The Soft Exemption

Press your finger into a silicone spatula. Feel how it yields—soft, warm, almost alive. Now press into a polypropylene container. It resists—hard, cold, industrial. One feels medical. The other feels cheap.

That sensation is not incidental. It is the basis of a regulatory exemption.

Silicone received a pass—from scrutiny, from restriction, from the kind of sustained investigation we applied to plastics—not because it was proven safe, but because it felt safe. The material's tactile properties signaled quality, which suggested biocompatibility, which translated into regulatory inertia. By the time anyone measured what migrated from silicone into food, into tissue, into breast milk, the material was already embedded in baby products, medical devices, and kitchens worldwide.

This is the soft exemption: the regulatory and psychological pass given to materials whose physical properties—flexibility, warmth, smoothness—create an impression of safety that preempts investigation.

You switched from plastic to silicone because someone told you it was better. You believed it because it felt better. Long-term data on what happens when silicone contacts food at high temperatures over years of repeated use remain limited.

This is not a story about one material being safer than another. This is a story about comfort functioning as camouflage—and what we find when we finally look underneath.

I. The Exemption in Action

The soft exemption operates through three mechanisms: tactile signaling, regulatory lag, and epistemic substitution—the replacement of safety data with material properties.

Tactile Signaling: How Materials Bypass Scrutiny

Silicone feels like living tissue. It has a compliance—a give—that mimics skin, mucosa, muscle. It is designed to feel benign: soft, yielding, body-adjacent.

That tactile similarity creates a cognitive shortcut: if it feels like the body, it must be compatible with the body.

Polypropylene feels industrial. It is rigid, cool to the touch, obviously synthetic. That tactile distance triggers skepticism. The material announces its artificiality.

But tactile properties have no relationship to molecular behavior. A material can feel soft while releasing endocrine disruptors. It can feel inert while accumulating in adipose tissue. The softness is a design feature. The migration is a chemical fact. They operate on different planes.

The soft exemption collapses this distinction. It treats tactile comfort as evidence of chemical safety—a substitution with no scientific basis.

Regulatory Lag: Studying Plastic While Using Silicone

Research attention has historically favored plastics over silicone. Studies on phthalates and BPA—the plasticizers and plastic additives—vastly outnumber studies on siloxane migration from consumer products.

Regulatory attention followed research volume. In 2012, the FDA amended food additive regulations to no longer authorize BPA-based polycarbonate in baby bottles and sippy cups—formalizing an industry petition confirming these uses had already been abandoned.¹⁵ The EU banned six phthalates in toys and childcare articles under Directive 2005/84/EC.¹⁶ Both actions came after decades of accumulating evidence and public pressure.

Silicone, meanwhile, moved through regulatory approval without equivalent scrutiny. It was certified as food-safe using migration tests that measured total extractables—the sum of everything that leaches—but not endocrine activity of those compounds. A material could pass safety testing while releasing hormonally active siloxanes, because the test did not measure hormonal activity.

This was not malice. It was method. Regulators tested for what they knew to look for: heavy metals, acute toxicity, total migration mass. They did not test for what we now understand matters: disruption of hormone signaling at parts-per-billion concentrations.

By the time methods existed to detect endocrine activity, silicone was already entrenched.

Epistemic Substitution: Properties Replacing Proof

Silicone's physical properties—heat stability, flexibility, durability—became proxies for safety.

The logic went:

• Silicone withstands 230°C without melting → it is thermally stable → stable materials are inert → inert materials are safe.

The reality is:

• Silicone withstands 230°C without melting → the polymer backbone is thermally stable → but residual cyclic siloxanes, which are not part of the backbone, volatilize and migrate at elevated temperatures → thermal stability of the matrix does not predict migration of byproducts.

This substitution—treating polymer stability as evidence of compound inertness—is the conceptual core of the soft exemption. It allowed silicone to be marketed as "medical-grade," "platinum-cured," "food-safe," and "non-toxic" without long-term migration studies, without endocrine activity screening, and without biomonitoring for tissue accumulation.

The material's performance characteristics were impressive. The performance characteristics were not safety data.

II. What Silicone Actually Is

The soft exemption was granted to a material we did not fully understand. We still don't.

