In the springtime, when people talk allergies, they’re usually talking about pollen. But there are other substances found in nature that can cause sneezing and wheezing and, in rare cases, more serious and even fatal reactions. Allergy to natural rubber latex, which is found in stretchy products such as condoms and medical gloves, as well as hard rubber items like pencil erasers, became increasing common during the 1990s. Proteins found in natural rubber latex can induce the formation of antibodies that travel to selected cells called mast cells. Upon re-exposure to latex, these cells release chemicals that cause allergy symptoms in sensitive people.
Because natural rubber latex gloves, particularly powdered gloves, can pose a serious threat to health care workers and patients who have been sensitized to natural rubber proteins, many health care institutions have switched over to synthetic gloves. And the use of these gloves is discouraged in other settings such as food service. But natural rubber latex gloves are still in use, and as people reach for protective gear amid fears of SARS and chemical weapons, it’s important to remember that latex poses its own dangers.
Robert Hamilton, PhD, professor of medicine and pathology at the Johns Hopkins University School of Medicine in Baltimore, was a member of the Latex Task Force at the Johns Hopkins Hospital. Below, Dr. Hamilton discusses natural rubber latex allergy and the efforts to minimize exposure to it.
What is latex?
Latex, also known as natural rubber latex, is a white milky substance. Most of the world’s rubber comes from the H. braziliensis tree, which is primarily grown in Southeast Asia. This plant, also known as the rubber tree, produces a particular latex that contains polyisoprene, which is essentially rubber.
When we say “latex,” I really think we need to focus on the term “natural rubber” because “latex” is also a term used by manufacturers to describe a substance which when put on a surface creates a single layer. Latex paint, for example, doesn’t contain natural rubber and therefore it poses no risk for exposure to latex allergic individuals.
What type of products is latex found in?
Most rubber products are one of two different types. One type is dipped rubber products, which are manufactured by a mold that is dipped into a vat of natural rubber latex. Dipped rubber products would include condoms, toy balloons and medical gloves.
The second type of product is a molded rubber product, where the latex rubber is allowed to harden, and then it is rolled out and the components are either stamped or cut out. Molded rubber products would be exemplified by rubber stoppers in pharmaceutical vials.
In terms of other products, you can find small amounts of natural rubber latex in some adhesives on Band-Aids, pencil erasers and rubber bands.
Why are people allergic to latex?
Natural rubber latex contains anywhere between 1 percent and several percent protein. It is the protein that causes the problem in terms of inducing IgE antibody (the antibody associated with allergies) and leading to allergic reactions.
The reaction severity relates to how much allergenic protein the individual is exposed to, how they’re exposed, how much allergen gets into either the nose or into circulation. Repeated exposure to an allergenic protein in an individual who is genetically predisposed to allergy disease will, in theory, induce higher levels of IgE antibody and make the allergy worse. It is tough to predict whether an individual will have a reaction or not.
What are different kinds of allergic reactions that people can have?
Latex allergy is like most other allergies. It can cause swelling and redness of the skin, a runny nose and watery eyes, and, in rare cases, a systemic anaphylactic reaction that can be life threatening. It is referred to as systemic because it can affect the organs, such as the respiratory tracts and the cardiovascular system.
An anaphylactic reaction occurs when a sensitized individual is exposed to a substantial amount of allergenic protein, either by inhalation or by injection. The allergenic protein gets into the system and can make it difficult to breath, and can lead to shock. The symptoms that one gets are identical to the anaphylactic reaction that occurs in an insect sting allergy or in a peanut-induced allergic reaction.
How common is the latex allergy in the United States?
There was an explosion of cases that sort of peaked in the latter 1990s. In the health care community, there are reports that put the prevalence of latex allergy at levels as high as 10 percent. Rates were also high among children with spina bifida, who had repetitive surgeries. The prevalence rates in some studies were as high as 40 percent.
