Impact of cross-reactive carbohydrate determinants on wood dust sensitization.

BACKGROUND: Occupational wood dust exposure can induce allergy and may be one cause of respiratory health problems among woodworkers. OBJECTIVE: The objective was to determine the prevalence and quantitative level of specific immunoglobulin E (sIgE) to beech and pine wood in exposed workers. Wood sensitization was specified with regard to cross-reactivity and was correlated to the reported symptoms. METHODS: Danish workers (n=701) were investigated for sIgE to beech and pine. Wood samples from workplaces were analysed and coupled to ImmunoCAPs. Workers sensitized to wood were tested for cross-reactive carbohydrate determinants (CCDs) and environmental allergens. IgE binding was specified for glycogenic vs. proteinogenic epitopes by inhibition tests. RESULTS: The prevalence of wood sensitization among all workers was 3.7%. There was no association between sensitization prevalence or sIgE concentrations and self-reported allergic symptoms. Beech- and pine-sensitized workers showed a high prevalence of CCD sensitization (73%). However, workers with a single sensitization to wood had no sIgE to CCDs. Specifying IgE epitopes demonstrated that sera of workers reporting allergic symptoms recognized proteinogenic IgE-epitopes on wood allergens, whereas workers without allergic symptoms had primarily sIgE-epitopes to glycogenic structures. Although 96% of the wood-sensitized workers were atopic, no significant correlation was found between wood sensitization and sIgE to beech and birch pollen, but an association was found between sIgE against CCDs and pine pollen. CONCLUSION: Sensitization prevalence to beech and pine wood measured by tailored ImmunoCAPs was not correlated to allergic symptoms. We recommend the application of CCD tools to assess the relevance of individual wood sensitization.

Increased incidence of respiratory symptoms among female woodworkers exposed to dry wood.

The aim of the present study was to investigate the occurrence of new respiratory symptoms in relation to wood dust exposure in a 6-yr follow-up study. A total of 1,377 woodworkers (1,137 males; 240 females) and 297 reference workers (137 males; 160 females) participated. Data on respiratory symptoms, employment and smoking habits were collected. Wood dust exposure was assessed from baseline dust measurements, and cumulative wood dust exposure was assessed by study-specific job exposure matrices and exposure time. The geometric mean (geometric sd) dust level decreased during the study period from 0.94 (2.1) to 0.60 (1.6) mg.m(-3). Adjusted analysis revealed positive associations for cumulative incidence proportion of chronic bronchitis and daily coughing for female woodworkers versus female reference workers. The cumulative incidence proportion of daily coughing and chronic bronchitis were found to be associated with baseline wood dust exposure in a dose-dependent manner. The odds ratio (95% confidence interval) for daily coughing (with reference to the lowest exposure quartile) was 1.6 (0.6-4.3), 3.2 (0.9-6.8) and 3.8 (1.5-9.7), respectively, in the second and third lowest and the highest quartile. The figures for chronic bronchitis were, accordingly, 2.3 (0.4-14.5), 3.0 (0.5-18.7) and 6.0 (1.2-28.8). In conclusion, female woodworkers in this low exposure cohort showed an increased incidence of coughing and bronchitis, whereas no relations to wood dust exposure were seen for male woodworkers.

Longitudinal lung function decline and wood dust exposure in the furniture industry.

The aim of the present study was to investigate the relationship between change in lung function and cumulative exposure to wood dust. In total, 1,112 woodworkers (927 males, 185 females) and 235 reference workers (104 males, 185 females) participated in a 6-yr longitudinal study. Forced expiratory volume in one second (FEV(1)), forced vital capacity (FVC), height and weight were measured, and questionnaire data on respiratory symptoms, wood dust exposure and smoking habits were collected. Cumulative inhalable wood dust exposure was assessed using a study-specific job exposure matrix and exposure time. The median (range) for cumulative wood dust exposure was 3.75 (0-7.55) mg x year x m(-3). A dose-response relationship between cumulative wood dust exposure and percent annual decrease in FEV(1) was suggested for female workers. This was confirmed in a linear regression model adjusted for confounders, including smoking, height and age. An additional difference of -14.50 mL x yr(-1) and -27.97 mL x yr(-1) was revealed for females exposed to 3.75-4.71 mg x yr x m(-3) or to >4.71 mg x yr x m(-3), respectively, compared with non-/low-exposed females. For females, a positive trend between wood dust exposure and the cumulative incidence proportion of FEV(1)/FVC <70% was suggested. In conclusion, in the present low-exposed cohort, female woodworkers had an accelerated decline in lung function, which may be clinically relevant.