How Silicone Is Made

Silicone production begins with silica—quartz sand—heated in an electric arc furnace at extreme temperatures, reducing it to pure silicon metal. That silicon is combined with methyl chloride in the presence of a copper catalyst, producing chlorosilanes. Those chlorosilanes are distilled, then polymerized into polydimethylsiloxane (PDMS)—the polymer we call silicone.

The polymerization process creates not only long-chain PDMS but also cyclic siloxanes: ring-shaped molecules (D3, D4, D5, D6) that are byproducts of incomplete polymerization. These cyclics remain in the final product as residual compounds. They are not additives. They are structural remnants.

The curing method determines residual catalyst. Platinum-cured silicone uses platinum catalysts, leaving minimal metal residues. Peroxide-cured silicone uses organic peroxides, which can leave breakdown products. Medical-grade silicone is typically platinum-cured. Consumer products may use either method. Labels do not distinguish.

The Chemistry Difference: Silicone vs Plastic

Plastic is carbon-based. Its backbone is carbon-carbon bonds—long hydrocarbon chains derived from petroleum. Polypropylene, polyethylene, polystyrene: all variations on carbon polymer structures.

Silicone is silicon-based. Its backbone is silicon-oxygen bonds—alternating Si-O chains that do not exist in petroleum chemistry. Si-O bonds are stronger than C-C bonds, giving silicone greater thermal stability.

This is why silicone can withstand 230°C while polypropylene softens around 120°C and melts at 160-170°C.²⁰ The polymer backbone is genuinely more stable.

But that stability applies to the backbone, not to everything in the material. Cyclic siloxanes—D4, D5, D6—have boiling points (175°C for D4,²¹ 210°C for D5²²) within or below the range of common oven temperatures (180-230°C). Volatilization can begin below boiling point. These compounds release under heat. The matrix stays intact. The cyclics do not.

Run your finger across a silicone baking mat after removing it from a 200°C oven. The surface is smooth, unchanged—no warping, no visible degradation. That stability is what you paid for. Now run your finger across it again, this time knowing: the heat that could not alter the Si-O backbone may be sufficient to release cyclic siloxanes into contact with food. The material's refusal to melt is also the condition that permits sustained high-temperature migration. What you touch as durability is simultaneous with permeability. The soft exemption is in your hand.

The Compounds That Migrate

When silicone products contact food or mucosa under heat, cyclic siloxanes (D4, D5, D6) migrate. These are not breakdown products of degradation. They are residual compounds already present, released when heat or mechanical stress disrupts the polymer matrix.

A 2023 study by Feng and colleagues, published in Science of the Total Environment, tested 42 silicone food-contact products—31 kitchenware items and 11 baby bottle nipples.¹ Samples were exposed to food simulant (95% ethanol) at 70°C for two hours under accelerated migration conditions. Eighty-four percent of kitchenware products showed endocrine-disrupting activity. Sixty-four percent showed estrogenic activity (mimicking estrogen). Forty-two percent showed androgenic activity (mimicking testosterone).

Bottle nipples showed no hormonal activity.

The study did not determine which specific compounds caused the activity, only that migration occurred under accelerated test conditions designed to simulate worst-case exposure.

This finding does not mean all silicone leaches endocrine disruptors. It means some silicone does, and we cannot distinguish which products are problematic from their labels, certifications, or appearance.

The Bioaccumulation Pathway

Cyclic siloxanes do not metabolize like familiar organic compounds. The human body has no evolutionary preparation to process silicon-oxygen ring structures.

According to research by Luu and Hutter published in Environmental Health Perspectives, D4 (octamethylcyclotetrasiloxane) accumulates in adipose tissue with a half-life of approximately 11-18 days.² Half-life measures how long it takes for half of a compound to clear. A 10-day half-life means 50% remains after 10 days, 25% after 20 days, 12.5% after 30 days. With daily exposure—from baking mats, from pacifiers, from food storage—tissue concentrations rise faster than clearance, creating accumulation.

D5 (decamethylcyclopentasiloxane) has been detected in human breast milk, indicating maternal body burden and lactational transfer to infants. Siloxanes in breast milk mean the infant is receiving maternally-transferred compounds during a developmental window when hormone disruption has permanent effects.

