Latex allergy still an issue for Hevea rubber growers?

31 October 2012 06:30 pm Views - 3804

by Dr. N.YOGARATNAM
It has been claimed that Russian dandelion (Taraxcacum kok-saghyz) and Guayule (Parthenium argentatum) performs like Hevea rubber but contains none of the proteins that cause latex allergies.


Latex allergy
It is a term that describes the range of allergic reactions to substances in natural latex. An allergy is a hypersensitivity disorder of the immune system. Allergic reactions appear when a person’s immune system reacts to nontoxic substances in the environment, in this case latex.

Latex can be natural or synthetic. It is found in the milky fluid that exists in about 10% of angiosperms (flowering plants).

 Latex is a complex emulsion (mixture of at least two liquids that are normally unblendable), consisting of resins, tannins, oils, sugars, starches, alkaloids, proteins and gums that go hard when exposed to air. Plants usually exude latex after there are injured, rather like a human bleeds after a skin lesion. Natural latex is usually white, but can be scarlet, orange, and yellow. Plants use latex as a defense against insects.

Rubber gloves are the main source of allergic reactions. Latex is also used in a wide range of products, such as condoms and some medical devices. Latex is used in over 40,000 products with many different uses.

 Examples of products we use that may have latex in them, include: Band-Aids (UK: sticky plasters),  Balloons, Blood pressure cuffs, Bottle nipples, Condoms, Catheters, Dental items, such as dams and orthodontic rubber bands, Diaphrams, Erasers, Rubber gloves, Helmets, IV tubes, Elastic waistbands in pants and underwear, Pacifiers, Rubber bands, Rubber cement (used in schools and offices), Rugs and bathmats, Shoes, Some articles of clothing, Some medical devices, Surgical gloves, Teething toys, Toys, Ventilator tubing and Watch bands. Not all the brands contain latex. People with allergies should check the labels, or get in touch with the manufacturer.

According to Medilexicon’s medical dictionary, an allergy is:”Hypersensitivity caused by exposure to a particular antigen (allergen) resulting in a marked increase in reactivity to that antigen on subsequent exposure, sometimes resulting in harmful immunologic consequences.”



What causes latex allergy?
The exact cause of latex allergies is unknown. It appears that repeated and frequent exposure to latex and rubber products may bring on symptoms in some people.

Since the late 1980´s there has been a dramatic rise worldwide in allergy to latex. A logical explanation is the use of universal precautions for preventing the spread of infectious diseases such as the AIDS virus. As a result, the use of latex gloves is nowadays widespread. Frequent exposures to latex and rubber products are common. Health care workers are at particular risk for latex allergy

.Allergic people’s immune systems identify latex as a pathogen - a substance or organism which harms health. Experts say that susceptible people react to a protein in the sap of the rubber tree. The immune system triggers cells in the body to produce IgE (immunoglobulin E); these are antibodies which fight the latex component. The next time the body comes into contact with latex, the IgE antibodies sense it and signal the immune system to release chemicals, including histamine into the blood stream. The more a susceptible person is exposed to latex, the greater their immune system is likely to be - this is called sensitization.



NR latex
Latex, as we know it for human use, is a natural product which comes from a fluid that is extracted from the rubber tree, Hevea brasiliensis.
During manufacturing this fluid is often modified. Different procedures are involved in the manufacturing process. Often, in the case of rushed production the latex product is not thoroughly washed. As a result, more “free” latex is present on the surface. This “free” latex is responsible for a significant proportion of latex allergies.
The powder used in surgical gloves is a major problem. Latex easily sticks to the powder that is commonly used in surgical gloves. During use, the gloves frequently “snap” when we are putting them on or taking them off. This snapping sends the powder into the air. This powder often has latex stuck to it. Inhaled latex can be a serious allergic problem.



 Cross reaction
Some people who are allergic to latex may also be allergic to specific foods - this referred to as, Cross Reaction. When this occurs, the body’s immune symptoms responds in the same way, producing the same allergic symptoms as would occur with exposure to latex.

