[Should infertile women with polycystic ovarian syndrome be treated with metformine?]

Polycystic ovary syndrome is a frequent endocrine disorder often associated with insulin resistance and hyperinsulinaemia which may play a role in hyperandrogenism and anovulation. The use of "insulin sensitizing" agents has been suggested to reduce insulin resistance and hyperandrogenism. In that respect, the use of metformin in polycystic ovary syndrome is reviewed. Although its mechanism of action is still unclear, metformin proved to be effective to restore cyclicity and spontaneous ovulation. The synergistic effect of clomiphene citrate and metformin was demonstrated in some studies, suggesting that metformin could be helpful for women with clomiphene citrate resistance. However, the potential effect of metformin administration for reducing hyperstimulation in women treated with exogenous FSH, or for preventing early miscarriages has to be confirmed. Here, we propose a guideline for the use of metformin, as an adjuvant therapy, to restore cyclicity and ovulation in women with polycystic ovary syndrome.

Beneficial effects of GnRH agonist administration prior to ovarian stimulation for patients with a short follicular phase

A short follicular phase is an early clinical feature of declining reproductive competence. The shortening of the follicular phase length is related to both advanced recruitment and selection of the dominant follicle secondary to an earlier and higher FSH rise during the luteal-follicular transition, while the late follicular growth is normal. As a short follicular phase may be detrimental for reproduction, it was postulated that increasing the duration of follicular phase could improve conception rate. For that purpose, gonadotrophin-releasing hormone agonist minidoses were administered in the mid-luteal phase to prevent the intercycle FSH rise before tailoring follicular growth by controlled exogenous FSH administration. This regimen, applied to 69 infertile ovulatory women with a short follicular phase (9.6 +/- 1.2 days) actually lengthened the follicular phase by about 3 days. It proved to be effective in 179 cycles to induce paucifollicular development (1.8 +/- 0.9 follicles) with a low cancellation rate (4%) and a moderate requirement for gonadotrophins [13.3 +/- 6.3 ampoules (75 IU)]. In those women with a high frequency (80%) of elevated basal FSH or oestradiol concentrations, the pregnancy rate reached 15.1%/cycle but the miscarriage rate remained high (44%). Thus, increasing the follicular phase length in patients with a short follicular phase may partially restore fecundity.

An epidemiological study of the respiratory health of workers in the European refractory ceramic fibre industry

OBJECTIVES

To investigate possible relations between respiratory health and past airborne exposure to refractory ceramic fibres (RCFs) and respirable dust in workers at six European factories, studied previously in 1987.

METHODS

The target population comprised all current workers associated with RCF production, plus others who had participated in 1987 "leavers". Information was collected on personal characteristics, chest radiographs, lung function, respiratory symptoms, smoking, and full occupational history. Regression analysis was used to study relations between indices of health of individual workers and of cumulative exposure to airborne dust and fibres, and likely past exposure to asbestos.

RESULTS AND DISCUSSION

774 workers participated (90% of current workers, 37% of leavers). Profusion of small opacities in exposed workers (51% 0/1+; 8% 1/0+) was similar to that among an unexposed control group but higher than in new readings of the 1987 study films (11% 0/1+, 2% 1/0+). The large difference between 1987 and recent films may be, at least in part, a reading artefact associated with film appearance. Small opacities of International Labour Organisation (ILO) category 1/0+ were not associated with exposure. An association of borderline significance overall between 0/1+ opacities and exposure to respirable fibres was found for some exposure periods only, the time related pattern being biologically implausible. Pleural changes were related to age and exposure to asbestos, and findings were consistent with an effect of time since first exposure to RCFs. Among men, forced expired volume in 1 second (FEV(1)) and forced vital capacity (FVC) were inversely related to exposure to fibres, in current smokers only. FEV(1)/ FVC ratio and transfer factor (TL(CO)) were not related to exposures. The estimated restrictive effect was on average mild. Prevalence of respiratory symptoms was low. Chronic bronchitis and its associated symptoms (cough, phlegm) showed some association with recent exposure to respirable fibres. This could be due to an irritant effect of RCFs.

