Selecting The Right Glove:
Understanding Latex Allergy And Glove Chemistry
By Edward Lehrman, MD (written ~August 29, 1996)
Over the past few years, there has been an increasing
incidence of allergic reactions among
health care workers
to latex medical gloves. Current estimates on the prevalence
of latex allergy among health care workers range as high as
17%. This is thought to be largely due to the institution of
universal precautions in response to the AIDS epidemic, and
the resultant dramatic increase in glove usage. A large body
of literature on this subject has built up in the allergy,
immunology, and nursing journals, but there have been
relatively few publications in the surgical literature,
so many surgeons and surgical subspecialists remain
relatively ignorant in this area. This review will
summarize the most important findings from this literature
from the point of view of the glove user (the surgeon and
nurse). A major theme of this monograph is that a latex
glove, like all medical devices, has benefits as well as
risks. There are potential side effects from this device,
and the surgeon needs to consider these in making his or
her choice of surgical glove. I hope to cover: You should understand what it is that you are putting
against your skin. It is important to consider the risk
of allergic sensitization when selecting gloves rather
than just choosing the lowest cost item available, or
simply relying on the hospital purchasing department to
make the appropriate choice for you. I am going to focus
on sterile gloves for use in surgery, but remember that
non-sterile examination gloves for use in the office are
important to evaluate as well.
What glove characteristics should we look for? There are several important considerations. First, gloves
offer barrier protection both for the health care worker and
the patient to guard against contact with blood, other body
fluids, and microorganisms. Latex has been in use for about
100 years, and has proven barrier protective capability. In
a series of studies, Korniewicz and co-workers9,10,11
have shown that vinyl gloves have higher leakage rates than
latex (less barrier effectiveness), and are therefore less
suitable for surgery. They reported that although both vinyl
and latex examination gloves provide protection to the user,
latex gloves maintain their integrity longer under in-use
conditions. The barrier effectiveness of synthetic rubber
gloves is not as well established at this time as for latex.
18 Second, a glove needs to be comfortable.
One should be able to don it (slip one’s hand into it) easily,
and then be able to perform surgery as if you weren’t even
wearing a glove at all. Again, latex excels - the synthetic
materials are frequently stiffer than latex, and less
comfortable to wear. Third, cost is important. Latex gloves are usually less
expensive than synthetic rubber gloves. So latex has substantial benefits as a material for surgical
gloves. What are the risks?
Latex Allergy A latex glove contains natural latex, cornstarch
powder frequently (added to help the surgeon don the glove),
and numerous chemicals, some of which will be discussed below.
These are foreign matter, and the human immune system sometimes
responds. There are 3 major types of reactions.
There are several groups of people known to be at increased
risk for latex allergy: patients who have had multiple
hospitalizations and been exposed numerous times to latex medical
products (especially patients with spina bifida), health care
workers, and workers in the rubber industry. Current estimates are
that 8-17% of health care workers become sensitized. The recent
emphasis on universal precautions, with a concomitant marked
increase in glove usage, is largely blamed for the increase in
allergy among health care workers. Atopic individuals (those with
other allergies or asthma) are at significantly greater risk to
develop latex allergy than the general population. It is
estimated that as many as 25-30% of atopic health care workers
may become sensitized. Another major issue is the cornstarch powder that has long
been used in latex gloves. Researchers have shown in several
papers3,4 that cornstarch powder binds the latex
protein in the surgical glove, which allows the antigen to
reach both the wearer’s skin more easily (when the hand becomes
moist during surgery) and the patient’s skin. Also, when the
surgeon both dons and removes the glove, cornstarch powder is
released into the air, and this becomes a significant source
of aerosolized latex protein that can sensitize health care
workers via inhalation. In a separate study done at the Mayo
Clinic,19 latex aeroallergen concentrations varied
from 10 to 208 ng/m3 in areas where powdered latex
gloves were used compared to 0.3 to 1.8 ng/m3 in
areas where powdered latex gloves were never or seldom used.
