Effects of damp and mould in the home on respiratory health: a review of the literature

Immunoglobulin G antibodies to moulds in school-children from moisture problem schools

BACKGROUND

The purpose of the present study was to evaluate mould-specific immunoglobulin G (IgG) antibodies in children exposed to moisture and mould problems in their school, and the association between IgG antibodies and mould allergy, active or passive smoking and respiratory symptoms.

METHODS

IgG antibodies were studied to 24 moulds in 93 children from three moisture problem schools and in 33 children from a reference school. The antibodies were measured by enzyme-linked immunosorbent assay and compared to positive adult sera.

RESULTS

There were no significant differences in mould-specific IgG concentrations between exposed and non-exposed school-children. Antibodies to moulds common in moisture damaged buildings were associated with allergic diseases, as well as with mould-specific immunoglobulin E (IgE) or skin prick test (SPT) findings. Aspergillus fumigatus and A. versicolor were the moulds with the most consistent findings. Active and passive smoking were associated with low levels of antibodies to many moulds. Though the association between asthma, wheezing or cough symptoms, and IgG to moulds was not significant, 7 (39%) of the 18 children with multiple (> 7) elevated IgG findings suffered from asthma or wheezing.

CONCLUSIONS

Allergy was, but asthma was not, associated with IgG antibodies to the moulds that can be found in moisture damaged buildings. However, no association was found between IgG antibodies to moulds and exposure to moisture and moulds in school.

The mycotoxins citrinin, gliotoxin, and patulin affect interferon-gamma rather than interleukin-4 production in human blood cells

Exposure to molds diminishes the numbers of T-helper type 1 (Th1) cells in the peripheral blood of children and is a risk factor for the development of allergic diseases (results of LARS: Leipzig Allergy Risk Children Study, Mueller et al. 2002). We hypothesized that mycotoxins are responsible for this effect and therefore investigated the influence of citrinin, gliotoxin, and patulin on human peripheral blood mononuclear cells (PBMC). CD3/CD28-stimulated PBMC of healthy donors were incubated for 24 h with the mycotoxins in serial dilutions and triplicates. Vitality and proliferation were tested using the MTT assay and T-cell function by the expression of cytokines (ELISA, intracellular cytokine staining, and real-time polymerase chain reaction (RT-PCR) for interferon-gamma (IFN-gamma) and interleukin-4 (IL-4). The cytokine secretion was inhibited at concentrations 2-130 times lower compared to vitality (ELISA versus MTT assay). The strongest inhibition of cytokine expression was found for IFN-gamma: 8.3 microg/mL citrinin, 34.2 ng/mL gliotoxin, and 64.8 ng/mL patulin caused a 50% inhibition of the IFN-gamma release (50% inhibitory dose, ID(50)). For IL-4 release the corresponding ID(50) values were 21.6 microg/mL citrinin, 82.8 ng/mL gliotoxin, and 243.2 ng/mL patulin. Furthermore, 3 ng/mL patulin caused a significant increase of IL-4 but a significant suppression of IFN-gamma. On the mRNA level, after 24 h an unaltered or enhanced IL-4 was observed compared to a reduced IFN-gamma expression. Using a method of intracellular cytokine staining, we were able to show that the described effects are caused by a reduction of the number of IFN-gamma-producing T lymphocytes rather than by a reduced functional capacity of the single cell. We suggest that mycotoxins primarily cause stronger inhibition of IFN-gamma-producing Th1 cells, which may lead to T-cell polarization toward the Th2 phenotype and may raise the risk for the development of allergies.

Taking STOX: developing a cross disciplinary methodology for systematic reviews of research on the built environment and the health of the public

STUDY OBJECTIVE

To develop a cross disciplinary literature search methodology for conducting systematic reviews of all types of research investigating aspects of the built environment and the health of the public.

DESIGN

The method was developed following a comprehensive search of literature in the area of housing and injuries, using 30 databases covering many disciplines including medicine, social science, architecture, science, engineering, environment, planning and psychology. The results of the database searches, including the type (or evidence) of research papers identified, were analysed to identify the most productive databases and improve the efficiency of the strategy. The revised strategy for literature searching was then applied to the area of neighbourhoods and mental health, and an analysis of the evidence type of references was carried out. In recognition of the large number and variety of observational studies, an expanded evidence type classification was developed for this purpose.

