Management of occupational allergy to natural rubber latex in a medical center: the importance of quantitative latex allergen measurement and objective follow-up

When our employees began coming to the Occupational Health Service, Dermatology, and Allergy Clinics with symptoms of allergy to rubber gloves 12 years ago, the Mayo Clinic initiated 3 responses. (1) The Allergic Disease Research Laboratory adapted well-established technology to measure both the IgE antibody specific to natural rubber allergens, and by use of this IgE antibody, the allergens in rubber products and in the air of the workplace. (2) The Division of Allergic Diseases and Internal Medicine reviewed the prevalence and severity of the problem. (3) The Clinical Practice Committee appointed a multidisciplinary task force to implement measures to reduce exposure. The 3 sections of this article describe the Mayo Clinic's experience of successful control of this occupational health problem. Use of only gloves with low or undetectable allergen content greatly reduced the concentration of allergen in the work site, reduced the number of new cases of occupational allergy to rubber, and allowed individuals with latex allergy to work at their usual jobs.

Latex allergy: the perspective from the surgical suite

Latex allergy in the perioperative setting presents unique challenges to the health care system. Specific needs of the latex-sensitive patient are paramount, but consideration must also include the impact on health care workers vis-a-vis latex sensitization, environmental allergen control, and barrier protection against blood-borne pathogens. It has been well documented that the greatest source of latex aeroallergen in the surgical setting is latex gloves (both sterile and nonsterile). Levels of latex aeroallergen correlate strongly with use of high-allergen and powdered gloves, total number of gloves used, and the hours of activity in a given environment. A significant reduction in aeroallergen (>10-fold) can be achieved by switching to low-allergen gloves. Ready availability of and encouragement to use nonlatex alternatives when appropriate can further reduce exposure to latex allergens. Since 1998, the Food and Drug Administration has required all medical devices (or their packaging) that contain natural rubber latex to be so labeled. In addition, industry has responded with a host of latex-free products for use in patient care. This has helped eliminate a great deal of confusion about which products are safe for use with latex-sensitive individuals. However, despite significant efforts to educate the public and the health care industry regarding latex allergies, considerable misinformation persists. Provision of a completely latex-free environment in most surgical suites may be unrealistic, but every effort should be made to minimize the unnecessary exposure of patients and health care workers to latex allergens in this high-risk arena.

Primary prevention of natural rubber latex allergy in the German health care system through education and intervention

BACKGROUND

The development of occupational asthma and allergic skin reactions caused by natural rubber latex (NRL) allergy are risks for health care workers. There are few published studies to suggest that intervention programs to reduce exposure will lead to primary prevention of sensitization.

OBJECTIVE

This study assesses the effects of intervention to reduce the incidence of NRL allergy in personnel working in health care facilities insured by the German statutory accident insurance company for health care workers, Berufsgenossenschaft für Gesundheitsdienst und Wohlfahrtspflege, with approximately 3 million insured employees, by switching to powder-free NRL gloves.

METHODS

The timing of introduction of intervention strategies, such as education of both physicians and administrators, together with regulations demanding that health care facilities only purchase low-protein, powder-free NRL gloves are reported. We reviewed the annual numbers of reported suspected cases of NRL-caused occupational allergies and the amount and type of gloves used in German acute-care hospitals since 1986.

RESULTS

The purchase of powder-free NRL examination gloves exceeded that of powdered gloves for the first time in 1998. This only became true for powder-free NRL sterile gloves 2 years later in 2000. The incidence of suspected occupational NRL allergy cases rose until 1998 and has declined steadily since. There was a 2-year lag between the beginning of the decline in the purchase of powdered NRL examination gloves and the beginning of a decline in suspected NRL-caused occupational asthma cases.

CONCLUSIONS

Despite the effect of increased recognition of NRL allergies, education about NRL allergies in health care facilities combined with the introduction of powder-free gloves with reduced protein levels has been associated with a decline in the number of suspected cases of occupational allergies caused by NRL in Germany on a nationwide scale. These results clearly indicate that primary prevention of occupational NRL allergies can be achieved if these straightforward and practical interventions are properly carried out and maintained.

