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Neonatal Sensitisation to Latex |
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A Medical Hypothesis
by
Jennifer Worth SRN, SCM,
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ABSTRACT
Babies born in delivery rooms of hospitals are exposed to latex through skin and
mucous membrane contact with prepowdered latex gloves worn by midwives and doctors, and through the inhalation
of latex bound starch powder in the air of the delivery room.
This paper examines the hypothesis that
they are at risk for latex sensitisation, and that part of the sharp increase of childhood asthma, eczema
and anaphylaxis in the past thirty to forty years may be linked.
These possibilities seem hitherto
unsuspected. In over seven hundred papers on latex allergy no mention of neo-natal exposure to latex
has been found. Even obstetric papers discussing the risks for an atopic mother (atopic-a tendency to
develop allergies) do not seem to anticipate any risk for the baby , who might also be atopic.
Latex
allergy is primarily regarded as an occupational hazard. This paper suggests that it is a hazard for
every baby handled by latex gloves at birth.
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The modern epidemic of allergic diseases is due to many, possibly thousands, of environmental and nutritional
allergens. Whilst recognising that there are many other possible causes for infant sensitisation, this
paper focuses specifically on latex and chemicals.
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Natural latex rubber is derived from Hevea brasiliensis. It contains many major and minor components,
some of which are powerful allergens (1). The chemicals used in manufacture, and chemical sterilisers
applied to the gloves can also act as contact allergens (1).
Allergic reactions to latex gloves involve
Type I and Type IV hypersensitivity reactions.
Type I - Immediate Reaction
This is an immunological
response to allergens which react with immunoglobin E (IgE) antibodies carried on the mast cells and
basophils. Symptoms include respiratory distress and asthma, rhinoconjunctivitis, itching of the skin,
swelling of the lips, tongue and throat, acute dizziness, abdominal pain, nausea, hypotension, anaphylaxis
(2). Type I reactions occur as an immunological response to latex proteins, through skin contact and
the inhalation of latex bound glove powder (1).
Type IV - Cell Mediated or Delayed Hypersensitivity
Antibodies are not involved, and the reaction depends on activated T- lymphocytes. Symptoms of contact
dermatitis result, including redness, swelling, thickening or cracking of the skin, and irritation (2).
Type IV reactions are caused by contact with the chemicals used in glove manufacture and contact with
the sterilising agents (1).
The most commonly observed clinical symptoms of latex allergy are asthma
and eczema.
The manufacture of latex rubber gloves
Surgical gloves have been used for most
of this century with little ill effects. Manufacture used to be simple, mainly involving boiling the
latex at high temperatures. The heat destroyed most of the natural proteins. Gloves were re- used,
and were sterilised between uses by boiling or autoclaving. This further destroyed natural proteins.
The gloves were supplied with no powder. Surgical gloves used to be made in the UK and European countries.
During the 1970s demand for gloves increased, and manufacture changed. Gloves became cheap, disposable,
and prepowdered. Chemical accelerators were added to the raw latex to speed up the manufacturing process,
and sterilisation by means of chemicals was introduced. Patenting laws protected firms from naming these
chemicals. It is difficult to discover what chemicals are used as they vary from firm to firm, and are
constantly changing.
Modern disposable gloves are pre-powdered and the released powder floats in
the air. Latex proteins have been shown to adhere to corn starch glove powder, thus creating a protein-polysaccharide
complex which can act as a potent aero-allergen (3). This will be inhaled by anyone in the vicinity,
and can cause acute inflammation of the lungs (3 and 4).
Newson and Shaw (5) have made a survey
of starch particles and latex proteins in the air of two hospitals. Concentrations of up to 3667 particles
per cubic metre were recorded in units where gloves were most frequently used. Rooms with no ventilation
showed the highest recordings.
Delivery rooms are small and frequently enclosed, but unfortunately
the survey did not include a maternity unit. (Personal communication from Dr. S. W. B. Newson.)
Exposure of the newborn to latex
The first hands to touch a newborn baby will be those of a midwife
wearing latex rubber gloves. The baby's skin will be handled all over, including sometimes a finger
placed in the mouth. The umbilical cord will be handled. It will be clamped and cut. Is it possible
for latex allergens to enter the blood stream via the umbilical cord? If pre-powdered latex gloves
are used, the air of the delivery room will contain latex bound starch powder; this will be inhaled by
the baby with its first breath.
In their early weeks of life, babies should be exposed as little as
possible to contact allergens, aero-allergens and chemicals, and for many years there has been evidence
linking early exposure with the development of allergic disease (6).
