1.4 Minimizing and Controlling Chemical Exposure
Occupational hygiene is the science devoted to the anticipation, recognition, evaluation, prevention, and control of environmental factors or stresses arising in or from the workplace which may cause sickness, impaired health and well-being, or significant discomfort among workers. This applies to all workplace hazards, including chemical exposures. Understanding the hazards of chemicals and how exposures can occur is critical to minimizing and controlling exposures. The recognized hierarchy of controls dictates that the elimination of a hazardous substance or its substitution with a less hazardous substance should be first approach. If elimination or substitution is not feasible, or does no completely eliminate a potential hazard, then engineering controls must be implemented to minimize the potential exposure hazard. If a hazard is not completely controlled following the implementation of engineering controls, then administrative and work practice controls must be employed, followed by the careful selection and use personal protective equipment in accordance with the University's Policy for Personal Protective Equipment in Research Laboratories.
1.4.1 Elimination and Substitution
Removing the hazard from the workplace is the most effective methods of minimizing exposure. Elimination of a hazardous substance from a process (aka “engineering out the hazard”,) or substitution of a hazardous substance with a less hazardous substance should always be the first approach in trying to minimize chemical exposures. The American Chemical Society Green Chemistry Institute and the USEPA’s Green Chemistry website are two resources offering information focused on minimizing the use and generation of hazardous substances.
1.4.2 Engineering Controls
If a chemical hazard cannot be eliminated, the next best strategy for its control is at its source with the use of engineering controls. Engineering controls are devices or actions that automatically isolate or physically limit exposure to a hazard, thereby reducing the risk to personnel. For this reason, engineering controls are often considered the “first line of defense” for reducing exposure to hazardous substances. Engineering controls must only be used as designed and not be modified unless appropriate testing and certification clearly indicates that protection of personnel will be equal to or greater than the original protection afforded by the control device.
The following is a summary of the most common engineering controls employed in academic research laboratories to control chemical hazards:
Chemical Fume Hood
A Chemical Fume Hood (CFH) is a device, integrated into the ventilation system of a laboratory, which serves to isolate airborne contaminants from laboratory workers by means of unidirectional, exhausted airflow. Typically considered the primary engineering control for hazardous chemicals in the laboratory, CFHs must be properly used and maintained to afford the user proper containment of hazardous airborne contaminants. For specifics on the proper use and maintenance of CFHs, please refer to the University’s Chemical Fume Hood Policy.
The following general guidelines must be observed when using a CFH:
- Use a ducted CFH for work with hazardous gases, volatile or potentially airborne hazardous substances, malodorous chemicals and OSHA Particularly Hazardous Substances, such as acute toxins, carcinogens, mutagens, and reproductive hazards.
- Avoid storage of materials in chemical fume hoods as it disrupts air flow, creating turbulence and the potential for exposure to airborne hazards.
- Work only within the sash height range certified by EH&S. Containment of airborne hazards cannot be assured outside of this range. Do not use a CFH unless it has been certified within the past twelve months by EH&S, which can be determined by observing the Fume Hood Certification sticker affixed to the hood.
- A fume hood that is identified as not functioning properly must be reported immediately to Facilities Operations (CUMC: 305-7367, Morningside: 854-2222 and LDEO: 845-365-8822) and a laboratory representative should place an “Out of Service-Do Not Use” sign on a hood. Do not use a CFH that is posted with an “Out of Service-Do Not Use” sign or is otherwise believed to be not functioning properly.
- Tip: Tape a Kim-Wipe to the bottom of the sash to verify the direction and qualitative force of the airflow.
Other Local Exhaust Ventilation
When hazardous chemicals cannot be used in a CFH, extractor arms/ventilation may be needed to minimize exposure. Extractor arms allow for capture and exhaust of hazardous substances close to the source of use, before their release into the laboratory environment. Although not as effective as a CFH, as CFHs have a high degree of containment, these devices, if properly designed and used, can be effective. These devices must be properly designed and installed to ensure their efficacy. Ventilated hazardous gas cabinets are another type of local exhaust ventilation, in which hazardous gases are stored and used to ensure segregation from the laboratory environment and ventilation of the hazardous gas(es) in the event of a leak.
A Glove Box is a sealed enclosure designed for the manipulation of high hazard substances in a safe manner. Built into its sides are gloves arranged to allow the user to place their hands into the gloves and perform tasks inside the box without breaking containment. The glove box is usually transparent to allow the user to see the materials being handled within. It is important to avoid wearing hand jewelry, watches or long nails or using sharp objects, such as needles, blades, etc., as they may puncture the gloves and breach containment.
1.4.3 Administrative Controls
Chemical labeling (see Section 1.2.4), training (see Section 1.8) and laboratory-specific standard operating procedures (SOPs) are the most common administrative controls in academic research laboratories. The Columbia University Guidelines for Laboratory Design, developed by the Columbia University Laboratory Design Work Group (LDWG), is an additional administrative control for the safe, efficient and consistent design of research laboratories. The Guidelines are primarily intended for the design and construction of new “wet” laboratories or renovations in which significant modifications will be made and where building systems and infrastructure are adaptable to the Guidelines. Although not primarily intended for “dry” or computational laboratories, components of the Guidelines may apply and should be incorporated in the design of these laboratories. The Guidelines do not take the place of code requirements or standards, but rather serve as a supplement in aiding the project team define and detail the scope of design.
Equipment Evaluation and Maintenance
Laboratory and emergency equipment shall be evaluated and maintained in accordance with regulation, University policy and, where appropriate, recognized industry standards. Refer to the appropriate sections of the Manual for equipment specific information.
Work Practices and Standard Operating Procedures
Adhering to proper work practices reduces the chance of occupational exposure to hazardous substances. Laboratory-specific SOPs should be developed by knowledgeable laboratory personnel and reviewed with all laboratory personnel to ensure a thorough understanding of the procedures. The Safety Rules and Policies noted in Prudent Practices in the Laboratory: Handling and Management of Chemical Hazards and those listed below can help minimize employee exposure to hazardous chemicals and should be employed in conjunction with laboratory-specific SOPs:
- Attend all required safety training courses.
- Establish and follow laboratory SOPs when conducting laboratory work involving hazardous substances or equipment.
- Never eat, drink, chew gum or tobacco, smoke or apply cosmetics in the laboratory.
- Select, use and maintain all personal protective equipment in accordance with the University’s Policy for Personal Protective Equipment in Research Laboratories.
- Store/segregate hazardous materials according to hazard class.
- Report unsafe conditions to a laboratory supervisor, PI and/or EH&S.
- Keep all work areas clean and uncluttered.
- Scale the size of the experiment and use the smallest amount of the material that is necessary for the work to be done.
- Remove gloves and wash hands and arms with soap and water after removing gloves and before leaving the work area or handling common items like phones, instruments, door knobs, etc.
- Properly manage and dispose of all hazardous substances.
1.4.4 Personal Protective Equipment
Personal Protective Equipment (PPE) represents the “last line of defense” against potential exposure. PPE should never be used as a substitute for proper engineering controls and prudent work practices, but only as an additional measure of protection once all other reasonable precautions have been taken. The University’s Policy for Personal Protective Equipment in Research Laboratories delineates requirements for the selection, use and maintenance of PPE in all laboratories where hazardous substances are stored or used.