MAIN RESULTS

From an analysis of 722 citations obtained by a housing and injuries search, an overlap of only 9% was found between medical and social science databases and only 1% between medical and built environment databases. A preliminary evidence type classification of those citations that could be assessed (from information in the abstracts and titles) suggested that the majority of intervention studies on housing and injuries are likely to be found in the medical and social science databases. A number of relevant observational studies (10% of all research studies) would have been missed, however, by excluding built environment and grey literature databases. In an area lacking in interventional research (housing/neighbourhoods and mental health) as many as 25% of all research studies would have been missed by ignoring the built environment and grey literature.

CONCLUSIONS

When planning a systematic review of all types of evidence in a topic relating to the built environment and the health of the public, a range of bibliographical databases from various disciplines should be considered.

Assessment and control of fungal allergens

Fungal sensitivity is a significant cause of allergic disease. Understanding the role fungi play in allergic disease, and how to best control exposure among those with allergy, can have important clinical ramifications.

Nasal hyperreactivity among teachers in a school with a long history of moisture problems

Upper airway symptoms have frequently been reported in people working or residing in damp buildings. However, little information has been available on objective pathophysiologic findings in relation to these environments. Twenty-eight teachers, who had worked for at least five years in a recently renovated school that had had severe moisture problems for years, were randomly selected for this study. Eighteen teachers, who had worked in another school that had no moisture problems, were randomly selected to serve as the control group. Although remedial measures had been taken, an increase in the prevalence of mucous membrane irritations was still reported by the teachers in the target school. We used a nasal challenge test with three concentrations of histamine (1, 2 and 4 mg/mL). Recordings of swelling of the nasal mucosa were made with rhinostereometry, a very accurate optical non-invasive method. The growth curves of mucosal swelling induced by the three concentrations of histamine differed significantly between the two groups (p < 0.01). The frequencies of atopy, evaluated with the skin-prick test, were almost identical in both groups. The study indicates that long-term exposure to indoor environments with moisture problems may contribute to mucosal hyperreactivity, of the upper airways. Such hyperreactivity also seems to persist for at least one year after remedial measures have been taken.

Involvement of urban living environments in atopy and enhanced eosinophil activity: potential risk factors of airway allergic symptoms

BACKGROUND

Airway allergic diseases, such as bronchial asthma and allergic rhinitis, have increased, especially in urban areas. These diseases are characterized by airway inflammation with enhanced eosinophil activity, and the risk of disease development has been shown to increase with the prevalence of atopy.

METHODS

Questionnaires were administered to 426 healthy adult women aged 30-74 years, living in an urban area of Osaka, Japan, to survey individual living environments and airway allergic symptoms such as cough, sputum, and wheezing. Moreover, serum house-dust-mite (Dermatophagoides pteronyssinus, [Der p])-specific immunoglobulin E (IgE) and serum eosinophil cationic protein (ECP) were examined by radioimmunoassay, and the atopic status (atopic sensitization) and enhanced eosinophil activity were assessed as Der p-specific IgE RAST scores of 2-6 and ECP levels of more than 10 ng/ml, respectively.

RESULTS

Intensive use of electric air conditioners in hot weather (odds ratio: 2.07 [95% CI: 1.11-3.87]) and mold proliferation in the kitchen (2.77 [1.34-5.73]) significantly increased the risk of atopic sensitization. Poor home ventilation and family smoking appeared to be positively but not significantly associated with atopic sensitization. Personal smoking and intensive use of the air conditioner appeared to be positively related to enhanced eosinophil activity. Atopic status showed significant involvement in the development of wheezing, and the development of cough was significantly associated with enhanced eosinophil activity.

CONCLUSIONS

The results suggest that some urban styles of living are involved in atopic sensitization and enhanced eosinophil activity in the Japanese urban population, probably due to living conditions, such as indoor dampness and poor home ventilation, caused by tight insulation, which increase exposure to indoor air pollutants, such as respirable mite allergens and tobacco smoke.

A minimum income for healthy living

BACKGROUND

Half a century of research has provided consensual evidence of major personal requisites of adult health in nutrition, physical activity and psychosocial relations. Their minimal money costs, together with those of a home and other basic necessities, indicate disposable income that is now essential for health.