The California Biomonitoring Program has identified cyclosiloxanes among its designated chemicals.⁴ A 1982 EPA survey detected D5 in the adipose tissue of 28 out of 46 people sampled,⁵ and subsequent studies have found D5 in human breast milk samples in Sweden.⁶ The compounds are present in human tissue. The long-term health outcomes of that presence are unknown.

This is the condition created by the soft exemption: widespread exposure to bioaccumulating compounds whose effects were not characterized before the material was embedded in consumer products.

III. The Comparison We Were Never Given

The soft exemption allowed silicone to be positioned as "the plastic alternative" without side-by-side comparison under equivalent testing conditions.

Migration: Silicone vs Polypropylene

What we know about silicone: Feng's 2023 study found 84% of kitchenware products showed endocrine activity at 70°C.

What we know about polypropylene: A 2025 study by Massahi et al. tested polypropylene food containers across temperatures.¹³ At 4-10°C, none of the target endocrine-disrupting chemicals were detected. At higher temperatures (up to 100°C), commercial PP products released DEHP (di(2-ethylhexyl) phthalate)—a plasticizer additive—at concentrations of 1,242 to 1,615 nanograms per liter. DEHP is a confirmed endocrine disruptor, restricted in toys and childcare articles above 0.1% by mass under EU rules.

What we don't have: A study testing polypropylene and silicone under identical conditions (same temperature, same duration, same food simulant, same endocrine assays) to compare their relative hormonal activity.

That study does not exist. Not because the question is unimportant. Because no one was required to ask it.

Both materials leach compounds under heat. Both show endocrine concerns. The compounds differ—siloxanes vs phthalates—but the outcome is similar: hormonal interference from materials certified as food-safe.

The soft exemption meant silicone was adopted as the solution before anyone measured whether it presented the same problem.

Temperature Stability vs Migration

Silicone's high melting point is marketed as safety. Baking mats and spatulas are rated to 230°C (446°F).²³ According to the British Plastics Federation, polypropylene softens at 120°C and melts at 160-170°C, limiting its high-heat use.²⁰

But melting point describes when the material fails structurally, not when compounds migrate.

Feng's study found endocrine activity at 70°C—well below silicone's rated temperature. Migration increases at higher heat, but it occurs across silicone's entire functional range.

Polypropylene's lower melting point is, inadvertently, a safety constraint. A PP container warps or melts if overheated, signaling failure. You cannot unknowingly use it beyond its thermal limit.

Silicone shows no visible degradation at 230°C. The surface remains smooth, flexible, intact. That stability is also the design feature that permits high-heat migration without user feedback. The material performs flawlessly while releasing compounds you cannot see, smell, or taste.

The soft exemption valorized stability without asking what stability permits.

Degradation Pathways

When polypropylene degrades, it fragments into microplastics—particles ranging from millimeters to nanometers. These persist in tissue, accumulate in organs, and have been detected in human blood, lungs, placentas, and breast milk. The long-term consequences are poorly understood but increasingly documented as harmful.

When silicone degrades, it releases cyclic siloxanes; when incinerated at high temperatures, it breaks down into silica, CO₂, and water. This is environmentally cleaner than plastic fragmentation. Silicone does not create the same microplastic pollution problem.

But "cleaner degradation" does not mean "safe exposure." Siloxanes bioaccumulate. They cross into breast milk. Their endocrine effects are under investigation. The fact that silicone's end-of-life is less environmentally damaging than plastic's does not address what happens during use.

The soft exemption allowed environmental advantage (less microplastic pollution) to overshadow exposure concerns (siloxane accumulation).

IV. The Regulatory Divergence

The soft exemption is not universal. Europe began withdrawing it.

What Europe Restricted

• 2019: Full ban on D4 in cosmetics (EU Regulation 2019/831).⁹
• 2020: Restrictions on D4 and D5 in rinse-off cosmetics above 0.1% (EU Regulation 2018/35).¹⁰
• 2026: EU Regulation 2024/1328 restricts D4, D5, D6 above 0.1% in consumer products (effective June 6, 2026) and cosmetics (June 6, 2027).¹¹

Canada classified D4 as toxic to the environment under the Canadian Environmental Protection Act.¹²

What the United States Did

Nothing. No federal restrictions on D4, D5, or D6 in food-contact materials, cosmetics, or consumer products.

