Airborne molds and bacteria, microbial volatile organic compounds (MVOC), plasticizers and formaldehyde in dwellings in three North European cities in relation to sick building syndrome (SBS)
Highlights
► We examine whether MVOCs, airborne bacteria, molds, formaldehyde and plasticizers in dwellings were associated with SBS. ► We also study the associations between MVOCs and reports on dampness and mold. ► The indoor levels of some MVOCs were positively associated with SBS. ► Levels of airborne molds and bacteria and some MVOCs were higher in dwellings with a history of dampness and molds. ► Information on levels of individual MVOCs is of more value than the total level of MVOCs.
Introduction
There is increased concern about the health effects of the indoor environment (Norback, 2009) and the home is the indoor environment where both adults and children spend most of their time. Several studies have shown that building dampness and indoor mold growth are common in dwellings (Bornehag et al., 2001, Brunekreef, 1992, Fisk et al., 2007, Husman, 1996, WHO, 2009). Building dampness and indoor mold growth is associated with an increased prevalence of both asthmatic symptoms and symptoms compatible with the sick building syndrome (SBS) (Bornehag et al., 2001, Brunekreef, 1992, Fisk et al., 2007, Husman, 1996, Peat et al., 1998). Dampness approximately doubles the risk of health effects (Bornehag et al., 2001, Peat et al., 1998). One large study in Swedish multi-family residential buildings found a strong association between building dampness and SBS symptoms (Engvall et al., 2001).
SBS is a set of non-specific symptoms (from eyes, upper airways, facial skin, headache, tiredness and nausea) occurring in a particular building (Norback and Edling, 1991). Various indoor factors, such as a low supply rate of outdoor air, high room temperature and low indoor air humidity have been shown to influence the prevalence of SBS-symptoms (Apter et al., 1994, Hodgson, 1995, Mendell, 1993, Norback, 2009). Moreover, personal factors such as female gender and history of allergic disorder have been associated with SBS (Apter et al., 1994, Bjornsson et al., 1998, Hodgson, 1995, Mendell, 1993).
Building dampness may lead to an increased exposure to various types of molds, bacteria, microbial compounds and chemical compounds (WHO, 2009). It is well known that molds and bacteria emit certain VOCs, so-called microbial volatile organic compounds (MVOCs), when growing on building materials. Examples of compounds that can be produced by microorganisms include certain ketones (e.g., 2-heptanone), alcohols (e.g., 1-octen-3-ol), terpenes and terpene derivatives (e.g., geosmin) and sulfur compounds (e.g., dimethyl disulfide) (Claeson et al., 2002, Korpi et al., 1998, Sunesson et al., 1996, Wilkins et al., 2000).
One early study, which analyzed MVOCs by gas chromatography–mass spectrometry (GC–MS) with selective ion monitoring (SIM) in air samples from damp and moldy buildings, reported data on concentrations of 26 different MVOCs. The concentrations were usually higher in indoor air than outdoor air (Wessen and Schoeps, 1996) One intervention study found that MVOC concentration was higher in a hospital building with dampness and SBS symptoms as compared to a dry control building (Wieslander et al., 2007). Another study reported that children living in dwellings with higher MVOC levels had a higher prevalence of asthma, hay fever, wheezing, and eye irritation, although the difference was not statistically significant (Elke et al., 1999). In a school environment study it was found that exposure to several MVOCs at school was associated with asthmatic symptoms in the pupils (Kim et al., 2007), while an earlier school environment study reported an association between asthma in school teachers and levels of MVOCs in the classrooms (Smedje et al., 1996). We found only one previous study on associations between MVOCs and SBS in dwellings. In that study, some MVOCs, especially 1-octen-3-ol, were associated with SBS (Araki et al., 2010).
The use of MVOCs as a marker of fungal or microbial exposure has been criticized, since these compounds are also emitted from other sources such as tobacco smoke, plants, furniture, furnishing, and building materials (Korpi et al., 1999, Korpi et al., 1998, Schleibinger et al., 2008). One study comparing MVOC levels in moldy and mold-free dwellings found no significant association between most MVOCs and the mold status. Only 2-methyl-1-butanol and 1-octen-3-ol showed significant but weak associations with mold status (Schleibinger et al., 2008).
Dampness may also influence the levels of volatile organic compounds which are not produced by microorganisms. Formaldehyde is a reactive volatile compound that may induce airway irritation at low concentrations, and the emission may be influenced by dampness in building materials (Sarigiannis et al., 2011). Indoor sources include cigarette smoke, insulating materials, particle board and plywood furniture containing formaldehyde-based resins, water based paints, fabrics, and various other consumer products. Plasticizers are another group of compounds that are commonly found in dwellings, and used in plastic material. Associations between phthalates, and asthma and rhinitis in pre-school children have been reported (Bornehag et al., 2004, Hsu et al., 2011, Naydenov et al., 2008). One study showed that building dampness in dwellings was associated with increased dust levels of phthalates, a common plasticizer in poly-vinyl-chloride (PVC) materials (Bornehag et al., 2005). Moreover, one school study found an association between the indoor air concentration of two common plasticizers (TMPD-MIB (2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, Texanol) and TMPD-DIB (2,2,4-trimethyl-1,3-pentanediol diisobutyrate, TXIB), and asthmatic symptoms in school children (Kim et al., 2007). Finally, the compound 2-ethyl-1-hexanol has been reported to be produced by molds (Claeson et al., 2002) as well as degradation of the plasticizer di-ethyl-hexyl phthalate (DEHP) or acrylate polymers in water-based carpet glue. This degradation is related to increased dampness in floor construction (Norback et al., 2000).
