The Cloth Diaper Laundry Soap Controversy: What the Evidence Actually Shows

The rabbit hole of cloth diapers all started when I was asked at an event if our laundry soap is “safe” for cloth diapers. My immediate response at the time was simple: our soap is made with straightforward, well-understood ingredients, so there was no obvious reason it wouldn’t be. But I quickly learned that in the world of cloth diapering, “safe” doesn’t mean what most people think it means. It has been redefined into something far more specific, and far more confusing, than basic ingredient safety.

What I initially understood “safe” to mean was safety for the skin and overall health. Human skin is not an impenetrable barrier. Certain substances can pass through it, and there is research showing that some ingredients used in personal care products can be absorbed to varying degrees. For example, some studies have demonstrated that surfactants can alter the skin barrier in ways that increase absorption, and compounds such as propylene glycol are known to enhance penetration under certain conditions.^1,2

At the same time, it’s important to be precise. With the thousands of ingredients used in products like laundry detergents, it is not accurate to make broad claims about skin absorption. Permeability depends heavily on the specific compound, its concentration, the formulation it is used in, and the condition of the skin itself. In other words, each ingredient, and each formulation, has to be evaluated on its own.

There are, however, certain categories of ingredients that appear frequently in laundry detergents and deserve closer attention. One of the most common is listed simply as “fragrance” or “parfum.” While it sounds like a single ingredient, it is often a complex mixture of multiple chemical compounds that are not individually disclosed on the label.

This lack of transparency matters because fragrance mixtures can include substances such as phthalates, which have been used in some formulations to help stabilize scent. Research over the past several decades has raised concerns about certain phthalates due to their potential biological effects.^3,4 For example, studies have examined the dermal absorption and metabolism of compounds such as di(2-ethylhexyl) phthalate (DEHP), as well as the ability of some phthalate diesters to penetrate human and animal skin underif a material is designed to tolerate a range of cleaning agents, what is the basis for strictly limiting one category over another? experimental conditions.^5,6

The challenge for consumers is that when “fragrance” appears on an ingredient list, there is no way to determine which specific compounds are included in that mixture. This makes it difficult to fully evaluate the product based on the label alone, and reinforces the importance of understanding how ingredient disclosure works.

I’m not going to walk through study after study to make the point that our skin is not a perfect barrier. The takeaway is simpler than that: what we put on our bodies matters, because some substances can interact with the skin and, under certain conditions, be absorbed.

There is also real-world data that reflects how people experience laundry products. In one survey of 3,841 individuals, 26% reported skin irritation they believed was associated with laundry products, and 21% reported perceived allergies. These effects were reported more frequently by females and were more common in children between the ages of 1 and 20.⁷ Even allowing for the subjective nature of survey data, those are not insignificant numbers.

This brings us back to what we wash our clothes with. Fabrics sit in prolonged contact with the skin, and any residual substances left behind after washing have the potential to interact with it. Fragrance compounds are a good example. If a product leaves a noticeable scent after washing, that indicates that some portion of those compounds remains on the fabric.

That does not automatically mean harm, but it does mean exposure. And once you understand that, it becomes clear that the composition of a laundry product is not just about cleaning performance. It is also about what may remain behind.

But that was an incorrect assumption on my part. I had interpreted “safe” to mean safety for the person wearing the clothing. In the context of cloth diapering, that’s not what the question was about.

The concern was not whether the laundry soap was safe for the baby’s skin. The concern was whether it was “safe” for the diaper itself.

Specifically, whether the soap could affect the performance of the diaper liner and potentially damage or reduce the effectiveness of what is often a significant investment.

In other words, the definition of “safe” had shifted entirely. It was no longer about biological safety. It was about material compatibility.

That shift in definition raised an interesting question. Cloth diapers are often chosen as an alternative to disposable diapers in order to reduce exposure to certain materials and to be more environmentally conscious. The focus is typically on what comes into contact with the skin, and what ends up in the environment.

Yet in this case, the primary concern had shifted away from the baby and toward the durability and performance of the diaper itself. Not whether the ingredients coming into contact with the skin were appropriate, but whether the detergent might affect the liner or reduce absorbency over time.

That contrast is worth paying attention to, because it highlights how easily the original intent behind a decision can become secondary to maintenance rules that develop around it.

 

First, when it comes to cloth diapers, it’s worth recognizing the intent behind that choice. Many parents choose them to reduce exposure to certain materials found in disposable products and to minimize environmental impact. That’s a thoughtful decision, especially considering that disposable diapers typically do not provide a full ingredient disclosure, leaving consumers with limited visibility into what materials may be in prolonged contact with the skin.

Second, if you’ve been told that you cannot use traditional cleaning agents such as soap, bleach, or vinegar, and instead must rely exclusively on specific branded detergents for cloth diapers, it’s worth taking a step back and examining that claim more closely.

