SECTION 6C: Controlling Chemical
Personal Protective Equipment (top)
Personal protective equipment (PPE) is special gear used to protect the
wearer from specific hazards of a hazardous substance. It is a last resort
protection system, to be used when substitution or engineering controls
are not feasible. PPE does not reduce or eliminate the hazard, protects
only the wearer, and does not protect anyone else.
PPE includes gloves, respiratory
protection, eye protection, and protective
clothing. The need for PPE is dependent upon the type of operations
and the nature and quantity of the materials in use, and must be assessed
on a case by case basis. Workers who rely on PPE must understand the functioning,
proper use, and limitations of the PPE used.
look very much like normal glasses buy have lenses that are impact resistant
and frames that are far stronger than standard streetwear glasses. Safety glasses with proper impact and shatter resistance will be marked "Z87" on the frame or lens. Safety
glasses must have side shields and should be worn whenever there is the
possibility of objects striking the eye, such as particles, glass, or
metal shards. Many potential eye injuries have been avoided by wearing
safety glasses. See Anecdotes for accounts
of a few of these incidents.
Standard streetwear eyeglasses fitted with side shields are not sufficient.
Workers who are interested in obtaining prescription safety glasses should
contact EHS at 8-5294. Safety glasses come in a variety of styles to provide
the best fit and comfort, including some designed to fit over prescription
Safety glasses do not provide adequate protection from significant chemical
splashes. They do not seal to the face, resulting in gaps at the top,
bottom and sides, where chemicals may seep through (see Anecdotes
for an actual incident where this occurred). Safety glasses may be adequate
when the potential splash is minimal, such as when opening eppendorf tubes.
Safety glasses are also not appropriate for dusts and powders, which
can get by the glasses in ways similar to those described above. Safety
goggles are best used for this type of potential exposure.
Chemical Splash Goggles should be worn when there is potential for splash
from a hazardous material. Like safety glasses, goggles are impact resistant.
Chemical splash goggles should have indirect ventilation so hazardous substances
cannot drain into the eye area. Some may be worn over prescription glasses.
Goggles come in a variety of styles for maximum comfort and splash protection.
Visorgogs are a hybrid of a goggle and safety glasses. They offer more
splash protection than safety glasses, but not as much as goggles. They
fit close to the face, but do not seal at the bottom as goggles do.
Face shields are in order when working with large volumes of hazardous materials,
either for protection from splash to the face or flying particles. Face
shields must be used in conjunction with safety glasses or goggles. A few
incidents where a face shield would have prevented injury are described
Contact lenses may be worn in the laboratory, but do not offer any protection
from chemical contact. If a contact lens becomes contaminated with a hazardous
chemical, rinse the eye(s) using an eyewash and remove the lens immediately.
Contact lenses that have been contaminated with a chemical must be discarded.
This particularly recommendation runs counter to what most of us were
taught previously. However, studies have shown that contact lenses
are safe to wear in the laboratory environment. For more information,
see the American
Optometric Association guidelines.
Protective Clothing & Footwear
When the possibility of chemical contamination exists, protective clothing
that resists physical and chemical hazards should be worn over street clothes.
Lab coats are appropriate for minor chemical splashes and solids contamination, while
plastic or rubber aprons are best for protection from corrosive or irritating
liquids. Disposable outer garments (i.e., Tyvek suits) may be useful when
cleaning and decontamination of reusable clothing is difficult.
(such as overlarge lab coats or ties), skimpy clothing (such as shorts),
torn clothing and unrestrained hair may pose a hazard in the laboratory.
Closed-toed shoes should be worn at all times in buildings where chemicals are stored
or used. Perforated shoes, sandals or cloth sneakers should not be worn
in laboratories or where mechanical work is conducted. Such shoes offer
no barrier between the laboratory worker and chemicals or broken glass.
Chemical resistant overshoes or boots may be used to avoid possible exposure
to corrosive chemical or large quantities of solvents or water that might
penetrate normal footwear (e.g., during spill cleanup). Leather shoes
tend to absorb chemicals and may have to be discarded if contaminated
with a hazardous material.
Although generally not required in most laboratories, steel-toed safety
shoes may be necessary when there is a risk of heavy objects falling or
rolling onto the feet, such as in bottle-washing operations or animal
Choosing the appropriate hand protection can be a challenge in a laboratory
setting. Considering the fact that dermatitis or inflammation of the skin
accounts for 40-45% of all work-related diseases, selecting the right glove
for the job is important.
Not only can many chemicals cause skin irritation or burns, but also
absorption through the skin can be a significant route of exposure to
certain chemicals. Dimethyl sulfoxide (DMSO), nitrobenzene, and many solvents
are examples of chemicals that can be readily absorbed through the skin
into the bloodstream, where the chemical may cause harmful effects.
Should Gloves Be Worn
should be worn when handling hazardous materials, chemicals of unknown
toxicity, corrosive materials, rough or sharp-edged objects, and very
hot or very cold materials. When handling chemicals in a laboratory, disposable
latex, vinyl or nitrile examination gloves are usually appropriate for
most circumstances. These gloves will offer protection from incidental
splashes or contact.