Overexpression of copper zinc superoxide dismutase impairs human trophoblast cell fusion and differentiation

The syncytiotrophoblast is the major component of the human placenta, involved in feto-maternal exchanges and secretion of pregnancy-specific hormones. Multinucleated syncytiotrophoblast arises from fusion of mononuclear cytotrophoblast cells. In trisomy 21-affected placentas, we recently have shown that there is a defect in syncytiotrophoblast formation and a decrease in the production of pregnancy-specific hormones. Due to the role of oxygen free radicals in trophoblast cell differentiation, we investigated the role of the key antioxidant enzyme, copper/zinc superoxide dismutase, encoded by chromosome 21 in in vitro trophoblast differentiation. We first observed that overexpression of superoxide dismutase in normal cytotrophoblasts impaired syncytiotrophoblast formation. This was associated with a significant decrease in mRNA transcript levels and secretion of hCG and other hormonal markers of syncytiotrophoblast. We confirmed abnormal cell fusion by overexpression of green fluorescence protein-tagged superoxide dismutase in cytotrophoblasts. In addition, a significant decrease in syncytin transcript levels was observed in superoxide dismutase-transfected cells. We then examined superoxide dismutase expression and activity in isolated trophoblast cells from trisomy 21-affected placentas. Superoxide dismutase mRNA expression (P < 0.05), protein levels (P < 0.01), and activity (P < 0.05) were significantly higher in trophoblast cells isolated from trisomy 21-affected placentas than in those from normal placentas. These results suggest that superoxide dismutase overexpression may directly impair trophoblast cell differentiation and fusion, and superoxide dismutase overexpression in Down's syndrome may be responsible at least in part for the failure of syncytiotrophoblast formation observed in trisomy 21-affected placentas.

Vibrotactile perception thresholds in four non-exposed populations of working age

The purpose of this study was to establish a basis for the use of a device for measuring vibrotactile perception thresholds for epidemiological purposes on a series of non-exposed populations. Vibrotactile perception thresholds (VPTs) were measured with a vibrometer in 218 men and 160 women belonging to two non-exposed male blue collar populations, one white-collar population and one age and gender stratified sample of the general population. VPTs were measured on the middle and the little finger of the dominant hand at 31.5 and 125 Hz. The VPTs were expressed in dB and the effect of a series of factors including the population, age, gender and digital temperature was assessed in a regression analysis weighted by the inverse variance of the measurements. Adjusted for age, no significant difference between the VPTs in the four male populations was observed. At frequency 125 Hz, the effect of age (0.3 dB per year) was more important than at frequency 31.5 Hz (0.2 dB per year). In the two female populations, the results were less stable than among males and the VPTs were higher than among males. However, the age-dependence was similar among males and females. The within-test variance is a valuable indicator of the quality of the VPT measurements. Weighting by its inverse improved the fit of the regression models. Normal values for VPTs in non-exposed populations were obtained, which were reproducible in four separate populations.

Defect of syncytiotrophoblast formation and human chorionic gonadotropin expression in Down's syndrome

The syncytiotrophoblast (ST) is a major component of the human placenta as it is involved in feto-maternal exchanges and the secretion of pregnancy-specific hormones. We have studied the formation and function of the ST in normal and trisomy 21 (T21)-affected placenta using the in vitro model of cytotrophoblast differentiation into ST. Cytotrophoblast cells were isolated from first trimester, second trimester and term placentae. In vitro cytotrophoblast cells isolated from normal placenta fused to form the ST. This was associated with an increase in the transcript levels and the secretion of human chorionic gonadotropin (hCG). However, the secretion of hCG decreased through pregnancy. In T21-affected placentae, we observed a defect (or a delay) in ST formation and a dramatic decrease in the synthesis and secretion of this hormone compared with cultured cells isolated from control age-matched placentae. These results were confirmed by a significant (P < 0.05) decrease in transcript levels of alpha and beta subunits of hCG in total homogenates of T21-affected placentae compared with controls. These results suggest a decrease in functional mass of ST in T21 placenta, and therefore a decrease in production of placental pregnancy-specific polypeptide hormones.

