Fungal Contamination in Public Buildings: Health Effects and Investigation Methods

2. Health Effects of Indoor Molds (Continued)

2.1.3 Building investigations

Sick building syndrome (SBS) describes a series of symptoms with no clear etiology, such as eye, nose and throat irritation, headaches and high frequency of airway infection and cough, which are associated with a building environment. It is distinguished from building-related illnesses (BRI) which are well-defined responses to biological, physical or chemical exposures occurring in indoor environments (Brightman and Moss 2000). SBS and BRI investigations were mostly cross-sectional (i.e. comparing occupants of buildings where problems were identified to those of "control" buildings). Some of these studies included a longitudinal component, as the health of exposed individuals was reassessed after exposure had been eliminated.

Some of these studies where mold contamination was investigated, along with other exposures, are summarized here. It should be kept in mind that because of their cross-sectional design and some other methodological issues (multiple concomitant exposures, possible bias in studies initiated following complaints), these studies cannot identify or demonstrate an independent association between an exposure such as mold and dampness, and a health outcome.

• In the United States, a health questionnaire was administered to 53 office workers with more than three months' employment in a water-damaged building where Stachybotrys growth was found, and to 21 office workers with similar duties, working in other buildings. Blood samples were also collected from every participant for immunologic tests. Employees from the water-damaged building had a significantly higher prevalence of lower respiratory problems (76% vs. 43%; p<0.01), and eye symptoms such as burning, irritation and blurry vision (57% vs. 19%; p<0.01). There was no difference between the two groups with respect to total white blood cell counts, but the proportion of eosinophils was marginally higher among employees from the water-damaged building ( p=0.06) (Johanning et al. 1996).
• In the United States, a health questionnaire was administered to workers employed in three buildings with severe water damage and contamination with Aspergillus versicolor and Stachybotrys chartarum, and to workers from two control buildings with no visible mold growth. In total, 197 people participated in that study. Workers from the water-damaged buildings had a higher risk of eye itching and watering (OR 2.49, 95% CI 1.02 to 6.27), stuffy or blocked nose (OR 4.48, 95% CI 1.93 to 10.68), runny nose (OR 3.06, 95% CI 1.16 to 8.53), dry throat (OR 3.74, 95% CI 1.42 to 10.42), lethargy (OR 10.62, 95% CI 4.50 to 22.10), difficult breathing (OR 13.47, 95% CI 1.90 to 72.83), and chest tightness (OR 10.41, 95% CI 1.46 to 62.83) (Hodgson et al. 1998).
• In Finland, 397 children from a water-damaged, mold- contaminated school (thereafter referred to as "School E") were compared to 192 children from a control school where inspection revealed no mold contamination ("School C"). All participants were aged 7 to 12 years. Questionnaires were sent to parents of children from both schools before and after remediation in School E, and a physician reviewed diagnosis and antibiotic prescriptions in the children's medical records. Before remediation, children from School E had a higher risk of common cold (OR 1.51, 95% CI 1.04 to 2.20) and bronchitis (OR 2.76, 95% CI 1.11 to 6.81), but these differences disappeared after mold remediation in School E (Savilahti et al. 2000).

2.1.4 Cohort studies

In cohort studies, subjects classified according to their exposure are followed over time to determine the incidence of the disease of interest. To date, no cohort studies have been published on the association between residental mold exposure and asthma, although a published study has investigated the association between mold exposure at school and childhood asthma (see below). In addition, there is an ongoing cohort study in Prince Edward Island, Canada.

In Sweden, a prospective study was carried out over four years; a total of 1,347 children was surveyed twice, in 1993 and in 1997. Their mean age in 1993 was 10.3 years. Participants were attending 39 different schools at the time of the first survey. Total mold concentrations were determined in 1993 and 1995 and ranged from 5 to 360 cells/m³ (arithmetic mean 26 cells/m³). After adjustment for sex, age, atopy in 1993, and smoking, the odds ratios for incident asthma (i.e. diagnosed during the follow-up period) per 10-fold increase in total mold levels in classrooms was 1.3 (95% CI 0.5 to 3.6). Among children who were not atopic in 1993, the odds ratio for incident asthma per 10- fold increase in mold levels, adjusted for sex, age and smoking, was 4.7 (95% CI 1.2 to 18.4) (Smedje and Norbäck 2001).