In the first year alone, babies sleep for a total of around 228 days! But don’t be lulled into thinking they’re just sleeping; that little body is busy building a robust immune system and nervous system and is growing rapidly. And, whenever rapid growth happens, there’s a greater potential for things to go awry, especially in the presence of toxic chemicals in crib mattresses that adversely affect development.
Why prioritize the crib mattress? Well, even though your baby may spend a good amount of time being rocked, bounced, and sung to sleep in your arms, eventually they’ll sleep in their crib for hours at a time.
Unlike most adult, babies are unable to remove themselves from a dangerous situation, such as a sleep set-up where blankets, stuffed toys, crib bumpers, or other soft items create a suffocation or overheating hazard. It’s our job, then, as parents and caregivers, to create the safest sleep environment we can for an infant. This means following basic sleep safety advice from organizations such as the American Academy of Pediatrics (AAP), who note that bedding in a newborn’s sleeping environment increases the risk of SIDS (Sudden Infant Death Syndrome) fivefold, independent of sleep position. If the infant is placed prone (on their front) to sleep, the risk of SIDS increases to 21-fold.
The ‘Back to Sleep’ campaigns have likely saved countless lives, but SIDS cases still occur and there are numerous theories as to why. The general scientific consensus these days is that there is a Triple Risk Model underpinning SIDS. This model proposes that a sudden infant death occurs when three conditions are present and occur at the same time. Those conditions are: a vulnerable infant; a critical period of development; and exposure to a stressor with which the infant is unable to cope.
Most SIDS cases occur between two and four months of age, with the most common exogenous stressors including prone position, overheating, head covering, co-sleeping, and infection. The two most common ‘vulnerabilities’ are preterm birth and maternal smoking.
There are, however, many more potential underlying causes of vulnerability, and many more potential exogenous (external) sources of stress that may overtax an infant’s coping abilities. And, as the Triple Risk Model suggests, it is the confluence of these factors that creates the greatest risk, given that most infants will be able to cope just fine with some stressors, while others have a harder time due to a greater vulnerability to the physiological impact of such stressors.
It should also be remembered that while SIDS is the most extreme outcome imaginable, other kinds of harm can befall a sleeping infant. Crib conditions may adversely affect their development, both physical and cognitive.
- Sleep Safety
- What to watch out for in crib mattresses
- Volatile Organic Compounds (VOCs)
- Polyurethane Foam
- What About CertiPur Foam Mattresses?
- Other flame retardants in mattresses
- Waterproof Covers – Polyvinyl Chloride (PVC), Phthalates, Polyester, and Polyurethane
- Antimicrobial treatments for crib mattresses
- Conventional cotton and pesticides
- Toxic off-gassing, SIDS, and crib mattress wrapping
- How to minimize risk and choose a healthier, safer crib mattress
The AAP, Australian Red Nose Society, and other organizations involved in safeguarding the health of infants and children make various recommendations for sleep safety, including advice to:
- Put your infant to sleep on their back from birth (not on their side or tummy)
- Avoid exposure to smoke (cigarettes etc.) before birth and after
- Breastfeed/nurse baby if possible
- Use a firm mattress and tightly fitting sheet to create a firm, flat sleep surface (sheepskin is not firm enough and may contain contaminants)
- Don’t put any blankets, pillows, stuffed toys, wedges, bumpers or other items in the crib
- Make sure your baby’s head and face are not covered
- Room-share, but don’t bed share for the first six to twelve months
- Make sure every sleep surface and environment is baby-safe (it’s all too easy to fall asleep with baby on a couch, in a chair, etc.).
Other recommendations include taking steps to:
- Use either a well-fitted sleep-gown or sleep sack or swaddle younger infants (until they show first signs of being able to roll onto their tummy)
- Keep cribs away from windows, air conditioning vents, and heat sources
- Make sure that cords for blinds, baby monitors, and fans, as well as toys, and other potential hazards can’t be pulled into the crib.
Most organizations limit their suggestions to those laid out above, but there is sufficient evidence to also support recommendations to choose products for a nursery or other sleeping environment, including a crib mattress, that are free from potentially problematic common chemicals and materials.
While they sleep or rest in their crib, a newborn breathes at a much faster pace than adults (30-40 times a minute while sleeping, 40-60 while awake vs. 12-16 times a minute for adults) (R). Their lungs are also still developing, and the volume of air they breathe in relative to body mass is also much higher than in an adult (at more than 300 L/kg per day compared to less than 50 L/kg per day for most adults, according to one study, when normalized for body mass). All of this means that an infant has a higher risk of being affected by chemicals in crib mattresses that do turn out to be toxic.