Symptoms, airway responsiveness, and exposure to dust in beech and oak wood workers

OBJECTIVES

To investigate the relation between levels of cumulative exposure to wood dust and respiratory symptoms and the occurrence of bronchial hyperresponsiveness among beech and oak workers.

METHODS

114 Male woodworkers from five furniture factories and 13 male unexposed controls were examined. The unexposed control group was supplemented by 200 male historical controls. Statistical analyses were performed excluding and including the historical controls. Dust concentration was measured by personal sampling methods. Cumulative exposure to dust was calculated for each woodworker by multiplying the duration of the work by the intensity of exposure (years. mg/m(3)). Bronchial hyperresponsiveness was assessed by the methacholine bronchial challenge test. Subjects were labelled methacholine bronchial challenge positive if forced expiratory volume in 1 second (FEV(1)) fell by >/=20%. The linear dose-response slope was calculated as the last dose divided by the total dose given.

RESULTS

443 Dust samples were collected. The median cumulative exposure to dust was 110 years.mg/m(3) with lower and upper quartiles at 70 and 160 years.mg/m(3) Overall, no declines in FEV(1) and forced vital capacity (FVC) were found with increasing exposures. A dose-response relation was found between intensity of exposure on the one hand, and sore throat, increased prevalence of positive methacholine bronchial challenge tests, and steeper dose-response slope, on the other.

CONCLUSION

Exposure to oak and beech dust may lead to the development of sore throat and bronchial hyperresponsiveness.

On planning the number of controls in cross-sectional studies using previous studies: an application in occupational epidemiology

BACKGROUND

In occupational epidemiology, it is common to use cross-sectional studies comparing exposed with matched non-exposed populations. When several such past studies are available within a relatively short time frame, it may be possible to use their control groups to reduce the number of controls in a new study and thus reduce its cost.

METHODS

We compare existing non-exposed populations within a standard random-effects model, to explore the natural between population variability and to compute the power increase when including these populations. An example is given from respiratory epidemiology, with the forced expiratory volume in 1 s as the outcome, using 13 previously-collected control populations obtained in recent studies.

RESULTS

We show that the reduction in the number of controls needed for a new study is equal to the ratio of the between subjects and the between group variance, observed in controls in previous studies. In the present example, the reduction in the number of controls needed for a new study was found to be 18. An optimal allocation of resources is obtained in this framework.

CONCLUSIONS

The use of past available control groups provides a significant reduction in cost only if they are very homogeneous, compared to the between-subject variance.

Pleural mesothelioma: dose-response relation at low levels of asbestos exposure in a French population-based case-control study

A hospital-based case-control study of the association between past occupational exposure to asbestos and pleural mesothelioma was carried out in five regions of France. Between 1987 and 1993, 405 cases and 387 controls were interviewed. The job histories of these subjects were evaluated by a group of experts for exposure to asbestos fibers according to probability, intensity, and frequency. A cumulative exposure index was calculated as the product of these three parameters and the duration of the exposed job, summed over the entire working life. Among men, the odds ratio increased with the probability of exposure and was 1.2 (95% confidence interval (CI) 0.8-1.9) for possible exposure and 3.6 (95% CI 2.4-5.3) for definite exposure. A dose-response relation was observed with the cumulative exposure index: The odds ratio increased from 1.2 (95% CI 0.8-1.8) for the lowest exposure category to 8.7 (95% CI 4.1-18.5) for the highest. Among women, the odds ratio for possible or definite exposure was 18.8 (95% CI 4.1-86.2). We found a clear dose-response relation between cumulative asbestos exposure and pleural mesothelioma in a population-based case-control study with retrospective assessment of exposure. A significant excess of mesothelioma was observed for levels of cumulative exposure that were probably far below the limits adopted in most industrial countries during the 1980s.

