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"Safe" Protein levels.

Is it possible to identify a "safe" level of protein in latex gloves ?

The main problem at present is that we do not know exactly which proteins cause Type I allergy. Whilst TEP results can give a good indication of the likelihood of a glove causing a hypersensitivity reaction, Citation:Yip Turjanmaa Ng Mok 1994 there is a theoretical possibility of a glove containing extremely low levels of proteins, where all of those proteins are allergenic and likely to cause a Type I reaction. Conversely, it is also possible that gloves low in allergen content may be high in TEP (Yunginger et al Citation:Yunginger 1994 Allergy Clin Immunol reported such a case where non-latex protein was added to the glove during manufacture).

The Food and Drug Administration (FDA) in the USA stated in March 1995 Citation:FDA March 1995 interim guidance on protein content latex medical gloves that

"

Although there are insufficient clinical data to set a protein level that dramatically reduces the incidence of reactions to latex protein, there is scientific consensus that reduced protein levels will lower the potential for both sensitisation of non-sensitised individuals and allergic reactions in sensitised individuals.

" The FDA now have a policy of

  1. allowing manufacturers to label their gloves with a specified protein level (based on their maximum process level, not the average figure),

  2. making it mandatory for manufacturers who include TEP figures to also include a statement as follows (unless clinical evidence can be submitted to verify the claims):

    "

    Caution: Safe use of this glove by or on latex sensitised individuals has not been established.

    "

  3. not allowing products to be labelled with TEP levels lower than 50 micrograms per gram as this is the sensitivity limit of the ASTM Lowry test method (which is very similar to the proposed CEN method).

The FDA has also proposed a ban on the use of the term "hypoallergenic glove" until it is properly defined. Some manufacturers use the term to refer to the fact that their gloves may contain reduced levels of chemical additives, or the fact that they use carbamates instead of thiurams as accelerators. Even so, these gloves may contain the same or higher levels of TEP than gloves not so labelled. Citation:Keith Amsterdam 1996 Others base their "hypoallergenic" claim on the results of modified Draize testing Citation:Yunginger Allergy Clin Immunol 1994 which is not an appropriate measure of the the ability of a product to induce a human IgE antibody response. The Canadian Medical Devices Bureau have suggested that a level of 50 nanograms/gram of TEP would be required for a truly hypoallergenic latex device.

It is clear that TEP levels are useful in guiding purchasing decisions, but for the moment there is no consensus on a minimum acceptable level. This situation is likely to change in the future as the allergenic proteins are identified, which will enable the development of tests specific for the known allergens. Already there is good evidence for a number of "marker" proteins known to cause Type I allergies. Citation:Czuppon Allergy Clin Immunol Nov 1993 Citation:Akasawa Hsieh Lin Serum reactivities to latex proteins Allergy Clin Immunol 1995 Citation:Beezhold Sussman Kostyal Chang latex protein 1994

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Pete Phillips <pete@smtl.co.uk>