What to watch out for in crib mattresses
Now, I know some folks might balk at me suggesting that it is wise to avoid chemicals and materials that the AAP and other organizations don’t explicitly say to avoid and that are permissible in crib mattresses under current law. However, even if a chemical or combination of chemicals hasn’t been directly linked to a SIDS case, that is not proof that these chemicals are safe. Indeed, many of these chemicals have been shown time and again to disrupt normal development and have adverse effects on human health.
The chemicals and materials I’m talking about, for the main part, include:
- Polyurethane foam – including ‘eco’ foam that is typically still mostly a gasoline product
- Volatile organic compounds – e.g. formaldehyde and benzene
- Flame retardant chemicals – e.g. antimony, phosphorus, PBDEs
- Antimicrobial treatments – including nanoparticle treatments
- Polyvinyl chloride (PVC) and associated plastics – which can off-gas and contain phthalates.
So, let’s dig into the evidence, as it stands, surrounding crib mattress safety, which chemicals you probably want to avoid when choosing nursery items, the mattress wrapping controversy, and other issues of sleep safety for infants.
Volatile Organic Compounds (VOCs)
Volatile organic compounds (VOCs) in crib mattresses come from resins, catalysts, adhesives (glues), solvents, and other products used in manufacturing the mattress. These may be present initially as residues that off-gas in a few days to weeks to month or may be intended to stay in a mattress during use to confer specific qualities. Such chemicals may act as stain repellants, flame retardants, antimicrobial agents, or water resistance treatments.
Research shows that VOC emissions from polyurethane foam mattresses are higher than those of polyester foam and that even minimal VOC emissions in pregnancy and in the postnatal period can be harmful for infants’ neurological development, growth, immune and respiratory function (including an increased risk of asthma and allergy), and overall health and well-being.
As I’ve noted before at Leaf Score, it’s a sad irony that nesting just before a baby is born can mean a nursery has the highest concentration of VOCs in the house. And greater exposure to VOCs in the weeks leading up to birth have been associated with an increased risk of respiratory wheezing in infants and a three-fold increase in the risk of developing atopic dermatitis.
Crib mattresses may be a significant source of VOCs, with the air space immediately surrounding the mattress showing the highest concentration of all, according to researchers from the University of Texas.
These researchers looked at 20 new and used crib mattress made with either polyurethane foam or polyester foam. They simulated sleeping conditions for an infant by creating a bedroom-sized chamber with a heated cylinder to imitate body heat generated by a baby. They then measured VOCs within the room (at 10 feet away from the crib) and in the breathing zone (determined as 2.5 cm or 1 inch above the mattress) to give area-specific emission rates (SERs).
All mattress samples emitted VOCs, with the mean total VOC SERs 56 microgram per meter squared per hour (μg/m2h) at 23 degrees Celsius and 139 μg/m2h at 36 C. More than 30 VOCs were found in the tests, with new mattresses releasing four times as many VOCs as older mattresses, on average. Polyurethane foam mattresses emitted a greater diversity of VOCs compared to polyester foam mattresses.
VOC concentrations were significantly higher in the breathing zone and in the interior pore air of the mattress compared to elsewhere in the room, by a factor of 1.8-2.4 and 7.5-21 respectively.
The VOCs found in the mattress samples in this study included:
- Neodecanoic acid
- Heaxnoic acid, 2-ethyl-
- 1-Heptanol, 3-methyl-
- Propanenitrile, 2,2′-azobis[2-methyl-
- 2-propanol, 1,3-dichloro-
- Linalyl acetate
- Cyclopropane, pentyl-
- -Hexanol, 2-ethyl-
- Oxalic acid, bis(2-ethylhexyl) ester
- 1-Decene, 3,4-dimethyl-
- Ethanol, 2-(2-butoxyethooxy)-
- Phenol, 2-(1-methylethyl)-
- Pentanoic acid
- Benzoic acid, 2-ethylhexyl ester
- Isopropyl Myristate
- Palmitic acid
- Propanoic acid, 2-methyl-, 1-(1,1-dimethylethyl)-, 2-methyl-1,3-propanediyl ester
- Octane, 1,1′-oxybis-
- Isopropyl Palmitate.
Some of the VOCs found are classified as environmental pollutants and developmental disruptors.
As with all chemicals, it’s the dose that makes the poison. And, unfortunately, it’s very difficult to quantify cumulative exposure to VOCs and other chemicals from all of the products we come into contact with each day. Testing just one product and finding low VOC emissions does not, therefore, offer much assurance of safety if this is just one of the sources in a household, daycare, school, or work environment.
Polyurethane foam is the most common filling material used to make crib mattresses. In addition to being made from fossil fuels and requiring a lot of energy to make, polyurethane foam is highly flammable and releases horribly toxic chemicals when it burns. This means that it is almost always treated with flame retardant chemicals in order to comply with fire safety regulations.