The objective of this study was to examine whether air borne levels of MVOCs, bacteria, molds, formaldehyde, Texanol and TXIB in dwellings in northern Europe are associated with the prevalence of sick building syndrome (SBS) symptoms. In addition, we investigated whether there was an association between levels of MVOCs and reports on dampness and molds in the home.
Section snippets
Study design and population
Our study is based on data from the Uppsala, Reykjavik and Tartu centers of the European Community Respiratory Health Survey (ECRHS) (Janson et al., 2001). ECRHS is a multi-center population study carried out on a random sample of subjects aged 20–44 years in 1990–1994 (Burney et al., 1994)with a follow-up in 2002 (ECRHSII) (The European Community Respiratory Health Survey II, 2002). Of a total of 1238 subjects from ECRHS II in these centers, 510 included in the random sample had not moved (from
Measurement of indoor microbial and chemical exposure
Indoor measurements included temperature, relative humidity, airborne molds, bacteria, and the 16 MVOCs, Texanol and TXIB. Temperature and relative air humidity were measured with an Assman Psychrometer type SK-RHG (Sato Keiryoki Mfg. Co., Tokyo, Japan). Airborne microorganisms were sampled on 25 mm nucleopore filters (pore size 0.4 μm) (2.0 l/min; 3 h). The nucleopore filters were stored in a refrigerator (+ 4 to + 10 °C) after sampling, and sent by priority mail to our department within 7 days and
Assessment of symptoms and personal factors
Information on age, sex, and smoking habits was collected from the screening and interview questionnaire. A current smoker was defined as one who, during the interview, reported current smoking, or who had ceased smoking less than a year ago.
Information on 16 symptoms compatible with SBS was obtained from the self-administered questionnaire (Bjornsson et al., 1998, Sahlberg et al., 2012). The recall period was 3 months. For each symptom, an answer could be given according to one of three
Blood samples
Blood and serum samples were collected and stored at − 20 °C for the measurement of total serum IgE, specific serum immunoglobulin E (IgE) at a central laboratory, and additional biomarkers locally. Specific serum levels against cat, timothy grass, the Cladosporium herbarium, mold and the house dust mite Dermatophagoides pteronyssinus, were determined by using Pharmacia CAP system (Pharmacia Diagnostics, Uppsala, Sweden). A level above 0.35 kU/L was considered a positive reaction. Atopy was
Data analysis
A geometric mean (GM) with a 95% confidence interval and maximum value for MVOCs, bacteria, molds, formaldehyde, temperature and relative air humidity, were calculated for both the total, and random sample. Association between weekly occurrence of any SBS symptoms, or mucosal symptoms and each exposure variable was calculated by multiple logistic regression analysis keeping age, gender, atopy, smoking and the particular home-exposure variable the model. Mucosal symptoms was defined as if a
Results
The distribution of subjects by center was 19% from Reykjavik, 40% Uppsala, and 41% from Tartu, in total 159 subjects. Of these 57% were females. The prevalence of any weekly SBS symptom was 19% for Reykjavik, 33% for Uppsala and 29% for Tartu, which was a significant difference. Moreover, the total MVOC level in the total sample differed between the centers' geometric means (GM): 9810 ng (95% CI 7800–12,340) in Reykjavik, 10,070 ng (95% CI 8370–12,120) in Uppsala, and 8100 ng (95% CI 6680–9790)
Discussion
In this cross-sectional study we found that levels of three specific MVOCs, formaldehyde and the plasticizer Texanol in dwellings were positively associated with any SBS symptoms. Regarding mucosal symptoms two specific MVOCs and viable bacteria were positively associated. Moreover, we found that certain MVOCs, as well as airborne molds and bacteria, were measured at higher levels in dwellings with a history of dampness and molds, as compared with dwellings without such reports. However, the
Conclusion
The indoor levels of 2-pentanol, 2-hexanon, 1-octen-3-ol, and 2-pentylfuran were positively associated with any SBS symptoms. Furthermore, 3-methylfuran was positively associated with mucosal symptoms. However, since none of these compounds, except 3-methylfuran, were associated with reports on dampness or molds, we found little evidence that they were emitted from microbial growth or damp building materials. On the other hand, 3-methylfuran has been shown to be formed by a broad spectrum of
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