CONTROLLING CHEMICAL EXPOSURES

The Lab Standard requires the employer to determine and implement control measures to reduce employee exposure to hazardous chemicals; particular attention must be given to the selection of control measures for chemicals that are known to be extremely hazardous.  There are three major routes of entry for a chemical to enter the body: inhalation, absorption, and ingestion.  Three types of controls for prevention of these various routes of entry include engineering controls, personal protective equipment, and administrative controls.  Each route of entry can be controlled in several ways, as explained below.

Inhalation Hazards

Inhalation of chemicals is the most common route of entry. To avoid inhalation exposures, hazard reduction methods such as substituting a less volatile or a less toxic chemical or substituting a liquid or solid chemical for a gaseous one is the best means of control.  If substitution is not practical, engineering controls such as ventilation should be used to lessen the chance of exposure.  The use of well-functioning local exhaust ventilation such as laboratory chemical hoods, biological safety cabinets, vented glove boxes and other local exhaust systems is often required to minimize exposure to hazardous chemicals.  Dilution ventilation may be used to reduce exposure to nonhazardous nuisance odors.  For extremely toxic chemicals such as those classified as poisonous gases by State or Federal agencies (e.g., arsine, phosgene), the use of closed systems, vented gas cabinets, fail-safe scrubbing, detection or other stricter controls may be required and would require prior approval.

If both substitution and engineering controls are unavailable, the use of personal protective equipment may be required to reduce inhalation exposures.  Respiratory protection from dust masks to self-contained breathing apparatus may be utilized to this end.  If laboratory employees wear respirators, requirements of the OSHA Respirator Standard (1910.134) must be met and a written respirator program must be implemented.  A respiratory program can be developed at https://ehs.uky.edu/ohs/respgate.php.  This Standard requires training on the proper use of respirators; medical surveillance to ensure the user can wear a respirator, and fit testing to ensure that the respirator fits properly.  A lab worker or his/her supervisor should contact the Occupational Health and Safety Department (257-3827) if respiratory protection is to be utilized to control exposures to hazardous chemicals.

In addition, the following principles should be utilized to reduce the risk of exposure to hazardous chemicals:

• Minimization of exposure time for individual employees
• Restricted access to an area where a hazardous chemical is used; and
• Proper signage on lab doors to indicate special hazards within.

Skin/Eye Contact Hazards

To reduce the risk of a chemical entering the body via skin and eye contact, use engineering controls such as substitution and appropriate ventilation as described above in Inhalation Hazards.  The more obvious means of preventing skin and eye contact is the wearing of personal protective equipment such as eye protection, face shields, gloves, appropriate clothing (long pants) and shoes, lab aprons, lab coats, and other protective equipment as appropriate to the hazard.  Since the chemical resistivity of the different types of protective equipment varies significantly, the lab supervisor should consult Appendix IV or other references to ascertain that the protective equipment material is resistant to the chemical being protected against.  Safety showers/eye wash equipment is required where corrosive chemicals are used.  Such equipment should be prominently labeled and not obstructed.

Ingestion Hazards

Ingestion of chemicals is the least common route of entry into the body.  However a Laboratory Worker can easily ingest chemicals into the body via contaminated hands if they are not washed prior to eating, smoking or sticking part of the hand, or a writing tool that has been in contaminated hands, into the mouth.  Some controls for preventing this route of exposure include engineering controls like isolating the hazardous substance so minimal contact is required (e.g., use glove box).  Also, administrative controls such as forbidding mouth pipetting, encouraging good personal hygiene and designating a well-marked nonchemical area where eating, drinking and the application of cosmetics is permitted.  And finally, personal protective equipment such as the wearing of gloves can reduce this type of exposure.

Exposure Assessment

At the request of faculty, staff or students, exposure evaluations may be conducted by OHS.  Records of exposure evaluations will be kept in the Occupational Health and Safety Department and provided to the department and affected employees and any other appropriate authorities at the University.  The following is a list of chemicals that require initial monitoring to determine exposures:

• Asbestos
• Vinyl chloride
• Inorganic arsenic
• Lead
• Cadmium
• Benzene
• Cotton dust
• 1,2-Dibromo-3-chloropropane
• Acrylonitrile
• Ethylene oxide
• Formaldehyde
• Methylenedianiline
• 1,3-Butadiene
• Methylene chloride

If you are using these chemicals in a process outside a fume hood, please contact OHS at 257-2924.