( Springer-Verlag 1997

Int Arch Occup Environ Health (1997) 69:487—490

OR IGIN A L A R TI C LE

Maija Hyto~ nen · Lasse Kanerva · Henrik Malmberg Rami Martikainen · Pertti Mutanen Jouni Toikkanen

The risk of occupational rhinitis

Received: 26 June 1996/Accepted: 16 October 1996

Abstract Objective Reports on the aetiology and risk of occupational rhinitis in different occupations are scarce. Method: The purpose of this study was to find the occupations with an increased risk of occupational rhinitis. Age and gender differences in occupational rhinitis and occupational asthma were also compared, and the most common causes of occupational rhinitis were analysed. Design: This study covered the cases of occupational rhinitis and asthma reported to the Finnish Register of Occupational Diseases during the years 1986—1991. The cases on the Register were linked to the longitudinal census data file from the Finnish censuses. Results: During 1986—1991, 1244 new cases of occupational rhinitis (747 women and 497 men) and 1867 new cases of occupational asthma (916 women and 951 men) were reported to the Register. Animal dander, flours, wood dusts, textiles, phthalic acid anhydrides and storage mites were important causes of occupational rhinitis. The highest relative risk of occupational rhinitis was among furriers, the age-standardized rate ratio (SRR) was 30.0. Bakers and livestock breeders had also a markedly elevated relative risk (SRR"22.0). Men had the highest incidence of occupational rhinitis at the age of 25—29 years and among women the incidence gradually increased and reached the peak in the group 40—44 years of age. Conclusion: Furriers, bakers, and livestock breeders had the most elevated relative risk of occupational rhinitis. Occupational rhinitis

M. Hyto¨nen ( ) · L. Kanerva · R. Martikainen · P. Mutanen · J. Toikkanen Finnish Institute of Occupational Health, Topeliuksenkatu 41 aA, FIN-00250 Helsinki, Finland. Fax: #358 9 2412414 e-mail: [email protected] H. Malmberg Department of Otolaryngology, Helsinki University Central Hospital, Haartmaninkatu 4E, FIN-00290 Helsinki, Finland

cases appeared at a younger age than asthma, suggesting that rhinitis often precedes asthma. Key words Asthma · Aetiology · Nose Respiratory-tract-diseases · Work-related

Introduction The reports on occupational rhinitis are usually case reports (Bernaola 1994; Kanerva 1988; Nilsson 1993; Oertmann and Bergmann 1995) or reports from a single workplace (Welch et al. 1995). Thus it is difficult to get on overall view of the aetiology of occupational rhinitis or to estimate the risk of an employee developing occupational rhinitis in various occupations. In Finland, the statistics on occupational diseases have been compiled since 1964 by the Finnish Institute of Occupational Health. Based on these statistics, a recent study sheds light on the frequencies of various types of occupational allergies in Finland (Kanerva et al. 1994). Most cases of occupational allergic rhinitis are caused by organic substances, but occupational rhinitis has been reported to be caused by some chemicals as well. The main causes of occupational rhinitis are animal dander, flours, wood dust, textile dust, food, spices, storage mites, enzymes, natural rubber latex, and numerous chemicals (Kup 1985; Delest et al. 1992; Hyto¨nen and Pekkarinen 1992; Slavin 1992; Kanerva et al. 1993). The prevalence of allergic rhinitis and asthma in the whole population has increased (Aberg et al. 1995; Howarth and Holmberg 1995; Rimpela¨ et al. 1995). In children and adolescents, atopy and asthma are more common among boys (Sears et al. 1993). In hay fever and perennial rhinitis, the ratio of affected males to females has been reported to vary with age, being highest among adolescents and diminishing with advancing age (Sibbald and Strachan 1995). Adult women

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report allergic rhinitis more often than men, but atopy defined according to skin tests to common allergens is similar in both genders (Charpin et al. 1988). A patient having allergic rhinitis has an increased risk of developing asthma, especially if the patient has bronchial hyperresponsiveness to metacholine (Braman et al. 1987). An asthmatic patient often has symptoms of rhinitis prior to his or her asthma symptoms (Gniazdowski 1979; Umeki 1994). However, the data on the incidence and connection of occupational rhinitis and occupational asthma in a population are very scarce. The purpose of this study was to find the occupations with an increased risk of occupational rhinitis. Age and gender differences in occupational rhinitis and occupational asthma were also compared, and the most common causes of occupational rhinitis were analysed.

