Has The Cause of Crib Death (SIDS) Been Found?

Organic Crib Mattress

Toxic Gases in Baby Crib Mattresses

By Jane Sheppard

Sudden infant death syndrome (SIDS), also known as crib death or cot death, is the number one cause of death for infants from one month to one year of age. 90% of all SIDS deaths are in babies under six months old. Ongoing SIDS research occasionally leads to discoveries of risk factors associated with these deaths, but after over 50 years, researchers say they still do not know how or why it happens. The prevailing official viewpoint on SIDS is that the cause is unknown (SIDS Alliance 2001).

It may seem inconceivable that over a million babies have died of this “syndrome”, and after almost half a century and many millions of dollars spent, no one in this age of science and technology can tell us why. But what many parents don’t know is that a highly convincing explanation for this tragedy has been proposed, along with a simple means of eliminating it. This explanation is backed by some evidence, but has been and continues to be completely ignored by SIDS organizations, the medical community, and the government – for a variety of reasons, including politics, financial liability, and vested interests. Are babies at risk from deaths that may easily be prevented?

Toxic Gases in Mattresses

Dr. James Sprott, OBE, a New Zealand scientist and chemist, states that crib death is caused by toxic gases, which can be generated from a baby’s mattress. He says chemical compounds containing phosphorus, arsenic and antimony have been added to mattresses as fire retardants and for other purposes since the early 1950’s. A fungus that commonly grows in bedding can interact with these chemicals to create poisonous gases (Richardson 1994). These heavier-than-air gases are concentrated in a thin layer on the baby’s mattress or are diffused away and dissipated into the surrounding atmosphere. If a baby breathes or absorbs a lethal dose of the gases, the central nervous system shuts down, stopping breathing and then heart function. These gases can fatally poison a baby, without waking the sleeping baby and without any struggle by the baby. A normal autopsy would not reveal any sign that the baby was poisoned (Sprott 1996).

Which Crib Mattresses are Safe for Babies?

There is a tremendous amount of confusing claims and misinformation on websites about organic crib mattresses. I wrote the following report to help you distinguish facts from misinformation.

Click here to Learn Which Organic Crib Mattresses are Safe and Non-Toxic for Your Baby

Has the Toxic Gas Explanation for Crib Death been Scientifically Proven?

No, it has not. Nor has it been disproven. We definitely need more research. But when you look at the evidence we do have, it’s compelling and it makes sense.

Click here to Learn Why More Research is Not Being Done.

In spite of denial and opposition from orthodox SIDS organizations, no research has disproved this gaseous poisoning explanation for crib death. No valid criticism of this explanation has ever been provided. This logical finding explains every factor already known about crib death, and is backed by scientific research (Sprott 1996, 2000) and two decades of practical proof consisting of a crib death prevention campaign that continues in New Zealand.

Ongoing research continues to support these findings. A four and a half year study by the Scottish Cot Death Trust published in the British Medical Journal (November 2, 2002) has shown that the re-use of infant mattresses triples the risk of cot death (Tappin 2002). Dr. Sprott explains that the risk of death increases when mattresses are re-used from one baby to the next because the fungus has already had a chance to establish itself in the used mattress. When the next baby uses the same mattress, the fungus is soon active. Toxic gas production begins sooner and is generated in greater volume. It is known that crib death rates increase markedly from the first baby in a family to the second, and from the second to the third, and so on (Mitchell 2001). Dr. Sprott warns, however, that new mattresses can also be unsafe because fungal growth can quickly become established in a new mattress once a baby begins sleeping on it (Sprott 2003).

Fortunately, their are now options for safe, non-toxic crib mattresses. Our report on organic crib mattresses will give you information on what to look for and what to watch out for when deciding on a crib mattress. See our recommendations for safe organic crib mattresses.

A 100% successful crib death prevention campaign has been going on in New Zealand for the past 20 years. Midwives and other healthcare professionals throughout New Zealand have been actively advising parents to wrap mattresses. During this time, there has not been a single SIDS death reported among the over 200,000 New Zealand babies who have slept on mattresses wrapped in a specially formulated polyethylene cover. The number of crib deaths in New Zealand that have occurred since mattress-wrapping began in 1994 is about 1020. The number of crib deaths that have occurred in New Zealand on a properly wrapped mattress is zero.

The covers used in this campaign are BabeSafe mattress covers. No other mattress covers that I know of have been tested to block gases.

In early 2002, a German doctor published the results of the New Zealand mattress-wrapping campaign, including statistical analysis carried out in conjunction with the University of Munich (Kapuste 2002). The statistics showed that the proof of the validity of mattress-wrapping for crib death prevention was one billion times the level of proof generally accepted by the medical community as proving a scientific proposition.

Prior to the commencement of mattress-wrapping, New Zealand had the highest crib death rate in the world (2.1 deaths per 1000 live births). Following the adoption of mattress-wrapping by many parents in New Zealand, the New Zealand crib death rate has fallen by 70%, and the Pakeha (non-Maori) crib death rate has fallen by an estimated 85% (NZMH). Pakeha parents have adopted mattress-wrapping with enthusiasm. “These reductions cannot be attributed to orthodox cot death prevention advice,” said Dr Sprott. “There has been no material change in that advice since 1992. The only significant change in cot death prevention advice, which has occurred since 1994, is the nationwide dissemination of my recommendations to wrap babies’ mattresses.”

