Exposure to grass pollen--but not birch pollen--affects lung function in Swedish children.

Allergic response to pollen is increasing worldwide, leading to high medical and social costs. However, the effect of pollen exposure on lung function has rarely been investigated. Over 1800 children in the Swedish birth cohort BAMSE were lung-function- and IgE-tested at the age of 8 and 16 years old. Daily concentrations for 9 pollen types together with measurements for ozone, NO2 , PM10 , PM2.5 were estimated for the index day as well as up to 6 days before the testing. Exposure to grass pollen during the preceding day was associated with a reduced forced expiratory volume in 8-yr-olds; -32.4 ml; 95% CI: -50.6 to -14.2, for an increase in three pollen counts/m³. Associations appeared stronger in children sensitized to pollen allergens. As the grass species flower late in the pollen season, the allergy care routines might be weakened during this period. Therefore, allergy information may need to be updated to increase awareness among grass pollen-sensitized individuals.

Lifestyle factors and sensitization in children - the ALADDIN birth cohort.

BACKGROUND: Several cross-sectional studies indicate that an anthroposophic lifestyle reduces the risk of allergy in children. We initiated the Assessment of Lifestyle and Allergic Disease During Infancy (ALADDIN) birth cohort to elucidate the role of specific factors supposed to mediate this effect. The aims of this study are to describe the ALADDIN cohort and to report patterns of exposure and allergic sensitization during the first years of life. METHODS: The ALADDIN study is a prospective birth cohort study of 330 children from families with an anthroposophic, partly anthroposophic, or nonanthroposophic lifestyle. The children and their parents were following an extensive data collection scheme, including repeated questionnaires and biological samples. Blood samples were collected from the parents and from the child at birth as well as at 6, 12, and 24 months of age. RESULTS: Several lifestyle factors differed between the groups, such as diet, medication, and place of delivery. Children of families with an anthroposophic lifestyle had a markedly decreased risk of sensitization during the first 2 years of life compared with children of nonanthroposophic families with adjusted OR 0.25 (95% CI 0.10-0.64) and P-value 0.004. A similar situation held true for children from families with a partly anthroposophic lifestyle, adjusted OR 0.31 (95% CI 0.15-0.54), and P-value 0.002. CONCLUSIONS: The anthroposophic lifestyle comprises several factors of interest for allergy development and is here shown to be associated with reduced risk of IgE sensitization already in infancy. Identifying the factors responsible for this association would be of significant clinical importance.

Symptoms to pollen and fruits early in life and allergic disease at 4 years of age.

BACKGROUND: The predictive value of reported early symptoms to pollen or fruits on later allergic disease is unclear. Our aim is to evaluate if symptoms to pollen and/or to fruits early in life are associated with allergic disease and sensitization to pollen at 4 years. METHODS: The study included 3619 children from the Barn (Children), Allergy, Milieu, Stockholm, Epidemiology project (BAMSE) birth cohort. Reported symptoms of wheeze, sneeze or rash to birch, grass or weed, symptoms (vomiting, diarrhea, rash, facial edema, sneeze, or wheeze) to fruits including tree-nuts at 1 or 2 years of age, and definitions of asthma, rhinitis and eczema at 4 years were derived from questionnaire data. Sensitization to pollen allergens was defined as allergen-specific IgE-antibodies to any pollen (birch/timothy/mugwort) > or =0.35 kU(A)/l. RESULTS: At 1 or 2 years of age, 6% of the children were reported to have pollen-related symptoms, 6% had symptoms to fruits, and 1.4% to both pollen and fruits. Children with symptoms to both pollen and fruits at 1 or 2 years of age had an increased risk for sensitization to any pollen allergen at age 4 (OR(adj) = 4.4, 95% CI = 2.1-9.2). This group of children also had a substantially elevated risk for developing any allergic disease (asthma, rhinitis, or eczema) at 4 years irrespective of sensitization to pollen (OR(adj) = 8.6, 95% CI = 4.5-16.4). CONCLUSIONS: The prevalence of reported symptoms to pollen and fruits is very low in early childhood. However, children with early symptoms to both pollen and fruits appear to have a markedly elevated risk for allergic disease.

Sensitization to inhalant allergens between 4 and 8 years of age is a dynamic process: results from the BAMSE birth cohort.

