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How does mould damage health? - Dr Mark Burgin

10/02/20. Dr. Mark Burgin BM BCh (oxon) MRCGP summarises the practical issues that face experts and solicitors in public liability cases on mould exposure.

The CDC ( and WHO ( (1, 2) have detailed resources on the health effects of mould and this article is written as a primer for use in personal injury.

There are five common types of mould Alternaria, Aureobasidium, Cladosporium, the familiar Penicillium (also on fruit) and the black mould Stachybotrys.

Direct contact can cause skin problems but moulds mainly cause ear nose and throat type respiratory tract infections and worsening of asthma.

Exposure to irritants such as cigarette smoke will often increase the individual’s response to an allergen so that even low levels will be enough to trigger reactions.

The mould will spore more readily under conditions such as dampness or at particular times of the year which explains variation in its respiratory effects.


People who have a history of allergic disease are more susceptible because their airways and skin are already primed to detect allergens by their underlying disease.

They will either sensitize to the new allergen with a delay after exposure or the allergen will cross react with antibodies against another allergen.

The science behind susceptibility is complex and not completely understood but good progress is being made and phenomena are being explained scientifically.

There is a complex set of associations based upon the shared features between allergens as different at food and an easy to read promo-educational guide is available online. (3)

In a high value case the court could call an expert in Immunology to determine if the patterns of allergies described by an individual are consistent with a single protein family.

Immune testing

The RAST blood test for allergies can be positive because of raised IgE which indicates the patient is reacting in an allergic way and is a simple test for susceptibility available in primary care. (4)

The RAST test for ‘mould mix’ is reported in a semi quantative way from 0 (less than 0.35kU/L) to 6 (greater than 100 kU/L) and can support a low value case.

The moulds that are tested vary and a typical choice is Penicillium notatum, Cladosporum, Aspergillus, Alternaria - missing out Stachybotrys although there is some cross reactivity.

Where the exact mould is known it is better to test for antibodies for a specific allergen such as the black mould Stachybotrys which is more expensive but supports causation.

Skin tests have high rates of false positives and for technical reasons panels of moulds are tested together requiring further tests to determine the exact type in secondary care.

Toxins in moulds

Stachybotrys produces mycotoxins called Macrocyclic trichothecenes and these toxins can either cause direct damage or an immune response.

There is some debate as to whether mycotoxins can cause ‘sick building syndrome’ with symptoms such as headache, runny nose, irritated eyes, fatigue and memory loss.

Although it is possible to analyse sera for trichothecenes this is not performed in clinical practice and is unlikely to be available to the court.

As these symptoms are clinically undisguisable from the effects of histamine release with any inhaled allergens the difference is not material in a court case.

There are however atypical reactions such as hypersensitivity pneumonitis, allergic alveolitis, chronic rhinosinusitis and allergic fungal sinusitis where further clinical tests will be available.


The World Health Organisation equates damp with growth of biological contaminants and a ‘strong, consistent indicator of risk of asthma and respiratory symptoms’.

From a health point of view further testing is unnecessary if dampness is present as there will be contamination and increased risk of illness.

Anybody will react with a sufficiently high exposure to allergens but those who are susceptible will have a greater response and respond at a lower level.

From a legal point of view dampness is insufficient to confirm that an individual would react in the way described and basic testing against RAST mould mix is recommended.

The mix used may not include the guilty mould and more complex testing is available in cases where the response is atypical or the case is higher value.

Doctor Mark Burgin, BM BCh (oxon) MRCGP is on the General Practitioner Specialist Register.

Dr. Burgin can be contacted on This email address is being protected from spambots. You need JavaScript enabled to view it. and 0845 331 3304 website

1. World Health Organization 2009 WHO guidelines for indoor air quality : dampness and mould

2. Centers for Disease Control and Prevention accessed 1 February 2020

3. A Clinical Reference Guide to Molecular Allergy Thermo Fisher.

4. Edmondson 2009 Immune Response among Patients Exposed to Molds Int J Mol Sci. 2009 Dec; 10(12): 5471–5484.

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