Results During 1986—1991, 1244 new cases of occupational rhinitis (747 women and 497 men, 60.0% and 40.0%, respectively) and 1867 new cases of occupational asthma (916 women and 951 men, 49.0% and 51.0%, respectively) were reported to the Register. The total numbers of new cases of rhinitis and asthma in the different age groups and according to gender are seen in Figs. 1 and 2. The causes of occupational rhinitis during the years 1986—1991 are listed in Table 1. Occupations with the highest SRR of occupational rhinitis are shown in Table 2. Occupations with SRR'1 and also the lower limit of the 95% confidence limit *1 are listed. The number of cases in most occupations was too small for comparisons within one occupation in the

Material and methods This study covers the cases of occupational rhinitis and asthma reported to the Finnish Register of Occupational Diseases during the years 1986—1991. The Register was established at the Finnish Institute of Occupational Health in 1964. It obtains its information from two main sources. According to the Act on the Supervision of Labour Protection, a physician is obliged to report a case of occupational disease to the provincial labour protection authority. Notification of every new case reported to the insurance companies as an occupational disease, regardless of the compensation decision, is sent to the Register. Information from these sources is combined so that each new occupational disease is registered only once (Toikkanen et al. 1994). In Finland each employee has insurance, paid for by the employer, covering the costs of occupational disease. The patient gets compensated for medications, reduced salary, and retraining or re-education for an accepted occupational disease. Also the costs of medical examinations when occupational disease is suspected are paid regardless of the final diagnosis. This ensures that the system covers the suspected cases well. Nearly all the cases of diagnosed occupational rhinitis in Finland are of allergic origin. The diagnosis is based on patient’s symptoms and signs, skin prick or radioallergosorbent tests (RAST), and provocation tests. In order to compare the rate of occupational rhinitis in different occupations, a standardized rate ratio method (Rothman 1986) was used. The information was gathered and linked together from two sources. The basic source of information was the longitudinal census data file from the Finnish censuses in 1970—1990 (Tilastokeskus 1991). The cases of the Finnish Register of Occupational Diseases were linked to this longitudinal census data file. The base population (cohort) was defined using the information from the 1985 census. The cohort consisted of wage earners and farmers at the age group of 25—64 years in the end of 1985. The cohort was followed to the end of the follow-up period, i.e. to the end of 1991, or until a case of occupational rhinitis appeared, or the person turned 65 years of age, or died. The information on occupation originates from the 1985 census data. The relative risk of occupational rhinitis in different occupations is expressed as the age-standardized rate ratio (SRR) (Rothman 1986). The SRR is the directly age-standardized rate of the disease for different occupations divided by the rate of the standard population. In this study the whole cohort was used as the standard population. The relative risk of occupational rhinitis in different occupations is calculated from the age of 25 years on, as the occupational stability of younger employees is considered to be too low due to professional training for example.

Fig. 1 The number of cases of occupational rhinitis in various age groups reported to the Finnish Register of Occupational Diseases during 1986—1991

Fig. 2 The number of cases of occupational asthma in various age groups reported to the Finnish Register of Occupational Diseases during 1986—1991

489 Table 1 The causes of occupational rhinitis in 1986—1991 Cause Animal dander Flours Wood dust Textiles Phthalic acid anhydrides Storage mites Various organic material Formaldehyde Hairdresser’s chemicals Various chemicals Plants Food(stuffs) Natural resins Minerals Epoxy resins Diisocyanates Pharmaceuticals Moulds Natural rubber latex Acrylates Rubber chemicals Amines Welding fumes Amylase Unknown Total

No. of cases 513 295 56 46 35 34 37 25 23 21 19 15 13 12 9 8 8 7 6 5 5 3 3 1 45

% 41.2 23.7 4.5 3.7 2.8 2.7 3.0 2.0 1.9 1.7 1.5 1.2 1.1 1.0 0.7 0.6 0.6 0.6 0.5 0.4 0.4 0.2 0.2 0.1 3.6

1244

Table 2 Occupations with the highest risk of developing occupational rhinitis: Occupations with standardized rate ratio (SRR) '1, and the lower limit of the 95% confidence limit *1 are listed.

Furriers Bakers Livestock breeders Food-processing workers Veterinarians Agricultural workers Assemblers of electronic products Builders of wooden boats, coach-body builders Horticulturists Tanners and leather workers Textile dyers Metal foundry workers Hairdressers, barbers Cabinet makers, joiners Plywood and fibre board workers (Industrial) sewerage workers Housekeeping managers Butchers Chemists Cooks Sawyers Oil refinery workers Laboratory technicians

SRR

95% confidence limit

30.0 22.0 22.0 13.0 11.0 8.3 7.7

12.0—74.0 17.0—29.0 5.5—89.0 4.8—35.0 3.4—33.0 7.1—9.7 4.9—12.0

7.3 5.1 4.6 4.5 4.3 4.0 3.8 3.8 3.5 3.2 3.1 2.7 2.5 2.5 2.4 1.9

1.7—31.9 4.3—6.2 1.1—18.0 1.6—12.0 1.6—11.0 1.8—9.1 1.8—8.2 1.5—9.2 2.4—5.0 1.8—5.7 1.3—7.5 1.1—6.5 1.6—4.0 1.3—4.9 1.0—5.8 1.0—3.4

different gender and age groups. In agriculture, however, comparisons could be made: the SRR of occupational rhinitis among younger women (age(45 years) was 8.4, older women (age *45) 3.7, and among younger men 4.8 and among older men 2.0.