What This Means

The same evidence—the same studies, the same bioaccumulation data, the same endocrine activity findings—led to opposite regulatory conclusions.

Europe applied the precautionary principle: restrict when evidence suggests potential harm, even if causation is not fully proven.

The U.S. applied a harm-documentation standard: restrict only after population-scale harm is established.

This divergence is not about politics. It is about how much unknown risk is acceptable when certifying a material as safe.

Europe decided the soft exemption was unjustified. The U.S. maintains it.

You live in that gap.

The material in your kitchen, in your child's pacifier, in your body, is simultaneously restricted in one jurisdiction and unrestricted in another—not because new data emerged, but because different governments drew different lines through the same uncertainty.

Someone is wrong. You are living with the consequences either way.

V. Where the Soft Exemption Was Justified

The soft exemption was not entirely mistaken. Silicone solves real problems that plastic cannot. The question is: where does function justify exposure?

Medical Devices

Medical-grade silicone is platinum-cured, biocompatibility-tested, and designed for long-term internal contact. It is used in catheters, implants, tubing, wound dressings, prosthetics.

Silicone provokes minimal immune response compared to other polymers. PVC can leach phthalates. Polyurethane degrades in vivo. According to the UK Health and Safety Executive, natural rubber latex triggers allergies in an estimated 1-6% of the general population.¹⁹

According to research by Giordano et al. in the Journal of Manufacturing and Materials Processing, silicone has been tested through 1,000 steam autoclave cycles, though studies show significant surface degradation—including a sixfold increase in crack length after 200 cycles, hardening, and loss of elasticity—accumulating over repeated sterilization.¹⁸ According to Ensinger Plastics, polypropylene homopolymer (PP-H) can handle approximately 800 autoclave cycles before significant mechanical degradation, though discoloration begins around 200 cycles.¹⁷

For applications requiring sterility, flexibility, and long-term biocompatibility, silicone is often the best available material. "Best available" does not mean "inert" or "risk-free." It means the alternatives present equal or greater harms.

In this context, the soft exemption is earned. The material's properties are matched to the application's requirements, and the exposure is justified by medical necessity.

Extreme-Temperature Applications

According to Cooper Standard, many silicone gasket grades are rated from -60°C to +270°C.²³ According to the British Plastics Federation, polypropylene grades typically function from -20°C to approximately +120°C before softening begins.²⁰

For industrial ovens, automotive engines, aerospace seals, laboratory autoclaves, and outdoor equipment exposed to freeze-thaw cycles, polypropylene is not viable. The alternative to silicone is not plastic—it is metal or ceramic, which lack silicone's flexibility and sealing performance.

In these contexts, the soft exemption is justified by absence of alternatives. Silicone is used because nothing else works.

Allergy Considerations

For individuals with latex allergies, silicone is often the only flexible, sealable material that does not trigger immune reactions. This is a narrow but critical use case. If you cannot tolerate latex and require a flexible seal, silicone may be the only option.

In these applications, the soft exemption functions as intended: a material with unique properties is used where no substitute exists.

VI. Where the Soft Exemption Was Not Justified

The soft exemption becomes problematic when it extends beyond necessity into convenience—when silicone is used not because it is required, but because it is pleasant.

Baby Products with Sustained Mucosal Contact

Bottle nipples. Pacifiers. Teething toys.

Pick up a silicone pacifier. Feel its weight—heavier than plastic, denser. Squeeze it. The material resists, yields, returns. That responsiveness mimics human tissue. Now hold it between your fingers and imagine what you cannot feel: your child's saliva at 37°C, contacting this surface for hours daily. Oral mucosa absorbs compounds rapidly. What migrates from silicone into saliva can be absorbed through the mouth's lining. The pacifier is designed to remain in the mouth—that is its function. The comfort you feel when you compress it is also the material property that permits molecular transfer. The soother is simultaneously the exposure.