Some of these recommendations may be based on concerns about fabric performance, such as residue buildup or reduced absorbency. However, others can blur the line between legitimate care instructions and brand-driven guidance. Understanding the difference is important, because it helps separate what is necessary from what may simply be encouraged.

One principle we come back to repeatedly is simple: show me the data. Claims about safety, effectiveness, or restrictions should be supported by evidence, not just repeated across blogs or forums. When we looked into the recommendations surrounding cloth diaper detergents, one thing became clear very quickly—many of the commonly repeated rules are not accompanied by clear, cited research.

Instead, the same guidance is often passed from site to site, sometimes paired with recommendations for specific products that are labeled as “safe” without a transparent explanation of why. That doesn’t necessarily mean the advice is incorrect, but it does mean it should be examined more closely rather than accepted at face value.

For parents trying to make informed decisions, this creates a difficult situation. You’re told to avoid certain cleaning methods, directed toward specific products, and given very little supporting information to evaluate those recommendations. At the same time, many of these products may still contain complex ingredient mixtures, including undisclosed fragrance components, which can make it harder to fully understand what is being used.

This is why it becomes important to step back and ask a simple question: what is actually supported by evidence, and what is being repeated without it?

So how does this kind of guidance become so widely accepted? In many cases, it’s simply repeated often enough that it begins to feel established, even in the absence of clear supporting evidence. Recommendations are shared across blogs, forums, and product pages, sometimes alongside specific detergent suggestions, and over time those recommendations can take on the appearance of standard practice.

At the same time, most people are not in a position to stop and dig through research papers or ingredient data for every product they use. They rely on what appears to be trusted information, especially when it comes to something as important as caring for an infant.

We tend to approach things a little differently. When we saw that some people were hesitant to even try a straightforward laundry soap on cloth diapers, it raised a question: what specifically was the concern, and what evidence was it based on?

Initially, it might seem like the concern would be cleaning performance. But that wasn’t the issue. The primary concern being discussed was the possibility of damaging the diaper or affecting its performance over time.

That distinction was important enough that it warranted a closer look. So we started digging into the reasoning behind these recommendations to see what they were actually based on. Here is what we found.

1. Cloth diapers can be a practical alternative to disposable options. Disposable diapers contribute significantly to landfill waste, and many of the materials used in them are not readily biodegradable under typical landfill conditions. While they have made diaper changes more convenient, that convenience comes with trade-offs, including environmental impact and prolonged skin contact with a combination of manufactured materials.

For families choosing cloth, the decision is often based on reducing that environmental footprint and having more control over what comes into contact with a baby’s skin. And when you consider how frequently diapers are changed throughout the day, those exposures—both environmental and skin contact—add up over time.

2. Modern cloth diapers are not simply “cloth” in the traditional sense. Most include, or are paired with, a waterproof layer commonly referred to as PUL (polyurethane laminate). This material typically consists of a polyester fabric bonded to a thin polyurethane coating, which helps prevent leaks while maintaining flexibility.

I’ll admit, when I first heard the term “cloth diaper,” I pictured something much simpler. But in practice, these systems have evolved to balance reusability with performance. The addition of materials like PUL allows for repeated use without the leakage issues that older cloth diaper designs were known for.

When properly cared for, these components can be reused many times, which is part of the appeal. It allows families to reduce waste while still maintaining a level of practicality that fits modern expectations.

In that sense, cloth diaper systems represent a balance. They aim to reduce environmental impact and provide more control over materials in contact with the skin, while still offering the functionality people expect today. And as with most reusable systems, there can also be a cost benefit over time.

3. One of the most commonly repeated claims in cloth diaper care is that certain cleaning agents should be avoided, particularly traditional soap, vinegar, bleach, and other standard cleaning ingredients. The reasoning often given is that these substances can cause issues such as residue buildup, reduced absorbency, or degradation of the diaper’s waterproof layer.

From a practical standpoint, it makes sense that parents would want to protect their investment. Cloth diaper systems can be expensive, and maintaining their performance over time is a reasonable concern.

Where things become less clear is when you start looking for the evidence behind these claims. There are many articles and guides that repeat the same recommendations, often with detailed explanations of what could go wrong. Soap scum buildup, liner degradation, and loss of absorbency are commonly cited.

However, when looking specifically for scientific data supporting these claims—particularly in relation to materials like polyurethane laminate—the information becomes much harder to find. While the concerns may be plausible, clear cited research directly demonstrating these effects under typical use conditions is not commonly presented alongside these recommendations.

That distinction is important. Repeated claims, even when widely accepted, are not the same as evidence. And without that evidence, it becomes difficult to determine which guidelines are necessary, and which may simply be carried forward without being closely examined.

