Farm environment in childhood prevents the development of allergies

Kilpeläinen, Maritta; Terho, E. O.; Helenius, Hans; Koskenvuo, Markku

doi:10.1046/j.1365-2222.2000.00800.x

Cited by 325 publications

(259 citation statements)

References 39 publications

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“…Estimates from the video questionnaire for the prevalence of wheeze in the previous 12 months were even lower, ranging 1.3-3.3% for the centres in China, whereas the global mean was 7.3%. The low prevalence of asthma-like symptoms and reported asthma in rural areas in China is consistent with recent reports of the scarcity of asthma and atopy among children raised on farms in several countries [7][8][9][10][11]. It has been postulated that the lifestyle associated with living on a farm (larger family size, more pets, heating frequently using wood or coal, less maternal smoking and more dampness) may be responsible for the low prevalence.…”

Section: Discussionsupporting

confidence: 85%

The prevalence of asthma and asthma-like symptoms among adults in rural Beijing, China

Chan‐Yeung¹,

Zhang²,

Tu³

et al. 2002

Eur Respir J

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No data have been reported on the prevalence of asthma in rural areas of China. The objective of the present study was to determine the prevalence of asthmalike symptoms, reported asthma and reported asthma attacks in rural Beijing, China, and to compare the prevalence in 20-44-yr-old participants with those reported for Canada and the European Community Respiratory Health Survey (ECRHS).For a cross-sectional survey, 30 villages were randomly selected in the counties of Shunyi and Tongxian, 50 km north and east respectively of the city of Beijing and within the municipality of Beijing. The International Union Against Tuberculosis and Lung Disease questionnaire on bronchial symptoms translated into Chinese was completed by village doctors for each individual of w15 yrs. The survey was completed by 22,561 individuals, representing 98% of the eligible population.The prevalence of asthma-like symptoms and reported asthma attacks was higher in females than in males and increased with age. Smoking significantly increased the prevalence of symptoms; the effect in females was greater than in males. Among the 20-44-yr-olds, the prevalence of reported asthma attacks in the previous 12 months was 0.67% in rural Beijing, very much lower than that reported in ECRHS centres (3.1%), urban Canada (6.9%) and semirural Canada (5.1%), after adjusting for age and sex. The prevalence of asthma-like symptoms was also very low in rural Beijing compared with ECRHS centres and Canada.It is concluded that the prevalence of asthma-like symptoms and reported asthma was low in rural China compared with other countries, consistent with reports of the relative scarcity of asthma in farms and the "hygiene hypothesis".

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Section: Discussionsupporting

confidence: 85%

The prevalence of asthma and asthma-like symptoms among adults in rural Beijing, China

Chan‐Yeung¹,

Zhang²,

Tu³

et al. 2002

Eur Respir J

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“…In previous studies, socioeconomic status, dwelling place and mother's parity were shown to be associated with atopic disorders [25][26][27] and depression. [28][29][30] Therefore, dwelling place and father's social class in 1966, as well as mother's parity, were evaluated as potential confounding variables.…”

Section: Confounding Variablesmentioning

confidence: 91%

Atopy and depression: results from the Northern Finland 1966 Birth Cohort Study

et al. 2003

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Several studies have suggested an association between IgE-mediated atopic allergies and depression. The present study extends our understanding about putative gender differences of this association and provides further epidemiological evidence for our previous finding that the association between atopy and depression may be characteristic for females only. In order to clearly determine the presence of atopic disorders and depression, we used more valid tools than had been employed earlier and we had access to a database (the Northern Finland 1966 Birth Cohort), in which individuals were followed up prospectively until the age of 31 years. The information on allergic symptoms, verified by skin-prick tests and comprising data of 5518 individuals, was used to ascertain the presence of atopy. Depression was assessed with the help of Hopkins' Symptom Checklist-25 and self-reported doctor-diagnosed depression. After adjusting for a father's social class, mother's parity, and place of residence, logistic regression analyses showed that the risk of developing depression increased in parallel with the increasing severity of depression and, when compared with nonatopic subjects, was 3.0 to 4.7-fold up in atopic females and statistically significant. In atopic males, the association between atopy and depression was statistically significant only in the highest depression scores, the odds ratio being 6.3-fold. The results indicate that females suffering from atopic diseases might possess an elevated risk of developing depression already during early adulthood. In males, the association between these two disorders is evident only among the most severe manifestations of depression. Possible background theories, that is, genetic abnormalities in serotonin metabolism, HPA-axis dysfunction, and histamine theory are discussed.