Parents Are Denied Findings

So why didn’t this profound and critically important information make the headlines of major newspapers or all over the evening news? Why aren’t crib death researchers and the government of the United States telling parents to wrap babies’ mattresses? Why are the manufacturers still adding fire retardants and other chemicals to mattresses?

There are various reasons, but one possible reason is that mattress manufacturers are required to use fire retardants through government regulations. Admitting that these chemicals are causing deaths would mean admitting to major liability. Furthermore, crib death research has been a significant source of funding for medical researchers in the U.S. Unfortunately, the ongoing complex and expensive research that leads to the discovery of “risk factors” for a so-called “syndrome” has pushed aside the simple and inexpensive solution of mattress-wrapping; a solution that can do no harm.

The Cot Death Cover-Up? (Penguin books, NZ, 1996), by Dr. Jim Sprott, reveals the amazing story of denial on the part of crib death researchers and the medical community, and the failure of these entities to accept such a simple explanation. Dr. Sprott first suggested a toxic gas theory for crib death in 1986, and in 1989 Barry Richardson of Britain, also a consulting chemist acting independently, publicized research on the finding. In response, the British government set up expert committees to investigate the findings. One committee published the Turner Report, which recommended the removal of the chemicals from baby mattresses and for babies to be tested for antimony. A second committee published the 1998 Limerick Report, which is frequently cited by SIDS organizations as finding no evidence to substantiate the claim that toxic gases cause crib death. Contrary to this publicity, the Limerick Report did not disprove the theory (Fitzpatrick 1998) – in fact, it provides further confirmation of it (Sprott 2000).

The main orthodox crib death prevention recommendation is to put babies to sleep on their backs. We know that babies do still die when sleeping on their backs, although face-up sleeping does reduce the risk. The gases are denser than air and tend to settle in a thin layer directly on top of the mattress, so babies sleeping face-down are more likely to inhale a lethal dose of the gases. The gases are also absorbed through babies’ skin, and this is one of the major reasons why face-up sleeping provides only partial protection against crib death (Sprott 1996).

However, no babies have died sleeping on a properly wrapped mattress. This is crucial information for parents. 2,100 babies continue to die every year in the United States from SIDS. Parents should be provided with the information so that they are able to decide for themselves whether they want to wait for the SIDS research organizations or the government to endorse mattress-wrapping or to “play it safe” as many parents have done in New Zealand. As Dr. Sprott points out and no one has denied, “All New Zealand crib deaths since mattress-wrapping began in late 1994 have occurred when parents have not wrapped their babies’ mattresses. An inexpensive, non-toxic protective cover can surely do no harm.”

The assumption that our government agencies do everything they can to protect our children is naive. The U.S. Consumer Products Safety Commission has stated that BabeSafe mattress covers do not constitute any safety risk to babies. These covers (manufactured in New Zealand) are the only mattress covers designed to protect babies from toxic gases generated in mattresses. Yet even though BabeSafe products are simple, inexpensive, and safe, the FDA requires the manufacturer to go through the expensive, complex, time-consuming procedure of obtaining pre-market approval in order for BabeSafe covers to be bulk imported into the U.S.

Instead of putting unnecessary hurdles in the way of a harmless and potentially live-saving product, why don’t the authorities endorse mattress-wrapping in the U.S. to see if the results achieved in New Zealand could be duplicated here? The score in New Zealand is now 1020 deaths (orthodox crib death prevention advice) to none (mattress-wrapping). With so many more babies born in the U.S. than in New Zealand, the potential to save lives is dramatically greater – thousands every year. Why should even one baby be denied something that could potentially save his or her life?

Though the toxic gas explanation has not been scientifically proven to cause crib death, I believe the 100% successful cot death prevention campaign in New Zealand is enough evidence to warrant taking a precautionary approach.

Find an organic crib mattress that is safe for your baby.

Learn about Factors That May Increase the Risk of Crib Death

Read our comprehensive report to Determine which Crib Mattresses are Safe and Non-Toxic for Your Baby


Use the information provided here as an educational resource for determining your options and making your own informed choices. Healthy Child does NOT make ANY claims that using a non-toxic mattress or wrapping a mattress will prevent SIDS since this has not been scientifically proven. There can be other factors involved in SIDS. However, the fact that there have been no SIDS deaths among the vast number of babies in New Zealand who have slept on correctly wrapped mattresses is crucial information for parents. This fact cannot be denied and should not be suppressed. The evidence is very compelling, and we believe that parents should be informed so they can make their own decisions on how to protect their babies.

Has the toxic gas theory been disproven?

