Update of an occupational asthma-specific job exposure matrix to assess exposure to 30 specific agents.

OBJECTIVES: We aimed to update an asthmagen job exposure matrix (JEM) developed in the late 1990s. Main reasons were: the number of suspected and recognised asthmagens has since tripled; understanding of the aetiological role of irritants in asthma and methodological insights in application of JEMs have emerged in the period. METHODS: For each agent of the new occupational asthma-specific JEM (OAsJEM), a working group of three experts out of eight evaluated exposure for each International Standard Classification of Occupations, 1988 (ISCO-88) job code into three categories: 'high' (high probability of exposure and moderate-to-high intensity), 'medium' (low-to-moderate probability or low intensity) and 'unexposed'. Within a working group, experts evaluated exposures independently from each other. If expert assessments were inconsistent the final decision was taken by consensus. Specificity was favoured over sensitivity, that is, jobs were classified with high exposure only if the probability of exposure was high and the intensity moderate-to-high. In the final review, all experts checked assigned exposures and proposed/improved recommendations for expert re-evaluation after default application of the JEM. RESULTS: The OAsJEM covers exposures to 30 sensitisers/irritants, including 12 newly recognised, classified into seven broad groups. Initial agreement between the three experts was mostly fair to moderate (κ values 0.2-0.5). Out of 506 ISCO-88 codes, the majority was classified as unexposed (from 82.6% (organic solvents) to 99.8% (persulfates)) and a minority as 'high-exposed' (0.2% (persulfates) to 2.6% (organic solvents)). CONCLUSIONS: The OAsJEM developed to improve occupational exposure assessment may improve evaluations of associations with asthma in epidemiological studies and contribute to assessment of the burden of work-related asthma.

Exposures and asthma outcomes using two different job exposure matrices in a general population study in northern Europe.

OBJECTIVE: We have recently published a study on new-onset asthma in a large population in northern Europe using a modified job exposure matrix (N-JEM) to better reflect exposure assignment in these countries. The aim of this paper was to investigate how the N-JEM differs in exposure assignment and asthma risks from an already established JEM. METHOD: The study comprised 6253 men and 7031 women from northern Europe, born 1945-1973, who had answered both a screening (1989-1992) and a follow-up questionnaire (1999-2001). During the study period (1980-2000), there were 136 men and 293 women with new-onset asthma. Hazard ratios of new-onset asthma were calculated for both JEMs using Cox regression models. The analyses were made separately for men and women and were also stratified for atopy. Cohen's kappa (κ) was used to show agreements in exposure assignment (yes/no) between the JEMs. Population attributable risks (PARs) were calculated as well. RESULTS: The agreement in exposure assignment between the JEMs was substantial for the group 'any exposure' to asthma agents (κ = 0.78). The agreement between comparable exposure groups in the JEMs varied from κ = 1.00 (pharmaceutical product antigens, textile dust, cleaning agents) to κ = 0.27 (low molecular weight agents). Significant increased asthma risks were seen for men exposed to isocyanates and accidental peak exposure with both JEMs. With the N-JEM, increased asthma risks were seen for men exposed to plant-associated antigens (all and non-atopic), epoxy compounds (all and non-atopic), and acrylates (non-atopic). With the other JEM, increased asthma risks were seen in men and women exposed to 'possible exposure to irritant gases or fumes' (all and non-atopic), a group classified as having low asthma risk. Men and women exposed to cleaning agents also showed significant asthma risks with both JEMs. PAR with the N-JEM was 14.3% for men and 6.6% for women, compared with 12.9% and 8.3% with the other JEM. CONCLUSIONS: Acrylates, epoxy compounds, and isocyanates are three exposure groups in the modified asthma JEM that might better reflect exposure situations in northern Europe than the already established JEM. Exposure to 'possible exposure to irritant gases or fumes', a low asthma risk group in the established JEM, seems to be a group with high asthma risk in northern Europe. It is important to continuously update JEMs, which are based only on occupational titles, in order to find new risk groups and to better reflect changes in work exposures when old risks disappear and new emerge.

