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Mattresses, Sheepskins And SIDS: What Parents Need To Know

Affiliate Disclosure | in Motherhood | by | with 95 Comments

Micah on his sheepskin

In The Bedroom Closet, Just Above My Little Black Dress

. . . a handcrafted sheepskin rug sits loosely rolled, listening eagerly for snippets of conversation about pregnancy tests and due dates as I rummage for a pair of matching flip flops. Lately, though it’s been looking a little listless, and I can’t help but wonder if it overheard me talking about it’s possible retirement. Here’s why:

Though sheepskins are often used in NICU’s to prevent heat loss, pressure sores, and increase positive outcomes such as weight gain and early discharge from the hospital, critics say they produce toxic nerve gases which trigger Sudden Infant Death Syndrome (SIDS). And it’s not just this favorite with the crunchy mama crowd, but regular mattresses, too.

Uh, What?

I’ll admit I almost brushed this off when I first heard it because it just sounds nuts. Hybridized grass spontaneously making cyanide and killing cattle sounds crazy too, though, and that really happened. So I did some digging, and here’s what I found:

Sheepskins and regular mattresses contain phosphorous, arsenic and antimony, which are the preferred food of a common household fungus, S. Brevicaulis.  While these elements are naturally occurring in some (but not all) sheepskins, they are actually added in via the manufacturing process of regular mattresses. Arsenic and antimony are used as preservatives in mandatory flame retardants and phosphorous is a plasticizer used in mattress covers – anything containing PVC will have these compounds.

According to Barry Richardson, a British chemist specializing in preventing the degradation of materials, when S. Brevicaulis gets established in a mattress it converts these compounds into toxic nerve gases which can shut down the nervous system, stop heart function and arrest breathing.

Stibine gas, which is formed from the interaction of the S. Brevicaulis fungus with antimony, is particularly heavy and – according to the theory –  clings to the surface of the mattress. “A baby sleeping face down will breathe this gas directly and is more likely to inhale a lethal dose,” says this this article in Midwifery Today, adding that “babies sleeping on their backs are still exposed to the lighter nerve gasses: arsine and phosphine. In a warm environment phosphine can be similar to the density of air, and easily inhaled by a baby sleeping on its back. In addition, face-up sleeping is not as effective in a cot or bassinet with enclosed sides, because the gasses cannot flow away.”

Now, Just Like The Controversy Surrounding Autism And Vaccines . . .

The connection here is disputed. Some scientists dismiss the theory, saying they were able to produce nerve gases in a lab environment but not in a crib setting.

While that’s true, it may be because the studies were working with crib mattresses that had a neutral PH. Real world mattresses often have traces of spitup, sweat and urine that can make the PH more acidic. S. Brevicaulis thrives in an acidic environment, so this might explain the varying results.

It’s not as if it hasn’t happened before. Back in the 1880s arsenic-laced pigments in wallpaper, curtains and carpets interacted with household bacteria and fungi to create a different deadly gas, trimethylarsine, which killed thousands of children. The source was discovered by the  Italian chemist Gosio in 1892, and continued work on his findings states that “many microorganisms (bacteria, fungi, and yeasts) and animals are now known to biomethylate arsenic, forming both volatile (e.g., methylarsines) and nonvolatile (e.g., methylarsonic acid and dimethylarsinic acid) compounds.” (source)

Before we jump into journal citations I’d like to share with you one fact that I found very compelling: The risk of SIDS increases (some say doubles) with the birth of each child – a trend that is most pronounced in low-income households (Source 1, Source 2, Source 3). Could this be because parents are likely to re-use the same mattress, allowing the fungus to become more established with the addition of each new little one? (Update: For info on why this study may not provide enough data see the comment from Dave below)

Studies, Counter-Studies, & Counter-Counter Studies

In the past few weeks I’ve spent, oh, maybe 16 hours sifting through articles and journal publications regarding the toxic gas theory. By this point in the research process I usually have a pretty clear opinion, but this is different. The data is too polarized for me to draw conclusions, but I felt it was worth presenting so you can make the decision you feel the most peace about. So let’s start at the beginning and work from there, okay? According to the Midwifery Today article, the original proponent of the theory, Dr. Richardson, began his research by asking:

