Detection and identification of actinomycetes

36

Mould, mould infestation and mould fungi

2

Effects of

indoor mould on human

health

Mould growth in indoor areas is considered a health risk; even without establishing a quantitative and causal relationship between the occur-rence of individual mould fungi or certain biogenic pollutants and health problems¹.

Scientific findings on health effects and related issues due to mould in-festation/damp in indoor areas, are available for a number of symptoms but for other complaints they are currently scarce (see Table 5).

When assessing the effect of mould infestation on the occupants’ health, their health status (predisposition) plus the extent of mould infestation with the release of bioaerosols (exposure) must be taken into account.

The AWMF mould fungi guideline¹ provides important information for medical diagnostics in cases of mould infestation.

Population-based studies have adequately shown that people exposed to indoor damp/mould infestation are at an increased risk of multiple res-piratory diseases (see Table 5).

The study results indicate an overall adverse development in the health of the affected children, particularly in the case of children growing up in accommodation with visible mould infestation and fungi/damp. In children with existing asthma, recent studies indicate a causal rela-tionship between mould infestation and worsening of the disease (see Table 5). A connection between damp indoor areas and/or mould in-festation and the onset of asthma, especially in children, can be con-sidered a certainty. In addition, there are relationships with the devel-opment of asthma and exacerbation of adult asthma, with respiratory infections as well as with symptoms such as cough, wheezing and dyspnoea (see Table 5). Indoor mould also appears to be associated with bronchitis and allergic rhinitis (hay fever) but evidence for hay fe-ver is not yet clear and there are only few studies on bronchitis (WHO Guidelines 2009).

It should be noted that prolonged or intermittent damp indoors, even without visible mould growth, is associated with an increased risk of res-piratory disease, resres-piratory tract infection or the enhancement of exist-ing asthma. It is also important to note that in rooms that are constantly damp there is a higher probability of hidden mould damage or invisible mould growth occurring. Table 5 gives an overview of the relationships between damp/mould infestation and health problems.

38

Effects of indoor mould on human health

Table 5

Strength of correlation between indoor moisture levels/mould infestation and health problems observed in epidemiological studies

Strength of correlation Symptoms

Sufficient evidence for a causal relationship

· Aggravation and worsening of symptoms of existing childhood asthma

Sufficient evidence for a relationship (Data make relationship appear likely)

· Aggravation and worsening of symptoms of an existing asthma disease

· Upper respiratory symptoms

· Cough

· Wheezing

· Development of asthma disease

· Shortness of breath

· Currently existing asthma

· Respiratory infections Limited evidence for a relationship

(Data allows a relationship as possible but not secured)

· Occurrence of bronchitis

· Symptoms of allergic rhinitis (hay fever)

Insufficient evidence for a relationship (Data has been checked but is not sufficient to prove any relationship)

· Altered lung function

· Occurrence of allergy or atopy

· Occurrence of asthma throughout life

(does not need to be present and to cause symptoms)

Source: According to WHO Guidelines for Indoor Air Quality: Dampness and Mould, 2009, supplemented by Kanchongkittiphonetal., 2015:

In-door Environmental Exposures and Exacerbation of Asthma: An Update to the 2000 Review by the Institute of Medicine, Env. Health Perspectives 123: 6–20.

So far, only a few studies have been conducted that examine the effect of reducing indoor damp and mould infestation. However, these show that reducing indoor moisture levels can reduce adverse health effects (asth-ma and respiratory allergies).

Occupants of rooms with moisture damage and mould infestation are also prone to nonspecific symptoms such as irritation of the conjunctiva, throat and nasal mucous membranes as well as coughing, headaches or tiredness. Eye irritation of the conjunctiva or nasal irritation may be as-sociated with both allergic and irritant effects; the other symptoms are mainly associated with irritant effects.

i

Scientifically substantiated conclusions about dose-impact relation-ships between indoor mould exposure and occupants’ health com-plaints are currently not possible. This is because the exposure to mould in population-based studies is usually only qualitatively based on a few indicators, for example,the detection of visible damp, known water damage, visible mould or a mouldy odour. Only a few mould fun-gi have been identified in the available quantitative measurements, although other factors such as (actino)bacteria, mites and cell constit-uents and biogenic substances remain largely unconsidered although they can also contribute to health problems.

Indoor damp and mould infestation are associated with an increased risk of respiratory disease as well as development and exacerbation of asthma symptoms,for those who live in such conditions.

In individual cases (patients), it is not possible to attribute health effects to the mould infestation in a particular indoor space as in principle, there are a large number of causes that may be respon-sible for the disease and sensitisation.

In individual cases, it is not possible to attribute health effects to the in-door mould infestation as a large number of causes may be responsi-ble for disease, also there is hardly any definite proof for the causes (see Chapter 5). This means that the health effects of indoor moulds cannot be attributed to a particular triggering agent and/or concentration of mould fungi and/or bacteria associated therewith. According to the cur-rent state of knowledge, in the case of mould growth indoors, an increase in risk for certain health complaints is generally assumed.

Particular risk groups needing protection include patients with certain immunosuppression and people with cystic fibrosis or bronchial asthma.

The risk of developing asthma is increased in patients with allergic rhi-noconjunctivitis or rhinosinusitis and in patients with atopy².

In the following, the various health effects (allergic, irritant effects and infections) in the case of exposure to mould are presented in principle and then evaluated with regard to the occurrence of indoor damp and mould. While allergic and irritant effects may be due to a variety of living as well as dead mould fungi (or their components), the ability to trigger infections is limited to a few mould fungi.

40

Effects of indoor mould on human health

Actinobacteria (see Section 1.4), like mould fungi, can cause irritative reactions in addition to allergies and infections in severely immuno-compromised individuals. In addition, they sometimes produce very strong “mouldy” or musty smelling odours. To detect mould infesta-tion, it is sufficient just to investigate mould fungi as an indicator or-ganism. However, if actinobacteria are investigated for specific is-sues and detected in higher concentrations (see Chapter 5), there is no reason to neglect actinobacteria in the evaluation or classify them as harmless compared to mould fungi.

In contrast, high concentrations of total bacteria in the air indicate con-taminated or heavily occupied indoor areas without any relevance to health.

Health effects after exposure to very high mould fungi concentrations (around 10⁶ to 10¹⁰ spores/m³), for example the Organic Dust Toxic Syn-drome (ODTS) or exogenous allergic alveolitis, usually only occur in cer-tain workplaces and generally do not occur in homes or offices.

i