Occupational exposure and new-onset asthma in a population-based study in Northern Europe (RHINE).

OBJECTIVES: In a large population-based study among adults in northern Europe the relation between occupational exposure and new-onset asthma was studied. METHODS: The study comprised 13 284 subjects born between 1945 and 1973, who answered a questionnaire 1989-1992 and again 1999-2001. Asthma was defined as 'Asthma diagnosed by a physician' with reported year of diagnose. Hazard ratios (HR), for new-onset adult asthma during 1980-2000, were calculated using a modified job-exposure matrix as well as high-risk occupations in Cox regression models. The analyses were made separately for men and women and were also stratified for atopy. RESULTS: During the observation period there were 429 subjects with new-onset asthma with an asthma incidence of 1.3 cases per 1000 person-years for men and 2.4 for women. A significant increase in new-onset asthma was seen for men exposed to plant-associated antigens (HR = 3.6; 95% CI [confidence interval] = 1.4-9.0), epoxy (HR = 2.4; 95% CI = 1.3-4.5), diisocyanates (HR = 2.1; 95% CI = 1.2-3.7) and accidental peak exposures to irritants (HR = 2.4; 95% CI = 1.3-4.7). Both men and women exposed to cleaning agents had an increased asthma risk. When stratifying for atopy an increased asthma risk were seen in non-atopic men exposed to acrylates (HR = 3.3; 95% CI = 1.4-7.5), epoxy compounds (HR = 3.6; 95% CI = 1.6-7.9), diisocyanates and accidental peak exposures to irritants (HR = 3.0; 95% CI = 1.2-7.2). Population attributable risk for occupational asthma was 14% for men and 7% for women. CONCLUSIONS: This population-based study showed that men exposed to epoxy, diisocyanates and acrylates had an increased risk of new-onset asthma. Non-atopics seemed to be at higher risk than atopics, except for exposure to high molecular weight agents. Increased asthma risks among cleaners, spray painters, plumbers, and hairdressers were confirmed.

Respiratory symptoms and exposure-response relations in workers exposed to metalworking fluid aerosols.

The aim of the study was to identify specific health risks and exposure-response relationships associated with exposure to metalworking fluid (MWF) aerosols. In a cross-sectional study of machine workers exposed to MWF aerosols in five companies in Sweden, a self-administered questionnaire about health symptoms, work tasks, and exposure situations was sent out to 2294 employees, 1632 exposed and 662 referents. Referents were office workers and metal workers not working with MWFs. In four of the companies, there were recent measurements of personal exposure to MWF aerosols. Log-binomial regression models were used to estimate prevalence ratios with 95% confidence intervals for different health outcomes in relation to different variables of exposure. The response rate after two reminders was 67% resulting in 1048 (923 male, 125 female) workers exposed to MWF aerosols and 451 (374 male, 77 female) referents. The study indicates that metal workers in Sweden currently exposed to a mean value of MWF aerosols of 0.4 mg m(-3) have a significantly higher prevalence of wheeze, chronic bronchitis, chronic rhinitis, and eye irritation compared to the referents. At a mean exposure of 0.4 mg m(-3), a level below the Swedish 8-h exposure limit value of 1 mg m(-3), machine operators showed increased prevalence of symptoms in eyes and airways. Thus, the current exposure limit value does not seem to protect the workers from such symptoms.

Domestic use of hypochlorite bleach, atopic sensitization, and respiratory symptoms in adults.