Management of natural rubber latex allergy

Issues of impairment, compensation, and disability are appropriately directed at health care workers with latex allergy and occupational asthma or anaphylaxis who may not be able to re-enter a work environment with ambient exposure to latex proteins. The following stepwise approach for managing a high-risk health care worker with natural rubber latex (NRL) allergy is recommended: (1) confirm the diagnosis of NRL allergy by using rational, validated methods; (2) justify cessation of further NRL exposure in the workplace; (3) determine whether there is impairment and disability resulting from NRL allergy; (4) advise employer and risk managers regarding the diagnosis and their responsibility to institute effective environmental interventions; (5) if accommodation efforts are unsuccessful, advise the worker to seek workers' compensation benefits and rehabilitation. Objective evidence of residual impairment caused by NRL-induced anaphylaxis or occupational asthma is often absent. Therefore, the physician must determine disability based on how work restrictions resulting from NRL allergy affect the worker's ability to perform current required tasks and duties. According to the Americans with Disabilities Act, the employer must make reasonable accommodations for an impaired employee. Therefore, an employee with NRL allergy and no objective evidence of impairment would not be considered to be disabled after successful interventions, which totally eliminate continued NRL protein exposure and the risks of work-related asthma and anaphylaxis.

Latex sensitivity: an industrial hygiene perspective

As a result of the increase in latex product manufacturing and use during the last 10 to 13 years, latex sensitivity has become an important health issue. Requests for evaluation and control of potential exposure to latex allergens have prompted questions about how to best sample surfaces and the air for the presence and concentration of latex allergens, a search for reasonable occupational exposure limits, and means and methods of control or remediation. In this article, evaluation of latex allergens on surfaces, in residual dust, and in the air is discussed. Interpretation and application of reasonable suggested occupational exposure limits and the need for additional research in this area are also discussed. Suggestions for control and remediation are based on successful programs and projects resulting in elimination of latex and residual latex allergens in health care settings. Measurement of latex allergens on surfaces and in the air and comparison with suggested occupational exposure limits are viable means of risk analysis, and control and remediation can be successful, permitting sensitized individuals to return to the workplace.

Allergic and latex-specific sensitization: route, frequency, and amount of exposure that are required to initiate IgE production

Quantitative data that documents human exposure-response relationships for IgE sensitization to allergens are limited. Although seemingly straightforward, documentation of exposure-response relationships can be difficult. Issues that are related to study design, allergen standardization, exposure assessment, and evaluation for sensitization can impact greatly on study results. Despite these issues, exposure-response relationships for sensitization to protein allergens have been documented in several occupational groups, which include enzyme-detergent workers, bakers, and laboratory animal workers. In general, atopy acts as an effect modifier in these settings, steepening the exposure-response relationship. Several studies suggest that the greatest risk for sensitization is within the first several years of exposure. For 1 allergen, the protease subtilisin, a short-term exposure limit of 60 ng/m(3) has been recommended by the American Council of Governmental Industrial Hygienists. With regard to natural rubber latex, exposure-related factors such as number of operations have been shown to be risk factors for sensitization of children with spina bifida. By contrast, fewer studies show exposure-response relationships for IgE sensitization of health care workers to natural rubber latex, and the area remains controversial. However, a recent cohort study that evaluated incident sensitization in dental hygiene students suggests strongly that, with sufficient exposure, employment in health care can lead to an increased risk of IgE sensitization to natural rubber latex.

Occupational asthma and rhinoconjunctivitis induced by natural rubber latex exposure

A number of reports indicate that occupational exposure to natural rubber latex (NRL) in health care workers can elicit symptoms of rhinoconjunctivitis with or without asthma in selected individuals who are sensitized. The prevalence or risk of NRL-induced asthma in relation to rhinoconjunctivitis is small in comparison with other forms of occupational allergic respiratory disease. The lower risk of NRL-induced asthma appears to be related to poor penetration of the allergen into the lower respiratory tract because of the relatively large particle size of allergen-bearing cornstarch particles. Because of a lack of large prospective studies, little is know about the incidence and natural history of latex-induced respiratory disease. Because of heightened awareness of NRL allergy and changing patterns in glove manufacturing and glove use, it is likely that the occurrence of NRL-induced occupational respiratory disease will decline and its natural history will change. Nevertheless, because large number of individuals are exposed to NRL in various occupations, the incidence, prevalence, and natural history of NRL allergy merit further monitoring.