“local coroners to cooperate by releasing mattresses on which SIDS babies had died. He received 200 mattresses of all varieties: foam, plastic, fabric and netted. By June 1989 all mattresses had been tested with the following results:

  • Every mattress was infected with the S. Brevicaulis fungus as an organism and spores.
  • All mattresses had one or more of the chemicals phosphorus, arsenic or antimony.
  • Each mattress generated one or more of the nerve gasses (phosphine, arsine or stibine) when brought to blood/body temperature.

At this time, Richardson analyzed six blood samples of the SIDS babies who died on mattresses with antimony and found high levels of antimony in each sample. In addition, Richardson learned that 95 percent of mattresses tested had been used by a previous baby.

In this subsequent study, however, researchers tested 19 SIDS case mattresses, 1 non-SIDS death, 20 used controls, and 10 new unused to determine if the fungus was present. Only four of the mattresses (3 of which were SIDS case mattresses) contained the S. brevicaulis fungus. However, the researchers did note that “differences were found between SIDS and used controls in the variety of fungal species isolated and the numbers isolated from fillings,” adding that “Scanning electron microscopy of mattress covers and fillings showed microbial ‘biofilms’ in the head areas of all SIDS cases examined. This was not seen on other samples.”

In another study the New Zealand Cot Death Study Group compared 393 case patients with SIDS with 1592 control subjects in order to examine sheepskin bedding as a risk factor. They found that:

The relative risk for SIDS with sheepskin use was significantly increased in the infants placed prone [on their tummy] to sleep . . . but not for infants placed in the supine [back] or lateral [side sleeping] position.

An interaction between sheepskin use and bed sharing was also found. Sheepskin use was associated with a decreased risk of SIDS among infants sharing beds  . . . but an increased risk among infants not bed sharing. We conclude that if an infant needs to be placed prone to sleep for medical reasons, a sheepskin should not be used as underbedding. However, for infants placed supine to sleep, sheepskins are not associated with an increased risk of SIDS.” (emphasis mine)

Was the increased risk of SIDS for tummy sleeping babies due to obstructed breathing from the lambskin or the presence of heavier-than-air stibine gas? It’s impossible to say. Why did the bedsharing babies experience a decrease in risk? I have theories on that which I’ll share later, but for now let’s look at a few criticisms of the theory.

Critics Say . . .

The toxic gas theory has been thoroughly disproved because it “cannot explain the characteristic[s] commonly associated with SIDS, for example the winter peak, or the higher risk in infants whose mothers smoked, were bottle-fed, were bed sharing, or who had intrauterine growth retardation.”(3) They also contend that SIDS sometimes occurs in circumstances where fungal growth is not a factor, such as a parents arms, and that SIDS investigations do not indicate poisoning by these gases. Proponents, on the other hand, say these objections can be seen from another perspective:

  • Perhaps the winter peak occurs because”[w]indows are kept shut, creating poor ventilation around the crib. Gasses are less likely to dissipate. Babies are often bundled in blankets during the winter, trapping gasses close to their bodies.” (source)
  • Poor lung development due to maternal smoking and intrauterine growth retardation could make a baby more susceptible to toxic gases
  • Bottle-fed babies typically develop different sleep patterns than breastfed babies (more on how this could be a factor in later)
  • As cited in the New Zealand Cot study above, bedsharing actually reduces the risk of SIDS when done safely
  • SIDS is an umbrella term that may have more than one cause, so although it might explain many cases, but some such as the loss of a child in a parent’s arms could have a different cause
  • “The lethal dose of nerve gas doesn’t make them ‘ill’ [as it would in an adult who was exposed over a long period of time]. It acts by shutting down the nervous system, stopping heart function and breathing. Research has shown neurochemical deficits in SIDS babies that are consistent with poisoning by nerve gas.” (source)

What About Vaccines? Haven’t They Been Implicated In SIDS?