Donald Beezhold has also written that body sweat inside latex
gloves may make latex proteins soluble, allowing absorption
through skin and sensitizing the wearer.4 He has
reported that the amount of free latex protein that can be
extracted from powdered latex gloves is consistently higher
than the amount that is liberated from non-powdered gloves.
4,12 He has suggested that cornstarch powdered
latex gloves should be eliminated.2 Here is another thing to remember: not all latex gloves
are created equal. There are significant (sometimes
astounding) differences between manufacturers and product
lines in the amount of free latex protein that can be
liberated from the glove and the number and types of
chemicals used in glove production. Also, gloves can be
soaked after production to try to leach out the protein
and chemicals, and once more there will be differences
between manufacturers in how effectively these are removed.
There is literature that clearly shows that some brands of
gloves are more allergenic than others.21
How are gloves made? Now on to some material about rubber in
general and how gloves are made.1,14,15,20 This
will be brief - a more detailed review at a level that a
physician or nurse can understand is the article by Truscott.
20 In order to make a surgical glove, in addition
to latex, one needs water, vulcanizing agents, accelerators,
activators, blockers, retarders, anti-oxidants, preservatives,
odorants, colorants, stabilizers, and processing aids. In other
words, you need a veritable chemical soup.
CONTENTS
Selecting The Right Glove: Understanding Latex Allergy And Glove Chemistry
What glove characteristics should we look for?
Latex Allergy
How are gloves made?
Synthetic Rubbers
Synthetic Alternative Gloves
Conclusions
References
Selecting The Right Glove: Understanding Latex Allergy And Glove Chemistry
![]() Picture courtesy Madegom Ltda. |
Latex is a natural product. Rubber trees (Hevea brasiliensis) produce the milky, viscous liquid. The tree bark can be shaved so that the latex bleeds, and it is then collected. Unless treated with chemicals soon after collection, the latex tends to harden into a gum. It was named rubber by the British chemist Joseph Priestly, who noticed that it could be used to rub away pencil marks. |
Natural latex is a polymer - that is, it is a long molecule composed of many repeating smaller molecular units. The basic unit of the polymer is called isoprene (synthetic rubbers use different chemicals as the basis for creating the polymer). Charles Goodyear first discovered a process that made rubber commercially useful. The story is that he accidentally dropped a mixture of rubber and sulfur into a fire. This produced a material that was no longer sticky, and had many desirable physical characteristics. Goodyear named this process vulcanization, after Vulcan, the Roman god of fire and craftwork. Vulcanized rubber is stronger yet also more elastic than the starting material. The sulfur cross-links the polymer chains in the latex. You can stretch vulcanized latex, but the polymer chains then snap back so the product returns to its original shape.
Nowadays, latex gloves are not produced with sulfur and fire. But sulfur is still very important as the primary vulcanizing agent. Accelerators are chemicals that speed the cross-linking process, either by donating sulfur atoms or because they are soluble within the natural rubber and help to draw the sulfur into the rubber by binding with sulfur. The major accelerators (and these are very important because they all can cause type IV allergy) are: thiurams, mercaptobenzothaizoles (usually abbreviated MBTs), and carbamates.
A second group of chemical sensitizers is the anti-oxidants. These are added to decrease the rate of rubber degradation. A wide variety of chemicals are available - glove manufacturers primarily use substituted phenols.
It is important to realize that different gloves will have different chemicals in differing concentrations in the final product. Also, since latex is a natural product, there will be some variation in the protein content from one lot to the next.
One brief comment about the word hypoallergenic - ignore it. The FDA proposed regulations in the summer of 1996 (which are not yet finalized as of this writing) that manufacturers not be permitted to use this term, since there is no established safe level below which latex protein or glove chemicals might not be harmful.
Gloves are created by dipping forms (which look like hands) into vats of liquid latex and admixed chemicals. The latex glove then hardens on the mold - it is formed with what will ultimately be the inside of the glove (touching your skin) on the outside of the mold. Then the gloves, still on the mold, go through one or more rinses to leach out protein and residual chemical (better rinsing equals less residua). Finally, the finished product is stripped off the mold, packaged, and sterilized.