When working with chemicals with high acute toxicity, working with corrosives
in high concentrations, handling chemicals for extended periods of time
or immersing all or part of a hand into a chemical, the appropriate glove
material should be selected, based on chemical compatibility.
the Appropriate Glove Material
When selecting the appropriate glove, the following characteristics should
- degradation rating
- breakthrough time
- permeation rate
Degradation is the change in one or more of the physical properties
of a glove caused by contact with a chemical. Degradation typically appears
as hardening, stiffening, swelling, shrinking or cracking of the glove.
Degradation ratings indicate how well a glove will hold up when exposed
to a chemical. When looking at a chemical compatibility chart, degradation
is usually reported as E (excellent), G (good), F (fair), P (poor), NR (not
recommended) or NT (not tested).
Breakthrough time is the elapsed time between the initial contact
of the test chemical on the surface of the glove and the analytical detection
of the chemical on the inside of the glove.
Permeation rate is the rate at which the test chemical passes
through the glove material once breakthrough has occurred and equilibrium
is reached. Permeation involves absorption of the chemical on the surface
of the glove, diffusion through the glove, and desorption of the chemical
on the inside of the glove. Resistance to permeation rate is usually reported
as E (excellent), G (good), F (fair), P (poor) or NR (not recommended).
If chemical breakthrough does not occur, then permeation rate is not measured
and is reported ND (none detected).
Manufacturers stress that permeation and degradation tests are done under
laboratory test conditions, which can vary significantly from actual conditions
in the work environment. Users may opt to conduct their own tests, particularly
when working with highly toxic materials.
For mixtures, it is recommended that the glove material be selected based
on the shortest breakthrough time.
The following table includes major glove types and their general uses.
This list is not exhaustive.
||Offers the highest resistance to permeation
by most gases and water vapor. Especially suitable for use with
esters and ketones.
||Provides moderate abrasion resistance but
good tensile strength and heat resistance. Compatible with many
acids, caustics and oils.
||Excellent general duty glove. Provides
protection from a wide variety of solvents, oils, petroleum products
and some corrosives. Excellent resistance to cuts, snags, punctures
||Provides excellent abrasion resistance
and protection from most fats, acids, and petroleum hydrocarbons.
||Highly impermeable to gases. Excellent
protection from aromatic and chlorinated solvents. Cannot be used
in water or water-based solutions.
||Exceptional resistance to chlorinated and
aromatic solvents. Good resistance to cuts and abrasions.
||Resists a wide variety of toxic and hazardous
chemicals. Provides the highest level of overall chemical resistance.
||Provides flexibility and resistance to
a wide variety of acids, caustics, salts, detergents and alcohols.
to Find Compatibility Information
Most glove manufacturers have chemical compatibility charts available for
their gloves. These charts may be found in laboratory safety supply catalogs
such as Fisher Scientific and
Lab Safety Supply. Best
Gloves offers copies of their glove
compatibility charts upon request. To obtain a copy, call them directly
at 800-241-0323. Best Gloves also
has a great deal of information available on their web site, including a
downloadable glove selection program.
Most material safety
data sheets (MSDS) recommend the most protective glove material in
their Protective Equipment section. There are MSDSs for many laboratory
chemicals available on the web through the EHS home page.
EHS also has a computer program with glove compatibility information
for hundreds of chemicals. Contact EHS at 258-5294 for more information.
There are several factors besides glove material to consider when selecting
the appropriate glove. The amount of dexterity needed to perform
a particular manipulation must be weighed against the glove material recommended
for maximum chemical resistance. In some cases, particularly when working
with delicate objects where fine dexterity is crucial, a bulky glove may
actually be more of a hazard.
Where fine dexterity is needed, consider double gloving with a less compatible
material, immediately removing and replacing the outer glove if there
are any signs of contamination. In some cases, such as when wearing Silver
Shield gloves, it may be possible to wear a tight-fitting glove over the
loose glove to increase dexterity.
Glove thickness, usually measured in mils or gauge, is another consideration.
A 10-gauge glove is equivalent to 10 mils or 0.01 inches. Thinner, lighter
gloves offer better touch sensitivity and flexibility, but may provide
shorter breakthrough times. Generally, doubling the thickness of the glove
quadruples the breakthrough time.
Glove length should be chosen based on the depth to which the
arm will be immersed or where chemical splash is likely. Gloves longer
than 14 inches provide extra protection against splash or immersion.
Glove size may also be important. One size does not fit all.
Gloves which are too tight tend to cause fatigue, while gloves which
loose will have loose finger ends which make work more difficult. The
circumference of the hand, measured in inches, is roughly equivalent
the reported glove size. Glove color, cuff design, and lining should
also be considered for some tasks.
Inspection, Use and Care
All gloves should be inspected for signs of degradation or puncture before
use. Test for pinholes by blowing or trapping air inside and rolling them
out. Do not fill them with water, as this makes the gloves uncomfortable
and may make it more difficult to detect a leak when wearing the glove.