Two of the key chemicals used to make polyurethane foam are toluene diisocyanate (TDI) and methylene diphenyl diisocyanate, mixed with water and polyols, reacted together with catalysts such as dibutylin (DBT). Polyols themselves are substances created through a chemical reaction using propylene oxide (methyloxirane).
Both methyloxirane and TDI are recognized as carcinogens by the State of California and the U.S. Centers for Disease Control. They’re known to cause tumors (mostly mammary and brain tumors for methyloxirane and TDI respectively) and are both listed on the List of Toxic Substances under the Canadian Environmental Protection Act. “Studies in animals have demonstrated that propylene oxide is a direct-acting carcinogen” (R). Even the US Environmental Protection Agency (EPA) has issues with the chemicals used in polyurethane manufacture and has highlighted manufacturing plants producing polyurethane foam as major sources of myriad hazardous air pollutants including:
- Methylene chloride
- Toluene diisocyanate (TDI) itself
- Hydrogen cyanide.
So, even if the end product (the foam mattress in this case) doesn’t itself pose a health risk, its production does have an impact on those making the product, those living near factories where the product is made, and anyone else exposed to these chemicals through air and water pollution.
According to the CDC, occupational and significant environmental exposure can result in isocyanate-induced asthma, respiratory disease, and death. While safety has improved greatly in U.S. factories in recent years, there remains the potential for health problems related to accidental exposure to high levels of TDI as well as to cumulative exposure. In one case, the State of North Carolina forced the closure of a polyurethane manufacturing plant because tests revealed that local residents were being exposed to potentially dangerous levels of TDI.
Largely due to a lack of data, the United States Occupational Safety and Health Administration (OSHA) has not established exposure limits on carcinogenicity for polyurethane foam from end-use products. This does not mean that an infant sleeping on a foam mattress isn’t being exposed to hazardous air pollutants, however.
Attributing specific health conditions to chronic exposure to chemicals found in mattresses is incredibly difficult. Nobody is going to conduct a controlled trial that may put human infants at risk. So, instead, we largely have to go on evidence from laboratory studies demonstrating the effects of short-term exposure to chemicals such as benzene, propylene oxide, and other chemicals in foam.
Polyurethane foam also poses a risk of exposure to the neurotoxin toluene, and dust from polyurethane may contain organotins, high concentrations of which are associated with growth abnormalities in mussels and oysters and mass mortalities of marine mammals. Dibutylin (a catalyst used in the manufacture of polyurethane foam) is a source of organotins, and has been found to cross the placenta in mammals and to accumulate in the brain, where it acts as a potent neurotoxin, killing brain cells. Organotins in general have been linked to disruption of behavioral functions, neurotransmitters, and neuroendocrine pathways.
Polyurethane foam can also contain chemicals including styrene, antimony, formaldehyde, and others, all of which could end up in the dust produced when the foam breaks down. Polyfoam mattresses are also quite porous, meaning that they can accumulate moisture and tend to harbor mold and mildew. So, most polyurethane mattresses come with a PVC cover to make them waterproof.
What About CertiPur Foam Mattresses?
I’ve seen quite a few round-ups of eco-friendly, non-toxic crib mattresses that include products made with CertiPur certified foam. This is rather irritating, given that CertiPur is a certification dreamt up by manufacturers with a vested interest in trying to greenwash polyurethane foam. Sure, some foam products are less problematic than others, but if you’re looking for a truly safe and eco-friendly mattress, avoiding polyurethane and polyester foam is the way to go.
The CertiPur-US™ logo does offer some assurance that the foam component of the pillow is free from polybrominated diphenyl ethers (PBDEs) and some of the most egregious flame retardants, and that levels of formaldehyde and other chemicals including ozone depleting substances, mercury, lead, and other heavy metals, and hormone-disrupting phthalates are low. However, foam is still resource-hungry, synthetic, and emits VOCs, so it is best avoided.
Indeed, CertiPur standards are far less robust than the Ecolabel requirements used in the EU (for certain substances). Products certified by CertiPur are only tested for 72 hours, compared to 7 or 28 days for Ecolabel. Emission standards for VOCs, including formaldehyde, toluene, styrene and other chemicals are also significantly more robust for Ecolabel compared to CertiPur.
If your choice is between a CertiPur certified foam mattress and a foam mattress not certified by CertiPur or Ecolabel, it probably is best to pick the CertiPur product. If you have the choice of a non-foam mattress, however, this is likely to be far healthier overall.