This paper has been criticised
by several immunologists and paediatricians on the grounds that the short period of time during delivery
in which a baby is exposed to latex, would not be sufficient to sensitise the baby. They point out that
in health workers, large doses of the allergen, over a long period of time, are necessary for latex allergy
to develop. But a new born baby is not an adult.
In 1977, E. E. Jarrett in Edinburgh showed, in newborn
rats, that IgE sensitisation occurs more easily following the administration of minute doses of parenternal
allergen than the administration of a large dose (7).
These experiments involved cows milk proteins.
There have been no similar experiments conducted to assess the level of latex protein required to sensitise
a baby. Until such experiments are conducted, and the findings published, no-one can say for certain
that a low level of latex exposure at birth would be insufficient to sensitise a baby.
No signs of
allergic reaction to latex have been reported in newborn babies. This is because at the time of sensitisation
(called the sensitising event) there are no symptoms. Sensitisation is acquired, and it is only on repeated
exposure that symptoms develop, starting weeks or years after the initial exposure.
Prematurity
Premature babies and other babies in neo-natal intensive or special care units are at the greatest risk
due to longer exposure to the latex allergens from gloves, and inhalation of aero-allergens. In addition
latex is used in the equipment of neo-natal intensive care units.
Incubators contain latex. Latex
mattresses or rubber sheets are often used. Syringe plungers, vial tops, respiratory face masks, catheters,
adhesives, and a great deal of other hospital equipment containing latex will be used, all of which will
increase exposure. A premature baby is usually bottle-fed, and the teat may be made of latex.
There
is a known link between lung disease and prematurity. Barnes et al. noted that:
"Prematurity is
a major risk factor for wheezing, which is the mildest form of chronic lung disease. Around 50% of very
low birthweight infants develop episodic lower respiratory illness in infancy." (8)
This appears
to be a relatively new phenomenon. Neither Conybeare on Asthma (1942) (9) nor Christie Brown on Prematurity
(1956) (10) refers to a link between asthma and prematurity. Something must have happened in the
care of premature babies during the past forty years to make prematurity a 50% risk factor in the development
of lung disease.
According to the National Eczema Society no figures are available about the incidence
of eczema in children who were born prematurely. However, the letter pages of its Journal contain a
high proportion of letters about babies with eczema who were also premature babies. This is anecdotal
evidence, which deserves further investigation.
Latex sensitisation may well be irreversible (1),
and sensitised individuals will need to avoid latex altogether. However, this is virtually impossible,
because many common household items encountered every day by the baby will include latex. This can
be in the cot and pram, the sundry items like sheeting, reins, clothes, toys, rubber bands, elastic.
Disposable nappies contain latex, and many health visitors today report chronic dermatitis or nappy
rash in babies. Contact of mucosal surfaces with latex is particularly liable to lead to latex allergy
(11). According to the customers' advisory service of Boots the Chemist, all dummies and about 40%
of bottle teats are made from latex. The antigens can be absorbed through the oral mucosa. If the mother
does not suspect that her baby has been sensitised to latex, and the possibility has not been suggested
to her, she will not attempt to provide a latex-free environment for her child. Nor can she be expected
to understand cross-reacting allergens.
Cross reactivity
Latex is derived from a plant,
and many every day plants seem to share a common allergen. Work is proceeding on identifying this allergen,
and there may be more than one.
Two known, specific cross-reactions occur with latex allergy:
1.
Food cross-reactions (12 - 20)
2. Plant and pollen cross-reactions (21)
1. Food
cross-reactions
Latex is very complex and exhibits about 200 distinct polypeptides, which are a
major cause of Type I sensitivity. Allergens cross-reacting with latex antigens are found in various
plant foods (13). Hevea brasiliensis is related to many tropical and sub tropical fruit trees and the
Brehler study of 1997 (14) identified fruit specific IgE antibodies in latex sensitive children, confirmed
by RAST. Specifically: papaya, mango, avocado, banana, chestnut, passion fruit, fig, melon, kiwi, pineapple,
peach, tomato. The November study of 1997 (12) identified the same fruit-specific IgE antibodies
in latex sensitive children, and found, in addition, sensitivity to apricot, grape, pear, apple, orange
and almond.
It is virtually impossible to avoid fruit when weaning a baby and, in any event, this
would be undesirable for nutritional reasons. Banana shares many common epitopes with latex (14).
Banana is nearly always given to a baby during weaning. The prevalence of eczema and asthma in children
have both increased markedly in the latter half of this century. The National Eczema Society and the
British Asthma Campaign both recognise food allergy and intolerance as being a contributory factor in
eczema and asthma, but both societies state that the problem is multicausal and inexplicable. An underlying
and unsuspected latex allergy, acquired at birth, might be a partial explanation.
Peanut allergy
Chestnuts and almonds are known to cross react with latex allergy (12, 14). Children who are allergic
to one type of nut are often allergic to other nuts, even though the nuts are not related botanically.