BACKGROUND: There is limited knowledge of the development of IgE-antibody levels over time in childhood, with respect to persistency and co-sensitization to specific inhalant allergens. METHODS: Data from 2033 children participating in the BAMSE birth cohort was used. Background factors and clinical parameters were obtained and IgE antibody (ab) levels to eight common airborne allergens were measured (>or=0.35 kU(A)/L) when the children were 4 and 8 years of age. RESULTS: Between 4 and 8 years the proportion of children sensitized to any of the inhalant allergens tested increased from 15% to 25%. At 4 years IgE-ab to birch and cat dominated, whereas at the age of 8, there was a considerable increase in the proportion of sensitization to timothy and dog. Except for mites and moulds, IgE-ab levels to all aeroallergens increased significantly between 4 and 8 years among those already sensitized at 4. Transient sensitization to inhalant allergen was uncommon. Furthermore, sensitization to birch pollen at 4 years increased the risk for becoming sensitized to timothy, cat and dog later in life. Such an association was not observed among those sensitized primarily to animal dander. CONCLUSIONS: There is a prominent process of sensitization at pre-school age to inhalant allergens, and in Northern Europe sensitization to birch pollen early in life seems to be important for this process. Such a process has a probable impact on the development of allergic disease in the growing child.

Allergic diseases and atopic sensitization in children related to farming and anthroposophic lifestyle--the PARSIFAL study.

BACKGROUND: The prevalence of allergic diseases has increased rapidly in recent decades, particularly in children. For adequate prevention it is important not only to identify risk factors, but also possible protective factors. The aim of this study was to compare the prevalence of allergic diseases and sensitization between farm children, children in anthroposophic families, and reference children, with the aim to identify factors that may protect against allergic disease. METHODS: The study was of cross-sectional design and included 14,893 children, aged 5-13 years, from farm families, anthroposophic families (recruited from Steiner schools) and reference children in Austria, Germany, The Netherlands, Sweden and Switzerland. A detailed questionnaire was completed and allergen-specific IgE was measured in blood. RESULTS: Growing up on a farm was found to have a protective effect against all outcomes studied, both self-reported, such as rhinoconjunctivitis, wheezing, atopic eczema and asthma and sensitization (allergen specific IgE > or = 0.35 kU/l). The adjusted odds ratio (OR) for current rhinoconjunctivitis symptoms was 0.50 (95% confidence interval (CI) 0.38-0.65) and for atopic sensitization 0.53 (95% CI 0.42-0.67) for the farm children compared to their references. The prevalence of allergic symptoms and sensitization was also lower among Steiner school children compared to reference children, but the difference was less pronounced and not as consistent between countries, adjusted OR for current rhinoconjunctivitis symptoms was 0.69 (95% CI 0.56-0.86) and for atopic sensitization 0.73 (95% CI 0.58-0.92). CONCLUSIONS: This study indicates that growing up on a farm, and to a lesser extent leading an anthroposophic life style may confer protection from both sensitization and allergic diseases in childhood.

Bacterial and fungal agents in house dust and wheeze in children: the PARSIFAL study.

BACKGROUND: Growing up on a farm and an anthroposophic lifestyle are associated with a lower prevalence of allergic diseases in childhood. This might be related to increased inhalatory exposure to microbial agents. OBJECTIVE: To assess the association between microbial agents in house dust and atopic wheeze in farm children, Steiner school children and reference children. METHODS: Levels of bacterial endotoxin, fungal beta(1,3)-glucans and fungal extracellular polysaccharides (EPS) in mattress and living room floor dust were measured in a population of 270 atopic (=Phadiatop-positive) children with self-reported wheezing, including 168 current atopic wheezers, and 441 non-atopic, non-symptomatic controls. These children were selected from a cross-sectional study in five European countries. RESULTS: In the study population as a whole, average levels of mattress dust endotoxin, EPS and glucans were slightly (1.1-1.2-fold; P<0.10) higher in control children than in atopic wheezers. Atopic wheeze was related to mattress levels of endotoxin, EPS and glucans in farm and farm-reference children. However, when adjusting for group (farm vs. farm-reference children), the associations became non-significant whereas the group effect remained. No associations between atopic wheeze and microbial agents were observed in Steiner and Steiner-reference children. For current atopic wheeze, the farm effect became non-significant after adjustment for microbial agent levels. CONCLUSION: Not only bacterial endotoxin but also mould components might offer some protection against atopic wheeze in children. However, the protective effect of being raised on a farm was largely unexplained by the mattress microbial agent levels measured in this study.

