Chronicle 10: Are You or Do You Think You're Allergic to Natural Rubber Latex?

August 12, 2022


Rubber Chronicles

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Yulex Natural Rubber Solid and Yulex Purified Latex have not been known to cause Type 1 Allergic Reactions.

Yulex is a material science and product company developing materials such as high performance foams, films and fibers from certified natural rubber - both solid rubber and liquid rubber (a.k.a. latex). We have decades of experience with natural rubber including expertise with our certified plantation partners, in our polymer development labs and in our factories.

A brief review of the types of allergic reactions to natural rubber products (latex or solid) are described below but first of all we'd like to clear some common misunderstandings about “rubber” (solid and latex).

First, When we refer to "latex" we are referring to the liquid form of rubber which is harvested directly from the rubber tree and processed as a liquid emulsion. Further, latex allergies refer to proteins in the latex and not to latex generally. So these terms have been and continue to be confused and misused.

Examples of products made from the latex include condoms, medical and household gloves, toy balloons, etc. Only about 12% of all natural rubber produced is kept in the latex or liquid form, the majority of natural rubber (~ 88%) is coagulated by various methods and converted into different grades of solid rubber which are then molded and vulcanized into rubber products.

Common products made from solid rubber include yoga mats, tires, wetsuits, outsoles for shoes, sport braces etc.

Second, all natural rubber products start from the natural rubber latex harvested from the Brazilian rubber tree (Hevea Brasiliensis).

Third, no “finished” natural rubber product actually contains natural rubber latex, because the latex is coagulated (made into solid) and/or is molded at high-temperatures and/or is vulcanized (treatment with sulphur and high heat) into solid rubber products. To state a product contains latex is incorrect although a product such as gloves can be made directly from latex versus solid rubber.

Fourth, the issue with latex allergies arose in the 1990s around the HIV infection pandemic when the Occupational Safety and Health Administration (OSHA) mandated the use of gloves from natural rubber latex if someone was going to be in potential contact with blood or bodily fluids (Universal Precautions). It was not known at the time that even small amounts of latex proteins would elicit a Type 1 allergic reaction. Latex protein allergies are dose related phenomenon. Everyone is different, so one person can immediately be sensitized while another person becomes sensitized after a few months or years. The Food and Drug Administration (FDA), the leading U.S. regulatory agency for protecting public health responsible for safety, efficacy, and security of human and veterinary drugs, biological products, and medical devices stated that during the 1990s about 16-18% of health care workers became sensitized to latex proteins. The healthcare industry then switched to synthetic rubber ("nitrile") gloves.

Fifth, "latex allergies" refers specifically to certain proteins found in natural rubber latex, because as you've already learned there are no products that contain liquid latex (only made from latex). Most medical and scientific articles refer to it as latex, which by definition is wrong, they are instead referring to the proteins from the latex which may reside in the product e.g. gloves.

Finally, high heat denatures proteins (any protein). Denaturing of proteins prevent or substantially reduce the risk of Type1 allergic reactions.  So when natural rubber latex is converted to a solid, and that solid to a closed-cell foam, the latex proteins have been exposed to high-temperatures 2-3x during processing and are denatured.  A good analogy is an egg, which uncooked is in a liquid form and when cooked turns into a solid. The egg proteins have been denatured. Some people who have egg allergies (usually to egg whites) can tolerate well-cooked eggs incorporated into foods (e.g. cakes).

What are the Types of Allergic Reactions Associated with Rubber Products?

Allergies occur when your body’s immune system sees a substance (protein) or an "allergen" as harmful and overreacts to it. The symptom is the allergic reaction. Allergens can get into your body in many ways (inhaling, ingesting, touching) to cause this allergic reaction. See the table of Latex allergens here.

There are 3 types of allergies to rubber products, or 3 ways that your body reacts. Type I is specific to natural rubber latex proteins, whereas Type IV and irritant dermatitis can be to both natural and synthetic rubber and not necessarily due to the natural rubber latex proteins.

1 - IgE-mediated allergic reactions (Type I)- the most severe and involves the immune system;

2 - Cell-mediated contact dermatitis (Type IV); and

3 - Irritant dermatitis.

In a Type I reaction, the body’s immune system makes antibodies called IgE antibodies that react with natural rubber latex proteins (allergens). In some people, this reaction can be severe (anaphylaxis). Reported data suggest that the average prevalence of natural rubber latex protein allergy worldwide remains 9.7%, 7.2%, and 4.3% among healthcare workers, susceptible patients, and general population, respectively. Maozong Wu et al. 2021, Current prevalence rate of latex allergy and why it remains a problem, J Occup Health. 2016 Mar 20; 58(2): 138–144.

A Type IV reaction is usually due to sensitivity to chemicals used to make the rubber products (natural or synthetic), rather than to the actual natural rubber latex proteins. There are many chemicals used in the manufacturing process, and any of these chemicals can cause contact dermatitis after exposure.

Irritant dermatitis, is NOT an allergy. It effects the top surface layer of the skin.

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