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In the New York City subway, I noticed a series of advertisements from a bedding company called Brooklinen. One advertisement had a surprising claim, which I found again on their website:

The average 2-year-old pillow contains 17 species of fungus.

I was a bit skeptical of this, so I did some digging.

My research so far

Brooklinen did cite a source: Mercola.com, which in turn linked to the website of the University of Manchester, though I was redirected away from the page and couldn't find anything else through the university. Mercola.com's version of the claim was a little different:

When researchers tested samples of pillows, which had been used anywhere from 1.5 to 20 years, they found several thousand spores of fungus per gram of pillow, which means any one pillow could contain more than 1 million spores.

Up to 16 different species of fungus, from varieties found in bread to varieties common in showers, were detected in the individual samples. Pillows made from synthetic materials tended to have higher levels, which is another reason why pillows made from natural wool are preferable.

I found what I think is the paper, Fungal contamination of bedding (Woodcock et al. 2005) (from researches affiliated with the University of Manchester), and it seems like it matches the summary on Mercola.com decently well. There are two key differences between the paper's conclusions (based on a sample of 10 pillows) and Brooklinen's claim:

  • None of the samples contained 17 species of fungus; they contained anywhere from 4 to 16.
  • The samples occupied a wide age range, from 1.5 years to over 20 years.

The point is, as far as I can tell, the study doesn't match Brooklinen's claim at all, unless I'm misreading it. The supposed number of fungus species found is different, as is the pillow age. It's different enough that I'm wondering if I found the wrong paper and Brooklinen is basing their claim based on some other data. It left me quite confused.

The question

Is there any merit, then, to Brooklinen's claim? Does the average two-year-old pillow really contain 17 distinct species of fungus?

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    i'm very sceptical it's only 17. Fungi are a varied and hardy lot.
    – bukwyrm
    Jul 29 '19 at 4:47
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    The bigger question is whether the claim, if true, tells us anything useful. If (hypothetically) an entire pillow had only 17 individual mold spores in it, and each of those spores happened to be of a different species, it would satisfy the claim. And yet, I would consider such a pillow mold-free for all practical purposes. Jul 29 '19 at 4:51
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    @piojo As far as possible, it's best to treat each claim and piece of evidence on its own merits. The fact that someone has previously published research which has been debunked would be at most a small supporting point within an answer, and would itself need to be well-referenced to avoid just being opinion.
    – IMSoP
    Jul 29 '19 at 12:36
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    How many species of fungus are in a brand new pillow? Jul 29 '19 at 13:41
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    This isn't an answer but perhaps could guide one, but scores of species of fungus live on our skin: ncbi.nlm.nih.gov/pmc/articles/PMC3711185 As other people have mentioned 17 is probably both a low estimate and no serious cause for concern.
    – Thegs
    Jul 31 '19 at 15:06
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Brooklinen removed the claim within 24 hours after I had a conversation about it with a Brooklinen supervisor (who later mentioned they discussed my question within an internal meeting). This by itself leads me to believe Brooklinen could not come up with evidence for this claim and that, therefore, this claim is false.

The claim's webpage now redirects to Brooklinen's home page. An archived version of the claim is here.


During my research of this claim I came to the same conclusion as @HDE226868. I could only find this paper by Woodcock et al., which fit the information on Mercola.com, but doesn't completely agree with Brooklinen's claim. Even today, nearly 2 years later, I have not found new literature that would shed more light on the claim.

  1. As @HDE226868 pointed out, the study included samples collected from pillows from 1.5 years old to over 20 years. Thus, the study is not representative of the average pillow at any age.

  2. Additionally, the relationship of the number of fungus to age is not reported at any point (it's not stated that pillows of different ages had varying numbers of fungi species).

  3. Third, Woodcock et al. examined 10 pillows: 5 synthetic and 5 feather. This is a small sample size and the authors do not at any point compute statistical significance, so even if the study supported the claim (which the study does not), it would not be strong evidence for the claim.

  4. Finally, because samples of the pillow were cultured and then identified, a pillow may have (many) more species of fungus than identified as some fungal spores may not have been successfully cultured.

I will end by saying that in addition to my conversation with the supervisor, I chatted with 4 Brooklinen customer service employees on the issues with this claim live and additionally sent two emails asking for further clarification. Here's an example of an emailed response from a Brooklinen "Customer Experience Senior Associate" (I also had at least 4 conversations via "LiveChat" for which I still have the transcripts):

Thanks for all of your time and interest! We are happy to provide all the answers that we can on this subject.

We do realize that sources are integral to the veracity of any claim, and we do wish you luck in your search for answers. What we do know is that the article sites its sources and that is the trail that we would recommend for digging deeper into this microbial issue.

We do use Ultra-Fresh antimicrobial treatments on our Pillows, which inhibits the growth of bacteria and fungi responsible for creating unpleasant smells and staining in textile and plastic products. By controlling unwanted microbes, Ultra-Fresh antimicrobials help to keep products fresh, hygienic, and odor free.

I sure hope this helps, or that your search provides more if needed, but let us know if we can do anything else for you. And have a great night :)

To answer the question:

Is there any merit, then, to Brooklinen's claim? Does the average two-year-old pillow really contain 17 distinct species of fungus?

There is absolutely no merit to Brooklinen's claim. Brooklinen promptly removed the claim within 24 hours of my contacting a supervisor, and following an internal meeting. Current scientific studies do not support the claim and also do not suggest how many species of fungi are on a two-year-old pillow (this simply has not been studied).

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  • I don't want to go into any of my numerous interactions with Brooklinen CS in this answer. The first CS agent promised to send me a source by email afterwards; this source mentioned the same study as Mercola. The second CS agent promised to follow-up with me after asking the team. The follow-up email never came as promised. This agent was dismissive of my questions about the Sleep Fact after my pointing this out. "I can definitely forward your concern about the Sleep Fact. Do you have a specific concern about one of our products?" The third agent directed me to his supervisor. Aug 24 '19 at 1:34
  • Supervisor sent the email quoted in the answer and didn't help. I also emailed hello@brooklinen.com 3 times, without any replies. I suspect the CS team at Brooklinen is small; in my most recent contact, Brooklinen CS recognized my question without my asking. I have asked for an email from Brooklinen CS stating they cannot find a reputable source if this is the case or a reputable source if they can find one. I do not expect any further information from Brooklinen. Aug 24 '19 at 1:36
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    I appreciate the investigative effort you've put in, but right now, your answer doesn't address the claim within site guidelines. It's somewhere between original research and naa.
    – fredsbend
    Aug 24 '19 at 15:15
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    @fredsbend Thinking about the question again, I still believe the claim is incorrect. Aug 24 '19 at 19:17
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    As this question has somehow popped to the front page, I will fix this answer. Jul 5 at 22:09

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