Disposable gloves should be changed when there is any sign of contamination.
Reusable gloves should be washed frequently if used for an extended period
While wearing gloves, be careful not to handle anything but the materials
involved in the procedure. Touching equipment, phones, wastebaskets or
other surfaces may cause contamination. Be aware of touching the face,
hair, and clothing as well.
Before removing them, wash the outside of the glove. To avoid accidental
skin exposure, remove the first glove by grasping the cuff and peeling
the glove off the hand so that the glove is inside out. Repeat this process
with the second hand, touching the inside of the glove cuff, rather than
the outside. Wash hands immediately with soap and water.
Follow the manufacturer’s instructions for washing and caring for
Proper Glove Removal
Gloves should be removed avoiding skin contact with the exterior of the glove and possible contamination. Disposable gloves should be removed as follows:
- Grasp the exterior of one glove with your other gloved hand.
- Carefully pull the glove off your hand, turning it inside-out. ............ The contamination is now on the inside.
- Ball the glove up and hold in your other gloved hand.
- Slide your ungloved finger into the opening of the other glove. ........ Avoid touching the exterior.
- Carefully pull the glove off your hand, turning it inside out again. .... All contamination is contained.
- Discard appropriately.
Gloves and Related Allergies
Allergic reactions to natural rubber latex have been increasing since 1987,
when the Centers for Disease Control recommended
the use of universal precautions to protect against potentially infectious
pathogens and HIV. Increased glove demand also resulted in higher levels
of allergens due to changes in the manufacturing process. In addition to
skin contact with the latex allergens, inhalation is another potential route
of exposure. Latex proteins may be released into the air along with the
powders used to lubricate the interior of the glove.
In June, 1997, the National
Institute of Occupational Safety and Health (NIOSH) issued an alert
Reactions to Latex in the Workplace (publication number DHHS (NIOSH)
Latex exposure symptoms include skin rash and inflammation, respiratory
irritation, asthma and shock. The amount of exposure needed to sensitize
an individual to natural rubber latex is not known, but when exposures
are reduced, sensitization decreases.
NIOSH recommends the following actions to reduce exposure to latex:
- Whenever possible, substitute another glove material.
- If latex gloves must be used, choose reduced-protein, powder-free
- Wash hands with mild soap and water after removing latex gloves.
Most laboratory equipment and operations do not produce noise levels that
require the use of hearing protection, with the exception of some wind tunnels,
as described below. Princeton University has a Hearing Conservation Program
in place for individuals who are exposed to noise levels equal to or exceeding
the OSHA action level of 85 decibels (dBA) averaged over eight hours, per
the OSHA Occupational
Noise Standard. This program includes workplace monitoring, personal
exposure monitoring, annual audiometric testing, use of hearing protection
and annual training.
Laboratory workers who would like to use hearing protection for noise
levels below the action level may do so without enrollment in the Hearing
Conservation Program. Using hearing protection, such as earplugs, earmuffs
or hearing bands, can improve communication or provide comfort to the
worker in a noisy environment.
The most common noisy equipment in the laboratories are ultrasonicators
and wind tunnels. EHS has measured noise levels of several ultrasonicators
used in the laboratories and found that noise levels were well below 85
dBA, averaged over eight hours. Some of the wind tunnels, particularly
the supersonic wind tunnels, are capable of very high noise levels. Users
should check with the principal investigator or EHS to determine whether
they need to be enrolled in the Hearing Conservation Program.
For more information about the Hearing Conservation Program, see Section
and Hearing Conservation, of the Princeton University
Health and Safety Guide. Contact EHS at 258-5294 to request
A respirator may
only be used when engineering controls, such as general ventilation or
a fume hood, are not feasible or do not reduce the exposure of a chemical
to acceptable levels. Since the use of a respirator is regulated by the
Protection Standard, respirator use at Princeton is subject to prior
review by EHS, according to university policy.
Any worker who believes that respiratory protection is needed must notify
EHS for evaluation of the hazard and enrollment in the Respiratory
Protection Program. This program involves procedures for respirator
selection, medical assessment of employee health, employee training, proper
fitting, respirator inspection and maintenance, and recordkeeping.
Use of a paper or cloth dust mask (left-most in above picture) is allowed without enrolling in the Respiratory Protection Program. However, if you believe you need to upgrade to a tight-fitting respirator, you must contact EHS prior. Tight fitting respirators are typically made of silicone or rubber and have filter cartridges or supplied air for breathing.
Self-contained breathing apparatus (SCBA) is available in E-Quad for use by
only trained individuals for changing out cylinders of highly toxic gases and
cleaning up chemical spills. They are not to be used for response to a fire.
Training is offered every Spring and Fall in E-Quad. Contact Brandon Chance (8-7882)
if you are interested and are not on the mailing list for this training.
For more information, see Section C4, Respiratory
Protection, in the Princeton University Health and Safety
7A: Safe Work Practices
6B: Fume Hoods and Laboratory Ventilation