Epidemiologic Notes and Reports Occupational Asthma from Inhaled Egg Protein -- Iowa

In January 1984, workers at an Iowa egg processing plant requested an investigation by the National Institute for Occupational Safety and Health (NIOSH) of the causes of "asthma-like" symptoms (wheezing, shortness of breath, tightness in chest) believed to be work-related (1). This plant daily processes up to a million and a half raw eggs into powdered whole egg or powdered egg yolk and liquid egg white.

After an initial site visit in March 1984, NIOSH investigators returned in August 1984 for an environmental and questionnaire survey (Table 1). They sampled for total and respirable dust and for several chemicals because the original request had listed cleaners, sanitizers, and germicides as possible irritants.

Results showed employees' levels of exposures to dust near the American Conference of Governmental Industrial Hygienists' guideline of 10 mg/m((3)) for total dust. Dust samples had a 50% protein content and an amino acid composition resembling egg yolk protein.

Ninety-four employees completed a screening questionnaire covering demographics, occupational history, personal habits, past medical history, and symptoms suggestive of asthma. Based on self-reporting, respondents were divided into two groups: Group 1 was made up of employees (23) experiencing at least one of the following symptoms--wheezing, shortness of breath, or tightness in the chest--in the preceding month; Group 2 was made up of employees (71) who had not experienced any of these symptoms.

In March 1985, NIOSH conducted a follow-up medical evaluation consisting of pulmonary function tests, skin-stick tests for sensitivity to egg protein, determinations of serum IgE and IgG antibodies to egg protein (whole egg, egg yolk, egg white, and egg fractions), and physical examinations and clinical histories by a physician trained in internal and occupational medicine. Because of attrition and the reluctance of some employees to participate, only 19 employees--10 in Group 1 and nine in Group 2--underwent full examination.

Based on medical examinations and clinical histories showing temporal association with workplace exposures*, the physician diagnosed five employees as having occupational asthma. All five were in Group 1. Results of antibody and skin-stick tests were consistent with these diagnoses. Three of the five employees were nonsmokers, and the other two each had a smoking history of 5 pack-years**; one had a history of atopy. Based on the medical examinations and clinical histories of the other five employees in Group 1, the physician judged their symptoms as nonasthmatic; this was also consistent with laboratory results. Using a modified case definition of "wheezing temporally related to work" the investigators identified five additional cases from a re-examination of the questionnaires (overall prevalence = 10/94 (10.6%)).

NIOSH made specific recommendations for local exhaust ventilation to control egg dust during plant operations and recommended appropriate medical therapy for selected individuals (2). They also reported the problem to all other plants producing dried egg products in the United States, to the trade association representing the companies, and to major trade unions representing the workers. Reported by Hazard Evaluations and Technical Assistance Br, Div of Surveillance, Hazard Evaluations, and Field Studies, National Institute for Occupational Safety and Health, CDC.

Editorial Note

Editorial Note: Chicken egg white is a common allergen; ingestion may provoke pruritus in atopic individuals and exacerbation of atopic dermatitis, rhinitis, urticaria, angioedema, and bronchial asthma (3). Egg yolk also contains proteins antigenically related to proteins in egg white (4). A previous report of allergy to inhaled egg protein involved eight of 13 bakery workers who developed respiratory symptoms from spraying meat rolls with a 25% mixture of egg white and yolk in water. Four of these workers were atopic with increased total serum IgE levels; one had changes in pulmonary function consistent with reversible airway obstruction (5). The current investigation, by contrast, identified five asthmatic individuals at the egg-processing plant: four were nonatopic; all had evidence of IgE-mediated allergic reactions to egg protein; and only one had an elevated total serum IgE level.

Liquid egg products are dried at 23 plants in the United States. An estimated 1,600 workers may be exposed to powdered egg dust in this industry (U.S. Department of Agriculture, personal communication). Currently, no standard exists for occupational exposure to egg protein, and no generic standard has been established for occupational exposure to dust of organic origin. The only enforceable standard applicable to this situation is the Occupational Safety and Health Administration's nuisance dust standard of 15 mg/m((3)). By definition, nuisance dusts are presumed to be biologically inert (6). Consideration must be given to developing a strategy for controlling adverse health effects from exposure to powdered egg dust in this industry.

References

1. NIOSH. Health hazard evaluation report no. HETA 84-163-1657. Cincinnati, Ohio: National Institute for Occupational Safety and Health, 1986.

2. Gilman AG, Goodman LS, eds. The pharmacological basis of therapeutics. 7th ed. New York: McMillan Publishing Co., 1985.

3. Langeland T. A clinical and immunological study of allergy to hen's egg white--I: a clinical study of egg allergy. Clin Allergy 1983;13:371-82.

4. Langeland T. A clinical and immunological study of allergy to hen's egg white--IV: specific IgE-antibodies to individual allergens in hen's egg white related to clinical and immunological parameters in egg-allergic patients. Allergy 1983;38:493-500.

5. Edwards JH, McConnochie K, Trotman DM, Collins G, Saunders MJ, Latham SM. Allergy to inhaled egg material. Clin Allergy 1983;13:427-32.

6. American Conference of Governmental Industrial Hygienists. Documentation of the threshold limit values. 4th ed. Cincinnati, Ohio: American Conference of Governmental Industrial Hygienists, 1980. *First symptoms appeared after beginning work at the plant; symptoms abated on leaving the worksite; and symptoms reduced in frequency while at home, on days off, and on vacation. **One pack-year is the equivalent of smoking 20 cigarettes a day for one year.

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