Pilot study of short-term acceptability and breakage and slippage rates for the loose-fitting polyurethane male condom eZ.on bi-directional: a randomized cross-over trial

OBJECTIVE

To assess the short-term acceptability and functionality of the eZ.on condom compared with currently marketed latex (Gossamer) and polyurethane (Avanti) condoms. Method Healthy, sexually active volunteers aged 18-50 years, self-selected from among the UK population, were enrolled in a randomized cross-over trial. Participants were required to test six of each of three condom variants. Data were collected on structured questionnaires by means of postal and telephone contacts. Main outcome measures were breakage and slippage rates, and short-term user acceptability based on participants' ratings documented in end-of-study questionnaires.

RESULTS

Forty-three couples entered the study, of whom 37 tested the condoms on 512 occasions. There was no statistically significant difference in the clinical breakage rate between eZ.on (3.7%) and the comparator condoms (3.5% for Gossamer and 2.9% for Avanti). Complete slippage rates were similar for eZ.on (2.4%) and Avanti (2.9%). Gossamer had the lowest slippage rate (1.2%), but this difference was not statistically significant. User acceptability was similar for the three condom types; however, there was a trend for more participants to express dissatisfaction with eZ.on, including difficulties with putting on the condom.

CONCLUSIONS

No firm conclusions can be drawn from this pilot study, but our observations suggest that eZ.on may be an acceptable option for some couples unwilling or unable to use a latex condom.

Glove powder reduction and alternative approaches

This article addresses the role of glove powder in facilitating allergic reactions to natural rubber latex (NRL) and to the chemical additives in synthetic and NRL gloves as well as its role in eliciting postsurgical complications. Various dusting powders have been used historically to prevent gloves from sticking to each other and to facilitate donning. All have manifested adverse consequences for health care professionals and patients. Manufacturing methods for powder reduction and elimination are presented. The recently developed ASTM methods for the quantitation of powder on powder-free and powdered gloves are reviewed along with the new ASTM maximum powder limits for all medical gloves. Caution must be exercised when methods of protein and powder reduction are implemented to minimize the possibility of creating other adverse consequences.

Performance of latex and nonlatex medical examination gloves during simulated use

BACKGROUND

In response to the rise in latex allergies, gloves made from a variety of nonlatex materials have been introduced into the health care environment. To date, at least 1 study, by Rego and Roley (1999), has reported that both latex and nitrile medical examination gloves provide comparable barrier protective qualities. The purpose of our study was to determine the effects of glove stress, type of material (vinyl, nitrile, copolymer, latex), and manufacturer on the barrier effectiveness of medical examination gloves.

METHOD

A total of 5510 medical examination gloves (1464 nitrile, 1052 latex, 1006 copolymer, and 1988 vinyl) were divided into 2 groups: stressed and unstressed. Unstressed gloves were visually inspected and water-tested according to the Food and Drug Administration water-testing standards. Stressed gloves were manipulated according to a designated stress protocol, visually inspected, and then subjected to the same Food and Drug Administration water-testing standards.

RESULTS

Our limited sample size demonstrated that nitrile gloves had the lowest failure rate (1.3%), followed by latex (2.2%); vinyl and copolymer gloves had the highest failure rate (both 8.2%). With use of a logistic regression analysis adjusting for manufacturer and stress, latex examination gloves were found to be 3 times more likely to fail than nitrile gloves (odds ratio, 3.2; 95% CI, 1.37-7.50). Nitrile gloves were also found to fail significantly less often than vinyl or copolymer gloves (odds ratio, 12.60; 95% CI, 5.80-27.40).

CONCLUSIONS

Nitrile examination gloves are a suitable alternative to latex, whereas vinyl and copolymer examination gloves were found to be less effective barriers. Further research is indicated to determine whether nitrile gloves can provide effective barrier qualities during clinical use versus laboratory simulations.

Latex allergy: past and present

Although latex products have been in use for over a century, allergic responses to latex proteins have only been recognized as a serious health problem for the past 15 years. Latex allergy particularly affects two groups, health care workers (HCW) and children with spina bifida (SB). This manuscript provides a brief history of latex allergy, and a review of the following: the manufacturing process for dipped latex products, the 11 latex allergens that have been characterized and received allergen designations by the International Union of Immunological Societies, the methods used in exposure assessment, the epidemiology and clinical management of latex allergy, and the use of animal models in investigating mechanisms underlying latex allergy.