Most children with a nut allergy also react to peanuts, even though peanuts are not a tree nut, but
a legume (15). There may be a soya connection, as many children who are allergic to peanuts, are also
intolerant of soya (15). The British Asthma Campaign and the National Eczema Society both report that
soya is becoming an increasing problem factor.
Peanut allergy is important, because it is a common
cause of anaphylaxis, and fatal reactions occur (16). Its prevalence has increased substantially,
with one in two hundred 4 year olds now having this form of allergy (16, 17). In 1996 Dr. Pamela
Ewan of Cambridge stated that peanut allergy was known to occur before the age of three in 55% of children
with this condition, and during the first year of life in 17%, for which there was no known cause.
A study from France found that 8% of babies up to age 4 months had IgE antibodies to peanut allergies
(19). A study from Southampton last year found that 80% of children with peanut allergy reacted to
their first known exposure to peanut containing foods (20). This indicated that they were already
sensitised.
In spite of international research and speculation no cause has been found.
I suggest
that children who are allergic to peanuts might have been sensitised at birth to latex, and that peanut
allergy could be a secondary cross reaction. No research has been conducted in this field.
Pollen
and plant cross reactions to latex
Natural latex shares IgE epitopes with certain grasses and weed
pollens, specifically mugwort, ragweed, timothy grass, and birch (21). These are all common plants
in temperate zones, and produce a great deal of pollen. In children who react violently to pollen the
possibility of a cross reaction to an underlying latex allergy might be considered.
Hevea brasiliensis
is a euphorbia. This genus contains over 1000 species, of which more than 100 are native to temperate
zones. Most of these plants contain latex, a white juice which oozes from the stem, and which is highly
allergenic. Euphorbias are a common cultivated and wild plant, and a child exposed at birth to latex
might react on contact with the latex in most of these plants.
No research has been undertaken to
suggest that contact dermatitis to euphorbias is related to latex dermatitis, but the possibility deserves
examination.
A new classification of plants based on their DNA structure was published in November
1998. The foregoing paragraphs about cross reactivity to the hevea brasiliensis are correct by the new
DNA classification. (Personally checked by Dr. Mark Chase, head of molecular systematic studies at
Jodrell Laboratory, Kew Gardens.)
Chemicals
Part of the problem with environmental chemicals
is the process of synergism - the phenomenon in which the combined action of two or more compounds is
greater than the sum of the individual effects of each compound. Two chemicals, each of low level, in
combination may increase their toxicities ten- fold over each of the chemicals when separate, and three
chemicals may increase toxicities one hundred-fold.
The identity, numbers, and combinations of chemicals
used in glove manufacture are unknown, and the effects on humans are unknown.
Allergic reactions
to contact with the chemicals used in glove manufacture and the chemical sterilisers used on gloves are
well documented (1). The occupational hazards are widely recognized and warnings to staff are given
(22).
Searches by the Royal College of Midwives and the Royal College of Obstetricians (over two
hundred papers) have revealed no literature suggesting that a newborn baby migh also react allergically
to these chemicals, and no warning that babies should not be touched by these gloves.
Multiple chemical
sensitivity is a concept not widely accepted by the medical profession. Nonetheless, pollutants, most
of which are chemical, may interact with each other (23). There is now good evidence of widespread
chemical reactions. (24).
Discussion
Until about the 1950s most babies in the UK were
born at home. Gloves were expensive and re-used. They were boiled between each use. Many district
midwives of my generation can remember that frequently, especially in rural areas, gloves were not worn
at all. The drive for safer hospital delivery gained pace, and by the 1970s only 1% of babies were born
at home. Hospital midwives deliver 75- 80% of all births (Royal College of Midwives Information). Latex
gloves are always worn.
In the past 15-20 years the dangers of cheap pre-powdered disposable gloves
have been recognized, but although alternatives are available, they are over ten times more expensive.
These expensive gloves are generally reserved for doctors. Nurses and midwives usually have to use
the cheap ones. In 1992 the Nursing Times reported (25):
"It is not uncommon to pull from a box
glove after glove with holes or tears, or fingers stuck together or missing, before finding two usable
gloves."
All the while, latex bound starch powder will be flying into the air of the delivery room
where the baby will be born.
Allergists and immunologists, who have little knowledge of the day to
day practicalities of midwifery, may be unaware of the degree of exposure for a baby. Midwives and obstetricians
who are not trained in allergies, may be unaware of the process of sensitisation, particularly as the
baby shows no sign of an allergic reaction in the first few days of life.
