Luca Martinelli
Medical disposable gloves: structural
materials different from latex
Publication nr. 34 – 18th December 2013
1. FOREWORD
In the last few years we have observed a
sudden rise of irritant allergic and not allergic reactions, due to the use of
latex gloves.
Those are caused by the proteins that
constitute latex and by chemical additives.
Generalizing, latex allergies can be listed
as follows: contact dermatitis eczema, allergic urticaria, generalized
urticaria, angioneurotic edema, edema of the glottis, anaphylactic shock.
To latex another cause of allergy is
added: the powder used as lubricant.
It was in fact demonstrated that the
powder added into the gloves to fit them easily, can cause conjunctivitis, rhinitis
and bronchial asthma because it work as an aeroallergen: means of transport of
causative agent to respiratory tract.
Deproteinization, dust delete and all
the other solutions adopted have considerably helped to decrease the percentage
of the allergic reaction cases but the problem hasn’t been finally solved yet.
For this reason in time it has developed
the search of alternative materials which could permit the manufacturing of not
in latex gloves but with barrier performance and functional characteristics
that would come close as much as possible to the latex one.
1.1 Medical disposable gloves standards
Technical standards that give requirements
to manufacture correctly gloves are UNI EN seria 455 “Medical disposable gloves”.
UNI EN 455 part 1 (455-1) specifies the
requirements and gives the method to test the
medical disposable gloves to determinate the absence of holes;
UNI EN 455 part 2 (455-2) specifies the
requirements and gives method to test the physical characteristics of medical
disposable gloves, to guarantee an adequate
protection level for the patient and for the user from mutual
contamination, during their use.
UNI EN 455 part 3 (455-3) specifies the
requirements for the assessment of biologic safety of medical disposable gloves
and gives requirements for label and packaging of gloves. It gives also
requirements on disclosure of info related to test method used;
UNI EN 455 part 4 (455-4) specifies
requirements for medical disposable gloves shelf life and specifies also
requirements on disclosure of info related to test method used.
As we know, technical standards are
requirements of voluntary alignment that eventually become technical
requirements if expressly indicated in lows or regulations and that give the
presumption of conformity to statutory and regulatory requirements.
Apart from technical standards, that, as
we have seen, are voluntary alignment requirements, the medical disposable
gloves are medical devices. As such, they have to be compliant to minimum
security requirements prescribed by the law. This means that they have to
satisfy the applicable provisions of DL 24th February 1997, nr. 46. Implementation
of the 93/42/CEE Directive about medical devices, as amended by 25th January
2010 DL, n. 37, Implementation of 2007/47/CE Directive.
We recollect that when transposing a
European Directive to national, every member of a State could apply some more restrictive
requirements than the same Directive. For this reason, for conformity, the
referement law is always the national law of recepiments, not only the European
Directive.
Done this technical standards foreword,
when we buy a medical device put on the market with CE standards (which is a
conformity declaration), we take for granted that the disposal is compliant and
we don’t care about all the reference technical standards; what we mostly care
is the use that we have to do, the price and, todays more than ever, the
material with which the gloves are made.
2. THE MEDICAL DISPOSABLE GLOVE: DEFINITIONS
Before analyzing the materials
alternative to latex, we recollect what is a medical disposable glove.
2.1 Medical disposable glove
Medical disposable gloves are gloves for
use in medical field to protect the patient and the user from crossed
contamination.
2.2 Surgical gloves
Surgical gloves are sterilized medical
gloves with anatomic shape with the thumb placed in front of the palmar surface
of the index finger, instead of being flat, for use in invasive surgery.
2.3 Examination/procedure gloves
Examination/procedure gloves are
sterilized or not sterilized. They can have or not have anatomic shape, they
can be used to make medical visits, diagnostic procedures and therapeutic and
to manipulate medical contaminated materials.
2.4 Medical gloves long
We can find two types of medical gloves
long:
a) surgical gloves with a minimum
overall length of 300 mm;
b) examination/procedure gloves with a
minimum overall length of 270 mm.
2.5 Medical welded gloves; welded gloves
The medical welded gloves are made with
flat films of material, joint by welding or by other assembly techniques.
3. CONSTRUCTION MATERIALS ALTERNATIVE TO
LATEX
The most used materials used for
manufacturing gloves alternative to latex are: nitrile, vinyl, neoprene and
last in order of arrival but first for performance, the synthetic polyisoprene,
which maintains all the characteristics of latex, although in a slightly lower,
but it misses all the problems related to the latex one because it doesn’t
contain latex
3.1 Latex
Latex (NRL - Natural Rubber Latex) is the most elastic
natural material today known. It’s a substance extracted by “Hevea
Brasiliensis” (also called rubber tree). This tree is mostly cultivated in Asia
in sountries like Malaysia, Thailand, Indonesia, that not by chance are the
major producers of latex gloves.
