The Anatomy of a Diaper
What's in a diaper? What components matter most for the safety of the baby versus the health of the planet? Here, Dr. Hopkins breaks it down:
- Top Sheet (the part that touches the baby’s skin): In an ideal world, the top sheet of every diaper would be made of organic cotton or other minimally processed plant-based fibers. However, a critical function of the top layer is to pull moisture away from the baby’s skin, and many other textiles do a better job of this. For now, what we expect from a non-toxic diaper brand are plant-based alternatives to fully petroleum-based plastics.
- Absorbent Core: Virtually all commercial diapers use a combination of wood pulp (fluff) and superabsorbent polymer (SAP) for their core. SAP is far superior at retaining liquid, and thus, the greater fluff to SAP ratio, the bulkier the diaper will be. We don’t rank diapers on how much fluff versus SAP they contain, but we do evaluate the material sourcing and processing to find the most sustainable and safest options. TCF-, ECF-, and FSC-certified fluff is chlorine free and was harvested from sustainably managed forests. Premium German or Sumitomo SAP are the cleanest on the market. (There's more on SAP below if you’re curious.)
- Back Sheet (outer waterproof layer): Like the top sheet, plant-based plastics (like bio-based polyethylene) are preferred over conventional fossil-fuel plastics. The back sheet also contains a barrier film to prevent leaks and the best diapers use a “breathable” film that allows vapor and heat to escape while still trapping liquid.
- Leak Guards & Elastics: Leak guards and elastics help create a secure fit and prevent side leaks. Natural latex rubber offers excellent stretch and recovery, but can rarely trigger allergic reactions and raises sourcing and processing concerns. Conventional synthetic rubbers avoid latex allergens but are typically petroleum-derived and vary in additive content depending on formulation. We generally prefer latex-free synthetic elastomers, such as SBS or SEBS, manufactured under clear quality controls. Transparent disclosure of rubber and elastic materials is essential for evaluating both safety and environmental impact.
- Adhesives & Inks: For diapers that are printed with graphics or a logo, we look for water- or pigment-based inks that are tested for heavy metals. Likewise, we look for water- or plant-based adhesives where present. We always avoid solvent-based systems and undisclosed dyes.
A Word on SAP
Superabsorbent polymer is a synthetic polymer (usually sodium polyacrylate) that can absorb and retain many times its weight in liquid. In modern disposable diapers, SAP is effectively unavoidable because no natural fiber can match its performance.
Although SAP is synthetic, it is biologically inert in its polymerized form and does not readily penetrate skin; safety considerations focus primarily on controlling residual monomer levels during manufacturing. We prioritize SAP produced by established manufacturers in Germany and Japan, including companies such as Sumitomo Seika Chemicals, where stringent chemical regulations and quality controls support consistently low residual monomer content.
From an environmental standpoint, while SAP is not biodegradable, its high absorbency reduces the total material required per diaper. Overall, this helps limit overall resource use relative to pulp-heavy diaper designs.
A Word on Textiles
We assess textile choices based on full life-cycle impact and chemistry. Conventional petrochemical plastics (like polypropylene and polyethylene) are fossil-fuel derived, carbon-intensive, and contribute tremendously to landfill pollution. However, they are mechanically efficient and low-impact to process once produced.
Viscose is plant-based yet heavily chemically processed (this includes bamboo viscose), often using carbon disulfide and other solvents with meaningful environmental and worker safety concerns. Lyocell is a type of viscose that improves on this by using a closed-loop solvent system, but it remains resource-intensive.
Cotton is natural and skin-friendly, yet large-scale use in waterproof layers is impractical because it lacks inherent barrier properties and is much more expensive than alternatives.
For these reasons, we prefer responsibly sourced plant-based plastics (e.g., bio-polyethylene) over conventional fossil plastics or bamboo viscose. They maintain performance and moisture protection while reducing fossil carbon inputs and avoiding the chemical impacts associated with regenerated cellulose processing.
Are disposable diapers toxic?
This is the question I am asked more than any other about diapers. Do even the worst disposables really pose a risk to the baby wearing them? Or is this mostly an environmental issue?
The short answer is that diapers can pose potentially pose risk to the baby wearing them, but only if you are choosing one of the very worst brands.