BACKGROUND: Professional use of hypochlorite (bleach) has been associated with respiratory symptoms. Bleach is capable of inactivating allergens, and there are indications that its domestic use may reduce the risk of allergies in children. OBJECTIVE: To study the associations between household use of bleach and atopic sensitization, allergic diseases, and respiratory health status in adults. METHODS: We identified 3626 participants of the European Community Respiratory Health Survey II in 10 countries who did the cleaning in their homes and for whom data on specific serum IgE to 4 environmental allergens were available. Frequency of bleach use and information on respiratory symptoms were obtained in face-to-face interviews. House dust mite and cat allergens in mattress dust were measured in a subsample. Associations between the frequency of bleach use and health outcomes were evaluated by using multivariable mixed logistic regression analyses. RESULTS: The use of bleach was associated with less atopic sensitization (odds ratio [OR], 0.75; 95% CI, 0.63-0.89). This association was apparent for specific IgE to both indoor (cat) and outdoor (grass) allergens, and was consistent in various subgroups, including those without any history of respiratory problems (OR, 0.85). Dose-response relationships (P < .05) were apparent for the frequency of bleach use and sensitization rates. Lower respiratory tract symptoms, but not allergic symptoms, were more prevalent among those using bleach 4 or more days per week (OR, 1.24-1.49). The use of bleach was not associated with indoor allergen concentrations. CONCLUSION: People who clean their homes with hypochlorite bleach are less likely to be atopic but more likely to have respiratory symptoms.

Exposure to substances in the workplace and new-onset asthma: an international prospective population-based study (ECRHS-II).

BACKGROUND: The role of exposure to substances in the workplace in new-onset asthma is not well characterised in population-based studies. We therefore aimed to estimate the relative and attributable risks of new-onset asthma in relation to occupations, work-related exposures, and inhalation accidents. METHODS: We studied prospectively 6837 participants from 13 countries who previously took part in the European Community Respiratory Health Survey (1990-95) and did not report respiratory symptoms or a history of asthma at the time of the first study. Asthma was assessed by methacholine challenge test and by questionnaire data on asthma symptoms. Exposures were defined by high-risk occupations, an asthma-specific job exposure matrix with additional expert judgment, and through self-report of acute inhalation events. Relative risks for new onset asthma were calculated with log-binomial models adjusted for age, sex, smoking, and study centre. FINDINGS: A significant excess asthma risk was seen after exposure to substances known to cause occupational asthma (Relative risk=1.6, 95% CI 1.1-2.3, p=0.017). Risks were highest for asthma defined by bronchial hyper-reactivity in addition to symptoms (2.4, 1.3-4.6, p=0.008). Of common occupations, a significant excess risk of asthma was seen for nursing (2.2, 1.3-4.0, p=0.007). Asthma risk was also increased in participants who reported an acute symptomatic inhalation event such as fire, mixing cleaning products, or chemical spills (RR=3.3, 95% CI 1.0-11.1, p=0.051). The population-attributable risk for adult asthma due to occupational exposures ranged from 10% to 25%, equivalent to an incidence of new-onset occupational asthma of 250-300 cases per million people per year. INTERPRETATION: Occupational exposures account for a substantial proportion of adult asthma incidence. The increased risk of asthma after inhalation accidents suggests that workers who have such accidents should be monitored closely.

Incidence of hand eczema in female Swedish hairdressers.

OBJECTIVE: To estimate the occurrence of hand eczema in hairdressers in Sweden. METHODS: The occurrence of hand eczema was estimated in a Swedish longitudinal retrospective cohort study including all female graduates from vocational schools for hairdressers from 1970 to 1995. A stratified sample from the general population acted as controls. A self-administered questionnaire including questions on the occurrence of hand eczema, skin atopy, working periods and number of hair treatments performed per week was sent to the participants. Incidence rate ratios (IRRs) of hand eczema were estimated. RESULTS: The incidence rate of hand eczema in hairdressers was 23.8 cases/1000 person-years, whereas in hairdressers who were aged <25 years it was 37.1/1000 person-years. The corresponding IRR for hairdressers compared with controls was 2.5 (95% confidence interval (CI) 2.2 to 2.8), and that for younger hairdressers was 3.1 (95% CI 2.6 to 3.5). The mean age at onset of hand eczema was 21.6 years for hairdressers and 21.2 years for controls. The 1-year prevalence of hand eczema was 18.0% for hairdressers and 12.1% for controls. A large number of hair treatments involving exposure to skin irritants and sensitisers were reported. The incidence rate of hand eczema was higher among individuals with a history of childhood eczema, both for hairdressers and for controls, giving an (age-adjusted) IRR of 1.9 and 2.2, respectively. The attributable fraction of hand eczema from skin atopy was 9.6%. A synergistic effect of skin atopy and hairdressing was found on the occurrence of hand eczema. The relative excess risk due to interaction was 1.21 (95% CI 0.21 to 2.21; p = 0.01). CONCLUSION: Hairdressers are highly exposed to skin-damaging substances. The self-reported incidence of hand eczema was substantially higher in female hairdressers than in controls from the general population and than that found previously in register-based studies. For many individuals, onset of hand eczema occurs early in life. Only about 10% of the hand eczema cases among hairdressers would be prevented if no one with skin atopy entered the trade.