Back in 1975, the State of California passed legislation (TB117) requiring manufacturers to treat mattresses and furniture to make them safe from cigarettes that could smolder and start a fire. This legislation did not, however, offer guidance as to how to make these products safe, meaning that manufacturers began dousing everything in Polybrominated Diphenyl Ethers (PBDEs).
For decades, PBDEs were the main chemicals used as flame retardants in mattresses and other furniture, including crib mattresses. PBDEs are released from mattresses as it breaks down, and babies can be exposed to flame retardant chemicals by breathing in air while sleeping on the mattress, by absorption through the skin, and through household dust getting onto hands and toys and then into a baby’s mouth.
Over the years, PBDEs have been linked to a whole host of health concerns and many have been banned in certain states, including in California. However, other PBDEs have taken their place, along with other chemicals that may be just as problematic. Again, there is no requirement for manufacturers to prove the safety of the chemicals they use, and there’s plenty of chemical industry lobbying money being thrown around that may influence how regulations are managed.
Thanks to their widespread use for many decades, PBDEs are easy enough to find in most homes. Researchers found PBDEs in the majority of dust samples collected from homes in California in 2015, even though the state updated TB117 in 2014 to enable, but not outright encourage, manufacturers to use other ways to make products smolder resistant. This revision does not explicitly call for the elimination of flame retardants such as PBDEs and many manufacturers continue to use these chemicals in their products.
Unsurprisingly, then, levels of PBDE in North America are reported to be higher than those in Europe and Asia, and the body burden of PBDEs is three- to nine-fold higher in infants and toddlers than in adults (R). This is likely because of exposure to PBDEs in maternal milk and dust.
The most common PBDE isomers found in humans are Tetra-, Penta-, and Hexa-BDEs. PBDEs have a long half-life, meaning that they persist in the environment. Studies suggest that these chemicals may cause (R, R):
- Disruption to thyroid function
- Neurodevelopmental deficits and long-lasting behavioral and motor activity anomalies
- An increased risk of cancer.
In a study published in 2012, researchers in California highlighted to interaction between epigenetics and the effects of early exposure to flame retardants. Specifically, they looked at exposure to BDE-47 (Tetrabromodiphenyl ether), the PBDE found at the highest concentrations in human blood and milk. This study examined the effects of this PBDE on mice genetically engineered for the autism phenotype found in Rett syndrome (linked to defects in the methyl-CpG-binding protein 2 gene MECP2 situated on the X chromosome).
In experiments using these mice, the scientists found that exposure to BDE-47, “presents an independent risk of neurodevelopmental deficits associated with reduced sociability and learning”. Their suggestion, based on these results in mice and on the difficulties of entirely avoiding PBDEs, is that anyone trying to conceive or who is pregnant do what they can to support healthy DNA methylation so as to counteract the negative effects of the PBDEs in our environment.
Long-term, the most sensible thing to do would be to limit or, ideally, eliminate, the use of PBDEs in manufacturing altogether. In Europe, pan-European Union legislation such as REACH and RoHS, as well as the Stockholm Convention (to which the USA is not a signatory) effectively mean that the use of brominated fire retardants is being phased out for good. Unfortunately, some of the flame retardants replacing the banned PBDEs also present potential risks to human health and the environment.
Other flame retardants in mattresses
Antimony, Boric Acid, and Halogenated Flame Retardants (HFRs) are some other commonly used chemical flame retardants found in mattresses. Antimony is a toxic heavy metal which can cause eye, heart, and lung problems. Boric Acid can cause eye and respiratory irritation.
Bromine, chlorine, fluorine and iodine are elements known as halogens. Halogenated flame retardants act directly on flames, interfering with the chemistry of the flame to prevent fire. Chlorine (chlorinated) and bromine (brominated) are both used as flame retardants, but brominated retardants are the most effective.
HFRs have been linked to a raft of health concerns, including (R):
- Abnormal reproductive development and delayed puberty
- Neurobehavioral changes, damage to brain and nerve function
- Thyroid disruption
As noted, flame retardants are found at increasing levels in household dust. And, because many halogenated flame retardants are persistent and bioaccumalative, they are increasingly present in human blood and breast milk, and in wild animals, with widespread environmental contamination and the highest concentrations in the Arctic and marine mammals (R). In the U.S., bans on the use of HFRs vary from state to state.
While some fire retardant chemicals have been banned, other potentially problematic chemicals continue to be used in children’s products, including Firemaster 550, a toxic phthalate-containing chemical cocktail. Unfortunately, many mattress manufacturers won’t let consumers know the specific chemicals they use to meet government flammability regulations, claiming that this information is proprietary. This is entirely legal but means it’s very difficult to know if a mattress is as good as a manufacturer claims.
