EU on Indoor Microbial Growth

[Guest guest]

I think they're on the right track, although still a bit shy when the

toxicity should be pointed out loud and clear.

I'm copying only the part that relates to indoor microbial growth. You

can read the complete text on this address:

http://ec.europa.eu/health/ph_risk/committees/04_scher/docs/scher_o_055.pdf

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Scientific Committee on Health and Environmental Risks

SCHER

Opinion on risk assessment on indoor air quality

3.3.3. Concerns in relation to building dampness/moisture and

microbial growth

Adverse health effects associated with building dampness and moisture

problems have been reported since the 1980ies but are a poorly

understood phenomenon. The available data about details of this

subject have recently been reviewed and summarised as a panel work

(IOM 2004).

An association has been shown in numerous epidemiological studies in

different environments, and in a number of countries (Bornehag et

al., 2001, 2004b). Intervention studies have indicated that renovation

of the building either decreases or abolishes the symptoms (Sudakin

1998, Meklin et al., 2005). Furthermore, a dose-response relationship

between the extent of damage and health effects has been shown

(Haverinen 2002).

Dampness and moisture problems in buildings are common in countries

where comprehensive studies have been done, and are likely to be an

underestimated indoor air problem in EU and should be evaluated more

thoroughly.

The associated adverse health effects range from irritation of mucous

membranes, respiratory symptoms and infections to permanent diseases,

such as asthma and allergy (IOM 2004). However, only a fraction of the

symptoms appear to be caused by IgE-mediated allergy, allergic

alveolitis (hypersensitivity pneumonitis) or organic dust toxic

syndrome, and other, still poorly known patho-physiological mechanisms

are involved. General symptoms, such as fever, fatigue, headache and

difficulties to concentrate have also been reported. Clusters of cases

of sarcoidosis, rheumatoid diseases as well as pulmonary haemorrhage

among infants have also been associated with indoor dampness

(Nevalainen and Seuri, 2005).

The majority of the health effects associated with dampness and

moisture of buildings are those of the respiratory system. Therefore,

it is likely that the major route of the exposure to the causative

agents is via the airways. There are many types of emission from a

microbial growth e.g., particles of microbial origin including

spores, vegetative cells and submicron-size fragments (Gorny, 2004)

that carry structural components, such as endotoxin and

1,3-beta-glucan, and non-volatile secondary metabolites, e.g. toxins

(Croft et al., 1986). Volatile organic compounds emitted from

microbial growth include those that are known as odour of mould.

Dampness and moisture may initiate chemical degradation of

material which may contribute to emissions of degradation products

into the indoor air and inadequate ventilation may increase the level

(Bornehag et al., 2005b).

Although the association between moisture problems and adverse health

effects has been demonstrated, the causative agents/exposures are not

defined. This is likely to be due to great complexity and variability

of the contributing factors but also due to lack of basic knowledge.

Respiratory inflammation, the most typical symptom, has been verified

in laboratory animals by a few microbes typical for moisture problems

(Jussila et al., 2001, Huttunen et al., 2003). Still, even in those

cases, the principal components causing the effects are not known.

Dampness or moisture may accumulate into the building structures or

finishing materials via leaks in roofs, windows or piping; due to

condensation as a result of insufficient ventilation or faulty

construction, or moisture from the ground may penetrate into the

building structure by capillary movement. Attempts to improve the

energy efficiency of the building e.g. by adding thermal insulation

may alter the functioning of the construction, if not done properly.

This may lead to moisture and mould problems. Excess water stimulates

microbial growth, usually fungi and bacteria, and in a more advanced

damage, also protozoa, nematodes and higher organisms such as mites

and insects. The substrate (material) in question and its moisture

content regulate the microbial profile that will develop, and also

their toxicity (Hyvärinen et al., 2002, Roponen et al., 2001,

Murtoniemi et al., 2001). Many of the bacteria and fungal species

detected in damp environments are the same as detected in " normal "

indoor air but their concentrations may be higher. There are

also species which typically exist in water damaged environments

(indicator species of the dampness problem). Microbial diversity in

various dampness situations varies and one water damaged site

(environment) only poorly predicts another (Nevalainen and Seuri,

2005). This may suggest that all dampness is not equally harmful.

There is also likely large individual variability in sensitivity to

react to those exposures, depending on e.g. the immunological status.

SCHER considers that the adverse health effects associated with

building dampness and moisture are a concern. The association between

building dampness and the common health effects has been documented,

however several other questions, indicated as data gaps in answer to

Question 2, are open and need further research before the wideness and

seriousness of the problem at EU level can be assessed.

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-Branislav