Cross reactions are not the same for all people. While some people react to all foods known to cause a cross reaction, others may not. In the same way, if you are allergic to any of the foods listed below, you might also be allergic to latex: Some fruits - strawberries, pineapple, pears, nectarines, cherries, passion fruit, papaya, melons, grapes, figs, plums, peaches, kiwi, bananas, and apples; Vegetables - tomatoes, avocados, celery; carrots, and raw potatoes ; Some nuts - hazelnuts and chestnuts and some Some cereals - rye and wheat

Anybody planning to undergo a medical procedure should tell their doctor if they are allergic to any of these foods. There is a risk they may have a cross reaction to latex. (Resources; American Latex Allergy Association)



Protein in latex
Like all plant materials, Hevea latex contains proteins. Of the approximately 1% of total proteins present in the latex system, about one-quarter are found on rubber particle surfaces (i), the remaining three-quarters are in the non-rubber phase [fractions (ii) and (iii)] of the latex, and they are mostly water soluble. When processed into latex concentrate, considerable amounts of the soluble proteins are removed. Further conversion of the latex concentrate into gloves removes more of these proteins through the leaching and washing steps. Therefore, the remaining levels of soluble proteins - or the residual extractable proteins implicated in allergic reactions - are markedly low. Depending on which manufacturing process is used, the level of residual extractable protein can vary widely.



Latex Allergens
Not all proteins in the residual extractable fraction cause the allergic reaction. Although to date 13 proteins (mostly soluble) in raw Hevea latex have been reported to be possible allergens as defined by their display of IgE antibody binding activities, it is unlikely that all of them would be present in the finished products after processing.
It is noteworthy that individuals with sera showing binding of IgE to latex proteins are not necessarily latex allergic. The binding could be due to cross-reactivity with other plant proteins with certain similarities, suggesting shared or common antigenic components among proteins from latex and foods. A study of binding patterns of IgE antibodies from the sera of individuals who were not latex allergic but who had reactions to fruits supported this. The findings also showed that multiple bindings occurred between latex serum proteins and IgE from many who reacted to extracts of fruits but not to latex gloves. On the other hand, more specific and fewer bindings to latex protein by those who skin tested positive to latex glove extracts were generally observed.



Protein Reduction - Produc Improvement
Residual extractable protein content of gloves can now be reduced from as high as 1,000-2,000 µg/g of gloves to a low of less than 50 µg/g using improved manufacturing technologies, which include:

•     Chemical or enzymatic deproteinization
•     Use of low-protein latex concentrates
•     Proper leaching protocols
•     Chlorination
•    Polymer-coating

Although natural latex is the best product available for price and performance, bad reputation and litigation potential has caused customers to shy away from it and look for more expensive and mostly inferior substitutes. Obviously many efforts were made to dispose off the proteins, however protein traces may still remain and cause irritation in sensitive people.

 Scientists after extensive research have suggested ways to eliminate the proteins with simple, elegant and inexpensive methods using some additives. The additive attaches itself to the rubber particle and substitutes the proteins. The proteins are then easily removed. All this has been performed on line, eliminating chlorination and/or extensive washing and handling of the products off line. There are many other technologies available now to overcome this problem.



Trade and global competition
There is a common belief in the Latex production sector that latex allergies are hyped up in some developed countries. One argument often advanced is that latex production workers in the producing countries do not become allergic, despite handling liquid latex in hot, sweaty conditions.
The counter-argument is that this comparison (health care workers {HCWs} in these countries -vs- plantation workers) is not valid, because of:

•  the powder coating on gloves which carries proteins into the lungs of health care workers,
• the number of gloves donned and removed,
• the fact that HCWs are exposed to gloves from many different manufacturers, with varying levels of protein and powder.

Nevertheless, the NR producers have their own mind-set: They honestly believe that this allergy issue is all about trade. They think that the multi-national glove producers are imposing ultra-strict manufacturing limits on gloves in order to drive smaller glove makers bankrupt and win back the market share they lost to local manufacturers in the 1980s and 1990s.

No matter how unwelcome this point may be, it is how the South-east Asian manufacturers (and some Europeans) see the issue. Cases of latex allergy are relatively uncommon in Europe and very uncommon in Asia. Perhaps it is only a matter of time before we get the pain that you have right now, but for the time being, this view seems to still remain very common in the glove and latex industry.

(The writer can be contacted at treecrops@gmail.com)