What Are Hormone Disruptors — and Why Are They in Your Laundry Detergent?

By Suzan Hernandez, Founder, Mama-P

I didn't set out to become an expert in endocrine chemistry. I became one because I had to. When my daughter started developing skin reactions I couldn't explain — redness, dryness, itching that no moisturiser fixed — I started reading ingredient lists. What I found on the back of our 'natural' laundry detergent bottle stopped me cold. I built Mama-P so other parents wouldn't have to do the same research I did. This is what I learned.

What Is an Endocrine Disruptor?

The endocrine system is the body's chemical messaging network. It uses hormones — estrogen, testosterone, cortisol, thyroid hormones — to regulate growth, reproduction, metabolism, immune function, and mood. Hormones work at parts-per-billion concentrations.

An endocrine disruptor is any chemical that interferes with that system — by mimicking a hormone, blocking a hormone receptor, or altering hormone production or metabolism. Research from the Endocrine Society confirms that small, sustained exposures — like detergent residue in fabric against your skin all day — are exactly the type of exposure that matters most.

Children and infants are disproportionately affected. Their endocrine systems are still developing, their skin is more permeable, and they have less capacity to metabolise and excrete chemical exposures. This is why what you wash their clothes in matters more than most people realise.

The Big 4: What Mama-P Removed and Why

Most laundry detergent conversations focus on what a product cleans. Mama-P's conversation starts with what it leaves behind. These are the four ingredients we removed:

1. SLS — Sodium Lauryl Sulfate

SLS is a surfactant that creates foam and lifts soil from fabric. It is effective. It is also a documented skin barrier disruptor. SLS strips the lipid layer that keeps skin hydrated and protected, causing redness, itching, and increased permeability. When skin permeability increases, it becomes more susceptible to absorbing other chemicals — including the rest of the detergent formula.

SLS appears in the majority of conventional detergents and in many products marketed as 'natural' because it is cheap and derived from coconut or palm oil. Mama-P uses coconut-derived surfactants (lauryl glucoside, coco-glucoside) that clean as effectively as SLS without disrupting the skin barrier.

2. Optical Brighteners — Fluorescent Whitening Agents

Optical brighteners work by coating fabric fibres with UV-absorbing chemicals that re-emit blue light, making clothes appear brighter than they are. They are a cosmetic effect, not a cleaning one. The problem: they do not rinse out. They remain on fabric permanently, in constant contact with skin.

Research published in dermatology literature has linked optical brighteners to contact dermatitis and photosensitivity reactions. They are particularly problematic for babies and children, whose skin has more contact surface area relative to body weight than adults. Mama-P removes them entirely. No residue. No glow.

3. Synthetic Fragrance

'Fragrance' as a label ingredient legally represents an undisclosed mixture of hundreds of chemicals. Synthetic fragrance is the leading cause of contact dermatitis from laundry products and is listed by dermatologists as the first ingredient to eliminate for eczema and sensitive skin management.

Mama-P is fragrance-free by formulation. Not lightly scented. Not naturally fragranced. Unscented.

4. MI — Methylisothiazolinone

Methylisothiazolinone (MI) is a preservative used to extend shelf life in liquid and sheet detergents. It is a documented allergen — banned in rinse-off cosmetics in the EU and flagged by the Scientific Committee on Consumer Safety for causing sensitisation at low concentrations.

Despite this, it continues to appear in US household cleaning products, including many marketed as eco-friendly. Mama-P's dry sheet format eliminates the need for MI entirely: the low-moisture content of a dry sheet prevents microbial growth without chemical preservation.

How to Read a Laundry Detergent Label

Ingredient disclosure is not legally required for cleaning products in the US in the same way it is for food or cosmetics. Here is what to look for:

• Look for the full ingredient list, not just marketing claims on the front of the pack. 'Natural,' 'eco,' and 'plant-based' are marketing terms, not formulation standards.
• Search for SLS, SLES, sodium lauryl sulfate, or sodium laureth sulfate anywhere in the list. If present, the product strips skin barrier.
• Search for 'fragrance' or 'parfum' as a single listed ingredient. This is always a mixture — the contents are not disclosed on the label.
• Search for optical brighteners, fluorescent brightening agents, or FWA. If the packaging claims 'makes whites whiter,' this typically indicates optical brightener use.
• Search for methylisothiazolinone, MI, or methylchloroisothiazolinone (MCI) in the preservative section.

What Mama-P Built Instead

The Mama-P formula starts with what to remove. What remains is a short, transparent list of ingredients chosen for one purpose: effective cleaning that does not compromise skin or the home environment.

The active cleaning agents are coconut-derived surfactants (lauryl glucoside, coco-glucoside) combined with three naturally-derived enzymes — subtilisin, amylase, and protease — that break down protein, starch, and organic stains at the molecular level. Professional-grade clean without the chemicals.

Every ingredient is on the label. No 'fragrance.' No 'other ingredients.' If it's in the formula, it's on the box.

See our full formula on the Laundry Detergent Sheets product page.

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Frequently Asked Questions

Is SLS an endocrine disruptor?

Evidence on SLS specifically as a hormone disruptor is limited compared to chemicals like phthalates or parabens. However, SLS is a well-documented skin barrier disruptor — and a compromised barrier increases absorption of other chemicals, including those with endocrine-disrupting properties. Eliminating SLS is particularly important in a product that stays in fabric contact with skin all day.

What do optical brighteners do to skin?

Optical brighteners coat fabric permanently and do not rinse out. Research links them to contact dermatitis and photosensitivity reactions. For babies and children, sustained contact through clothing is a particular concern given higher skin permeability.

Are laundry detergent sheets safer than liquid detergent?

Format does not determine safety — the formula does. Some laundry sheets contain the same problematic ingredients as conventional liquid detergents, including SLS, optical brighteners, and synthetic fragrance. What matters is the ingredient list, not the form factor. Always read the ingredients regardless of packaging format.

How much detergent residue stays in fabric after washing?

Ingredients that do not dissolve completely — particularly optical brighteners and some synthetic fragrances — are documented to leave residues in fabric fibres. Mama-P sheets are formulated for complete dissolution, leaving no residue on fabric or skin.

Why do many 'natural' laundry detergents still contain SLS?

SLS can be derived from coconut or palm oil, allowing it to be marketed as plant-derived despite its skin-disrupting properties. Ingredient sourcing and ingredient safety are different questions. 'Plant-based' on a label does not guarantee skin safety — always read the full ingredient list.