Sick-building symptoms in office workers in northeastern France: a pilot study

STUDY OBJECTIVES

To verify that sick building symptoms are present in north-eastern France office workers; to try to identify new confounding factors.

METHODS

The design was that of a cross-sectional study with control group. We studied with the same methods the personnel of an air-conditioned building (n=425), and of a naturally ventilated building (n=351). Air temperature and humidity, bacterial and fungal densities were measured by the same technical staff in the two buildings. A standard questionnaire on irritative and respiratory symptoms, personal and family history, and lifestyle was completed by the participants.

RESULTS

In univariate analysis, exposure to air-conditioning was associated with an increased prevalence of symptoms (odds ratios-OR-between 1.54 and 2.84). A significant increase in sickness absence was also found among subjects working in air-conditioned offices. As a series of factors were suspected to interfere with these associations, logistic regression was applied. This method confirmed exposure to be an independent determinant of 7 symptoms, and also identified two determinants not previously described: a family history of respiratory diseases and "do-it-yourself' activities.

IN CONCLUSION

we found the sick building symptoms to be present in a group of French office workers exposed to air-conditioning. We confirmed the influence of a number of confounding factors and described two further confounders - do-it-yourself activities at home and a history of familial respiratory disease.

Respiratory symptoms and bronchial responsiveness in lifeguards exposed to nitrogen trichloride in indoor swimming pools

OBJECTIVES

To measure the levels of exposure to nitrogen trichloride (NCl3) in the atmosphere of indoor swimming pools and to examine how they relate to irritant and chronic respiratory symptoms, indices of pulmonary function, and bronchial hyperresponsiveness to methacholine in lifeguards working in the pools.

METHOD

334 lifeguards (256 men; 78 women) recruited from 46 public swimming pools (n = 228) and 17 leisure centre swimming pools (n = 106) were examined. Concentrations of NCl3 were measured with area samplers. Symptoms were assessed by questionnaire and methacholine bronchial challenge (MBC) test by an abbreviated method. Subjects were labelled MBC+ if forced expiratory volume in one second (FEV1) fell by > or = 20%. The linear dose-response slope was calculated as the percentage fall in FEV1 at the last dose divided by the total dose given.

RESULTS

1262 samples were taken in the 63 pools. Mean NCl3 concentrations were greater in leisure than in public pools. A significant concentration-response relation was found between irritant eye, nasal, and throat symptoms-but not chronic respiratory symptoms-and exposure concentrations. Among women, the prevalence of MBC+ was twice as great as in men. Overall, no relation was found between bronchial hyperresponsiveness and exposure.

CONCLUSIONS

The data show that lifeguards exposed to NCl3 in indoor swimming pools are at risk of developing irritant eye, nasal, and throat symptoms. Exposure to NCl3 does not seem to carry the risk of developing permanent bronchial hyperresponsiveness, but this association might have been influenced by self selection. The possibility that subjects exposed to NCl3 are at risk of developing transient bronchial hyperresponsiveness cannot be confidently ruled out.

[Normal coronary angiography. Have the indications changed during the 1980's?]