Though there is no formal acknowledgment of a causal relationship, critics of the current vaccine program often point out the peak age for SIDS-related deaths (2-4 months) coincides exactly with the introduction of vaccines if the recommended schedule is followed. In the next post ‘ll be talking more this theory and how these two theories may not be competitors, but rather two parts of one picture.

In the meantime, if you have a question or comment please leave it below!

Disclaimer This information is purely for educational purposes and is NOT meant to be SIDS prevention advice. It is not intended to diagnose, treat, cure, or prevent any disease. Mommypotamus does NOT make ANY claims that using a non-toxic mattress will prevent SIDS since this has not been 100% scientifically proven, and there can be other factors involved in SIDS. None of the information or options presented here are considered to be SIDS prevention advice or medical advice.

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95 Responses to Mattresses, Sheepskins And SIDS: What Parents Need To Know

  1. Do Vaccines Cause SIDS? « The Mommypotamus says:

    […] As I wrote about earlier this week there’s certainly a lot of evidence indicating that’s the case, but I don’t think it’s an either/or thing. In fact, the two factors may be working synergistically to induce SIDS. Children often run fevers after vaccination, and a modest increase in body temperature could speed up the production of toxic gases by up to 10 times. (Source) […]

  2. Toxin-Free Tuesdays: Flame Retardants in {Crib} Mattresses says:

    […] Syndrome (SIDS). You’ve got to be kidding me, right?  Mommypotamus goes into a lot of detail here, explaining how the toxic nerve gas put off by the fungus is heavier than air, and might result in […]

  3. Kate says:

    Thanks for this great article. I’ve written about SIDS on my blog and had no idea about this connection to mattress flame retardants.

  4. Nathan says:

    An excellent well-documented summary of the link between vaccines and sudden infant death can be read here:

  5. Katharine Trauger says:

    It would not be too hard to make a simple mattress, would it? I mean, I used to live in Mississippi and knew a cotton farmer. I bet I could have coaxed him into selling me the raw stuff, after de-seeding. I could sew a rectangle box shaped thing and stuff it. I could tack it together with those long needles and mattress buttons.
    And want about a really, really old mattress, made before the days of fire retardants?
    And what about rubber pads, as in real rubber? A plain cotton sheet over that? etc.

  6. stephanie moore. says:

    I know about the cot death cover up story and met Jim Sprott who wrote and found about cot death in NZ. That was 10 years ago and had kept it in the back of my mind.. Im pregnant now and went out to buy a nature baby organic mattress.. its plant latex surrounded by wool…. I forgot about the wool factor. What should I do? I feel stupid now having this beautiful mattress but its wool and I guess it would be best to cover it now huh???

    • Heather says:

      Hi Stephanie, I can’t say what is right for you to do, but I want you to know that before I knew about this my little ones slept with me in our non-organic mattress all the time. Though I think a non-toxic mattress is ideal, I personally believe there are other factors that are often involved in SIDS.

    • Frankie says:

      Stephanie, Are you still pregnant? (If not, I hope congrats are in order :). ) I’m waaay past that and am on to different interests now, one being essential oils (EOs). The idea of sheepskins possibly being the culprit in infant deaths sounded fishy to me. What did our ancestors use? I’m sure that some used sheepskin. So I looked up the offending fungi and found several scholarly articles on various EOs that neutralize these fungi. No brands mentioned but if you are so inclined to pursue this path, I’d go with organic EO so as to avoid the toxic solvents. Sure wish I knew THEN what I know now. :/

  7. Dave says:

    Thank you for all your research. I started looking into the issue, and it is indeed very confusing since people on both “sides” of the debate make false statements–but of course they can’t both be wrong.

    I have a correction to offer for one point. The positive correlation between SIDS rates and birth order is real in a sense, but misleading, and doesn’t mean what you and others interpret it to mean. The three “sources” you provide do not show that it does, either. The issue is that the original studies making this claim of positive correlation were not stratified by family size (# children).