Position Papers publicized by US SIDS organizations say there is not enough evidence to support the toxic gas theory, and that parents should continue to put their babies to sleep on vinyl-covered crib mattresses. They base this on a report commissioned by the British government, under Lady Limerick. The 1998 UK Limerick Report did not disprove the toxic gas theory for cot death (crib death).  In fact, the Limerick Committee’s research proved the gas generation on which the toxic gas theory is based.  For information on fallacies contained in the Limerick Report, visit http://www.cotlife2000.com and click on the side heading “Limerick Report”.

See Jane’s recent blog post on why it’s important to not ignore this issue:

Are Toxic Gases in Crib Mattresses Causing Crib Death SIDS?


Fitzpatrick, M.G. 1998. SIDS and The Toxic Gas Theory (letter), New Zealand Medical Journal, October 9, 1998.

Kapuste, H. 2002. Giftige Gase im Kinderbett (“Toxic Gases in Infants’ Beds”), Zeitschrift fuer Umweltmedizin No. 44; January-April 2002:18-20

Mitchell, P.R. 2001. Analysis of Official UK Statistics for Cot Deaths and Infant Deaths by Other Causes, 1996-1999.

New Zealand Ministry of Health (NZMH) Cot Death Statistics.

Richardson, B.A. 1994. Sudden Infant Death Syndrome: A Possible Primary Cause. Journal of Forensic Science Soc. Jul-Sep; 34(3):199-204.

SIDS Alliance. 2001. www.sidsalliance.org

Sprott, T.J. 2000. Critique of the 1998 UK Limerick Report. www.cotlife2000.com

Sprott, T.J. 1996. The Cot Death Cover-Up? Auckland, New Zealand: Penguin Books.

Sprott, T.J. 2000. Personal communication with an officer of the Ministry of Health. August 11, 2000.

Sprott, T.J. 2000. Research Which Confirms and Supports the Toxic Gas Theory For Cot Death

Sprott, T.J. 2003. The Cause of Cot Death and How to Prevent It, Cot Life 2000, March 2003

Tappin et al, Used infant mattresses and sudden infant death syndrome in Scotland: case-control study, British Medical Journal 2002; 325:1007


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  24. Ok… But some questions remain. For example, most babies are in cribs until about age two and almost all toddler beds come with fire-retardant mattresses similar to infant crib mattresses. Furthermore, many adult mattresses are fire-retardant and, I’m assuming, contain the same chemicals. Yet SIDS is only an issue until 1 year of age, most prevalent before 6 months of age with the highest rate being found in babies between 2 and 4 months of age.

    This theory doesn’t explain any of this. Particularly that SIDS affects 2-4 month old babies when a newborn would be far more succeptible to poison than a slightly older baby.

    1. This is a great question! Dr. Sprott says this:

      “A significant number of babies sleep on new mattresses, and it takes around one to two months for fungi capable of gas generation to become established in a mattress. However, a baby less than one month old can die of cot death if he or she is placed on a mattress which has recently been used by another baby and is already capable of generating toxic gas.”

      Regarding babies over 6 months:

      “An older baby is more able to respond physically to the initial distress which is caused the exposure to the toxic gases. An older baby experiencing this distress (e.g. the initial headache which occurs) can take action by flailing around in the cot, throwing off bedding, or sitting or standing up in the cot. This attracts the attention of adults. It also disperses gases from around the baby; or physically removes the baby from the gases (if the baby sits or stands up in the cot), since these gases are more dense than air.”

      Babies over 1 year, children, and adults are affected by toxic gases, but not in a fatal way, since their nervous and elimination systems are more developed and they can handle more toxins than a small baby.

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  26. If I had purchased an organic mattress for my first born, can I reuse it or do I need to purchase a new one for my second born?

    1. It really depends on what materials are in your organic mattress. Not all mattresses labeled organic are safe and non toxic. If there are chemicals in the mattress, from fire retardants or a vinyl covering, it’s best to get a new one that contains only safe materials.

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  29. I believe this to be the cause as well. I also believe that cigarette smoke is another factor. My brother was found in his crib by my kinship person and myself not breathing. His heart had stopped and we got him breathing again. I remember the paramedics looking at his matttess and I remember one of they saying they believed It was from the chemicals in the mattress. This happened about 25 years ago so this information is not new.

    1. Yes, agree that it could be an accumulation of stressors. It seems the biggest environmental stressors that babies are exposed to – up close, long-term mattress exposure and vaccinations – are not even mentioned in this article. Makes sense that circumcision is also a major stressor in boys. Important to put all the pieces together and take a precautionary approach to all potential stressors.

  30. There is also a Scottish study that shows a significant link to using an old mattress that originates from outside the home. This would seem to suggest that there is a bacterial/viral link, because a baby would have some kind of natural immunity to germs from within the family, but far less/none to those from outside.
    Apparently there is also a medical reason (that i didn’t understand) that makes babies more susceptible to pathogens around 3 months of age.
    Wrapping the mattress would of course block access to germs in the mattress as well as gases.
    Another thing: When i was expecting, and i knew that there was a mold problem in my mattress, i found that if i lay on a regular pillow i would be coughing terribly, and had to sleep very propped up – far away from the source of irritation, presumably.
    Most likely there are a variety of factors responsible for SIDS.

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