If the indications of coronary angiography are well chosen, the percentage of normal coronary angiographies should decrease. The authors analysed 7858 primary coronary angiographies performed between 1981 and 1990 in patients without valvular or congenital heart disease. The second 5 years were compared to the first. The percentage of primary coronary angiographies decreased (63% vs 75%; p < 0.01), the percentage of women increased (21.7% vs 18.4%; p < 0.001), and the mean age increased (58.5 +/- 0.3 vs 53.9 +/- 0.3; p < 10(-9)). The lesions were less extensive: 16.3% triple vessel disease versus 24.2% (p < 0.001); 31.3% double vessel disease versus 28.1% (p < 0.02); 49.1% single vessel disease versus 44.2% (p < 0.001). The percentage of normal coronary angiographies remained constant: 20.2% in the second five years versus 19.9% in the first. Over the 10 year period, there was no significant difference one year from another. The percentage of normal investigations remained the same in men (15.7%), decreased in women (34.7 vs 40.1%, p < 0.04), remained constant in patients under 60 years of age (24.5 vs 23.8%), but increased in the more elderly (14.9 vs 10.2%; p < 0.001). The percentage remained unchanged in stable angina (19.6 vs 19.8%) and in unstable angina (12.3 vs 11.2%): it increased in cases of atypical chest pain (72.2 vs 54.3%; p < 0.01). Although, globally, the number of normal coronary angiographies was unchanged at 20%, the indications of this investigation were more selective in the younger patients, especially women, in the second five years, but coronary angiography was more commonly performed in elderly patients because of the possibility of benefiting from coronary angioplasty.

Airway responsiveness, respiratory symptoms, and exposures to soluble oil mist in mechanical workers

OBJECTIVES

To assess the relation between measured levels of exposure to soluble oil mists in a plant manufacturing ball bearings, and both respiratory symptoms and airway responsiveness in the workforce.

METHODS

114 male workers exposed to oil mist and 55 unexposed male controls from nearby factories were studied. Soluble oil mist concentrations were measured with area samplers. Respiratory symptoms were assessed by questionnaire and measurement of airway responsiveness to methacholine with an abbreviated method. Subjects were labelled positive to methacholine airway challenge (MAC+) if forced expiratory volume in one second (FEV1) fell by > or = 20%. The linear dose-response slope was calculated as the percentage fall in FEV1 at the last dose divided by the total dose given.

RESULTS

Geometric mean concentrations of oil mists ranged from 0.65 mg/m3 (GSD 1.29) to 2.20 mg/m3 (GSD 1.55) based on 92 measurements obtained from 1979-93. The prevalence of chronic cough or phlegm, bouts of bronchitis, and dyspnoea was greater among exposed workers than among controls (odds ratio (OR) 4.64, P = 0.002 for chronic cough and phlegm). After adjustment for smoking and age, dyspnoea was significantly related to an index of cumulative exposure to oil mist (OR 1.44, P = 0.006/10 y.mg/m3). The proportion of MAC+ subjects was similar in the two groups. However, after adjustment for baseline FEV1 and age, the dose-response slope was significantly steeper among exposed workers than among controls (P = 0.01), a finding indicating airway hyperresponsiveness in the exposed workers. Furthermore, the dose-response slope was significantly related to baseline FEV1, age, and, after adjustment for FEV1, the index of cumulative exposure to oil (P = 0.004).

CONCLUSION

Subjects with exposure to soluble oil mist in the metal industry are at risk of developing both respiratory symptoms and airway hyperresponsiveness.

Airflow obstruction in chalkpowder and sugar workers

Our aim was to investigate the relationship between suspected occupational hazards and airflow obstruction in industrial workers. The study was a cross-sectional survey of 314 male workers from a chalkpowder plant (n = 158) and from a sugar refinery (n = 156). Occupational exposure to chalkpowder and sugar dust was assessed by individual job classification. Outcome variables included respiratory symptoms and routine spirometric parameters. Statistical analysis was done for each industry separately. Overall, mean pulmonary function parameters fell either within or above the normal range in both industries. However, analysis by job classification showed that in the chalkpowder plant, all indices of airway obstruction declined significantly with increasing dustiness. Additionally, workers in the dustiest workplace (chalk sacking) had significantly lower airflow parameters than workers from other workstations. In the sugar refinery, workers exposed to sugar dust in the sugar cube manufacture workstation had significantly lower forced expiratory volume in 1 s (FEV1) (p = 0.02) than the non-exposed ones. For both industries, the proportion of subjects complaining of cough and/or phlegm was greater among the most exposed subgroups than among the remaining workers but the differences were not statistically significant. In conclusion, coupling spirometry to job classification proved useful in disclosing a relationship between airflow obstruction and exposure to either chalkpowder or sugar dust in industrial workers.