Latex, simplifying, is made by water
65%, polyisoprene 33%, resins 2% and by protein 1,8%.
Its elastic capacity, its capacity to
return into original shape after subjected to pressure or elongation, its
adaptability to shape, in this case of the hand, are the main characteristics
for which latex has always been the favorite material to make gloves.
Unfortunately the numerous advantages
coexist with the phenomena of sensibilization and the allergies that the
protein of latex cause to man.
3.1.2 Advantages and disadvantages of
latex
As we have told before, one of the most
advantage of latex is its elasticity and capacity to adapt to shape. It has a
high tear strenght, good waterproof, bio-degradability so sustainable.
Among the disadvantages the most is its
potential to cause allergic reactions and irritations; we add also a poor
resistance to chemicals.
3.2 Nitril
Nitril (NBR - Nitril Butadiene Rubber) is
a synthetic material obtained by polimerization of è un materiale sintetico
ottenuto dalla polymerizzazione of Acrylonitril and Butadiene.
It’s wrongly called also synthetic
rubber for its capacity to imitate the elasticity of natural rubber and also
because the raw material, necessary to its manufacture, is in the liquid state.
They are widely used because they permit
to obviate the latex problems but even because they have characteristics that
make them resistent both to chemicals and mechanical stress.
They are more resistant to perforation
compared to latex and to other materials. They are also more resistant to
elongation.
Nitril gloves have chemical and
mechanical resistance characteristics and are suitable for contacts with acids,
greases and for food contacts, peculiarity that latex and vinil gloves don’t
have.
3.2.1 Advantages and disadvantages of
nitril
The most appreciable advantage of
nitrili s its capacity to reply the latex characteristics, surely with a good
resistance to mechanical stress, a good chemicals resistance and eligibility to
contact with food (in the case of dental is of little relevance).
Among the disadvantages we find a
limited sensitivity capability, this means that they don’t permit to act with
the same skill as a latex glove, causing also a certain fatigue in hand.
However we underline that after a few
minutes that you wear a nitril glove, the glove tends to conform to the anatomy
of the hand.
Certainly less important for the
salitary aspect are its not bio-degradability and then poor eco sustainability.
3.3 Neoprene
Neoprene gloves are made with a
chloroprene polymer (2-chlorine-1, 3-butadene). They offer a protection/barrier
similar to the latex one, thanks to a crosslinked film petroleum based.
This material permits a resistance to
perforation almost double than the latex one.
Neoprene has got a good resistance to
the most chemical solvents and acids, alcohols, caustics, detergents and
ketones.
Its form, which means the force to
stretch the glove, is quite similar to the latex one. Its degree of elasticity
gives al excellent wearability.
The comfort level is significantly above
Il livello di comfort è notevolmente superiore al nitrile e vinile.
3.3.1 Advantages and disadvantages of
Neoprene
Excellence resistance to chemicals, in
particular oils, fats, alkalis, chlorinated hydrocarbons and fluorinate acids.
Excellent tactile qualities and improved
resistance to aging, exposure to sunlight, ozone and weather.
In contrast, compared to other
materials, we have a low abrasion resistance to cutting and perforation and a
poor resistance to aromatic and axygentated solvents.
3.4 Vinyl
Vinyl gloves have wide distribution
because represent a good budget option.
They are made with PVC (Poly Vinyl Chloride), the same material as saliva ejectors, with the addition of plasticisers (mainly phthalates) needed to make them soft and moldable.
The mechanical strength of these gloves,
in comparison with latex, neoprene, nitril and polyisoprene gloves, is
significantly lower due to the low molecular cohesion of PVC (plasticizers
don’t chemically bind with PVC). Then the glove is less elastic and more prone
to breakage (also micro breakage) and then definitely less suitable for running
biohazard procedures.
In fact, despite the plasticizers used in vinyl to give elasticity, and therefore a good fit, vinyl stretches with difficulty, presenting a low elasticity and wide wrists, resulting in barrier-integrity high risk and fit.
For this reason it would be appropriate
to limit its use to short procedures in low biological risk situation, with no
exposure to blood, body fluids and/or chemicals.
Finally we report some publications that highlight cases of skin reaction due to chemical additives used in manufacturing process.
Vinyl gloves are used for food, but with the exclusion of foods containing fats and alcohol, as they cause the dissolution, and transfer of plasticizers into the food.
This poor resistance to degradation by chemicals, like alcohol used to clean work surfaces, makes them advised against, even for the cleanliness of areas to be decontaminated or to treat with aggressive substances.
3.4.1 Advantagesantaggi and
disadvantages of vinyl
The best advantage is its good
biocompatibility and its cost.