    Imagine there are two types of parents: type 1 has many resources at their disposal, including information/education; type 2 has very few resources. It also happens that type 1 parents only have 1 child while type 2 parents have 2 children. Prevalence of types 1 and 2 in the population is 50% each. Because type 1 knows about back sleeping and not smoking (etc.), the SIDS rate is 0.1 deaths (per 10,000). Because type 2 parents are liable to put babies on their stomachs, the rate is 9.9. If we look at all first children (in terms of birth order) in the population, half are from type 1 parents, and half are from type 2 parents, so the SIDS rate is (0.1+9.9)/2=5.0. If we look at all second children, they only come from type 2 parents, so the rate is much higher (almost double): 9.9.

    So it *appears* the SIDS rate increases with birth order. Technically, it does–but only because of confounding factors (education, etc.) correlated with family size. What we really want to know is, e.g., given that a parent has 2 children, is the second child more likely to die of SIDS than the first child? This is statistically simple to do (just stratify/split your sample up by family size).

    The following study (from J Paediatr Child Health) corrects the methodological issue and finds a *negative* correlation between birth order and SIDS rates, given a fixed family size:
    Note: this does *not* mean that the toxic gas theory is wrong; it doesn’t even necessarily disprove that mattress reuse increases SIDS rates. But it *does* mean that there is no empirical support for either statement from the data on SIDS and birth order.

    If there are other studies from different populations that employ family-size stratification and find non-negative correlation between SIDS rate and birth order, I would be interested to see them. I by no means claim to have done a thorough literature review, and more information is always better to have than less.

    (On a personal note, as a university professor with a PhD in statistical/econometric theory, such wide dissemination of “facts” based on faulty statistical analysis always makes me cringe–I have seen this “fact” on countless websites discussing SIDS.)

  8. Crunchy Baby Must Haves | Whistle Pig Hollow says:

    […] 1. An organic crib mattress. I didn’t comprehend the importance of this with B, and come to find out, he had the most toxic mattress on the market (sadness). We remedied the situation by wrapping with a BabeSafe mattress wrap, which I feel great about. I am fine to use the same crib mattress for baby #2 now that it’s wrapped. For more information on finding an organic crib mattress and why it’s so important, see here. […]

  9. Monica says:

    What happened to the follow-up post about vaccines and SIDS? The widget below takes me to an error page.

  10. Kendra says:

    Hi! I’ve been reading and re-reading your posts on mattresses. Our house flooded out two weeks ago and we have to replace quite a lot. Can you recommend adult mattresses and baby mattresses that are cost conscious? I desperately want to make a safe decision, but I also have to factor in cost because we are on a limited budget and are having to replace so very much.

    • Heather says:

      Oh, I am so sorry to hear that! Though my favorite brand, intelliBED, is actually cheaper than most on a cost-per-year basis, it requires more of an up-front investment than some traditional beds. Unfortunately I’m unable to speak with confidence about any other brand because I don’t have personal experience with their products. A good friend of mine recently bought and expensive organic bed that looked perfect on paper but made her husband miserable, so she had to send it back. Her experience has made me leery of making recommendations based on materials used alone, so I’m sticking with what I know. Again, I am so sorry about the flood. I hope you are able to find great deals for everything you need to replace!

      • Kendra says:

        From your research on sheepskin/wool and SIDS, did it apply if the mattress was stuffed with wool? I found a mattress from IKEA that was more natural than most, but stuffed with wool. My only concern with that is that I co-sleep my babies.

  11. david says:

    Hi Heather,
    If I read your article carefully, it seems that the culprit in sheepskins and mattresses are the chemicals arsenic and antimony. How do you feel about lambskin rugs that actually are certified free of such chemicals as per Oko-tex Standard 100?

    E.g. the following one?

    I am inclined to buy one for my toddler to play on, not for sleeping.


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