Some companies are investigating novel strategies to make mattresses fire-resistant, such as using nanomaterials to coat fibers. Unfortunately, there is limited safety data on nanoparticles (and what there is has caused some concern) and some of the chemicals used to disperse nanoparticles in treated fibers may themselves be toxic (R). Other researchers are investigating the use of tartaric acid derivatives as a natural flame retardant (R). This chemical looks promising as an eco-friendly treatment and is produced in large quantities in the normal course of making wine.
In one article, Arlene Blum, a biophysical chemist and visiting scholar at the University of California, Berkeley, suggested that, “Instead of adding new fire retardant chemicals that ultimately may be shown to cause health problems, we should be asking whether we need to use these chemicals or if there are other ways to achieve equivalent fire safety.”
Blum goes on to say, “so many of the chemicals we have banned in the past were flame retardants—think about asbestos, polychlorinated biphenyls, polybrominated biphenyls, tris(2,3-dibromopropyl) phosphate, PBDEs—[and] they all ended up in the environment and in people. We need to think carefully about adding these sorts of chemicals to consumer products before there is adequate health information.” I couldn’t agree more, especially as natural materials such as hemp, wool, and flax offer effective alternatives to chemical flame retardants.
Chemical flame retardants aren’t necessary in any mattress, given that natural materials can be just as effective for meeting flammability standards. And, when you consider that chemical flame retardants have been linked to neurodevelopmental problems and hormone disruption in children, it seems pretty clear that there’s no place for these chemicals in crib mattresses.
Waterproof Covers – Polyvinyl Chloride (PVC), Phthalates, Polyester, and Polyurethane
If you’ve ever had to deal with a wailing infant following a 2 am poop explosion, you’ll know that a waterproof mattress pad or cover is a must.
In a 2016 study of foam mattresses randomly selected in a hospital setting, researchers found that of 77 samples, 44 showed bacterial growth (R). They concluded that mattresses support the growth of microbes that could cause infection, although the samples in this study were mercifully negative for Staphylococcus aureus, including methicillin-resistant S. aureus. In another study, however, S. aureus was found in used foam crib mattresses and the researchers, who simulated the movement of a newborn’s head on the mattress, noted that these microbes became airborne and could be breathed in by an infant sleeping on a contaminated mattress (R).
Any tear or opening in a waterproof mattress cover (or a mattress without any cover at all) will allow bodily fluids to enter and contaminate the mattress. Given the likelihood of poop, pee, spit-up, and other bodily fluids being present in or around a baby’s crib, a waterproof crib mattress and/or mattress cover seems smart to me, especially as there is an increasing body of evidence to suggest that bacterial infection plays a role in some SIDS cases (R).
Unfortunately, most crib mattresses have a waterproof cover made with polyvinyl chloride (PVC) made with phthalates, chlorine, and flame retardants. PVC is one of the most environmentally unfriendly plastics around, with a variety of harmful chemicals like chlorine gas, ethylene dichloride, vinyl chloride, mercury, and dioxins, used in its manufacture, which are then released into the environment.
Vinyl chloride (VC) gas is a volatile organic compound used to create PVC, and more than 27 million metric tons of VC are produced worldwide every year (R). Environmental exposure to VC is common, and one recent study found that newborn infants already have adult exposure levels to VC and other VOCs (R). Why is VC a problem? Well, because research shows that it affects mitochondrial respiratory function and exacerbates non-alcoholic fatty liver disease, among other things (R).
According to TreeHugger.com, every kilogram of PVC requires roughly 17 kg of abiotic materials, mostly petrochemicals, to produce, and uses around 680 liters of water in its manufacture. A kg of PVC also requires 11.6 kg of air, which becomes greenhouse gases and other gases. Add to that the energy involved in shipping the raw materials (petroleum) around the world and shipping the mattress to you, and an organic cotton and wool crib mattress made in the US from locally produced raw materials starts to look even better. All in all, PVC is pretty bad news, especially for a product that will be mere millimeters away from your baby’s face.
PVC is a hard plastic, meaning that chemical plasticizers such as phthalates have to be used to make it flexible and soft. Phthalates may make up around 30-40% of the weight of a PVC cover on a crib mattress, and these phthalates are not bound to the vinyl and can leach out and off-gas quite easily, especially in a hot and humid environment.
Phthalates are a family of industrial chemicals used in crib mattress covers, waterproof crib mattress pads, teething guard rails, and other parts of cribs. A sleeping baby may absorb or inhale phthalates through their skin or from the air while sleeping all warm and snuggly in their crib.
Phthalates themselves and their metabolites are biologically active once absorbed. Adult bodies have some capacity to metabolize and eliminate phthalates, but an infant’s body is less capable of doing this and may be more vulnerable to the effects of phthalates, given their rapid growth and development.
