Latex is a product of the Hevea brasiliensis rubber tree. A milky sap flows in lactifers under the surface of the bark, which is collected by making diagonal cuts in the bark of the tree. Natural rubber latex contains cis-1,4-polyisoprene (the major component), proteins, lipids, carbohydrates, and numerous inorganic constituents such as potassium, manganese, copper, zinc, and iron.4 Over 250 proteins have been identified in latex and about 30-60 of these are responsible for virtually all latex-related IgE-mediated immediate hypersensitivity (i.e., Gell and Coombs Type 1) reactions.4-6
Once the latex sap is harvested, ammonia is added to prevent autocoagulation and bacterial contamination.5,7,8 There are two types of ammonia-latex concentrates: high ammonia-latex concentrate (0.7% ammonia by weight) and low ammonia-latex concentrate (0.2-0.3% ammonia by weight). While the higher ammonia concentration is more effective in strengthening and stabilizing natural rubber latex, it also increases the incidence of latex glove-related irritant contact dermatitis.7,9
In order to enhance elasticity, the stabilized ammonia-latex concentrate is subjected to vulcanization, i.e., it is heated in the presence of sulfur. To reduce the time and temperature required for the process, numerous “accelerators” and “promoters” (e.g., thiurams, mercaptobenzothiazoles, and carbamates) are added. Residuals of these chemicals are primarily responsible for latex-related cell-mediated delayed hypersensitivity (i.e., Gell and Coombs Type IV) reactions such as allergic contact dermatitis.7-12
The incidence of latex allergy in the general population is 1 to 2%.13 Patients with spina bifida, because of repeated exposure of mucous membranes to latex products during various medical/surgical procedures, are at highest risk of latex allergy with a prevalence rate that ranges from 20 to 67%.13 Healthcare workers have the second highest risk of developing latex allergy with sensitization rates that are three times higher than in the general population.7,13-16
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