Latex allergy in children
is considered to be rare, because only a few children show an immediate and obvious hypersensitive reaction
to latex. However, low levels of sensitivity may be latent, and not recognised without undergoing special
investigative procedure. The child who has asthma, eczema, or a history of anaphylaxis may be tested
for common allergens, such as milk or house dust mite, but testing babies or children for latex is rare,
because it is unsuspected.
Beyond the special case of children with spina bifida, in whom latex allergy
has been reported in up to 70% (26), there has been very little study of latex allergy in atopic children,
and there is no evidence on the means of sensitisation.
The Niggemann study of 1998 (27) of children
with urticaria, eczema, asthma and anaphylaxis, who are latex allergic, states:
"Medical history,
certain foods, pacifiers, mattress composition, toys, and socio-economic data proved not to be a significant
risk factor in latex sensitisation." (my italics),
and concludes:
"Besides the number of operations
and the atopic pre-disposition no other defining risk factors for developing sensitisation or allergy
to latex can be identified in children up to five years of age." (my italics)
The study only examined
children who were over one year of age, and states:
"It cannot therefore be excluded that there were
patients who were already sensitised at the age of one year." (my italics)
The report concludes:
"Latex allergy occurs in children with no known risk factor for latex sensitisation" (28).
Conclusion
In spite of international research, no-one has been able to explain why allergic diseases in childhood
have increased so much in the latter half of this century.
Epidemiological thinking today is that
early life exposure to allergen is more likely to lead to sensitisation than at any other time in life
(6). Researchers are examining the effects of many possible culprits: house dust mite, cows milk,
wheat, pollens, cat epithelium, and many more. Unless latex and the chemicals used in glove manufacture
are included, such research will be incomplete.
The upward spiral continues, and the number of atopic
children has more than doubled in the past ten years alone. One in five children now have either asthma
or eczema in childhood. Many babies today seem to be born with eczema or asthma, or to develop it within
a few days of birth.
Asthma and eczema are known clinical reactions to latex allergy, but it is possible
that other allergic diseases might be traced to the same source. Sensitisation to any allergen renders
the individual prone to hypersensitive reactions to other, unrelated substances, and the symptoms of
allergic disease can be manifest in any system of the body, including the brain.
Pre-powdered latex
gloves have been in use for about thirty-five years. A whole generation has been exposed to them at
birth, possibly sensitising many children who are now adults and having children of their own. It is
well known that the atopic tendency runs in families.
The questions must therefore be asked: are
babies sensitised and develop the atopic condition by exposure to a powerful allergen at birth? or
were they atopic in the first place and latex and chemical exposure at birth triggers the early development
of allergic disease?
The Niggeman Report (27) states:
"While it is well known that the atopic
disposition plays a key role in developing sensitisation and clinical symptoms to latex allergy, there
is no information about the beginning of sensitisation and the risk factors during the first years of
life." (my italics)
The evidence is in keeping with the hypothesis that neo-natal exposure to latex
from gloves worn at the time of delivery may be a significant sensitising exposure.
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The Way Ahead
Research
is needed. But more practical and more effective would be a ban on the use of pre-powdered latex gloves
in maternity units. I call upon the Royal College of Midwives and the Royal College of Obstetricians
to take action. Other groups such as the British Asthma Campaign or the Anaphylaxis Group could also
act. Self-help groups, such as these, which are usually run by lay people, can be very influential.
Thousands of babies have severe asthma and eczema in the first weeks of life. Anaphylactic reactions
are becoming more common. If there is the slightest possibility, even though it is unproven, that latex
exposure at birth could be partly responsible, these gloves should be removed from use in maternity hospitals
immediately. The risk is otherwise too great.
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JENNIFER WORTH is a retired ward sister and midwife.
She is author of Eczema and Food Allergy,
Merton Books 1997. (AAA Publications) ISBN. 1. 872560. 02. 4.
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Copyright Jennifer Worth
Enquiries regarding
reproduction of this essay in any form should be addressed to Action Against Allergy, PO Box 278, Twickenham,
TW1 4QQ.
This essay won a special award for outstanding merit 1998 Essay Competition.
Any proceeds
from the sale of this essay will go to Action Against Allergy.
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Action Against Allergy Note
We believe this hypothesis to be without
precedent. The author makes it clear that there is no proof to substantiate her theory, but its very
plausibility is compelling, and calls for research. The only real way to validate or disprove the theory
would be an epidemiological study, but in the first place review if necessary. Jennifer Worth has been
invited by the British Asthma Campaign to apply for a research grant. She has also been asked by the
Cochrane Airways Group, and the Cochrane Skin Group to undertake a systematic review study. For personal
reasons, she can undertake neither. Any research student who could follow up these offers is invited
to contact AAA, PO Box 278, Twickenham, London, TW1 4QQ
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