I’ve written more about the problems of phthalates in cribs here, and the same basic concerns apply with crib mattresses that have a plastic cover that contains phthalates. Some phthalates have been banned for use in children’s products sold in the US, but not all phthalates are banned and many simply haven’t been tested to determine safety. So, what’s the alternative?
Some crib mattress manufacturers are wise to the problems with phthalates and have begun replacing PVC covers with fabric covers that have a polyurethane backing. Unfortunately, this means that while the mattress filling is protected, there’s still a layer of fabric surrounding the mattress that is not waterproof and may well harbor mildew, mold, and fungus. And, again, polyurethane isn’t particularly environmentally friendly, nor non-toxic.
Some companies use polyester in crib mattresses, claiming that this is healthier than PVC. While they’re right in some senses, what they fail to acknowledge is that polyester production is energy intensive, leading to significant greenhouse gas emissions, including carbon dioxide, as well as nitrous oxide, hydrocarbons, sulfur oxides and carbon monoxide, acetaldehyde and 1,4-dioxane (another potential carcinogen).
Polyester production also generates water-borne emissions, including dissolved solids, acids, iron, and ammonia. So, even though a polyester product may be labeled as ‘green’, this is likely less to do with the environmental impact and more to do with the end product not off-gassing toxic chemicals. Sadly, more common certifications such as Oeko-Tex 100 do not factor in the impact of manufacturing processes and only assess the end product. Oeko-Tex 1000 is better, but few fabric manufacturers carry this certification.
Other manufacturers have taken to spraying the equivalent of a Teflon or Scotchguard PFC (perfluorinated chemical) coating onto mattress covers. This boggles my mind, given the health issues associated with PFCs.
If you see a mattress marketed as waterproof but claiming to be ‘phthalate-free’ and/or ‘PVC-free’, don’t assume this means it doesn’t contain some other kind of toxic chemical. Such mattresses may still contain PVC, polyurethane, polyester, or one of the other undesirable chemical coatings.
A waterproof food-grade polyethylene cover or effective use of puddle pads is preferable. Don’t be confused if you see ‘polyethylene foam’ on a mattress law label as this is just a strange legal language issue whereby a waterproofing sheet is classified as foam. What you want to avoid is polyurethane foam, not polyethylene ‘foam’.
The Leaf Score Verdict? Avoid crib mattresses or waterproof mattress pads that are made with phthalates, polyurethane, or PVC, where possible. Instead, choose a mattress with a polyethylene cover that can be wiped clean and use a wool puddle pad or additional polyethylene mattress pad that you can remove quickly for middle of the night clean-up.
Antimicrobial treatments for crib mattresses
Antimicrobial treatments for crib mattresses and sheets may make it sound like you won’t need to wash bedding as often, but that’s just not true. Babies are messy in ways you can’t even begin to imagine until you’re in the thick of it.
Considering how tiny they are, they sure create a lot of laundry, and an antimicrobial treatment on the mattress or sheets won’t do much at all to keep your sheets or mattress clean or prevent your baby from getting sick. In fact, over time, these unnecessary coatings and treatments may increase your baby’s risk and your own risk of falling ill with an antibiotic resistant superbug. Plus, antimicrobial treatments can upset hormones and normal development.
For instance, antibacterial nanosilver particles have been linked to mutagenic and genotoxic effects (R), as well as potentially affecting neuronal development and physiological function, including testicular function (R, R). And triclosan, another antibacterial chemical used to treat some bedding items, has been associated with disruption of thyroid hormones as well as increased antibiotic resistance (R).
The Leaf Score verdict? Avoid any crib mattress (or sheets) that have an antimicrobial coating or treatment. It’s a waste of money and potentially harmful, with no real benefit.
Conventional cotton and pesticides
Conventionally grown cotton is resource-hungry and involves the use of pesticides and other chemicals that damage the environment and are bad for human health. Given that you can’t wash a crib mattress to get rid of any residues of these pesticides, I’d definitely avoid buying a crib mattress made with conventional cotton.
Rather worryingly, recent groundbreaking research revealed the presence of a variety of pesticides in the brain tissue of fetuses and infants who died of sudden intrauterine unexplained death syndrome (SIUDS) and sudden infant death syndrome (SIDS) (R). The same study noted that some of these organochlorine pesticides, that is α-chlordane, γ-chlordane, heptachlor, p,p-DDE, p,p-DDT, and the two most commonly used organophosphorus pesticides (OPPs), chlorpyrifos and chlorfenvinfos, were found in samples.