Validation of questions on asthma and wheeze in farming and anthroposophic children.

BACKGROUND: In most epidemiological surveys the estimated prevalence of asthma is based on questionnaire responses, which may depend on the individual's perception as well as medical consulting habits in a given population. Therefore, measurement of bronchial hyper-responsiveness as a key feature of asthma has been suggested as an objective parameter for asthma. OBJECTIVE: The aim of the present study was to validate questionnaire responses on asthma and wheeze against bronchial response to hypertonic saline (HS) (4.5%) in populations previously shown to have a lower prevalence of asthma and allergies: farmers' children and children from anthroposophic families. METHODS: Children whose parents had completed a written questionnaire in the cross-sectional PARSIFAL-study were drawn from the following four subgroups: 'farm children' (n=183), 'farm reference children' (n=173), 'Steiner schoolchildren' (n=243) and 'Steiner reference children' (n=179). Overall, 319 children with wheeze in the last 12 months and 459 children without wheeze in the last 12 months performed an HS challenge. RESULTS: Odds ratios, sensitivity, specificity, likelihood ratios and measures of association did not differ significantly between the four subgroups. The correlation between the bronchial response to HS and wheeze and asthma questions was moderate and similar for farm children, farm reference children, Steiner schoolchildren and Steiner reference children (kappa for 'wheeze': 0.25, 0.33, 0.31, 0.35, respectively, P=0.754, kappa for 'doctor's diagnosis of asthma': 0.33, 0.19, 0.33, 032, respectively, P=0.499). CONCLUSION: The findings from this study suggest that the reliabilitiy of questionnaire responses on asthma and wheeze is comparable between farmers' children, children raised in families with anthroposophic lifestyle and their respective peers.

Bacterial and fungal components in house dust of farm children, Rudolf Steiner school children and reference children--the PARSIFAL Study.

BACKGROUND: Growing up on a farm and an anthroposophic lifestyle are associated with a lower prevalence of allergic diseases in childhood. It has been suggested that the enhanced exposure to endotoxin is an important protective factor of farm environments. Little is known about exposure to other microbial components on farms and exposure in anthroposophic families. OBJECTIVE: To assess the levels and determinants of bacterial endotoxin, mould beta(1,3)-glucans and fungal extracellular polysaccharides (EPS) in house dust of farm children, Steiner school children and reference children. METHODS: Mattress and living room dust was collected in the homes of 229 farm children, 122 Steiner children and 60 and 67 of their respective reference children in five European countries. Stable dust was collected as well. All samples were analysed in one central laboratory. Determinants were assessed by questionnaire. RESULTS: Levels of endotoxin, EPS and glucans per gram of house dust in farm homes were 1.2- to 3.2-fold higher than levels in reference homes. For Steiner children, 1.1- to 1.6-fold higher levels were observed compared with their reference children. These differences were consistently found across countries, although mean levels varied considerably. Differences between groups and between countries were also significant after adjustment for home and family characteristics. CONCLUSION: Farm children are not only consistently exposed to higher levels of endotoxin, but also to higher levels of mould components. Steiner school children may also be exposed to higher levels of microbial agents, but differences with reference children are much less pronounced than for farm children. Further analyses are, however, required to assess the association between exposure to these various microbial agents and allergic and airway diseases in the PARSIFAL population.

Immunoglobulin G4-antibodies to rBet v 1 and risk of sensitization and atopic disease in the child.