Occupational risk factors for asthma among nurses and related healthcare professionals in an international study.

OBJECTIVE: The authors examined the relations between self-reported work tasks, use of cleaning products and latex glove use with new-onset asthma among nurses and other healthcare workers in the European Community Respiratory Health Survey (ECRHS II). METHODS: In a random population sample of adults from 22 European sites, 332 participants reported working in nursing and other related healthcare jobs during the nine-year ECRHS II follow-up period and responded to a supplemental questionnaire about their principal work settings, occupational tasks, products used at work and respiratory symptoms. Poisson regression models with robust error variances were used to compare the risk of new-onset asthma among healthcare workers with each exposure to that of respondents who reported professional or administrative occupations during the entire follow-up period (n = 2481). RESULTS: Twenty (6%) healthcare workers and 131 (5%) members of the referent population reported new-onset asthma. Compared to the referent group, the authors observed increased risks among hospital technicians (RR 4.63; 95% CI 1.87 to 11.5) and among those using ammonia and/or bleach at work (RR 2.16; 95% CI 1.03 to 4.53). CONCLUSIONS: In the ECRHS II cohort, hospital technicians and other healthcare workers experience increased risks of new-onset current asthma, possibly due to specific products used at work.

Non-positive autoimmune responses against CYP2E1 in refrigeration mechanics exposed to halogenated hydrocarbons.

The aim of the study was to determine if occupational exposure to hydrofluorocarbons (HFC) and hydrochlorofluorocarbons (HCFC) generates autoimmune responses against CYP2E1. HFCs and HCFCs have replaced the chlorofluorocarbons (CFC) in e.g. refrigeration installations and air-conditioning systems. During the substitution period, refrigeration mechanics reported symptoms like asthma, influenza-like reactions, and joint troubles. These symptoms resemble those of chronic inflammatory diseases with an autoimmune component. Since exposure to structurally similar chemicals, e.g. halothane, has previously been associated with autoimmune responses and diseases, autoimmunity among the refrigeration mechanics might hypothetically explain the reported inflammatory symptoms. Serum from 44 Swedish men, occupationally exposed to halogenated hydrocarbons, was screened for antibodies against CYP2E1 with enzyme-linked immunosorbent assay. Thirty of the workers had asthma, joint problems or influenza-like symptoms whereas 14 of them had no such symptoms. They were all selected from a cohort of 280 refrigeration mechanics. Unexposed, healthy, Swedish men (n=35) constituted control group. The study was approved by the Ethics Committee at Karolinska Institutet. No increase in autoantibodies against CYP2E1 was detected among the occupationally exposed workers as compared to the unexposed controls. Further, there was no difference in antibody titer between the exposed workers with symptoms and the exposed, asymtomatic workers or the unexposed controls. The present study does not completely exclude a connection between exposure and effect but makes the relation less likely at these exposure levels.

Fertility among female hairdressers.