Cross-shift changes in FEV1 in relation to wood dust exposure: the implications of different exposure assessment methods.

BACKGROUND: Exposure-response analyses in occupational studies rely on the ability to distinguish workers with regard to exposures of interest. AIMS: To evaluate different estimates of current average exposure in an exposure-response analysis on dust exposure and cross-shift decline in FEV1 among woodworkers. METHODS: Personal dust samples (n = 2181) as well as data on lung function parameters were available for 1560 woodworkers from 54 furniture industries. The exposure to wood dust for each worker was calculated in eight different ways using individual measurements, group based exposure estimates, a weighted estimate of individual and group based exposure estimates, and predicted values from mixed models. Exposure-response relations on cross-shift changes in FEV1 and exposure estimates were explored. RESULTS: A positive exposure-response relation between average dust exposure and cross-shift FEV1 was shown for non-smokers only and appeared to be most pronounced among pine workers. In general, the highest slope and standard error (SE) was revealed for grouping by a combination of task and factory size, the lowest slope and SE was revealed for estimates based on individual measurements, with the weighted estimate and the predicted values in between. Grouping by quintiles of average exposure for task and factory combinations revealed low slopes and high SE, despite a high contrast. CONCLUSION: For non-smokers, average dust exposure and cross-shift FEV1 were associated in an exposure dependent manner, especially among pine workers. This study confirms the consequences of using different exposure assessment strategies studying exposure-response relations. It is possible to optimise exposure assessment combining information from individual and group based exposure estimates, for instance by applying predicted values from mixed effects models.

Indices of asthma among atopic and non-atopic woodworkers.

AIMS: To investigate the relation between wood dust exposure and different indices of asthma among woodworkers and non-exposed subjects. METHODS: A total of 302 woodworkers and 71 non-exposed subjects answered a respiratory health questionnaire, underwent a non-specific bronchial provocation test using the Yan method, and received a skin prick test with 12 common inhalant allergens. Subgroups performed repeated peak flow monitoring and underwent a reversibility test. A total of 347 dust measurements among 234 woodworkers were performed with passive dust monitors. RESULTS: The overall geometric mean (geometric standard deviation) exposure to inhalable dust was 0.96 (2.02) mg/m3. There was a tendency to increased risk of asthma among atopic woodworkers compared to atopic non-exposed subjects, with ORs between 3.0 (0.8-11.9) (symptomatic BHR) and 1.3 (0.5-4.2) (work related symptoms). In woodworkers, asthma was associated with atopy, with ORs between 7.4 (2.8-19.7) (symptomatic BHR) and 4.2 (2.4-7.7) (asthma symptoms). Asthma was related to dust level, most pronounced for symptomatic BHR among atopics, with OR 22.9 (1.0-523.6) for the highest compared to the lowest dust level. For work related asthma symptoms the association with dust level was seen only for non-atopics. CONCLUSIONS: Wood dust exposure was associated with asthma, despite a low dust level compared to other studies. Atopy was an important effect modifier in the association between asthma and wood dust exposure.

Only few workers exposed to wood dust are detected with specific IgE against pine wood.

BACKGROUND: Our aim was to investigate the frequency of pine allergy in woodworkers with respiratory symptoms and to identify high molecular weight allergens in pine wood extracts. METHODS: In a cross-sectional study we examined work-related respiratory symptoms in 2033 furniture workers and 474 controls by questionnaires. Clinical examination was performed in 365 wood dust exposed and 116 nonexposed subjects. Blood samples were collected for measuring pine-specific immunoglobulin (Ig)E by an immunoassay and Western blots. RESULTS: Eleven exposed and three nonexposed subjects had pine-specific IgE. In the group with clinically defined asthma eight persons (5.4%) had pine-specific IgE compared with six persons (1.8%) in the group without asthma (P < 0.05). In the groups with and without respiratory symptoms, 13 (3.8%) and one (0.7%) subject, respectively, had pine-specific IgE (P = 0.06). Western blots demonstrated pine-specific IgE to components in the molecular range of 14 - 100 kD in eight samples (all wood dust exposed). Five samples had pine-specific IgE against components in a 43 - 59 kD zone and against two bands at 27 and 29 kD that are candidates for major allergens. CONCLUSION: Some workers in the Danish furniture industry are specific IgE sensitized against pine wood dust. Pine-specific IgE probably explains a minor part of the respiratory symptoms in workers exposed to pine wood dust.