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“…For instance, in the traffic exposure-response study by Montnémery et al (114) (Table 2), although there were significant associations of asthma symptoms and diagnosis to traffic density, there were no urban-rural differences. In addition, some recent studies that specifically examined farming environments, found a decreased risk of asthma and atopy among children living on farms (137,138), particularly where there is regular contact with farm animals. This prompted these investigators to hypothesize that a "protective farm factor" may reflect the influence of microbial agents on T H 1 versus T H 2 cell development or reflect the development of immunotolerance (137,138).…”

Section: Coherence With Traffic Studies By Trends In Asthma and Urbanmentioning

confidence: 99%

“…In addition, some recent studies that specifically examined farming environments, found a decreased risk of asthma and atopy among children living on farms (137,138), particularly where there is regular contact with farm animals. This prompted these investigators to hypothesize that a "protective farm factor" may reflect the influence of microbial agents on T H 1 versus T H 2 cell development or reflect the development of immunotolerance (137,138). This possibility, in addition to potentially high levels of confounding by uncontrolled factors that vary by geography, makes it difficult to clearly interpret the cross-sectional studies on urban versus rural areas or ecologic studies of international differences.…”

Section: Coherence With Traffic Studies By Trends In Asthma and Urbanmentioning

confidence: 99%

Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research.

Delfino

2002

Environ Health Perspect

269

152

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Outdoor ambient air pollutant exposures in communities are relevant to the acute exacerbation and possibly the onset of asthma. However, the complexity of pollutant mixtures and etiologic heterogeneity of asthma has made it difficult to identify causal components in those mixtures. Occupational exposures associated with asthma may yield clues to causal components in ambient air pollution because such exposures are often identifiable as single-chemical agents (e.g., metal compounds). However, translating occupational to community exposure-response relationships is limited. Of the air toxics found to cause occupational asthma, only formaldehyde has been frequently investigated in epidemiologic studies of allergic respiratory responses to indoor air, where general consistency can be shown despite lower ambient exposures. The specific volatile organic compounds (VOCs) identified in association with occupational asthma are generally not the same as those in studies showing respiratory effects of VOC mixtures on nonoccupational adult and pediatric asthma. In addition, experimental evidence indicates that airborne polycyclic aromatic hydrocarbon (PAH) exposures linked to diesel exhaust particles (DEPs) have proinflammatory effects on airways, but there is insufficient supporting evidence from the occupational literature of effects of DEPs on asthma or lung function. In contrast, nonoccupational epidemiologic studies have frequently shown associations between allergic responses or asthma with exposures to ambient air pollutant mixtures with PAH components, including black smoke, high home or school traffic density (particularly truck traffic), and environmental tobacco smoke. Other particle-phase and gaseous co-pollutants are likely causal in these associations as well. Epidemiologic research on the relationship of both asthma onset and exacerbation to air pollution is needed to disentangle effects of air toxics from monitored criteria air pollutants such as particle mass. Community studies should focus on air toxics expected to have adverse respiratory effects based on biological mechanisms, particularly irritant and immunological pathways to asthma onset and exacerbation.

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Farm environment in childhood prevents the development of allergies

Cited by 325 publications

References 39 publications

The prevalence of asthma and asthma-like symptoms among adults in rural Beijing, China

The prevalence of asthma and asthma-like symptoms among adults in rural Beijing, China

Atopy and depression: results from the Northern Finland 1966 Birth Cohort Study

Epidemiologic evidence for asthma and exposure to air toxics: linkages between occupational, indoor, and community air pollution research.

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