Here are our two biggest health concerns with disposable diapers:
- The phthalates that may be used not only in the plastic components of diapers but also in the glues, synthetic fragrance, and dyes. In a recent study for the National Library of Medicine out of South Korea, four leading diaper brands (as well as several brands of sanitary pads) were shown to all contain varying amounts (and in some cases, very high levels) of phthalates. In addition, phthalates proved to be the hardest ingredient to suss out during our investigation. A surprising number of “non toxic” or “sustainable” diaper brands don’t actually make any claim about phthalates, and you’ll see in our reviews below that we note whether each brand is “phthalate-free.”
- Allergens and irritants. TBT, parabens, latex, and more are often found in diapers. These will most likely be present in fragrance, lotions, and dyes.
While this is the least sensational potential risk, good old-fashioned diaper rash is probably the greatest concern for most babies wearing disposable diapers.
The best way to avoid diaper rash (or a more serious reaction) is to avoid any disposables with dyes, fragrance, and lotions, and to look for diapers that explicitly state they are free of latex, parabens, and TBT.
Do we need to worry about bleaching/dioxins in diapers?
This is another question I get a lot, and it’s certainly relevant from an environmental perspective. The organochlorines present in the effluent produced by paper mills during the bleaching process are a well-documented environmental pollutant.
However, in terms of a danger to the baby, you should know that the level of dioxins present in disposable diapers is:
- Comparable to that found in cotton (cloth) diapers.
- Thirty thousand to 2.2 million times lower than the average dietary dioxin exposure resulting from “low level contamination of the food supply.” (From this peer reviewed study using commercially available diapers purchased in and around San Francisco.)
In other words, we are exposed to tens of thousands of times more dioxins from our food supply than the trace levels found in chlorine-bleached diapers. Does that mean you should buy bleached diapers? No, definitely not—their production is really bad for the planet. But if the hospital puts your newborn in one, don’t worry; it’s not going to harm her.
Total Chlorine Free (TCF) versus Elemental Chlorine Free (ECF)
If you’ve been educating yourself on the best nontoxic diapers/biodegradable disposable diapers, you’ve probably heard that ECF diapers are basically Sneaky Stuff and that you MUST buy only TCF diapers.
(Quick primer: ECF means bleached with chlorine dioxide instead of elemental chlorine. TCF means bleached using any chemicals other than chlorine, chlorine dioxide, or hypochlorite.)
We are probably the only “green bloggers” saying this, but the distinction between TCF and ECF is totally not important.
Here’s why: as we just said, the use of chlorine in pulp and paper mills is really an environmental issue, not a health and safety issue. Yes, ECF bleached diapers might sometimes still contain trace amounts of dioxins, but we are talking about levels that are several orders of magnitude lower than the levels of dioxins we are all exposed to by simply eating food.
And here’s why it doesn’t even matter from an environmental standpoint: Although the waste products of TCF pulp is technically “cleaner” than ECF pulp, TCF produces a lower yield (it takes more wood pulp and energy to produce the same amount of finished product), effectively canceling out the benefits over ECF.
Moreover, the environmental impact of ECF versus TCF bleaching depends on the practices and procedures of the individual paper mill and how the waste products are handled. Click here to download a PDF of a recent report that concluded the theoretical benefits of TCF versus ECF bleaching have not been realized in the real world and that there is no appreciable difference between ECF and TCF. Scratch that one of your worry list!
273 comments
Dan
Why is ecoriginals not included in the list?
Word Search
This 2024 updated guide is an exceptionally thorough, science-backed, and honest resource for navigating the complex world of “non-toxic” diapers.Word Search
Sudoku
This 2026 non-toxic disposable diaper guide evolves the author’s 2010 research, ditching bamboo viscose (due to harsh processing) for cotton/lyocell/PLA blends, with rigorous FSC/OEKO-TEX standards. Dr. Hopkins’ scientific vetting ranks 40+ brands (Best/Good/Okay/Bad/Sneaky), highlighting Healthybaby (EWG-verified, transparent) and Kudos (cotton top-sheet) as top picks, while calling out greenwashing and phthalate risks. For a break from parenting research, try logic puzzles at https://www.classicsudoku.org.
Seedance 2.0
Ultimate guide to non-toxic diapers, updated 2024, incredibly thorough. Packed with safe options, it’s a must-read for parents wanting chemical-free diapering choices for their babies.Seedance 2.0
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