What Are Mycotoxins?
If you've been researching mould, you've probably come across the term mycotoxins. They're frequently mentioned online, in documentaries and on social media, but they're often misunderstood.
Mycotoxins are real, but their presence, significance and how they're detected are more complex than many sources suggest. Understanding the basics can help separate evidence from assumption.
What exactly are mycotoxins?
Mycotoxins are naturally occurring chemical compounds produced by certain moulds as part of their life cycle.
Unlike mould spores, which are living reproductive structures, mycotoxins are not living organisms. They are secondary metabolites – chemicals that some mould species produce under specific environmental conditions.
It's important to understand that:
Not all moulds produce mycotoxins.
Not all species within a mould genus are capable of producing them.
Even moulds that can produce mycotoxins do not do so all the time.
Production depends on a range of factors, including:
The mould species
Moisture availability
Temperature
Available nutrients
Competition with other microorganisms
The stage of fungal growth
Finding mould does not automatically mean mycotoxins are present.
Which moulds can produce mycotoxins?
Some well-known mould genera contain species capable of producing mycotoxins, including:
Aspergillus
Penicillium
Stachybotrys
Fusarium
Chaetomium
However, these are genera rather than individual species. Some species within these groups can produce mycotoxins, while others cannot. This is one reason why identifying mould to genus level alone cannot tell us whether mycotoxins are likely to be present.
Do all mouldy homes contain mycotoxins?
No.
A property may contain visible mould without measurable mycotoxins, while another building may have environmental conditions that have supported mycotoxin production in the past.
Every building is different. The presence of mould should never be taken as proof that mycotoxins are present.
Can you see mycotoxins?
No.
Mycotoxins are microscopic chemical compounds. They cannot be identified by sight, and the colour of mould tells us nothing about whether mycotoxins are present.
This is one reason why terms such as "black mould" can be misleading. The colour of mould does not determine whether it is capable of producing mycotoxins.
How are mycotoxins tested?
Mycotoxins cannot be identified during a visual inspection.
If mycotoxin analysis is considered appropriate, samples are collected and analysed by specialist laboratories using validated analytical techniques.
Depending on the investigation, testing may be carried out on:
Household dust
Surface samples
Building materials
Other environmental samples
Laboratory results should always be interpreted alongside the wider building investigation, including moisture conditions, visible microbial growth and the property's history.
Why does this matter?
Understanding mycotoxins is useful, but it's important to keep them in context.
If mould is growing inside a property, it tells us that moisture has been present. Whether mycotoxins are present is a separate question that cannot be answered by visual inspection alone.
Rather than making assumptions, the priority should always be to investigate why mould has developed in the first place.
The important thing to remember
At Mould Focus, we don't assume mycotoxins are present simply because mould has been found.
Our approach is to investigate the building, identify the source of moisture, assess the indoor environment and recommend appropriate laboratory testing where necessary. By understanding the cause of mould growth first, it's possible to make informed decisions based on evidence rather than assumption.
Frequently Asked Questions
Are mycotoxins the same as mould spores?
No. Mould spores are living reproductive structures that allow mould to spread. Mycotoxins are chemical compounds that some mould species may produce under certain environmental conditions.
Does black mould always produce mycotoxins?
No. "Black mould" is simply a description of colour, not a scientific classification. Even mould species capable of producing mycotoxins only produce them under certain conditions.
Can mycotoxins be identified by looking at mould?
No. Mycotoxins cannot be seen with the naked eye. Laboratory analysis is required to determine whether they are present.
Should every mould investigation include mycotoxin testing?
Not necessarily. Every property is different. Whether laboratory testing is appropriate depends on the objectives of the investigation and should be considered alongside the building's condition, moisture sources and other environmental findings.
Need an independent investigation?
At Mould Focus, we investigate mould, moisture and indoor environmental conditions using building science and evidence-based methods.
If you're concerned about mould in your property, we'll help identify the underlying cause, explain what's happening within the building and recommend appropriate next steps, including laboratory testing where it's considered beneficial.