An infant using a pacifier eight hours daily represents sustained mucosal contact with whatever migrates. Oral and nasal mucosa are highly absorptive. This is the exposure pathway of highest concern: prolonged contact with absorptive tissue during the developmental window when endocrine disruption causes permanent harm.

Feng's study found that bottle nipples showed no endocrine activity, which is encouraging. But 84% of other tested products did. We do not know what differentiates nipples from kitchenware—different formulation, different curing, different residual cyclics. Without that data, we are left with statistical probability: most silicone products tested showed hormonal activity under accelerated test conditions. Some nipples are in that 84%. We cannot identify them.

The soft exemption allowed silicone baby products to be marketed as the safe alternative to plastic without long-term studies of siloxane accumulation in developing tissue.

This is the exemption's failure: choosing the material that feels safest instead of proving which material is safest.

High-Heat Baking and Roasting

Silicone baking mats, muffin cups, and roasting liners are marketed on heat tolerance. They are designed to withstand 180-230°C—temperatures at which migration accelerates.

Feng found endocrine activity at 70°C. Baking occurs at 180-220°C—110 to 150°C hotter than the test conditions that already showed hormonal disruption.

The material does not melt. It does not discolor. It does not signal failure. But compounds are migrating into food at the temperatures the product was designed for.

Alternatives exist: bare metal pans, cast iron, unbleached parchment paper, stainless steel. These require more labor—greasing, lining, scrubbing—but they do not release endocrine-active compounds into food.

The soft exemption allowed convenience to justify exposure that could be eliminated.

Prolonged Food Storage

Silicone stretch lids. Reusable bags. Food covers.

Open your refrigerator. Touch the silicone lid stretched over a glass bowl. It is cold, inert-feeling. The chill suggests nothing is happening—the food preserved, the surface stable. Now consider: that bowl has been sealed eighteen hours. The curry inside is acidic, oily. The silicone contacts moisture, fat, acid—the three conditions that accelerate migration. You cannot see it. You cannot smell it. But time is a solvent. The cold slows the process; it does not stop it. When you peel the lid back and reheat the bowl, you introduce the second temperature cycle. What migrated slowly in the cold migrates faster in heat. The lid that preserved your leftovers also altered their chemistry.

Glass containers with metal lids (with small silicone gaskets at the rim) are widely available and reduce polymer contact area from the entire food surface to a narrow sealing edge.

Stainless steel containers with snap-fit lids (no gaskets) exist but provide less airtight sealing. For most refrigerated storage, imperfect sealing is sufficient.

The soft exemption allowed sealing performance to justify whole-surface polymer contact when partial contact (gasket-only) would suffice.

VII. The Epistemic Condition

The soft exemption was granted in the absence of data. It remains in place despite mounting evidence—not because the evidence is reassuring, but because the evidence is incomplete.

What We Know

• Cyclosiloxanes are detected in human adipose tissue and breast milk.
• Eighty-four percent of tested silicone kitchenware showed endocrine activity under accelerated migration testing.
• Polypropylene products release phthalates under heat.
• Both materials show migration patterns that increase with heat and duration.
• Siloxanes bioaccumulate. Microplastics bioaccumulate. Both persist in tissue.

What We Do Not Know

• Long-term health outcomes of chronic low-level siloxane exposure.
• Whether platinum-cured silicone presents meaningfully lower risk than peroxide-cured.
• Cumulative effects of siloxanes + phthalates + PFAS + other synthetic exposures.
• At what tissue concentration siloxanes interfere with development.

What We Cannot Know Under the Current System

• Population-level harm patterns, because no adverse event reporting exists for consumer silicone.
• Which brands use platinum vs peroxide curing, because labeling is not required.
• Actual migration from specific products in your home, because consumer testing is not accessible.

This is the condition created by the soft exemption: You are not waiting to discover whether silicone is safe. You are living with a material whose safety was never established by the methods we now understand to be necessary.

The absence of proven harm is not a finding about the material. It is a surveillance gap.

The soft exemption treats that gap as permission.

VIII. The Decision Framework

You cannot eliminate polymer exposure entirely. The goal is to direct scrutiny toward exposures where the soft exemption is least justified: high heat, prolonged contact, absorptive surfaces, and convenience applications where alternatives exist.

