Association between domestic mould and mould components, and asthma and allergy in children: a systematic review

Abstract

Critical reviews over the past 10 yrs have found increased respiratory and allergic health outcomes for children living in damp and mouldy environments. However, recent studies have suggested that early childhood exposure to specific mould components may actually protect children from developing allergy.We conducted a systematic review of observational studies published in English from January 1980 to July 2010. This review was conducted according to systematic guidelines for Metaanalyses of Observational Studies in Epidemiology (MOOSE). The literature was searched using a computerised bibliographic database, PubMed. In order to increase the quality of the reviewed studies, meta-analyses of the effects of visible mould exposure on allergic health outcomes were performed and we evaluated the findings according to the Bradford Hill criteria for evidence of causation.The literature search identified 1,398 peer-reviewed scientific publications, and 61 studies that fulfilled the inclusion criteria were included in this review. We observed increased risks of allergic respiratory health outcomes in children exposed to visible mould and mould spores. These findings were confirmed by the results of the meta-analysis and in line with the evaluation criteria according to Bradford Hill. Visible mould was positively associated with asthma (OR 1.49 (95% CI 1.28-1.72)), wheeze (OR 1.68 (95% CI 1.48-1.90)) and allergic rhinitis (OR 1.39 (95% CI 1.28-1.51)). However, there was a tendency of lower risk for allergic health outcomes in children exposed to mouldderived components such as (1,3)-b-D-glucan and extracellular polysaccharides.These findings suggest that home environments with visible mould and mould spore exposure increase the risk of allergic respiratory health outcomes in children. However, further investigations are needed to examine the effects of exposure to mould-derived components as the current literature is inconclusive. In order to disentangle the different effects of overall microbial exposure on children's health, research should focus on specific microbial markers in the home, in combination with new assessment techniques including molecular methods.

Housing characteristics and indoor environment in relation to children’s asthma, allergic diseases and pneumonia in Urumqi, China

“…A recently published 10-year longitudinal study of adults in Uppsala, Sweden, found that signs of dampness in floor construction of any workplace building during follow up (cumulative exposure) were associated with incidence of mucosal symptoms (OR=2.43) including nasal catarrh, nasal obstruction, dryness in throat, sore throat or irritating cough [25]. Although the exact mechanism is unknown, it has been generally agreed that home mold or dampness is a risk factor for children's allergic diseases including asthma [26][27][28][29]. On the other hand, a recently published longitudinal study from Sweden found that self reported dampness or mold could be biased, since the baseline findings of a strong association between dampness and allergies disappeared in the follow-up study 5 years later [30].…”

Impact of dwelling characteristics on concentrations of bacteria, fungi, endotoxin and total inflammatory potential in settled dust

“…Airborne microorganisms have a tendency to aggregate into particles of different sizes depending on source, species, relative humidity and the mechanism of aerosolization [26,36]. Several studies have indicated that the presence of fungi, bacteria and endotoxin in the indoor environment is associated with serious inflammation-related health risks such as asthma, allergies and respiratory discomfort [18,32,58]. Furthermore, several studies indicate that dose response relationship between exposure to microorganisms and the development of asthma exacerbate the symptoms [16,19,28,31,41,42].…”

Seasonal Variations of Indoor Microbial Exposures and Their Relation to Temperature, Relative Humidity, and Air Exchange Rate

“…Therefore, these microbial agents were quantified in this study. Fungal genera typically found within the indoor environment are sources of potent allergens and inflammogens (22), and several epidemiological studies have coupled fungal exposure with asthma, allergy, and sick building syndrome (5,8,21,45,56). Exposure to bacteria has been associated with blocked nose and eye symptoms (14).…”