Respirable Silica (available at: http://www.osha.gov/Publications/OSHA3763.pdf*).