These chemicals, which are endocrine disruptors, are able to overcome the placental barrier, reaching the fetus. They can also cross the blood-brain barrier and impact the basal ganglia which controls vital functions. While it’s impossible to say with certainty that these pesticides contributed to the unexplained deaths, the authors strongly recommend that further research is carried out into the possible connection.
Fortunately, we can limit exposure to pesticides by choosing products made with organic cotton that is grown and processed without pesticides, formaldehyde, or other harmful chemicals. Organic cotton is natural, non-toxic, firm, and nowhere near as flammable as petroleum-based foam. Nor does it release toxic fumes if it does somehow catch on fire.
Toxic off-gassing, SIDS, and crib mattress wrapping
There’s little dispute that certain mattress materials emit VOCs. Instead, there’s considerable debate about the significance of the effects of this off-gassing. Things can quickly get confusing when talking about toxic off-gassing, however, because of a controversy that started back in the 1980s. A specific type of ‘Toxic off-gassing’ was cited as a, or perhaps the, significant cause of SIDS, which led to claims that a particular mattress wrapping technique could prevent SIDS. This has not been proven and most governmental health authorities and other serious public health organizations do not recognize ‘toxic off-gassing’ as a serious concern for crib mattresses.
Indeed, the Australian Red Nose Society specifically calls out companies and individuals making a direct link between ‘toxic off-gassing’ from cribs and SIDS, noting a lack of evidence to substantiate a direct connection. I understand this position, given that many of those perpetuating these claims stand to gain financially by inducing fear in parents and caregivers to encourage the purchasing of items such as ‘natural’ crib mattresses and mattress wrapping products, and because a mattress wrap may create a false sense of security that encourages unsafe sleep practices.
However, I think there’s a worthwhile distinction to be made between a potentially financially motivated conspiracy theory and a legitimate, mechanistically sound concern over a component or components of a product that may pose a risk and are entirely unnecessary. Basically, this falls under my general feeling at Leaf Score that if there’s no good reason to include a chemical in a product, why do so, especially if there’s even the slightest concern over their safety?
So, what’s all the fuss about mattress wrapping? In short, a couple of scientists back in the 1970’s and ‘80’s published some research that seemed to support a hypothesis that microbes dwelling in a crib mattress may use chemicals present in flame retardants, such as antimony and phosphorus, as a food source, resulting in ‘toxic off-gassing’ that could be a cause of SIDS. This was suggested as a reason why mattress reuse may be problematic, because a used mattress may be contaminated and have a higher microbial load than a newer mattress.
In a case control study in Scotland, researchers looked at 131 infants who died of SIDS between 1 January 1996 and 31 May 2000 and 278 infants matched for age, season, and obstetric unit (R). What they found was that the risk of SIDS was more than three-fold higher (3.07 odds ratio) for infants routinely sleeping on a mattress previously used by another child (and more than six-fold higher for last sleep). The risk was even higher if the mattress was from another home (4.78 odds ratio) rather than from the same home (1.64 odds ratio).
This study doesn’t explain why this association exists or offer sufficient evidence to determine if this indicates cause and effect. It may be that a reused mattress harbors microbes, sags and compresses causing airway issues, or has some other, as yet unidentified, problem. Whatever the association, a three-fold increase in risk is nothing to sneer at. To my mind, this study certainly suggests that, if you can, you might want to avoid reusing a crib mattress, especially if the mattress is from outside the home.
However, in another study, from 2000, researchers found that there was, “no evidence to suggest that the levels of [antimony, phosphorus, arsenic and bismuth] in cot mattress foam have a causal relation to SIDS” (R). The same study did find detectable levels of antimony trioxide in 52% of mattress samples tested and the authors suggested that PVC mattress covers may be the source of this element in the sample, but the researchers did not detect volatile forms of the four elements ‘off-gassing’ from the foam.
In an article published in 2016, researchers conclude that, “our current understanding of antimony biochemistry and biogeochemistry is roughly equivalent to where that of arsenic was some 20 years ago” (R). This doesn’t mean, of course, that we’re guaranteed to uncover some devastating truth about antimony and antimonotrophs (the microorganisms using antimony as, essentially, a food source). I do think, though, that it is a useful reminder of human hubris when it comes to throwing chemicals into consumer products with little or no effort to first conduct serious safety research.
The original study that sparked this whole mattress wrapping controversy has been replicated numerous times (including in collaboration with the original researcher) without finding the same results. And researchers much more experienced than me have combed through the evidence and concluded that it is insufficient to warrant advising that all crib mattresses should be wrapped to avoid toxic off-gassing.
Having read and re-read the research on this, I’m of the mind that this potential issue with crib mattresses has become overhyped to the point of being a conspiracy theory, which doesn’t help promote healthy, scientifically-sound debate and discussion. There’s definitely a lot of misinformation out there and this is an area where emotions, understandably, run very high. As always, hyperbole hampers healthy debate and means folks become entrenched in their opinions, and it’s all too easy to cherry pick data and research.