Discussion In Finland the Register of Occupational Diseases makes it possible to study the incidence of occupational diseases. The number of diagnosed cases of occupational rhinitis has increased in recent years and is close to the number of diagnosed asthma cases; for example, in 1993 there were 336 new cases of rhinitis and 386 new cases of asthma (Toikkanen et al. 1994). Most of the reported occupational rhinitis cases in the literature as well as in the Register are allergic rhinitis, as the causal connection between rhinitis of other origin and occupation is more difficult to prove. The causative agents of occupational asthma and rhinitis are very similar (Toikkanen et al. 1994). Occupational allergic rhinitis can be an early sign of respiratory impairment. Some studies report that an allergic patient has had rhinitis symptoms before developing asthma (Gniazdowski 1979; Braman et al. 1987; Umeki 1994) and many of the asthma patients encountered in general practice have rhinitis symptoms (Pedersen and Weeke 1983). In this study, most of the occupational asthma patients appeared at an older age than those with rhinitis, suggesting that rhinitis precedes asthma. The total number of occupational rhinitis cases diagnosed was higher among women than among men, 60% and 40%, respectively. Furthermore, there was a gender difference at which age the occupational rhinitis developed. Men had the highest incidence in the age range of 25—29 years, after which the incidence gradually declined. Men in younger age groups may also be more prone to develop occupational rhinitis, as they are reported to have more atopy and allergic rhinitis in general at a younger age (Sears et al. 1993, Sibbald and Strachan 1995). Among women the incidence of occupational rhinitis gradually increased and peaked in the group aged 40 to 44 years. In the older age groups (*45 years) the upper respiratory symptoms which appear may be regarded as vasomotoric, and thus the connection with work and rhinitis symptoms is not clarified. However, the greater prevalence of occupational rhinitis among women can also be due to the fact that men and women are engaged in different kinds of jobs and are exposed to different allergens in their work. The incidence of occupational rhinitis decreases after the age of 45 years. It is well known that skin reactivity in prick tests decreases with increasing age. This can prematurely eliminate a number of probable

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occupational rhinitis patients at the beginning of the examination. For example, if an elderly farmer has a negative cow skin prick test, or a baker a negative flour skin prick test, this can halt the examination, although occupational rhinitis is still possible. In the diagnosis, if there is suspicion of occupational rhinitis based on the patient’s history, a provocation test is needed to prove the causal connection between the symptoms and the work exposure. The highest relative risk (SRR"30.0) of occupational rhinitis in this study was among furriers who are exposed to different kinds of animal epithelium. Bakers exposed to different kinds of flours, and also livestock breeders had a markedly elevated relative risk (SRR"22.0). Also an essentially increased relative risk was found among food-processing workers, veterinarians, farmers, assemblers of electrical, electronic and telecommunications products, and boat builders. The main causes of occupational rhinitis were animal dander and flours. These two causes together accounted for two-thirds of all the occupational rhinitis cases. In addition wood dusts, textiles, phthalic acid anhydrides and storage mites were important causes of occupational rhinitis. The number of cases in most occupations was too small to make comparisons within one occupation between the different gender and age groups. In agriculture, however, women had a nearly two-fold relative risk of developing occupational asthma and occupational rhinitis. Also among the younger agricultural workers (age (45 years) the risk of developing occupational rhinitis was over two times higher than among older workers. Exposure to airborne allergen should be minimized in occupations with a high risk of developing occupational rhinitis, i.e. among furriers, bakers and cattle breeders. Technical improvements should be made and personal protective clothing should be properly used to reduce the exposure levels. However, it should be kept in mind also that low molecular compounds operating as haptens can cause allergic rhinitis and asthma. Occupational rhinitis worsens the quality of life and the ability to work properly and this alone is a reason to diagnose and treat occupational rhinitis. However, based on the results of earlier studies and the present study, it seems that occupational rhinitis is also an early sign of respiratory impairment. If the exposure to allergens persists, the disease may develop into asthma. Early diagnosis of occupational allergic rhinitis may thus prevent asthma from developing.

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