METHODS

In a first application we identified such representative minimal costs for healthy, single, working men aged 18-30, in the UK. Costs were derived from ad hoc survey, relevant figures in the national Family Expenditure Survey, and by pragmatic decision for the few minor items where survey data were not available.

RESULTS

Minimum costs were assessed at 131.86 pound sterling per week (UK April 1999 prices). Component costs, especially those of housing (which represents around 40% of this total), depend on region and on several assumptions. By varying these a range of totals from 106.47 pound sterling to 163.86 pound sterling per week was detailed. These figures compare, 1999, with the new UK national minimum wage, after statutory deductions, of pound 105.84 at 18-21 years and 121.12 pound sterling at 22+ years for a 38 hour working week. Corresponding basic social security rates are 40.70 pound sterling to 51.40 pound sterling per week.

INTERPRETATION

Accumulating science means that absolute standards of living, "poverty", minimal official incomes and the like, can now be assessed by objective measurement of the personal capacity to meet the costs of major requisites of healthy living. A realistic assessment of these costs is presented as an impetus to public discussion. It is a historical role of public health as social medicine to lead in public advocacy of such a national agenda.

(1-->3)-beta-D-glucan and endotoxin in house dust and peak flow variability in children

House dust-associated bacterial endotoxins have been shown to be associated with asthma severity, and a similar role has been suggested for fungal (1-->3)-beta-D-glucans. In this study the relation between these agents and peak expiratory flow (PEF) variability was investigated in 148 children 7 to 11 yr of age of whom 50% had self- or parent-reported chronic respiratory symptoms. All children self-monitored twice daily their PEF for a period of 16 wk. Dust samples were collected from mattresses and from living room and bedroom floors, and endotoxin and (1-->3)-beta-D-glucan were measured in dust extracts. The relations with mean daily PEF variability (Ampl%mean) were investigated by linear regression analysis, adjusting for dust mite allergen levels, presence of pets, and type of floor cover. In unadjusted analyses the levels of both endotoxin and (1--> 3)-beta-D-glucan per square meter of living room floor were significantly associated with PEF-variability (but not when expressed per gram of sampled dust), particularly in atopic children with asthma symptoms. Adjusted analyses showed the same association for (1--> 3)-beta-D-glucan but not for endotoxin. Although no associations were found with microbial agent levels in bedroom floor or mattress dust, high levels of (1-->3)-beta-D-glucan in living room floor dust apparently increase PEF variability in asthmatic children.

Is prevention of allergy and asthma possible?

Allergy and asthma are common diseases today. Ways to stop the ongoing increase in incidence of these diseases are highly desired. In this review the scientific basis for allergy and asthma prevention is discussed.

RESULTS

Although secondary preventive measures are generally regarded as important, the views regarding the possibility of primary prevention vary. There is today only weak evidence that breastfeeding may reduce the risk of developing allergy, and if it does the effect is limited in degree and duration. There is some evidence that prolonged breastfeeding reduces the risk of developing asthma, at least in allergy-risk infants. There is also some evidence indicating that withholding solid foods in children at risk may have a beneficial effect. A dose-dependent risk of becoming sensitized to house dust mite and pet animal allergens has clearly been shown, but to what extent this sensitization is combined with asthma or clinical allergy is less well elucidated. Passive smoking increases the risk of wheezing problems and the indoor environment in damp houses seems to act synergistically with passive smoke.

CONCLUSION

Primary prevention is rarely possible, but the risk of developing asthma and allergy may to some extent be reduced by taking certain measures, such as avoidance of tobacco smoke and damp houses. Breastfeeding seems to reduce the risk of wheezing, but as allergy-preventive measures, breastfeeding and avoiding pet animals have only marginal effects.

Association of asthma symptoms and severity with indoor bioaerosols

BACKGROUND

In this study, repeated measurements were made of levels of mold spores, bacteria, and dust-mite allergens over a 7-month period in the homes of asthmatics, and relationships with measures of asthma severity were evaluated.

METHODS

A sample of 57 asthmatic individuals, living in 44 homes in East Moline, Illinois, and nearby communities, participated in a panel study. The homes were visited up to nine times during the study to collect air and dust samples. Asthma severity indicators were derived from questionnaire data and from the daily health records from the panel study. Associations between indoor levels of mold spores, bacteria, and dust-mite allergens were tested with several asthma severity indicators.

