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Air Contaminants in Dentistry

June 21, 2019 2943

A dental practice that uses formaldehyde, glutaraldehyde or nitrous oxide must familiarize itself with the applicable regulations. The chemicals are all known air contaminants and employers must ensure occupational exposure does not exceed established permissible exposure levels (PEL) or short term exposure limits (STEL). If an employee expresses concern about the levels of an air contaminant, an employer must provide the employee with documentation that contaminant levels are within permissible limits. Permissible exposure levels for all air contaminants are listed in the California Code of Regulations, Title 8 Section 5155.

Formaldehyde

  • 0.75 ppm — Permissible exposure limit (PEL). The maximum permitted eight-hour time-weighted average concentration
  • 2.0 ppm — Short term exposure limit (STEL). A 15-minute time-weighted average exposure that is not to be exceeded at any time during a workday even if the eight-hour time-weighted average is below the PEL.

Cal/OSHA requires each employer in an establishment where formaldehyde is present to monitor employees to determine their exposure. The exception to this requirement is when an employer documents, using objective data, that the presence of formaldehyde or formaldehyde-releasing products in the workplace cannot result in concentrations of airborne formaldehyde that would cause any employee to be exposed at or above the action level (0.5 ppm calculated as an eight-hour time- weighted average concentration) or at or above the STEL under foreseeable conditions of use. Such objective data may

be available from the manufacturer of the sterilizing unit. An employer could also do initial monitoring. If initial monitoring indicates an exposure level higher than either of the above limits, steps to reduce it must be taken. Follow-up monitoring should be conducted every six months, and may be discontinued if two consecutive measurements, taken at least one week apart, record levels below the permissible limits. Refer to the excerpt from Title 8 Section 5217 below. (Reference: § CCR 5217)

Formaldehyde is a known carcinogen and its use must be reported to Cal/OSHA. Request a “Report of Use of Regulated Carcinogens” form via email at [email protected], or by phone at 916.574.2993. The form is not available on the agency’s website. (Reference: § CCR 5203)

Glutaraldehyde

  • 0.05 ppm – Permissible exposure limit (PEL). The maximum permitted eight-hour time-weighted average concentration

Glutaraldehyde solutions are used for cold sterilization and high-level disinfection in the dental and medical fields and the biotechnology industry. Employees should handle glutaraldehyde with care because health assessments indicate the solution can cause occupational asthma and skin sensitization responses such as contact dermatitis. Exposure related symptoms may include one or more of the following: shortness of breath, chest tightness, wheeze, cough, skin rash, hives, and irritation of the nose, throat, skin or eye. Other potential effects of overexposure to glutaraldehyde are headaches, nausea, asthma and allergic reactions.

Required hazard communication training provided to employees should address these health hazards and symptoms along with the measures taken by the employer to evaluate and control exposures that can include medical evaluations, exposure monitoring, ventilation systems, work practices and personal protective equipment. Inform employees of where to report possible health symptoms and where to ask questions, report concerns and receive information about the employer’s evaluation and control measures.

Recommendations to Minimize Airborne Concentrations

In light of current health information, CDA recommends the following precautions for those using glutaraldehyde:

  • Use steam sterilization when feasible to replace the need for cold sterilization or use disposable instruments.
  • Augment general ventilation by mechanically directing air movement away from the breathing zone of the individual responsible for sterilizing instruments and direct glutaraldehyde vapors away from areas where individuals pass through or gather. Portable fans may be used for this purpose. Care must be taken to ensure that air currents do not direct vapors to other portions of the work area that might affect other people.
  • Cover the holding tank and minimize the surface area by using a container that is narrow and deep with a tight-fitting lid at all possible times (except when emptying spent solution, mixing new solution and loading or unloading tools or instruments from the bath).
  • Mix solutions in a closed container instead of in an open bath to minimize vapor loss.
  • Use appropriate personal protective equipment such as nitrile gloves and chemical goggles when working around this chemical.
  • Provide emergency eyewash in close proximity to the cold sterilization mixing and use areas.
  • Select a sterilization area in the office, bearing in mind the need for good ventilation and isolation of the chemical use area from other activities. Rooms without mechanical or natural ventilation are not good options for sterilization areas because lack of ventilation will raise the airborne concentrations. In addition, areas situated away from foot traffic will minimize the chance of spills.
  • Provide local exhaust ventilation for items drying on work surfaces or while rinsing instruments after cold sterilization and at the lip of the cold sterilization bath when possible.
  • Minimize the number of times the cold sterilization container is opened and closed to minimize vapor losses.
  • Keep a glutaraldehyde spill kit in the office to neutralize spilled chemical minimize vapors and protect the environment should the chemical be released.
  • Discontinue use of glutaraldehyde for surface disinfection due to increased potential for skin contact and higher airborne concentrations.

As with all chemicals used in the workplace, be sure that staff reviews the manufacturer’s safety data sheet, which includes additional health and safety recommendations and chemical data.

Nitrous Oxide

  • 50.0 ppm – Permissible exposure limit (PEL). The maximum permitted eight-hour time-weighted average concentration

Effective scavenging equipment and periodic inspection of equipment should keep nitrous oxide exposures to within acceptable limits. Recommendations for the safe use of nitrous oxide in the dental office are included in articles published in the Journal of the American Dental Association:

  • Nitrous oxide–oxygen administration: When safety features no longer are safe. Donaldson, M., et al. JADA February 2012 143(2): 134-143
  • Evaluation of Two Nitrous Oxide Scavenging Systems Using Infrared Thermography to Visualize and Control Emissions. Rademaker, A., et al. JADA February 2009 140(2): 190-199
  • Nitrous oxide in the dental office. ADA Council on Scientific Affairs; ADA Council on Dental Practice JADA March 1, 1997 128(3): 364-365

Pregnant Employees

Once an employer is notified of a pregnancy, the first obligation is to assess the risks within the workplace for the pregnant employee. CDA recommends:

  • assessing the risks to which a pregnant woman, woman who has recently given birth, or woman who is breastfeeding is exposed and the length of the exposure;
  • informing any employee concerned with identified risks with information on the control/protective measures that will be put in place; and
  • determining the practical measures to be implemented in the workplace to protect against the risks.

Resources

The U.S. National Institute for Occupational Safety and Health (NIOSH) has online resources:

U.S. Department of Labor - OSHA

Air Contaminant Personnel Monitors

CDA does not endorse any one company that provides individual vapor monitors but provides this list for the convenience of members.