Altered partition of T cell subsets in the peripheral blood of healthy workers exposed to flour dust

Occupational exposure to organic compounds can induce obvious immunological disorders or more subtle modifications. We investigated peripheral blood lymphocyte subsets in 34 bakers and 82 millers exposed to wheat flour dust, and 51 salt factory workers. Significantly decreased levels of CD4+, CD8+, CD57+ and CD8+/57+ cells were noted in mill workers, and of CD57+ cells in bakers. CD29+ and CD4+/CD29+ cells were significantly lower in millers, CD4+/CD45RA+ cells higher in all exposed workers. The lower numbers of positive cells noted in millers appeared associated to significantly higher (p < 0.001) levels of CD29 and CD45RA expression as measured by fluorescence intensity. These data are opposite to those previously reported in asthmatic workers exposed to flour dust. Since the individuals tested here were clinically healthy, the alterations of T-cell subsets observed could be interpreted as a successful attempt at immunoregulation maintaining homeostasis.

Airway responsiveness to methacholine, respiratory symptoms, and dust exposure levels in grain and flour mill workers in eastern France

Our goal was to assess the relation between dust exposure levels and the respiratory health status of workers in grain and flour mills in eastern France. We studied 118 male workers from 11 mills and 164 unexposed male controls. Dust concentration was measured by personal sampling methods. Outcome variables included respiratory symptoms, routine pulmonary function tests, and indices of airway responsiveness to methacholine. A great within- and between-area variability of inhalable dust concentration was found in all mills. A dose-response relationship was observed between dust exposure levels and chronic respiratory symptoms, suggesting that exposure to grain and flour dust may lead to chronic bronchitis. A significant relation was found between dust exposure and airway hyper-responsiveness; this finding is important since it has been hypothesized that the latter abnormality may lead to or be a predisposing factor in subsequent chronic, irreversible airflow obstruction.

Humoral immune responses of workers occupationally exposed to wheat flour

Wheat flour is a complex organic dust likely to induce immune responses when inhaled in work environment conditions. We compared the humoral status of 159 exposed workers from 11 flour mills and one industrial bakery with that of 41 workers from a salt factory. IgG, IgA, and IgM levels of antibodies to whole flour and to gliadin were assayed using ELISA tests in serum and saliva samples. Serum levels of IgG and IgA to both antigens were significantly higher (p < 0.0001) in occupationally exposed workers. Exposed workers had significantly higher levels of salivary IgG (p = 0.005) and IgA (p < 0.0001) to whole flour and of salivary IgG (p = 0.0005) to gliadin. In both groups, similar levels of anti-gliadin salivary IgA antibodies were observed. These data suggest that occupational exposure to wheat flour triggers specific immune responses, most likely through stimulation of the mucosal immune system. The presence of significant levels of serum antibodies, however, indicates that a systemic immunologic response is also present among exposed individuals.

Tracheal wheezes during methacholine airway challenge (MAC) in workers exposed to occupational hazards

