Sarah Merson looks into the growing incidence of latex allergy and how it can affect those who suffer from it.

Latex allergy can be a disabling, and even a life-threatening condition. Many will experience itching or swelling whilst others will have breathing, nasal or eye problems. When latex is in direct contact with the mucous membranes, some may even experience anaphylactic shock. According to the British Association of Dermatologists, the number of people suffering from latex allergy is unknown but the best estimate is that it probably affects less than 1% of the general population, but it seems to be on the increase.

Who suffers from latex allergy?

Latex allergy is more common in certain groups. These include those who have atopic conditions such as eczema, asthma and hay fever, children who have spina bifida, those who are subject to repeated exposure at their workplace (such as healthcare workers) and, especially, those have pre-existing hand dermatitis. Those who are allergic to fruits may also become allergic to latex.

Atopy

Atopy is a tendency whereby some become sensitised and produce IgE antibodies in response to ordinary exposure to allergens. Eczema, asthma and hay fever are common ‘atopic’ diseases, and atopy is common among people with latex allergy.

Constant exposure

Children with spina bifida have the highest incidence of latex allergy. This is because of repeated exposure of the mucous membranes to latex from operations and catheterisations. People who have undergone operations for other reasons may also be at increased risk.

Healthcare workers are especially prone to latex allergy, and it is in these people, and in children who undergo repeated surgical procedures, that the increase in the condition is occurring. This is thought to be caused by the general requirement for healthcare workers to use latex gloves to help prevent contact with body fluids during treatment procedures. This is required because of the increasing prevalence of blood-borne viral diseases such as hepatitis and AIDS.

According to the British Association of Dermatologists, studies among healthcare workers show a sensitisation rate (positive latex allergy tests) of about 10%. Many healthcare workers became allergic to latex in the 1990s when high protein, powdered latex gloves were in routine use.

Gloves and powder

Synthetic, polyethylene or vinyl, powdered gloves are now available, which generally cause no problems. However, there are sometimes complications and they don’t always provide the same barrier against infection. Glove powder which becomes airborne during the working day in the operating theatre may contribute to the asthma problems of latex-sensitive theatre nurses. It has been shown that the concentration of latex-coated starch particles increases during the working day in operating theatres when powdered gloves are used. This powder may not only cause latex-allergic people to react, but may also precipitate the latex allergy in the first place.

Ansell Healthcare Products has a continually expanding collection of both latex and latex-free examination gloves. The Micro-Touch® Nitrile E.P.® is a textured, all nitrile, powder-free examination glove. Ansell also offers the Affinity®, a textured, latex-free (polychloroprene), powder-free examination glove that is designed to provide the fit and feel of latex.

Regent Medical offers a deproteinised natural rubber latex surgical glove. The latex, powder-free Biogel Eclipse™ is made from highly-refined deproteinised natural rubber latex. Deproteinised natural rubber latex is the finished product of a patented process that's said to reduce extractable latex proteins in the raw material by 90%.

Hand dermatitis

Pre-existing hand dermatitis is another risk factor for latex allergy.

People with hand dermatitis often wear latex gloves in an attempt to protect their skin from chemicals or other hazardous materials, but because their skin is already damaged from the dermatitis, latex proteins easily penetrate the skin and sensitisation then becomes more likely. Hand dermatitis, and therefore latex allergy, is more common in atopic individuals, whose skin is easily irritated by soaps, detergents, oils and solvents.

Latex and fruit

About 40% of people who have latex allergy may also have an allergy to plant-derived foods, especially fresh fruit. This association is called the latex-fruit syndrome.

It occurs because there are proteins in some foods that are structurally similar (due to the sequence of their amino acid building blocks) to latex proteins. These can act as allergens in the same way latex proteins do. The foods that most commonly cause reactions in people with latex allergy are avocado, kiwi, banana and chestnut. There are however many other cross-reacting foods.

What exactly is latex and what do people react to?

Latex is the name for a type of gluey sap produced by many plants. The latex that comes from Hevea Braziliensis (the rubber tree) is the starting material used in the manufacture of rubber, which is used in thousands of products from household goods, to sports equipment and personal items.

Types of reaction

There are two types of allergic reactions to latex. One is to the latex protein, a natural component of rubber, which is known as Type I (IgE-mediated) allergy.

The other is Type IV (contact) allergy, more likely to be caused by the chemicals used in processing natural rubber products, than the latex itself.

How does sensitisation occur?

Sensitisation, an increasingly strong allergic reaction to the same amount of allergen over time, occurs when exposure to latex proteins causes the body's immune system to develop antibodies to these proteins.

Because the body perceives the latex protein as a threatening foreign substance, it prepares to launch a defence against it in future encounters using the antibodies it has created. Therefore, people may have been sensitised to latex without yet showing external allergic symptoms. They are, however, at risk of becoming increasingly sensitised and eventually symptomatic if exposure to latex continues.

Amongst theories as to the origins of latex allergy is the suggestion that sensitisation begins in newborns.

In a paper on the ‘Neo-natal sensitisation to latex’, former midwife, Jennifer Worth, hypothesises that latex allergy may be caused by the exposure of newborn babies to latex through skin and mucous membrane contact with pre-powdered latex gloves worn by midwives and doctors, and through the inhalation of latex- bound starch powder in the air of the delivery room.

The paper goes on to suggest that latex poses the greatest threat to premature and other babies in neo-natal intensive or special care units who are 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. ‘Neo-natal sensitisation to latex – a medical hypothesis’ is available from Action Against Allergy.

Latex and food service

One of the most recent realisations is that latex can be found in abundance in food service. As well as the use of rubber latex gloves in food preparation, wrappers and packaging used for a wide variety of foods contain hidden quantities of latex rubber.

Tests funded by the Food Standards Agency (FSA) on 21 types of packaging, last year, showed that a third were contaminated with latex, which in some cases was transferred to the food. The findings prompted calls for new labelling rules to ensure that consumers are aware of the use of latex in packaging across Europe.

Latest Research

A recent study in Clinical and Molecular Allergy Journal which looked at the immune response modulation by curcumin in a latex allergy model, suggests that the Indian spice is capable of reducing or suppressing the Th2 response induced in mice by exposing them to latex allergens. Whilst this shows great hope in terms of therapeutic value, further studies are called for.

See the next page for alternatives and for a list of the everyday items which may contain latex.

First published in 2007

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