Occupational asthma caused by natural rubber latex: outcome according to cessation or reduction of exposure

BACKGROUND

The long-term effects of reducing exposure to latex in subjects with latex-induced asthma remain unknown.

OBJECTIVE

The purpose of this study was to compare the health and socioeconomic outcomes of subjects with latex-induced asthma before and after reduction or cessation of exposure to latex.

METHODS

Thirty-six subjects with latex-induced asthma as ascertained by specific inhalation challenges were investigated after a median follow-up of 56 months (range, 12 to 92 months). Initial and follow-up visits included use of a detailed questionnaire and measurement of the concentration of histamine causing a 20% fall in FEV(1) (PC(20)). At follow-up, information on employment, financial status, and quality of life was collected.

RESULTS

At follow-up, 16 subjects were no longer exposed to latex, whereas 20 subjects had reduced exposure. In the subjects who avoided exposure, asthma severity decreased from a median score of 8.5 to 3.5 (P =.001) and the median histamine PC(20) value increased from 0.4 mg/mL to 2.3 mg/mL (P =.002). In the subjects who reduced their exposure, asthma-severity score improved from 6.5 to 2.5 (P <.001) and PC(20) values rose from 0.5 mg/mL to 2.4 mg/mL (P <.001). Cessation of exposure to latex was associated with asthma-related work disability (69%) and loss of income (62%) more frequently than was reduction of exposure (35% and 30%, respectively).

CONCLUSION

Reduction of exposure to latex should be considered a reasonably safe alternative that is associated with fewer socioeconomic consequences than removal from exposure.

Occupational asthma in France: a 1-yr report of the observatoire National de Asthmes Professionnels project

Observatoire National des Asthmes Professionnels (ONAP) was created in 1996 by two French professional societies to estimate the incidence of occupational asthma and to promote preventive measures against it. Occupational and chest physicians were asked to report newly diagnosed cases of work-related asthma and reactive airway dysfunction syndrome (RADS), the information collected included age, sex, occupation, suspected causal agents and diagnostic methods. In 1997, 82.3% of 559 cases reported (64% males, mean age 36 +/- 13 yrs) involved occupational asthma, 4.7% RADS and 12.7% atypical asthma syndromes. Incidence rates (expressed as number of cases per million workers) showed a regional variation that ranged from 4 to 73 (national mean: 25.7). The most frequently suspected agents were flour (23.3%), followed by isocyanates (16.6%), latex (7.5%), aldehydes (5.5%), and persulphates (4.1%). Occupations at risk were bakers (23.9%), healthcare workers (12%), painters (9.1%), hairdressers (5.2%), wood industry workers (4.8%) and cleaners (3.5%). These results are compared to those of other systems set up in Europe and North America. Because of the considerable bias inherent in a surveillance system based on voluntary, reporting, the number of occupational asthma cases reported is probably lower than the real incidence. Nevertheless, the French National Observatory for Occupational Asthma encourages physician awareness of occupational asthma and provides an estimate of its incidence and aetiologies in France.

Tomato allergy in children and young adults: cross-reactivity with latex and potato

BACKGROUND

Several studies have shown that allergy to natural rubber latex is associated with cross-reactivity to certain foods such as tomato and potato. The objective was to investigate the clinical and immunologic differences between a group of patients with clinical allergy to tomato and latex and another which had only clinical allergy to tomato. We also aimed to assess, in vitro, the relationship of tomato and latex allergens, which could explain the cross-reactivity.

METHODS

Forty patients with histories of adverse reactions to tomato and IgE-mediated hypersensitivity were enrolled in the study. Tomato, latex, and potato components were analyzed by SDS-PAGE immunoblotting. CAP and immunoblot inhibition were used to study allergen cross-reactivity.