However, the longevity of this theory does present some problems for analysis, largely because mattress manufacturing and sleep safety advice has changed quite significantly since the late 1980s and because there are serious differences in how SIDS statistics are gathered across countries and across the years. As such, it’s rather difficult to figure out how much of an effect any single sleep safety measure has on the incidence of SIDS; given these conditions, I’m not sure the ‘Toxic off-gassing’ theory of SIDS will ever be disproved or proved to everyone’s satisfaction.
So, while I am not an expert on SIDS, nor a biochemist, public safety official, or MD, what I can say is that there does appear to be the potential for certain elements in a mattress to interact with other factors (namely microbial contamination, chemical flame retardants, heat, and humidity) to create an exogenous stressor that may pose a problem for a vulnerable infant during a critical period of development. This fits with the Triple Risk Model and could encompass newer findings about vulnerability related to genotype.
And, even if we dismiss the very idea of, say, antimony-microbe interaction and toxic off-gassing, there is still a clear danger from mold, mildew, and bacterial contamination of a crib mattress. What this all boils down to is that it’s almost certainly a good idea to wrap a mattress in a waterproof membrane or at least use a waterproof cover made with food-grade non-toxic polyethylene.
So, while I won’t rush to line the pockets of anyone using fear to push a product, I do think that it’s a decent idea to support the availability of a cheap, non-toxic, and effective waterproof mattress covers. This would also go a long way to reducing ‘green guilt’ for lower income families who struggle to afford the ‘perfect’ non-toxic eco-friendly mattress but are concerned about the content of a cheaper foam mattress or about reusing a mattress that may be contaminated.
How to minimize risk and choose a healthier, safer crib mattress
There’s clearly a lot at stake when choosing a crib mattress. It certainly makes me anxious to think that my choices could have anything but a beneficial effect on my baby’s health, but being overly anxious is also problematic. My feeling, then, is that it’s smart to avoid or minimize avoidable risks wherever doing so doesn’t create a more significant risk.
As an example, if you’re worried about a petroleum-based foam mattress catching fire easily, don’t buy a mattress treated with flame retardant chemicals that may themselves pose a health risk (and that may be ineffective, according to recent research). Instead, opt for a crib mattress made with organic cotton and wool as a natural fire barrier that meets safety standards without the need for any added chemicals. With the foam, at best you’re just swapping one potential risk for another potential risk and at worse you’re adding one risk to another with no benefit.
As a less obvious example, well-meaning parents and caregivers may buy a crib mattress on the basis of it being marketed as ‘breathable’ because it is strongly implied by the manufacturer that this may lower the risk of SIDS and/or other issues related to toxic off-gassing. Breathable mattresses are not quite as good as they may seem intuitively, however. And, frankly, marketing a product by claiming it can reduce the risk of SIDS is illegal and disingenuous.
Not everyone has the luxury to spend weeks tracking down and reading material data safety sheets, poring over scientific studies, re-running statistics, and then stumping up a load of cash for a product that may be slightly safer than something that costs a lot less.
As the Australian Red Nose Society note on their website, as parents and care givers, we want the best for our babies, but it can be hard to make decisions on what to buy for the nursery, given that “There are many items available for sale, but unfortunately, many are simply not safe”. As in the US and elsewhere, “there is currently no explicit market-wide requirement under the Australian Consumer Law for manufacturers or retailers to proactively ensure that the products they sell are safe”. Companies can sell potentially dangerous products without any requirement to act unless a product causes serious injuries. The same is true in the US.
It’s important, then, to acknowledge your limits. Driving yourself up the wall with worry can also be detrimental to health and happiness for the whole family. This means I try to be forgiving to myself and others where limited knowledge, education, finances, and such mean there’s a limited capacity to avoid risks.
In general, my advice for buying a crib mattress is to:
- Avoid foam crib mattresses where possible
- Use an effective waterproof barrier to avoid mattress contamination
- Don’t reuse a mattress if possible (due to sagging and possible contamination)
- Make sure the mattress fits snugly in the crib with no gaps
- Make sure the crib mattress is firm and doesn’t sag or compress excessively
- Favor crib mattresses made with organic cotton, wool, flax, hemp, and well-wrapped natural latex
- Avoid crib mattresses made using chemical flame retardants, stain repellants, antimicrobial treatments, spray on PFC waterproofing, and other unnecessary chemicals
- Look for a mattress with a polyethylene waterproof barrier and use a puddle pad or another polyethylene cover on top of the mattress (just don’t machine wash polyethylene pads).