OBJECTIVES: The study investigated whether working as a hairdresser has a negative impact on fertility, measured as time to pregnancy and miscarriage risk. METHODS: Self-administered questionnaires were sent to 5289 Swedish hairdressers (response rate 50%) and to 5299 age-matched women from the general Swedish population (response rate 54%). Information was collected on time to pregnancy or trying time for women who had tried, but failed, to conceive at the time of the study. The outcome of the pregnancy was determined and categorized as either miscarriage or stillbirth or live birth. The hairdressers were compared with the referents with respect to these two outcomes. Within the hairdresser cohort, the effects of hair treatments, as well as physical workload and stress were investigated. RESULTS: The hairdressers were less successful than the reference cohort in conceiving (fecundability ratio 0.91, 95% confidence interval 0.83-0.99). The effect was reduced after first-month conceptions were excluded, the indication being that the effect may be the result of birth control bias. Within the hairdresser cohort, a self-perceived stressful work situation seemed to prolong the time to pregnancy. No effects were found for the different chemical hair treatments. There was no cohort difference with respect to miscarriage risk (odds ratio 1.12, 95% confidence interval 0.88-1.42), but miscarriage risks were increased for most of the hair treatments and for self-perceived stressful work situations. However, none of these effects were statistically significant. CONCLUSIONS: The present study indicates a negative impact on time to pregnancy and miscarriage risk for working as a hairdresser".

Time to pregnancy among partners of men exposed to di(2-ethylhexyl)phthalate.

OBJECTIVES: This study assessed paternal occupational exposure to di(2-ethylhexyl)phthalate (DEHP) in association with reduced fertility. METHODS: Men working in three plants with DEHP exposure were studied retrospectively. Male and female employees and their partners were invited to participate if they had reported a pregnancy or an attempt to achieve a pregnancy. Postal questionnaires and telephone interviews were used to collect additional data from the men and women, respectively. Information on time to pregnancy was eligible for 326 pregnancies fathered by 193 men. Male exposure to DEHP during every month of their time to pregnancy was classified into one of three exposure categories. The exposure ranged from <0.1 to 2.1 mg/m3. The fathers of only four pregnancies had DEHP exposure of >0.5 mg/m3 during the time to pregnancy. The pregnancies of employed women with unexposed partners or pregnancies of employed men unexposed during the time to pregnancy formed the reference group. RESULTS: The fecundability ratio for time to pregnancy was 1.07 [95% confidence interval (95% CI) 0.84-1.35] for those with low exposure and 0.97 (95% CI 0.70-1.33) for the highly exposed after adjustment for the father's age, mother's age, and length of recall. When the analyses were restricted to first pregnancy, the fecundability ratio was 1.13 (95% Cl 0.83-1.56) for low exposure and 1.02 (95% CI 0.66-1.59) for high exposure. CONCLUSIONS: Time to pregnancy is not prolonged among couples with paternal exposure to DEHP at a mean exposure level of <0.5 mg/m3.

Supercritical fluid extraction (SFE) for determination of metalworking fluid aerosols.

A common methodology for analyzing metalworking fluid (MWF) aerosols in workplace air is based on gravimetry before and after organic solvent extraction of the MWFs from a suitable collection filter. Because MWFs have different chemical and physical properties, various mixtures of organic solvents have been used to extract the MWFs from their collection device. An alternative to organic solvents, used in the work presented in this article, is the use of a supercritical fluid. The efficiency of supercritical fluid extraction (SFE) was investigated by weighing conditioned filters before and after extraction of samples spiked with MWFs at different concentrations using the American Society for Testing and Materials method. For three common straight oil MWFs spiked on filters, supercritical carbon dioxide gave recoveries of 92-101% with a low standard deviation (0.2-1.9%). For semisynthetic MWFs, carbon dioxide had to be mixed with methanol to obtain recoveries above 80%. With the optimized method using 7% methanol in carbon dioxide, the 10 investigated MWFs could be extracted in 30 min with a recovery of 90-98%. The amount of MWFs spiked on the filters varied between 0.10-1.65 mg. In Sweden, the limit value for MWFs is 1 mg/m3. Thus, our spike level is in the range of 10-200% of the limit value if sampling for 8 hours with 2 L/min. The use of SFE methodology results in small volume extracts (3 mL) with concentrations at such high levels that analysis of chemical components in the MWF can be carried out without further volume reduction.