Since originally looking into this topic, I revisited the available literature to see whether more direct evidence had emerged. While there is research on material durability and chemical interactions in broader contexts, clear, consumer-relevant data specifically evaluating common laundry ingredients on cloth diaper materials under typical use conditions is still not widely presented alongside the claims being made.

Another pattern that becomes apparent when reviewing these recommendations is the frequent pairing of restrictions with specific product suggestions. Many articles advise avoiding certain ingredients while simultaneously directing readers toward particular detergents that are described as “safe” for cloth diapers.

Rather than focus on individual sources, it is more useful to look at the broader pattern. These recommendations are widespread, but often presented without clear, cited evidence explaining why certain ingredients should be avoided in the context of the materials involved.

If there is well-supported research demonstrating these effects under typical use conditions, it should be available and referenced. And if it exists and was missed in this review, it is worth examining. The goal here is not to dismiss information, but to understand what is actually supported by data.

That is ultimately why this article was written. Not to promote a specific product, and not to criticize individual recommendations, but to encourage informed decision-making. It is difficult to make informed choices when guidance is presented with certainty but without clearly accessible supporting evidence.

When looking specifically for research comparing the effects of different cleaning agents on cloth diaper materials under typical use conditions, there is very little directly applicable data readily presented alongside these claims. In the absence of that, many conclusions appear to rely on personal experience and repeated guidance rather than controlled evaluation.

Personal experience can be useful, but it has limitations. Variables such as water composition, wash cycles, drying methods, detergent concentration, and frequency of use can all influence outcomes. Without controlling for those variables, it becomes difficult to draw broad conclusions that apply consistently across different situations.

This does not mean the recommendations are necessarily incorrect. It does mean they should be viewed with appropriate context. Repeated claims and anecdotal observations are not the same as controlled, reproducible data, and understanding that distinction is important when evaluating guidance that affects both product performance and potential exposure.

Asking where information originates, how it is supported, and whether it is being repeated without verification is a useful exercise in any area, including this one. Because once a recommendation becomes widely accepted, it can be difficult to separate what is necessary from what is simply assumed.

Since direct comparative studies on cloth diaper liners washed with soap versus detergent were not readily available, the next step was to look at the material itself. Cloth diaper waterproof layers are commonly made from polyurethane laminate (PUL), so understanding how polyurethane behaves under different conditions provides useful context.

Information from polyurethane manufacturers indicates that many polyurethane materials are designed to withstand exposure to commonly used cleaning agents, including various commercial cleaners, disinfectants, alcohol, and even diluted bleach solutions, when used appropriately.⁸ This suggests that contact with typical cleaning agents, in and of itself, is not inherently incompatible with the material.

What is notably absent from these material descriptions is a clear distinction between “detergent” and “soap” as it relates to compatibility with polyurethane. While that does not prove equivalence in every real-world scenario, it does raise an important question: if a material is designed to tolerate a range of cleaning agents, what is the basis for strictly limiting one category over another?

The same material literature also highlights a different factor that plays a significant role in polyurethane degradation: hydrolysis. This is a process in which moisture and heat contribute to the breakdown of the material over time, potentially leading to brittleness or surface degradation.⁸

This is particularly relevant in the context of cloth diapers, which are routinely exposed to moisture, heat, and repeated wash cycles. These conditions alone are known stressors for polyurethane-based materials, independent of the specific cleaning agent used.

Taken together, this suggests that material wear over time may be influenced by multiple factors, including environmental conditions and usage patterns. While cleaning methods may play a role, the available material data does not clearly support the idea that one category of cleaning agent is universally incompatible while another is inherently safe.

That distinction matters, because it shifts the conversation away from absolute rules and toward a more complete understanding of how materials behave under real-world conditions.

Health is something we take seriously, and this topic is not just theoretical. It affects real people making real decisions every day. I’ve seen firsthand how much effort goes into trying to do the right thing, especially for those balancing limited time, limited resources, and the responsibility of caring for a child.

That’s why it’s important to pause when guidance is presented with certainty but without clearly accessible supporting evidence. Whether information originates from manufacturers, retailers, or well-meaning individuals sharing what they’ve read elsewhere, the outcome can be the same: decisions are made based on recommendations that may not have been thoroughly examined.

The concern here is not about any single product or method. It is about how conclusions are formed, how they are repeated, and how easily they can become accepted without being supported by clear, relevant data. When it comes to both product performance and potential exposure, those distinctions matter.

If there is strong, well-supported research demonstrating that specific cleaning methods significantly impact cloth diaper materials under typical use conditions, it should be available, cited, and open to review. Until then, it is reasonable to question recommendations that are presented as definitive without that level of support.

Because at the end of the day, informed decisions require more than repeated claims. They require evidence.

In conclusion:

1. When it comes to skin exposure, the composition of a laundry product matters. Ingredients that come into prolonged contact with fabrics can remain in trace amounts and interact with the skin. Understanding what those ingredients are, and how they behave, is an important part of making informed decisions.

