States typically regulate TENORM under their general radiation safety regulations.

Technologically Enhanced Naturally Occurring Radioactive Materials on Oil and Gas Sites

Radioactive decay of radium and radon may potentially expose oilfield workers to ionizing radiation.

The National Institute for Occupational Safety and Health (NIOSH) has identified several potential occupational health risks on oil and gas well sites. These include noise, silica, hydrocarbons, and also ionizing radiation hazards in the form of technologically enhanced naturally occurring radioactive materials (TENORM).

The ANSI/HPS N13.53-2009 standard Control and Release of Technologically Enhanced Naturally Occurring Radioactive Material (TENORM) defines it as "naturally occurring radioactive material disturbed or altered from natural settings or present in a technologically enhanced state due to past or present human activities and practices, which may result in a relative increase in radionuclide concentrations, radiation exposures and risks to the public, and threat to the accessible environment above background radiation levels." Oil and gas well drilling, with subsequent produced water, muds, and other wastes, can "disturb" these materials and release them to the above-ground environment. While  radioactive materials are not necessarily present in the soils at every well or drilling site, some areas of the country, such as Texas and the Gulf Coast states, are more likely to contain radioactive material. California, Utah. Wyoming and Colorado typically have much lower levels. It is estimated that approximately 30 percent of oil and gas wells produce TENORM, with amounts varying greatly from well to well.1

The primary radioactive materials in oil and gas drilling wastes are typically radium and radon gas. 2,8 Radium radioactively decays to radon gas--an odorless, tasteless, noble gas that is relatively non-reactive chemically. Radon then quickly decays (half life approximately four days) to produce radon decay products (radon daughters or radon progeny).2, 8 The decay of both radium and radon releases ionizing radiation in the form of alpha particle radiation. Unlike radon gas, the radon progeny are solids that typically adhere to atmospheric dust and aerosols. These particles can be inhaled and lodge in the lower reaches of the lungs. Subsequent decay of these progeny can expose the lung tissue to alpha radiation. Exposure to radon gas and its progeny in indoor air has been linked to lung cancer.3

TENORM on Oilfield Sites
Radon is released to the environment when the produced water, muds, and other wastes containing radium are extracted from underground reservoirs and placed in ponds or pits for evaporation, re-use, or recovery or are otherwise discharged. TENORM materials may also accumulate in slimes, sludge, tank sediments, and in mineral scale accumulations inside transfer pipes.

States typically regulate TENORM under their general radiation safety regulations. Several states, however (e.g., Texas, Oregon, Ohio) have specific NORM (naturally occurring radioactive materials) or TENORM regulations of which employers should be aware.4,5,6 These regulations appear to focus primarily on proper disposal of TENORM-contaminated materials.

Worker Protection
As noted above, radioactive decay of radium and radon may potentially expose oilfield workers to ionizing radiation. The following precautions should be taken to assist in minimizing exposure to TENORM-contaminated materials.2,7,8

1. Employees and contractors should be advised of the presence of this contamination and of procedures to minimize exposure.

2. Areas with detectible levels of NORM should be subject to radiological controls.

3. Direct skin contact with radioactive scale and solids should be avoided to the extent reasonably possible. Neoprene, PVC gloves should be worn to minimize skin contact.

4. Eating, drinking, smoking, and chewing should not be allowed in the work area where work is being performed on contaminated equipment or where contaminated soil is being handled.

5. Personnel should thoroughly wash their hands and faces after working with contaminated equipment, and before eating, drinking, or smoking and at the end of the day.

6. Only essential personnel should be allowed in NORM-contaminated areas.

7. If possible, openings on contaminated equipment should be sealed or wrapped in plastic. Work on contaminated equipment, such as cutting, grinding, sand-blasting, welding, drilling, or polishing, should be kept to a minimum.

8. Change out of potentially contaminated clothes and shoes before leaving the work site (i.e., before returning to the car, home, or office).

9. Do not re-use or bring home discarded equipment or material such as pipes, devices, bricks, rocks, or water.

10. If work requires any action that might produce dust or if loose contamination is suspected, the following additional precautions should be taken:

  • A respirator appropriate for radioactive particulates should be worn and activities should be conducted in well-ventilated areas to which access has been restricted.
  • Suitable coveralls and gloves should be worn.
  • Plastic ground covers should be utilized to the extent possible to contain contaminants and facilitate cleanup.
  • Gloves, respirators, coveralls, and rags should be decontaminated or placed in double bags, sealed, and held for proper disposal.

Because radon is a gas, it will disperse into the atmosphere upon release. Exposure may be reduced by avoiding:

  • Enclosed or confined spaces where the gas may accumulate
  • Areas where produced water or other waste materials are being agitated or aerosolized

As noted above, radon decay progeny are solids and usually attached to airborne dust particles. NIOSH-certified respirators with N95 filters or better when used with a respirator program complying with 29 CFR 1910.134 or similar regulations may help reduce the potential inhalation exposure to these particles.

Because radium is also a gamma emitter, radiation exposure may still occur without physical contact or inhalation of contaminated materials. Individual exposure will vary with site and job task. Therefore, employers may want to consult with a Certified Health Physicist® (CHP) to develop an overall radiation protection plan, including worker exposure assessments and controls that include personal protective equipment selection. The CHP also may be able to assist with determination of proper reuse or disposal of materials contaminated with TENORM. State radiation safety offices or the American Academy of Health Physics ( may be able to help identify CHPs in the area.

1. Industrial Sectors with TENORM. TENORM.COM and Gas Production Scale and Sludge (downloaded April 2014).
2. Radioactive Wastes from Oil and Gas Drilling, US EPA (downloaded April 2014).
3. Radiation Protection – Radon, US EPA (downloaded April 2014).
4. Oregon Health Authority, Public Health Division, Regulation and Licensing of Naturally Occurring Radioactive Materials (NORM) (downloaded December 2013).
5. NORM/TENORM Information Sheet--Ohio Department of Health (downloaded April 2014).
6. Railroad Commission of Texas--NORM Naturally Occurring Radioactive Material (downloaded April 2014).
7. Guidelines for the Management of Naturally Occurring Radioactive Material in the Oil and Gas Industry. Report 412, September 2008. International Association of Oil and Gas Producers.
8. Radiation Protection and the Management of Radioactive Waste in the Oil and Gas Industry--Safety Report Series # 34. International Atomic Energy Agency (2003).

This article originally appeared in the June 2014 issue of Occupational Health & Safety.

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