Disadvantages are very few. To the ones
already anticipated, we add that applying the “simulation of use” method, the
most of the studies shows that vinyl medical gloves have more problems of leak
compared to nitril or latex exploration gloves.
It was even demonstrated that barrier/protection against microorganisms of vinyl exploration gloves is lower than the one guaranteed by the nitril and latex ones.
It was even demonstrated that barrier/protection against microorganisms of vinyl exploration gloves is lower than the one guaranteed by the nitril and latex ones.
Moreover, vinyl gloves are to be avoided
in case of handling chemiotherapy drugs.
They are not biodegradable and so not eco
sustainable.
3.5 Polyethylene
Polyethylene (PE) is one of the most
cheap and common plastic.
It is not largely used in medical
practice because its use is hygienic: it prevents the direct contact between
the hand and what is touched by it.
Polyethylene gloves are manufactured by
dinking and heat sealing of the film.
It’s a plastic with excellent chemical
stability. For this reason it is often used as insulating. It is produced in
film intended for contact with food (bags and film).
High density polyethylene (HDPE) is more
rigid and hard compared to low density. It is used for cheap gloves.
Low density polyethylene (LDPE) is a
more ductile material. It is used for gloves that need a bigger sensitivity and
soft welding, as for exaple in medical field.
3.5.1 Advantages and disadvantages of
polyethylene
We can say that they are quick to wear,
cheap and can be in contact with food. Against they have a poor resistance,
they have welding and a very poor barrier.
3.6 Synthetic Polyisoprene (synthetic
rubber)
This materiali s still little known. It
is very suitable for medical use because it maintains all the latex glove
characteristics with few degrees of inferiority in the corresponding
properties, without having any track of latex.
Natural polyisoprene is the major component
of natural rubber (latex). Synthetic polyisoprene is made by synthesis. It is a
synthetic rubber manufactured imitating natural rubber, which is obtained,
industrially, by catalysis.
Nowadays new synthesis process permits
to have a degree of purity very similar to natural latex.
Polyisoprene gloves is the best one that
can compete with latex glove.
3.6.1 Advantages and disadvantages of
polyisoprene
The first advantage is surely the
absence of latex allergenic properties. It ha salso a high elasticity and break
resistance. Its elasticity permits a great manipulation. Practically, as
already told before, it has the same characteristics of latex glove, with
slightly lower performances.
The most sensitive disadvantage is the
cost, which nowadays is quite considerable compared to the latex gloves.
4. QUICK REFERENCE COMPARATIVE TABEL
Quickly resuming the properties and characteristics of gloves manufactured
with materials different from latex, we can see the following chart (Fig.1).
COMPARATIVE TABEL OF
FUNCTIONAL CHARACTERISTICS AMONG THE MAIN MATERIALS USED TO MANUFACTURE MEDICAL
GLOVES
(no polyethylene gloves are considered
in this tabel)
CHARACTERISTICS
|
LATEX
|
NEOPRENE
|
NITRIL
|
POLYISOPRENE
|
VINYL
|
Protection barrier
|
Excellent
|
Very good
|
Excellent
|
Excellent
|
Enough for short term use
|
Strenght/duration
|
Excellent
|
Very good
|
Excellent
|
Excellent
|
Sufficient
|
Elasticity
|
Excellent
|
Very good
|
Very good
|
Excellent
|
From sufficient to poor
|
Resistance
to perforation
|
Very good
|
Good
|
Excellent
|
Very good
|
From sufficient to poor
|
Fitting,
tactility, comfort
|
Excellent
|
Very good
|
Very good
|
Excellent
|
Sufficient
|
Chemical resistance
|
Good
|
Very good
|
Excellent
|
Good
|
Poor
|
Fig.1
5. CONCLUSIONS
In the last few years many allergies to
latex have been observed.
The reactions after the use of latex
gloves can be summarized as follows:
-allergy to latex protein;
-allergy mainly to latex chemical
additives;
-not allergic reactions that can become
a way to allergic reaction.
This phenomena moved the research of
alternative to latex materials.
Those materials are different one
another with barrier, fit and tactile sensitivity characteristics.
Thinking about a merely personal list we
can say that just after latex, the best material to use are the polyisoprene
gloves and then the neoprene and nitril ones.
The use of vinil gloves must be
carefully checked: it is supposed to be chosen when it is not necessary a sure
biologic barrier and for short term use only.
6. Bibliography
-Norma UNI EN 455-1:2002;
-Norma UNI EN 455-2:2013;
-Norma UNI EN 455-3:2007;
-Norma UNI EN 455-4:2009;
-DL 24 febbraio 1997, n. 46. Attuazione
della Direttiva 93/42/CEE, concernente i dispositivi medici;
-Dlgs 25 gennaio 2010, n.
37, Attuazione della direttiva 2007/47/CE;
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14 giugno 1993 concernente i dispositivi medici;
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