RESULTS

Patients from group A had a mean age of 13.2 years, and in group B the mean age was 21.7 years. In group B, 9/10 patients belonged to the latex-fruits syndrome. All patients of both groups tolerated potato. Immunoblotting patterns obtained with patients' sera from pool A showed IgE-binding bands to tomato ranging from 44 to 46 kDa and a triple band at 67 kDa. For latex, there was a strong binding at 44 kDa, and potato showed a strong band of 44 kDa and a 67-kDa triple band. In pool B, the binding to the band of 44 kDa in latex and tomato was more intense than in pool A. In pool A, immunoblot inhibition with potato allergen showed an intense inhibition of the three allergens (potato, latex, and tomato); with latex, inhibition was partial and with tomato, a complete inhibition of tomato and latex was observed, and a partial inhibition of potato. In pool B, the inhibition pattern followed a similar tendency to pool A. The CAP inhibition confirmed the high rate of cross-reactivity between tomato, potato, and latex.

CONCLUSIONS

In our study, tomato, potato, and latex showed a common band of 44-46 kDa probably corresponding to patatin. This protein could be implicated in the high cross-reactivity between tomato, latex, and potato observed in the immunoblot and CAP inhibition.

[Latex allergy. Diagnosis and therapeutic aspects]

In the last two decades of the 20th century, latex allergy has reached epidemic proportions. Epidemiological studies demonstrate that 3-25 % of health personnel is allergic to latex. The main risk groups are health workers, machine operators in latex factories, and children with spina bifida and urogenital anomalies. From the allergenic point of view, latex contains 240 peptides but approximately 50 are able to react to IgE. Latex elongation factor Hevdl is the relevant allergen in patients with spina bifida. Prohevein (hev B6) behaves as a major allergen, since it reacts to IgE in most of the sera of patients with latex allergy. The nature of latex is complex; it is an allergenic mixture that depends on chemical, immunological and epidemiological variables. Latex proteins show strong cross reactivity with several proteins from fruit and vegetable grains such as avocado, potato, banana, tomato, chestnut, and kiwi. In vivo studies have shown that class I chitinase from avocado and chestnut behave as major allergens in allergic patients with latex-fruit syndrome. The clinical manifestations related to the use of latex products depend on the type of exposure, the amount of the allergen, and individual variability. The most useful diagnostic method is the skin prick test. Several perioperative guidelines are recommended in patients sensitized to latex as well as various alternatives to rubber gloves. An increasing number of studies describe the efficacy of etiological treatment (immunotherapy), using different guidelines and routes of administration. These preliminary data encourage the hope that in the near future immunomodulatory therapy will be available to mitigate against the latex allergy epidemic.

Repeated latex aeroallergen challenges employing a hooded exposure chamber: safety and reproducibility

BACKGROUND

Bronchial, nasal, and conjunctival challenges are useful for clarifying discordant clinical history (Hx) and skin and/or serologic tests and in assessing semiquantitative changes in biologic sensitivity over time. The objective of this study was to determine the safety and reproducibility of repeated latex-allergen challenges with a hooded exposure chamber (HEC).

METHODS

The HEC system comprises a powered forced-air respirator with a fitted face shield and hood that uses glove-derived latex-allergen associated cornstarch particles (LAC) to expose simultaneously the conjunctiva, nose, and lungs. Serial control and incremental LAC challenges are conducted until an endpoint based on upper and/or lower respiratory tract symptoms and peak expiratory flow rates is reached. Six latex-allergic (Hx and puncture skin test [PST]- and 5/6 radioallergosorbent test [RAST]-positive) subjects were challenged on three separate occasions at least 2 weeks apart. Serial latex PST midpoints and serum anti-latex IgE by RAST were monitored at each visit and at a fourth follow-up visit.

RESULTS

All subjects responded to LAC, but not to air or control cornstarch administered as controls. All responses were confined to mild symptoms of allergic rhinoconjunctivitis and/or asthma that either resolved spontaneously or were reversed with inhaled albuterol. No subject experienced a systemic or delayed reaction. There were no significant changes in the endpoint LAC doses over the three challenge visits (P>0.2). The mean coefficient of variation for log2 endpoints within-subjects was 17.3+/-17.2% (SD). The serum latex-specific IgE was not significantly boosted by the three challenges (P>0.2). The concentration of latex extract necessary to produce an 8-mm wheal by PST was not significantly changed during the study (P>0.1), indicating that latex sensitivity was not affected by the repeated LAC exposures.

CONCLUSIONS

The results of this study indicate that repeated HEC latex-allergen challenges are both reproducible and safe, and do not increase latex sensitivity.