Sensitisation to occupational allergens in bakers' asthma and rhinitis: a case-referent study.

OBJECTIVES: To study the importance of sensitisation to occupational allergens for the occurrence of asthma and rhinitis in bakers. METHODS: This is a nested clinical case-referent study of bakers based on a cohort of Swedish former bakery students. Cases were asthmatic ( n=25) or rhinitic bakers ( n=20). Randomly selected bakers ( n=44) were referents. All subjects underwent skin prick tests (SPTs) with common allergens, flours, fungal alpha-amylase and the storage mite L. destructor. Indices of airway inflammation were assessed in serum and the nose. RESULTS: Seven of the asthmatics and eight of the rhinitics reported onset of disease during bakery work. Flour SPTs were positive in 43% of the asthmatics or rhinitics vs 16% of referents. The corresponding figures for alpha-amylase were 29%, 25%, and 7%. The odds ratio, adjusted for atopy, for an SPT positive to flour or alpha-amylase for asthmatics with onset during bakery work was 5.8 (95% confidence interval 1.1-32), and 2.6 (0.4-16) for the corresponding rhinitics. The positive predictive value of sensitisation to flour or alpha-amylase in relation to a clinical diagnosis of asthma or rhinitis was 71%. Sensitisation to L. destructor was rare. The indices of airway inflammation were similar in cases and in referents. CONCLUSIONS: Bakers' asthma is associated with sensitisation to flour and/or alpha-amylase, atopy taken into account. A similar association was suggested in bakers' rhinitis. Indices of airway inflammation were of low predictive value for detecting bakers' asthma or rhinitis in this study.

Population-based study of non-infectious rhinitis in relation to occupational exposure, age, sex, and smoking.

BACKGROUND: Many types of occupational exposure are associated with the risk of non-infectious rhinitis. We investigate the risk factors for this association. METHODS: A random population of 2,044 subjects (aged 21-51) answered a questionnaire that was comprised of detailed questions on occupational exposure, nasal complaints, and smoking. NIR was defined as the sensation of nasal blockage and/or attacks of sneezing without having a cold. The incidence rates for NIR among exposed and unexposed were calculated. In the different exposed groups, only NIR with onset after the start of exposure was regarded as exposed. If a subject reported NIR before the relevant exposure started, he/she was excluded from that analysis. Relative risks (RR) were calculated as incidence rate ratios. Odds ratios controlling for smoking, age, and atopy were also calculated. RESULTS: The incidence rate for NIR was 13.5/1,000 person-years. Males exposed to fire fumes (RR 2.5, 95% confidence interval (CI) 1.5-4.1), women exposed to paper dust (RR 2.0, 95% CI 1.5-2.9), and male cleaners (RR 3.1, 95% CI 1.9-5.1) displayed an increased risk of developing NIR. Smoking was associated with an increased risk of NIR for both sexes. CONCLUSIONS: Exposure to several occupational irritants is associated with a higher risk of developing NIR.

The incidence of respiratory symptoms in female Swedish hairdressers.

BACKGROUND: Airway diseases in hairdressers are a concern. The objective of this investigation is to evaluate the risk for three respiratory symptoms, wheeze, dry cough, and nasal blockage, in hairdressers. METHODS: A questionnaire on respiratory symptoms, atopy, smoking, and work history was answered by 3,957 female hairdressers and 4,905 women from the general population as referents. Incidence rates (IR) and incidence rate ratios (IRRs) for the three symptoms were estimated. RESULTS: The IRs of all three studied symptoms were higher in the hairdressers compared with the referents. Smoking modified the effects of cohort affiliation for all three symptoms; the combined effect from hairdressing work and smoking was less than expected. In addition, the effect of cohort affiliation for wheeze was also modified by atopy, and the effect of cohort affiliation for nasal blockage was also modified by calendar year. CONCLUSIONS: Hairdressing work was associated with increased incidences of respiratory symptoms. Smoking had a negative modifying effect.