BACKGROUND: In 1993 extremely high levels of birch-pollen were recorded in Stockholm, Sweden. This provided an opportunity to evaluate the effects of aeroallergen exposure (exp.) on the early immune response. OBJECTIVE: To assess the influence of exp. to birch-pollen during pregnancy and infancy on the allergen-specific IgE- and IgG4-antibody (ab) response and the development of atopic disease in children. METHODS: A total of 970 children with atopic heredity and born in Stockholm 1992, 1993 or 1994 were investigated at age 4.5-5 years. They were divided into five groups; high-dose exp. at 1 year of age, high-dose exp. at 0-3 months, low-dose exp. at 0-3 months, high-dose exp. during pregnancy and low-dose exp. during pregnancy. The children were examined and skin prick tested with inhalant and food allergens. IgE abs (against birch-pollen and recombinant Bet v 1(rBet v1)) and IgG4 abs (against rBet v 1) were analysed in serum. All children were assembled in one group to assess the effects of different ab responses (IgE/IgG4) on the development of atopic disease. RESULTS: Children exposed to high doses of birch-pollen during the first 3 months of life more often had detectable levels of IgG4 abs to rBet v 1 than the children in the other groups (P < 0.001), independent of sensitization to birch. Overall, the risk of allergic rhinoconjunctivitis was increased among children sensitized to birch-pollen and appeared more pronounced in children without detectable levels of IgG4 ab to rBet v 1 (Odds ratio 9.4; 95% Confidence interval: 5.5-16.1). IgE sensitization to birch-pollen seemed to have a stronger influence on the development of atopic disease than the IgG4-ab response. CONCLUSION: Exposure to high doses of inhalant allergens during the early postnatal period is associated with detectable levels of allergen-specific IgG4 ab even at 5 years of age. An immune modulating effect by IgG4 on symptoms of allergic rhinoconjunctivitis is suggested in children sensitized to birch.

Exposure to high doses of birch pollen during pregnancy, and risk of sensitization and atopic disease in the child.

BACKGROUND: The role of maternal allergen exposure during pregnancy in sensitization and development of atopic disease in the child remains controversial. In the spring of 1993, extremely high levels of birch pollen were recorded in Stockholm, Sweden. In 1994, the corresponding pollen levels were low. The aim of this study was to assess the influence of exposure during pregnancy to high/low doses of birch pollen on the risk of sensitization and development of atopic disease in children. In addition, a comparison was made with children exposed to birch pollen in early infancy. METHODS: Three hundred and eighty-seven children with atopic heredity, born in Stockholm in July-October 1993 or 1994 (mothers exposed during pregnancy), were investigated at age 4.5 years. The children were clinically examined and were skin prick tested (SPT) with inhalant and food allergens. IgE antibodies (RAST) against birch pollen and recombinant birch pollen allergen (rBet v 1) were analysed in serum. A comparison was made with a similar group of children exposed during the same incident, but in the first 3 months of life, in 1993. RESULTS: The children of mothers high-dose exposed during pregnancy in 1993 tended to be more sensitized (SPT > or = 3 mm) to birch pollen than the children with low-dose exposure during the corresponding period in 1994 (7.6 and 4.6%, respectively, OR: 1.7; 95% CI: 0.7-4.1). A similar but weak tendency was seen for positive RAST analyses (> or =0.35 kU/l) against birch pollen and rBet v 1. Children of mothers high-dose exposed during pregnancy were significantly less sensitized to birch pollen than the children high-dose exposed in early infancy (17.9%, OR: 0.4; 95% CI: 0.2-0.7). There was an overall trend towards a slightly increased prevalence of bronchial asthma, allergic rhinoconjunctivitis and atopic dermatitis in the group with mothers high-dose exposed during pregnancy, compared to those with low exposure. CONCLUSION: Exposure of the mother during pregnancy to high levels of birch pollen resulted in a tendency towards increased risk of sensitization to the same allergen and symptoms of atopic disease in children with atopic heredity. Furthermore, our data indicate that exposure of the mother during pregnancy to inhalant allergens is less likely to result in sensitization in the child than exposure of the child in early infancy.

Atopy in children of families with an anthroposophic lifestyle.