The problem appears to be diminishing because individuals are taking action to minimize exposure to latex allergen in a health care setting. But defining cases clearly depends upon having good diagnostic methods and, at least in the United States, we do not have an US Food and Drug Administration-licensed diagnostic skin testing material and our blood tests for IgE anti-latex antibodies have been less than perfect.
How are latex allergies treated?
The first and primary method of treatment is avoidance. Avoidance needs to be viewed within the context of the individual’s life. Each individual case is a little different in terms of how one optimizes their avoidance practices, and precise guidelines can be provided by the individual’s allergist. But in general, the rule of thumb is that anyone who has a latex allergy and has to get medical care needs to find a physician and/or a dentist who does not use natural rubber latex gloves in their practice. That’s number one. And then, depending upon the relative degree of sensitivity, people have to be educated about the sensitivity. If the individual with the allergy is a child, for example, the parents have to educate the child and the school.
Although there are no allergy shots for latex, medications such as antihistamines, which are used to manage other allergies, can treat symptoms. If an individual has had a systemic reaction, they might carry an Epi-pen, which is a small, auto-injecting device of epinephrine. Epinephrine is given to reverse an anaphylactic reaction. If an individual feels they’ve been exposed, they can self-administer this epinephrine and then get themselves to a hospital. Again, latex allergic individuals should see their allergist for guidance on avoidance practices.
Can certain foods exacerbate a latex allergy?
There are certain proteins in natural rubber latex that are structurally similar to those found in certain foods like banana, avocado and kiwi. So an IgE antibody that would bind to a protein in natural rubber latex and can also cross-react or bind to a similar protein structure in a banana, avocado or kiwi. Blanket avoidance of these foods is not encouraged. Rather, selective avoidance should be conducted if the individual knows that they experience a reaction upon eating a particular food.
Are latex gloves used outside the healthcare environment?
The natural rubber latex glove has been used in food services. But there has been an effort to try to eliminate the use of natural rubber latex gloves in places where they’re really not necessary, such as in housekeeping and food handling, where they’re basically being used just to protect the hands of the individuals.
If an individual puts on a natural rubber latex glove that contains high levels of allergenic protein, and then they handle food, in theory, the allergenic protein can be transferred onto the food. Now whether the food with the allergenic protein on its surface represents a risk to an individual or not is the issue that’s in dispute.
Latex gloves can be used in other settings as well. For example, we had a farmer from a rural area of Baltimore who bought natural rubber latex gloves from the pharmacy down the street and used to wear them in the field to keep his hands clean. There was really no need for him to use latex gloves but those were what he had available. He managed to sensitize himself and when he went into surgery, he had a very severe reaction to the surgeon’s gloves. So any area where a natural rubber latex glove is not necessary, alternatives should be used. These are equally cost effective and effective in terms of protecting the individual.
What is being done to reduce or eliminate latex exposure?
Most hospitals in the world ask patients whether they have allergic reactions to rubber products. That farmer, however, claimed three times that he had no problems with natural rubber products, and yet he had a systemic reaction when he was exposed. He later was shown to have a high level of IgE antibody in a blood test. So even individuals who may be sensitized may not know that they have an allergy.
There has also been a concerted effort on the part of many health care institutions in the United States and in the world to eliminate the highly allergenic, powdered latex examination glove and the sterile latex surgeon glove. In the early days, latex gloves were very cost effective. Today, the synthetic gloves, made with nitrile or vinyl, are effective and cost competitive.
Also, manufacturers of medical glove products who continue to make natural rubber latex gloves are taking steps to reduce the allergenic protein, and develop better methods of measuring the allergenic protein in rubber products.
What advice would you people with latex allergy about staying protected?
If someone makes the statement that they have a problem with natural rubber latex products, they should be taken seriously. Sensitive people should avoid exposure by minimizing your contact with anything that you know contains natural rubber.
It is difficult to know the severity of an individual’s sensitivity. It’s changing all the time depending on the person’s exposure. So people should just use common sense. Anything that has a stretchy rubber texture should be considered a question mark, even though it’s very difficult these days to know if it really actually contains natural rubber or synthetic materials.