2. When it comes to cloth diaper performance, the concept of “safety” is often framed around preserving the integrity of the materials. However, available information suggests that multiple factors influence durability over time, including moisture, heat, frequency of use, and overall care practices.

Because cloth diapers are routinely exposed to moisture during use and cleaning, managing how long they remain wet and how they are dried may play a meaningful role in their longevity. Reducing prolonged exposure to moisture and excessive heat are commonly cited considerations when maintaining polyurethane-based materials.

At the same time, broad claims that one category of cleaning agent is inherently “safe” while another is not, are not clearly supported by readily available, directly applicable data in typical use scenarios. This makes it important to evaluate recommendations carefully and understand the reasoning behind them.

Ultimately, the goal is not to follow rules without question, but to understand what factors actually matter. Because once you understand that, you can make decisions based on evidence and context, rather than assumption.

3. Will soap-based laundry products lead to buildup or residue? Under typical conditions, properly formulated and adequately rinsed cleaning agents are designed to be removed during the wash process. Residue can occur in some situations, particularly if products are overused, not fully rinsed, or if water conditions contribute to incomplete removal. Adjustments such as proper dilution, appropriate wash settings, and additional rinse cycles can help address these issues if they arise.

4. Will different types of cleaning agents affect how well cloth diapers are cleaned? This is an area where clear, directly applicable comparative data is limited. Cleaning effectiveness depends on multiple factors, including formulation, wash conditions, soil load, and rinse efficiency. Without controlled comparisons under consistent conditions, it is difficult to draw broad conclusions about one category of cleaning agent over another.

5. Will this information be updated if stronger evidence becomes available? Yes. If well-designed, peer-reviewed research directly evaluating cleaning methods and material compatibility under typical use conditions becomes available, it should be considered. The goal is to base conclusions on evidence, and that includes revisiting and updating positions as new data emerges.

 

There is a difference between soap and detergent, and there are also a number of persistent myths surrounding both. Some of the information available online is accurate, but much of it is either exaggerated or presented without proper context. In many cases, discussions focus heavily on cleaning performance or material compatibility, while a key consideration is often overlooked: how these substances may interact with the skin.

To better understand that aspect, I looked into research comparing infant skin to adult skin. What I found was more nuanced than expected. In full-term infants, the skin barrier develops relatively quickly after birth and can function similarly to adult skin in many respects. However, this is not the case for premature infants, whose skin is not fully developed and is more permeable, increasing the potential for transdermal absorption of certain substances.⁹

Even with that understanding, this is an area where the science is still evolving. Skin permeability can be influenced by multiple factors, including age, skin condition, hydration, and the specific compounds involved. As a result, broad conclusions should be approached with caution, particularly when applying generalized statements across different populations and conditions.

At this point, the takeaway should be clear. When strong claims are made about what you can and cannot use, those claims should be backed by clear, relevant evidence. In the case of cloth diaper laundry guidance, many of the commonly repeated rules are presented with a level of certainty that does not appear to be matched by readily available, directly applicable data. That does not automatically make them wrong, but it does mean they should be questioned.

Before choosing a product based on those claims, take the time to look beyond the recommendation itself. Ask what the claim is based on, whether the reasoning is explained, and whether supporting data is actually provided. Because once you start asking those questions, you may find that some of the strongest-sounding rules are built more on repetition than on evidence.

And that is where the real issue lies. Not necessarily in the products themselves, but in how confidently conclusions are presented without being clearly supported. If that distinction is overlooked, it becomes very easy to follow guidance that feels authoritative, but has not been thoroughly validated.

References:

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2. Benson HAE. Transdermal drug delivery: penetration enhancement techniques. Current Drug Delivery. 2005;2(1):23–33.
3. Schettler T. Human exposure to phthalates via consumer products. Int J Androl. 2006;29(1):134–139.
4. Swan SH. Environmental phthalate exposure in relation to reproductive outcomes and other health endpoints. Environ Res. 2008;108(2):177–184.
5. Janjua NR, Frederiksen H, Skakkebaek NE, et al. Urinary excretion of phthalates and metabolites after dermal application. Environ Health Perspect. 2008;116(7):895–900.

6. Elsisi AE, Carter DE, Sipes IG. Dermal absorption of phthalate diesters in rats and humans. Toxicol Appl Pharmacol. 1989;100(3):434–442.

7. Steinemann A. Fragranced consumer products: exposures and effects from emissions. Air Qual Atmos Health. 2016;9:861–866.

8. Polyurethane Manufacturers Association. Polyurethane Material Properties and Resistance Characteristics. Available from industry technical literature on polyurethane durability and hydrolysis.

9. Kalia YN, Nonato LB, Lund CH, Guy RH. Development of skin barrier function in premature infants. J Invest Dermatol. 1998;111(2):320–326.