BACKGROUND: Increased prevalence of atopic disorders in children may be associated with changes in types of childhood infections, vaccination programmes, and intestinal microflora. People who follow an anthroposophic way of life use antibiotics restrictively, have few vaccinations, and their diet usually contains live lactobacilli, which may affect the intestinal microflora. We aimed to study the prevalence of atopy in children from anthroposophic families and the influence of an anthroposophic lifestyle on atopy prevalence. METHODS: In a cross-sectional study, 295 children aged 5-13 years at two anthroposophic (Steiner) schools near Stockholm, Sweden, were compared with 380 children of the same age at two neighbouring schools in terms of history of atopic and infectious diseases, use of antibiotics and vaccinations, and social and environmental variables. Skin-prick tests were done for 13 common allergens, and we took blood samples from children and their parents for analysis of allergen-specific serum IgE-antibodies. FINDINGS: At the Steiner schools, 52% of the children had had antibiotics in the past, compared with 90% in the control schools. 18% and 93% of children, respectively, had had combined immunisation against measles, mumps, and rubella, and 61% of the children at the Steiner schools had had measles. Fermented vegetables, containing live lactobacilli, were consumed by 63% of the children at Steiner schools, compared with 4.5% at the control schools. Skin-prick tests and blood tests showed that the children from Steiner schools had lower prevalence of atopy than controls (odds ratio 0.62 [95% CI 0.43-0.91]). There was an inverse relation between the number of characteristic features of an anthroposophic lifestyle and risk of atopy (p for trend=0.01). INTERPRETATION: Prevalence of atopy is lower in children from anthroposophic families than in children from other families. Lifestyle factors associated with anthroposophy may lessen the risk of atopy in childhood.

Increasing prevalence of asthma over 12 years among dairy farmers on Gotland, Sweden: storage mites remain dominant allergens.

BACKGROUND: Earlier studies from several countries have shown that IgE-mediated allergy in rural populations is of considerable importance and that storage mites are dominant allergens. OBJECTIVE: In an epidemiological follow-up study among farmers on the island of Gotland, Sweden in 1996 we wished to investigate the prevalence of respiratory allergy and to find out whether storage mites are still important allergens in a farming environment. METHODS: A questionnaire concerning airway symptoms, social and working conditions and smoking habits was distributed to all Gotland farmers aged 15-65 years and was completed by 1577 (86.7%), of whom 1015 were dairy farmers. Based on the answers, 500 dairy farmers were invited to undergo a medical examination which included a skin-prick test (SPT) and blood sampling for RAST analyses. Prevalence figures (symptoms, RAST and SPT) given for the whole population (n = 1015) were based on the investigation of the 461 farmers who took part in the examination. RESULTS: Immediate onset hypersensitivity was present in 41.7% of the 1015 farmers studied, which is almost the same figure as in 1984 (40.0%). The prevalence of asthma had increased significantly during the previous 12 years (5.3% vs 9.8%), as had asthma in combination with rhinoconjunctivitis (3.7% vs 7.0%). Rhinoconjunctivitis, on the other hand, had not changed significantly (36.5% vs 33.1%) and remained one of the most common symptoms. The prevalence of storage mite allergy in the farming population in 1996 was 6.5% and constituted an important cause of allergic symptoms. CONCLUSION: Over 12 years, Gotland dairy farmers have developed significantly more respiratory symptoms from the lower airways, although the proportion with atopy is unchanged. Storage mites are still dominant allergens for developing allergic disease.

Dietary factors and risk of lung cancer in never-smokers.

We studied dietary risk factors for lung cancer among never-smokers in a population-based case-control study in Stockholm, 1989-1995. Study subjects were older than 30 years of age and had never smoked regularly. A total of 124 cases (35 men, 89 women) and 235 controls (72 men, 163 women) participated. Exposure information was obtained at interview with study subjects. The never-smoking status was validated by interviews with next-of-kin. A protective effect was suggested for vegetables, mediated primarily by carrots (relative risk [RR], 0.7; 95% confidence interval [CI], 0.4-1.3, and 0.6, 0.3-1.1 for intermediate and high consumption of carrots, respectively). Non-citrus fruits appeared to lower the risk as well, with RR 0.6, 95% CI 0.3-1.3 and 0.5, 0.3-1.0 for intermediate and high consumption, respectively. A protective effect with dose-response was also seen for intake of beta-carotene and total carotenoids. Increased risks were seen for cultured milk products in both genders (RR 2.0, 95% CI 1.1-3.9 for intermediate and 1.6, 0.9-2.9 for high consumption), but for milk only among male high consumers. Our results support evidence linking a diet rich in vegetables and non-citrus fruit with decreased lung cancer risk and suggests that among vegetables, carrot consumption is the most important component or marker for this effect in Sweden. The results regarding milk products could be consistent with dietary fat as a risk factor for lung cancer, although a more comprehensive assessment of fat intake is necessary to explore this relation.