Nasal patency is related to dust exposure in woodworkers.

OBJECTIVES: A cross sectional study of 54 furniture factories and three control factories was conducted to investigate the relation between subjective and objective nasal obstruction and exposure to wood dust. METHODS: Acoustic rhinometry was performed on 161 woodworkers and 19 controls. For each person, four measuring rounds were performed: before work, after 4 hours of work, and after 7 hours of work before and after decongestion. Before the first and third measuring round, each person rated the current feeling of nasal obstruction in the left and right nostril separately, using a visual analogue scale. Personal passive dust measurements were performed on 140 woodworkers. RESULTS: The mean (SD) of equivalent inhalable dust was relatively low, 1.17 (0.62) mg/m(3), range 0.17-3.44 mg/m(3). The exposure was divided into four levels: controls, low exposure, medium exposure, and high exposure. For the two highest concentrations of exposure, a significant increase in congestion--decreased nasal cavity volume and cross sectional areas--was found after 4 and 7 hours of work, compared with before work. Multivariate linear regression analysis showed positive correlations between concentration of dust and change in mucosal swelling. A significant increase in self rated nasal obstruction was found after work compared with before work for the two highest exposure groups. No correlation between objective nasal variables and self rated nasal obstruction was found. CONCLUSION: Exposure to wood dust was related in a dose dependent manner to acute nasal obstruction measured by acoustic rhinometry and self reported obstruction, but no correlation was found between measured and self reported obstruction.

Variations in exposure to inhalable wood dust in the Danish furniture industry. Within- and between-worker and factory components estimated from passive dust sampling.

Variability of exposure to wood dust at large factories in the Danish furniture industry was studied. Three repeated exposure measurements of 292 workers at 38 factories were included in the study. The measurements were carried out by use of personal passive dust monitors. The components of variance were estimated by means of a random effects ANOVA model. The ratio of within- to between-worker variance was 1.07. Based on this result, and three repeated exposure measurements, the observed relation between health outcome and exposure will be attenuated to 74% of the true value. Grouping by factory showed very poor exposure contrast, as the contrast in exposure level among factories was as low as 0.15.

Wood dust exposure in the Danish furniture industry using conventional and passive monitors.

A study of wood dust exposure at furniture factories in one county in Denmark was performed as a cross sectional study. Dust exposure was measured with personal passive dust monitors and calibrated against active sampling on filters. Measurements of 1685 workers were included in the exposure assessment. The passive dust monitor conversion models for equivalent concentrations of inhalable dust and total dust based on data from the present study were not significantly different from the original models. Therefore models based on all available data were used. The parameters of the distribution of equivalent concentration of inhalable dust were 0.94 mg/m3 (geometric mean) and 2.10 (geometric standard deviation). Compared with a national cross sectional study from 1988 the exposure level (geometric mean) was reduced by a factor 2.0. Inhalable dust exposure was about 50% higher than exposure measured by the Danish 'total' dust method.

Selection bias in determining the age dependence of waiting time to pregnancy.

Many studies have found decreased fecundability, that is, the ability to conceive in a menstrual cycle, with increasing female age. To evaluate the effect of maternal age on waiting time to pregnancy, the authors reviewed hospital charts of all pregnant women attending prophylactic antenatal care at Odense University Hospital, Denmark, during 1972-1987. Only the first pregnancy of each woman and only planned pregnancies were included (n = 14,754). The fecundability odds ratio (FR) was calculated as the odds of a conception in a menstrual cycle among the older women divided by the odds among women aged 15-24 years. The FR for women aged 25-29 years was 1.12 (95% confidence interval (CI): 1.04, 1.20), for women aged 30-34 years it was 1.15 (95% CI: 1.01, 1.30), and for women above 34 years the FR was 2.44 (95% CI: 1.84, 3.22) after adjustment for confounders. The increased fecundability with age is contrary to previous studies and may be explained by selection bias, as sterile women were not included. In addition, some very fertile young women who became pregnant by accident before efficient birth control methods were available and therefore were excluded from time to pregnancy studies may now use oral contraceptives until they plan a pregnancy later in life and are included.