Methacholine airway challenge (MAC) is a simple and useful means to assess bronchial hyperreactivity in workers exposed to various occupational hazards. Recently, wheeze detection by tracheal auscultation has been proposed as an indicator of bronchial responsiveness during bronchial provocation test in children. Our aim was to examine the relationship between the appearance of wheezes and the concurrent changes in forced expiratory volume in one second (FEV1) observed during MAC test in adults. Three cumulative doses of a methacholine solution (100 micrograms, 500 micrograms and 1500 micrograms) were inhaled by 45 workers with occupational exposure to flour dust. Spirometry was done using an electronic spirometer. Tracheal sounds were recorded with an electronic stethoscope placed over the anterior cervical triangle, 2 cm above the sternal notch. The amplified sounds were stored on magnetic tape, band-pass filtered (50-2000 Hz), and digitized at a sampling rate of 4096 Hz into a GenRad Vibration Control System. Wheezes were detected by fast Fourier transform (FFT) analysis and their presence compared to a 20% fall in FEV1. A positive MAC test by spirometry was found in 12 subjects whereas wheezes were identified in 14 subjects. Among the wheezing subjects, nine had a positive MAC test (range of fall in FEV1 = 20.6 to 42.3%) and five had a negative one (range of fall in FEV1 = 3.6 to 16.9%). Moreover, no wheezes were found in the remaining three subjects with a positive MAC test (range of fall in FEV1 = 20.7 to 27.4%). Taking a 20% fall in FEV1 as reference, wheezes were 75% sensitive and 84.8% specific to detect airflow obstruction. In conclusion, since it carries a significant although small false-negative rate, the acoustic technique based upon wheeze detection cannot, at the present time, fully replace spirometry during airway challenge testing in subjects with suspected asthma.

Respiratory symptoms and airway responsiveness in apparently healthy workers exposed to flour dust

Our aim was to measure the levels of exposure to wheat flour dust in a modern industrial bakery, and to assess the relationship between respiratory symptoms, sensitization to wheat flour antigens and airway responsiveness in the workforce. Forty four flour-exposed male workers and 164 unexposed controls were examined. Inspirable dust concentrations were measured using personal samplers. Respiratory symptoms were assessed by questionnaire, sensitization to wheat flour antigens by skin-prick tests, and methacholine airway challenge (MAC) test using an abbreviated method. Subjects were labelled MAC+ if forced expiratory volume in one second (FEV1) fell by 20% or more. The linear dose-response slope (DRS) was calculated as the percentage fall in FEV1 at last dose divided by the total dose administered. Inspirable dust concentrations were within acceptable limits in all working areas but one. The proportion of subjects with one or more symptoms and with airway hyperresponsiveness was significantly greater among flour-exposed workers than among controls. Using logistic or linear regression analysis, airway responsiveness was found to be strongly related to working at the bakery and to the baseline level of lung function. A positive skin-prick test was found in only 11% of flour-exposed workers and 6% of controls. In conclusion, our data show that despite exposure to relatively low concentration levels of inspirable flour dust, subjects working in the baking industry are at risk of developing both respiratory symptoms and airway hyperresponsiveness.

Respiratory symptoms and airway responsiveness in apparently healthy workers exposed to flour dust

Our aim was to measure the levels of exposure to wheat flour dust in a modern industrial bakery, and to assess the relationship between respiratory symptoms, sensitization to wheat flour antigens and airway responsiveness in the workforce. Forty four flour-exposed male workers and 164 unexposed controls were examined. Inspirable dust concentrations were measured using personal samplers. Respiratory symptoms were assessed by questionnaire, sensitization to wheat flour antigens by skin-prick tests, and methacholine airway challenge (MAC) test using an abbreviated method. Subjects were labelled MAC+ if forced expiratory volume in one second (FEV1) fell by 20% or more. The linear dose-response slope (DRS) was calculated as the percentage fall in FEV1 at last dose divided by the total dose administered. Inspirable dust concentrations were within acceptable limits in all working areas but one. The proportion of subjects with one or more symptoms and with airway hyperresponsiveness was significantly greater among flour-exposed workers than among controls. Using logistic or linear regression analysis, airway responsiveness was found to be strongly related to working at the bakery and to the baseline level of lung function. A positive skin-prick test was found in only 11% of flour-exposed workers and 6% of controls. In conclusion, our data show that despite exposure to relatively low concentration levels of inspirable flour dust, subjects working in the baking industry are at risk of developing both respiratory symptoms and airway hyperresponsiveness.