Sea to Summit · Waterproof Smartphone Cases
TPU Guide Waterproof Smartphone Case Large
TPU itself lower concern, but waterproof treatment unknown. No brand disclosure.
TPU is inherently water-resistant and typically PFAS-free, but the waterproofing method is undisclosed. Sea to Summit provides no PFAS transparency for this product.
The safe swap
Mophie
Mophie Juice Pack Battery Case for iPhone 15
85/100 safety
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
TPU (thermoplastic polyurethane) with waterproof coating
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Waterproof / stain-resistant treatment
water-repellent coating treatments have historically used PFAS.
Category baseline
other is a category where PFAS exposure is more common.
No PFAS disclosure
No public statement about PFAS in this product.
The full breakdown
What it's made of and why it matters
TPU (thermoplastic polyurethane) is a synthetic elastomer that does not contain BPA, phthalates, or PVC, making it chemically simpler than many phone case alternatives. The material itself is stable at normal temperatures and does not off-gas volatile organic compounds under typical use. However, the waterproof coating applied to achieve the IP-rated seal is not specified by Sea to Summit in public materials, and such coatings commonly rely on fluorinated compounds or siloxanes to repel water, which may carry their own health profiles.
The brand's record and disclosure
Sea to Summit has not published detailed material safety data sheets or PFAS testing results for this specific case model in publicly accessible sources. The brand does not appear to have signed the PFAS Stewardship Program or similar transparency commitments. They market the product as waterproof and durable but offer no disclosure of the waterproofing agent chemistry, which is a significant transparency gap for a water-contact product.
How it compares in its category
TPU cases are a middle-ground option: safer than silicone (which can leach oligomers) and PVC-based cases, but less transparent than rigid plastic alternatives in terms of coating disclosure. Many competitors (Lifeproof, OtterBox) also do not disclose waterproof treatment chemistry publicly, so this is an industry-wide gap rather than a Sea to Summit-specific problem. Hard plastic cases avoid waterproof coatings entirely but offer less shock absorption.
If you buy it
Inspect the case regularly for cracking, peeling, or discoloration of the waterproof coating, especially around seams and port covers; replacement every 2-3 years is reasonable depending on use intensity. Avoid prolonged contact with extreme heat (leaving in direct sun in a car) or harsh chemicals (bleach-based cleaners). Rinse with fresh water after saltwater or chlorinated water exposure. Do not assume the waterproof seal is permanent; resealing compounds you apply yourself may introduce unknown chemicals, so plan for eventual replacement.
Beyond PFAS: other things we checked
Established hazard classes for this product type, assessed from public information. These never change the PFAS grade; a Likely flag caps the Verdict at “Buy with care.”
Undisclosed waterproof coating chemistry
Sea to Summit does not publicly identify the waterproofing agent (likely fluorinated or siloxane-based). PFAS content in such coatings is possible but unconfirmed; this is the primary unknown for this product.
Coating degradation and microparticle shedding
TPU cases can experience peeling or flaking of the waterproof layer over time with heavy use or UV exposure. Shed coating particles are not characterized but are a recognized failure mode for elastomer-based protective cases.
Volatile organic compounds from manufacturing residue
TPU itself is stable, but residual solvents or processing chemicals from manufacturing can off-gas, especially when new. The waterproof coating may add to this; airing out a new case for 24-48 hours reduces any potential odor.
Allergic contact reaction to TPU or additives
TPU is not a known sensitizer in published literature for the general population, though individuals with polyurethane sensitivity are rare. Sea to Summit does not disclose colorant or plasticizer additives in the TPU formulation.
Bacterial or fungal growth in sealed waterproof enclosure
If the case traps moisture against the phone, or if the interior is not dried before sealing, microbial growth is theoretically possible. This is a usage risk rather than a manufacturing hazard but is relevant to long-term phone health.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 45% confidence. It is not a lab result.
No independent PFAS lab test is on record for this exact product. A lab test could move the score in either direction.
The brand has not made a specific, verifiable PFAS-free statement, so part of this score reflects that missing disclosure rather than a confirmed material.
Formulations and coatings change between production runs. Always check the current label before buying.
Safer alternatives in Waterproof Smartphone Cases
Mophie
Juice Pack Battery Case for iPhone 15
Lithium-ion battery, plastic housing, metal contacts
No known PFAS use; battery cases rarely require fluorinated coatings.
⚠Brand says nothing about PFAS
Mophie
Juice Pack Battery Case for iPhone 15 Pro
Lithium-ion battery, plastic housing, rubber grips
Lower concern. Battery cases lack typical PFAS-prone coatings; no public disclosure available.
⚠Brand says nothing about PFAS
Pelican
Shield Phone Case for Samsung Galaxy S24 Plus
Polycarbonate shell, rubber grip
Lower concern; typical phone case with no known PFAS applications.
⚠Brand says nothing about PFAS
More waterproof smartphone cases grades
How we score: every product runs through the same public 0–100 rubric based on materials, coatings, brand disclosure, lab findings, and recalls. See the full methodology → Spotted a mistake? Report an error.