Fecundability in relation to body mass and menstrual cycle patterns.

Few studies have investigated the association between body mass index and fecundability, that is, the ability to conceive in a menstrual cycle, among fertile women with normal menstrual cycle pattern. We examined the independent and combined effects of duration and regularity of the menstrual cycle, body mass index, and fecundability from records on pregnant women attending antenatal care at Odense University Hospital, Denmark, between 1972 and 1987. We included only the first birth of each woman who had planned pregnancies and no pre-pregnancy disease (N = 10,903). We estimated the fecundability odds ratio (FR) as the odds of conception in a menstrual cycle. After adjusting for confounders, the fecundability for women with a body mass index >25 kg/m2 was lower than for women with a body mass index of 20-25 kg/m2 [FR = 0.77; 95% confidence interval (CI) = 0.70-0.84]. FR was lower for women with long (>35 days) (FR = 0.74; 95% CI = 0.63-0.87) or irregular cycles (FR = 0.78; 95% CI = 0.70-0.87), even when their body mass index was within the normal range (20-25 kg/m2) and/or their cycles were regular.

[Contact eczema caused by pine wood]. / Kontakteksem udløst af arbejde med fyrretrae.

A 34 year-old woman, working with pine wood treated with sodium hydroxide and pyrogallol, developed dermatitis on arms, face and neck. Patch testing showed allergic reaction to colophony and pine wood, but not to sodium hydroxide or pyrogallol. Pine wood contains colophony. Since avoiding pine wood, she has had no further attack of dermatitis.

[Asthma, bronchitis and chronic obstructive pulmonary disease in occupational exposure to wood]. / Asthma, bronkitis og kronisk obstruktiv lungesygdom ved erhvervsmaessig udsaettelse for traestøv.

Two million workers worldwide are regularly exposed to wood dust in the work place. In Denmark alone approximately 40,000 workers are employed in the furniture industry where they are exposed to wood dust on a daily basis. This article reviews epidemiological at studies concerning the relationship between wood dust and the development of asthma, chronic obstructive pulmonary disease (COPD) and bronchitis. Fourteen cross-sectional studies and one register-based cohort study form the basis of this review. The conclusion is that despite possible methodological problems there seems to be a relationship between occupational exposure to the types of wood dust used in Denmark and the development of these pulmonary diseases. The results would indicate that further studies are clearly needed in order to study the incidence of these diseases and the relation to the specific types and amount of wood dust.

Seasonal variation in the time to pregnancy: a secondary analysis of three Danish databases.

Three Danish databases were reanalysed to investigate seasonal variation in the time to pregnancy. Information was available on cohorts of women selected on the basis of union membership or residence in a given area: textile workers in Denmark (with 1,053 first and 1,771 second pregnancies), pharmacy assistants in Denmark (with 734 first and 725 second pregnancies) and pregnant women in the 36th week of pregnancy in two Danish cities (with 3,657 first and 3,526 second pregnancies). The influence of the season was of primary interest, because it is presumed to cause impaired ovarian function and hence a prolonged time to pregnancy. Furthermore, we studied whether the waiting time was prolonged in other situations with possibility of decreased ovarian function: in young and older women. In genera, seasonality in the time to pregnancy based on the time of conception was found with a higher chance of a prolonged waiting time before conceiving in February-April and a lower chance of a prolonged waiting time before conceiving in August-October. This association was not distorted by the age of the women or diabetes mellitus. A prolonged time to pregnancy was found in women of 30 years or older. Women of 20 years or younger did not have a prolonged waiting time, but most of them were well beyond the age of menarche and thus beyond the period of impaired ovarian function. On a population level, there was evidence for seasonality in the time to pregnancy, which is compatible with seasonal variation in pregnancy planning as well as with biological influences.

Communication Concerning the Risks of Occupational Exposures in Pregnancy.

The health professional who is involved in communicating information about reproductive risks from occupational hazards needs to consider several important aspects. Uncertainties in risk assessment, timing of exposure in relation to pregnancy, and the consequences of different preventive measures for the woman (family), as well as for the employer and other persons at the workplace are examples of such aspects. The basis for the pregnant woman's perception of risk must be recognized. The risk-communication goal is that the persons concerned fully understand the risk and its possible consequences, so that they will be able to make informed decisions about how to act. More attention should be given to risk communication in the training of health professionals.

