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 may 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.
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 may be able to 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.”
However, 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.”
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 disproven 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 later 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)
Is there a connection between mattresses, sheepskins and SIDS?
I am unconvinced either way, but if we have another child I may reconsider how I use mine. What do you think?
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 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.