Assess Exposure By

1. Contact time — Seconds (spatula) vs hours (pacifier)
2. Temperature — Room temperature vs 230°C
3. Surface absorptivity — Skin (low) vs mucosa (high)
4. Functional necessity — Medical device vs baking convenience

Replace First: Highest Exposure

High-heat bakeware (above 150°C) → Bare metal pans, cast iron, parchment. Migration accelerates with heat. Alternatives exist. The soft exemption is not justified here.

Insertable products (menstrual cups, pacifiers with sustained use) → Natural rubber latex if no allergy, organic cotton alternatives. Mucosal absorption is rapid. Sustained insertion is prolonged exposure during sleep or daily wear. The soft exemption is not justified here.

Infant feeding products → Natural rubber nipples if no latex allergy. Oral mucosa is highly absorptive. Developmental window compounds risk. The soft exemption is not justified here.

Replace Second: Moderate Exposure

Long-contact food storage → Glass with metal lids (accepting small gasket). Prolonged contact increases total migration. Alternatives reduce contact area. The soft exemption is questionable here.

Slow-cooker and pressure-cooker seals → Difficult to replace without losing function. If the tool is necessary, exposure may be justified. If the tool is convenience, re-evaluate. The soft exemption is contextual here.

Replace Last: Brief Exposure

Cooking utensils (spatulas, spoons) → Wood or stainless steel. Contact time is brief (seconds). Easy to replace, but lower urgency. The soft exemption is weak but low-stakes here.

Jar lid gaskets → Contact area is small. Natural rubber or cork alternatives exist but are not priority. The soft exemption is weak but tolerable here.

Retain Where Justified

Medical devices requiring silicone → Catheters, implants, tubing. Medical-grade formulations. No viable alternative. The soft exemption is justified here.

Accessibility and disability tools → If silicone enables grip strength, motor control, or independence, functional benefit justifies exposure. The soft exemption is justified here.

Extreme-temperature industrial seals → No alternative material functions. The soft exemption is justified here.

IX. What You Can Do

Walk through your kitchen. Identify silicone products by temperature, contact duration, and necessity.

High-heat (above 150°C): Baking mats, roasting liners, muffin cups → priority replacement. Alternatives: bare metal pans, parchment, cast iron.

Prolonged contact: Stretch lids, storage bags → medium priority, easy replacement. Alternatives: glass with metal lids.

Brief contact: Spatulas, spoons → lower priority, inexpensive alternatives. Alternatives: wood, stainless steel.

Small contact area: Jar gaskets → lowest priority unless all other sources eliminated.

For parents: Assess latex allergy history. If none exists, consider natural rubber nipples (require replacement every 4-6 weeks). If latex allergy present, evaluate stainless steel or glass feeding methods appropriate for child's age.

For menstruating individuals: Assess latex allergy. If none, consider natural rubber menstrual cups. If allergy present, evaluate organic cotton products with natural fiber waterproofing (check construction—many use PUL, reintroducing polymer exposure).

This is not about purity. It is about withdrawing the soft exemption where it was never justified—where comfort substituted for scrutiny, and convenience substituted for proof.

X. The Reframe

The soft exemption was not a conspiracy. It was a cognitive error: the belief that materials which feel safe are safe.

Silicone feels medical. That is a design achievement. It is not a safety finding.

The material was adopted based on its properties—heat stability, flexibility, tactile quality—and those properties were treated as evidence of biocompatibility. But properties are not proof. Stability is not inertness. Softness is not safety.

The soft exemption allowed us to choose based on how a material felt in our hands instead of what it did in our bodies.

You thought you were choosing the safer alternative. You were choosing the understudied alternative that feels safer.

Now you know the difference.

The exemption is not granted by regulators alone. It is granted every time you select silicone because it feels right without asking whether it was proven right.

You can withdraw that exemption. Not by eliminating silicone—it has justified uses—but by directing it toward applications where necessity, not comfort, justifies exposure.

The soft exemption ends when we stop mistaking tactile reassurance for chemical proof.

Sable Chen writes about what things are made of and what they do to us.