[Significance of occupational factors for women's fertility and menstrual cycles]. / Arbejdsmiljøfaktorers betydning for kvinders frugtbarhed og menstruationsforhold.

Reduced fertility is frequent, reflected by the fact that 15% of all couples desiring pregnancy try for more than one year without achieving it. Women at work are often exposed to chemical or physical agents, some of which are carcinogenic or teratogenic. Fertility seems to be affected by exposure to lead, mercury, solvents, textile dyes, noise and some pesticides. The purpose of this paper is to summarize the current knowledge of the relations between fertility, menstrual irregularity and occupational exposures. There are still some methodological problems to be solved in relation to fertility. Waiting time to pregnancy seems to be an appropriate measure of fertility. The full distribution of time to pregnancy over months or menstrual cycles should be used in the analysis.

Waiting time to pregnancy and pregnancy outcome among Danish workers in the textile, clothing, and footwear industries.

The relationship between time from planned to achieved pregnancy and pregnancy outcome has been studied in a group of 18,658 workers in the textile, clothing and footwear industries. Information on pregnancy outcome and delay in conception in the period 1979-84 was collected by self administered questionnaires in 1985. The response rate was 70.3%. During the study period there had been 5,171 live births and 708 spontaneous abortions. Information on delay in conception was collected in broad categories. The data were analysed by means of a newly developed statistical parametric model in order to collect all possible information from the highly grouped data. Median waiting time before a pregnancy which ended in spontaneous abortion was 1.68 times longer than median waiting time before a pregnancy leading to a live birth. There seems to be a correlation between the length of the waiting time and abortion.

PIP: This study examined, in a cohort of 18,658 women members 40 years of age in the textile, clothing, and footwear national union in 1985 in Denmark, the time span between planned and achieved pregnancy as it relates to pregnancy outcome. The response rate of the self-administered questionnaire was 70.3%. Information on all pregnancies between 1979 and 1984 was collected. Outcome data revealed 5171 pregnancies and 708 spontaneous abortions. Distribution of waiting times was modeled using Boldsen and Schaumburg techniques and assumes constant conception probability. Differences were represented by a gamma distribution with defined alpha and beta parameters. the results show that the waiting times resulting in spontaneous abortion are more likely to be unknown (chi square = 5.49, df = 1, p.05). There is a high likelihood that unplanned pregnancies result in spontaneous abortion (odds ration = 2.72, 95% confidence interval = 1.93-3.77). Abortion risk expected values closely approximate observed values of pregnancy resulting in spontaneous abortion. The median waiting time span for a pregnancy leading to spontaneous abortion is 1.68 times the median waiting time for pregnancy with a live birth. The risk of spontaneous abortion increases with the length of waiting time. Social conditions such as heavy smoking regimes, exposure to industrial chemicals, and lower educational levels may partially explain the results. There was a longer waiting time before conception also. A similar study among pharmacy assistants showed that outcome of pregnancy was unrelated to waiting time. Pregnancies may be considered unplanned more often when spontaneous abortion results, and may bias results. The long waiting times may mean impaired conception or very early pregnancy loss or an unknown biological explanation. Further research is suggested on other groups of women and waiting times.

[Cigarette smoking and time before pregnancy among Danish pharmacy assistants]. / Cigaretrygning og ventetid til graviditet hos danske apoteksassistenter.

The relationship between time to pregnancy and cigarette smoking was studied in a group of 4,924 pharmacy assistants under 40. The information was collected by means of a self administered questionnaire and the response rate was 92%. The data were analysed by a recently developed statistical model for description of time to pregnancy, which provides a more revealing test than the classic contingency table analysis. The study shows that smokers have a median time to pregnancy which is 27% longer than for non smokers. This may partly be due to lifestyle associated with smoking (e.g. alcohol and caffeine intake). Lifestyles such as these have been reported to prolong time to pregnancy. It is shown that time to pregnancy is an easily obtained measurement of fecundity. Only 3.6% of the women were unable to remember their time to pregnancy. The conclusion of the study was that information pertaining to the relationship between fertility and smoking habits/lifestyle should be a part of the instruction for women who wish to become pregnant.