Updated 30 October 2017

Is that mould in your home toxic?

‘Toxic mould’ has, on a number of occasions, been the subject of chain mails and internet hoaxes. Plus, it’s been blamed for a couple of deaths. But how dangerous is mould really?

When 32-year-old Hollywood star Brittany Murphy of Girl Interrupted and Clueless fame died suddenly in December 2009, her fans and fellow actors were shocked. The autopsy revealed she had pneumonia and anaemia, and there were rumours of cocaine addiction and an eating disorder.

Just as the news of her death was settling, her husband also died of pneumonia and anaemia. 

Five years after their deaths, authorities have suggested that mould – of which there were unusually high amounts in the star’s dirty, unhygienic Los Angeles mansion – may have contributed to her death. 

“Living in poor housing conditions like that is likely to have had a debilitating effect, and contributed to her infection and death,” pathologist Dr Richard Shepherd, who also examined the death of Princess Diana, told Britain’s Daily Mail.

But even though mould could have contributed to Brittany Murphy’s death, it doesn’t mean you should be overly concerned about the mould in your bathroom or kitchen. Just because something in the environment looks “bad” doesn’t mean it’s necessarily bad for your health…

Read: Mould may make you depressed

What is mould?

Mould has been around since the beginning of time and, yes, it’s everywhere – indoors and outdoors. It’s the common word for any fungus that grows on food or damp surfaces, and can be black, white or almost any colour. 

Mould often looks like a stain or smudge, and it may smell musty. It can enter the home through windows, vents, open doorways, heating and air-conditioning systems, and by attaching itself to clothes, shoes, linen, bags and pets.

Some of the common places in homes where mould can be found include:

- Leaky roofs, windows or pipes
- Ceiling and wall tiles
- Wood products
- Dust
- Paints
- Wallpaper
- Insulation
- Drywalls
- Carpets
- Upholstery

Is mould harmful?

Often reports about the effects of mould include the term “toxic mould”. However, experts say this term can be misleading, since only certain mould spores produce toxins, and only under certain conditions.

“Just because a particular mould can produce toxins, doesn’t mean it will. Even if the mould is producing toxins, a person must breathe in a sufficient dose to be affected. It’s highly unlikely that you could inhale enough mould in your home or office to receive a toxic dose,” researchers say in Lung Disorders Special Report: 9 Common Mould Myths, published as part of the John Hopkins Medical Alert.

Although only toxic under exceptional conditions, mould can adversely affect your health, especially if you suffer a pre-existing respiratory condition such as asthma

According to the findings published recently in the journal Respirology, indoor mould can increase the risk of active asthma, even in those who aren’t allergic to mould. “Reducing home exposure to mould and environmental tobacco smoke might reduce asthma and asthma-related respiratory symptoms,” the researchers said.

Some people are especially sensitive to mould and may display symptoms that include: 

- Eye, nose and throat irritation
- Coughing and phlegm build-up
- Wheezing and shortness of breath
- Symptoms of asthma and any number of allergic reactions

Read: Mould may trigger severe asthma

Tackling mould at home

Indoors, mould can be found where humidity levels are high, such as in basements or showers. Most times, it’s not necessary to get professional help to remove it. You can simply remove it with over-the counter products.

However, the following measures by the US Centres for Disease Control and Prevention can help you avoid mould in your home altogether:

- During humid months, use an air conditioner or a dehumidifier.
- Make sure there is adequate ventilation.
- Before painting, add mould inhibitors to the paint.
- Use mould killing products to clean your bathroom and kitchen.
- Don’t carpet your bathrooms and basements.
- Remove or replace previously soaked carpets and upholstery.

Read more:
Fight the common mould allergy
Mouldy homes tied to kids' asthma and allergies
Asthma triggers

Image: Mould from Shutterstock


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Professor Keertan Dheda has received of several prestigious awards including the 2014 Oppenheimer Award, and has published over 160 peer-reviewed papers and holds 3 patents related to new TB diagnostic or infection control technologies. He serves on the editorial board of the journals PLoS One, the International Journal of Tuberculosis and Lung Disease, American Journal of Respiratory and Critical Medicine, Lancet Respiratory Diseases and Nature Scientific Reports, amongst others.Read his full biography at the University of Cape Town Lung Institute

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