What about synthetic rubbers? Remember that most of the world’s natural rubber trees are found in tropical countries such as Malaysia. During World War II, the supply of natural rubber from the Far East was disrupted. This led to the development of synthetic rubbers. Various types of synthetic rubber are in production around the world today - the properties of the end product depend on the chemical that is used as the building block to form the final polymer. Much of the world’s synthetic rubber is made from styrene and butadiene, which are found in petroleum. For our purposes, here is a list of synthetic rubbers used in making non-latex surgical gloves and some of the brand names: |
Synthetic Rubber | Glove name | Manufacturer |
---|---|---|
Polychloroprene (Neoprene) | Duraprene | Baxter |
Dermaprene | Ansell | |
Biogel Neo-tech | Regent | |
Neolon | Maxxim | |
Styrene butadiene | Elastyren | Hermal |
Styrene ethylene butadiene | Allergard | J and J |
Tactyl 1 | SmartPractice | |
Synthesys | SmartPractice |
Even with synthetic rubbers, there are still numerous chemicals (carbamates, etc.) involved in manufacture. Once more, there will be differences from one manufacturer to the next. It is still possible to have a serious type IV allergic reaction (contact dermatitis) to a synthetic rubber. However, type I natural latex allergy does not occur in response to synthetic rubber and these gloves are therefore required when treating a patient with known type I hypersensitivity, or for the health care worker who has either become type I sensitized or cannot find a suitable latex glove because of type IV allergy.
Conclusions
Clearly, we need gloves that provide excellent barrier protection, surgeon comfort, and acceptable cost. I would add that the literature indicates that the ideal glove, if it is latex, should be powder free, very low in extractable latex protein, and have the smallest concentration and the fewest number of residual chemicals from manufacture 6,18 Even when considering glove selection from the cost side alone, the cost at the time of purchase is only one part of the equation. As Fay7 points out, failed (torn) gloves cost the hospital money for replacement and waste removal, and one needs to consider the very real costs of providing the more expensive synthetic gloves for workers who become sensitized to latex or the major costs of disability payments for those who become so seriously sensitized that they are occupationally disabled.8,18 The risk of serious allergic reactions in patients who are already sensitized to latex must not be overlooked.
Alternately, the surgeon might consider that perhaps the ideal surgical glove is a synthetic rubber, such as polychloroprene (Neoprene) or one of the copolymers that contain styrene and butadiene. But there are pitfalls to this approach as well. The barrier properties of nonlatex synthetic rubber gloves are not as clearly defined. The cost of the synthetics is greater. The user still needs to pay attention to the chemical composition of the glove, because dangerous type IV reactions are possible. And the surgeon who chooses synthetic rubber gloves should be prepared to potentially sacrifice on glove comfort, dexterity, and grip because the fit, feel, and elasticity of the synthetic materials differ from natural rubber latex.
Glove choice should also be appropriate to the situation. One should consider wearing non-latex gloves (such as vinyl) when the superior barrier protection of latex is not needed. So, for example, a very short (less than 10-15 minute) procedure with minimal prospect for blood or body fluid contact might be one for which a vinyl glove could be considered an acceptable choice. Non-latex gloves may also be appropriate for the nurse who preps the surgical site prior to the start of surgery if the patient’s skin is intact, making body fluid contact highly unlikely.
In addition, here are a few common sense reminders.13 Prior to use, medical gloves should not be stored under conditions of excess heat or light, nor be near sources of ionizing radiation, since this will cause more rapid rubber degradation. Health care workers should be sure to remove gloves promptly when completing a procedure, and then wash his or her hands after glove use to minimize skin contact time with potential allergens. Also, health care workers should avoid touching their eyes, noses, or mouths while wearing latex or immediately upon removing a latex glove, in order to avoid potential latex sensitization via these mucosal routes.
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Or check out the other articles in this series:
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