RESULTS

There was evidence of associations between all asthma severity measures and levels of total and gram-negative bacteria, but mold-spore abundance was associated only with emergency room (ER) visits for asthma. No significant associations were found with house-dust-mite allergen and any of the asthma severity indicators, but the levels of dust-mite allergen were low, with median concentrations of 0.18 microg/g dust Der f 1 and 0.19 microg/g dust Der p 1.

CONCLUSIONS

Some evidence was found for associations of increased concentrations of gram-negative bacteria and mold spores with asthma severity, particularly with ER visits. No association was found between house-dust-mite allergen and asthma severity indicators; however, the mite-allergen levels in the study homes were generally well below the proposed threshold level of 2 microg/g dust.

Increased levels of markers of microbial exposure in homes with indoor storage of organic household waste

As part of environmental management policies in Europe, separate collection of organic household waste and nonorganic household waste has become increasingly common. As waste is often stored indoors, this policy might increase microbial exposure in the home environment. In this study we evaluated the association between indoor storage of organic waste and levels of microbial agents in house dust. The levels of bacterial endotoxins, mold beta(1-->3)-glucans, and fungal extracellular polysaccharides (EPS) of Aspergillus and Penicillium species were determined in house dust extracts as markers of microbial exposure. House dust samples were collected in 99 homes in The Netherlands selected on the basis of whether separated organic waste was present in the house. In homes in which separated organic waste was stored indoors for 1 week or more the levels of endotoxin, EPS, and glucan were 3.2-, 7.6-, and 4. 6-fold higher, respectively (all P < 0.05), on both living room and kitchen floors than the levels in homes in which only nonorganic residual waste was stored indoors. Increased levels of endotoxin and EPS were observed, 2.6- and 2.1-fold (P < 0.1), respectively, when separated organic waste was stored indoors for 1 week or less, whereas storage of nonseparated waste indoors had no effect on microbial agent levels (P > 0.2). The presence of textile floor covering was another major determinant of microbial levels (P < 0.05). Our results indicate that increased microbial contaminant levels in homes are associated with indoor storage of separated organic waste. These increased levels might increase the risk of bioaerosol-related respiratory symptoms in susceptible people.

Clinical experience and results of a Sentinel Health Investigation related to indoor fungal exposure

This is a review of exposure conditions, clinical presentation, and morbidity of children and adults with indoor fungal exposure such as toxic Stachybotrys chartarum. Indoor exposure was characterized using different methods including microscopic, culture, cytotoxicity screening tests, and chemical analyses. Clinical case histories and physical and laboratory findings are presented of children (age < 18 years, n = 22; mean age 9 years; 60% females) and adults (age >18 years, n = 125; mean age 39 years, 67% females) who consulted an environmental health specialty clinic. In the pediatric patients' exposure history, widespread fungal contamination of water-damaged building materials with known toxic or allergic fungi was identified. Primarily disorders of the respiratory system, skin, mucous membranes, and central nervous system were reported. Some enumeration and functional laboratory abnormalities, mainly of the lymphatic blood cells, were observed, although no statistically significant differences were found. IgE or IgG fungi-specific antibodies, used as exposure markers, were positive in less than 25% of all tested cases. In an evaluation of a symptomatic girl 11 years of age (sentinel case investigation) living in an apartment with verified toxigenic fungi (i.e., S. chartarum), several health indicators showed improvement after exposure cessation.

Reversing the trend: reducing the prevalence of asthma

BACKGROUND

We urgently need to take steps towards reducing the prevalence of asthma in countries where the prevalence has become unacceptably high in recent years. Because we do not have any good information about causes of the increased prevalence, we cannot act directly to reverse the trend. Therefore we need to take an indirect approach and use known information of etiologic factors to try to reduce asthma in the next generation, while acknowledging that we may be dealing with different factors from those responsible for the increased prevalence. Any successful strategies will also help to ensure that developing countries do not attain such high rates of asthma in their children in coming years.

OBJECTIVE

This article summarizes the roles of the risk factors that identify "high-risk" children, that provide insights into mechanisms, or that have potential for primary prevention. The factors with the most potential for primary prevention are allergen exposure, parental smoking, breast-feeding, and dietary fatty acids.

CONCLUSION

In other health models, information about risk factors has been used in successful public health interventions. It is disappointing that the important risk factors for asthma are well documented but that there have been few trials of primary prevention and no changes in public health policies.