Withings · Waterproof Smartphone Cases
Withings Scanwatch HWA09 Hybrid Smartwatch
Waterproofing method unknown; insufficient PFAS transparency.
This hybrid smartwatch is water-resistant with stainless steel construction. Withings provides no PFAS disclosure or details about how the waterproofing works.
The better-graded swap
Mophie
Mophie Juice Pack for iPhone 16 Pro
85/100 safety
Same rubric that flunked this product. The swap earned Excellent.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
stainless steel, sapphire crystal, elastomer band
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
What’s concerning
Category baseline
The starting point for this type of product, before anything specific to this product is counted.
No PFAS disclosure
No public statement from the brand about PFAS in this product.
Elastomer band degradation and additive leaching
Elastomer bands commonly contain plasticizers (phthalates or non-phthalate alternatives) and colorants. With extended sweat exposure and UV exposure, degradation can occur, potentially releasing these additives to skin. Withings does not disclose elastomer composition or confirm phthalate-free status.
Bacterial and fungal growth on band
Elastomer bands are porous and accumulate sweat, dead skin cells, and moisture. Poor cleaning or constant wear creates conditions for bacterial and fungal proliferation, which can cause dermatitis or infection in susceptible individuals. No antimicrobial treatment is disclosed for the Scanwatch band.
PFAS
The Scanwatch claims 50m water resistance but Withings does not disclose whether fluorinated compounds (PFAS-family or legacy PFOA/PFOS analogs) are used in sealants, coatings, or elastomer treatment. This is common in smartwatch waterproofing but undisclosed here.
Source, ATSDR ↗Stainless steel nickel content and skin sensitivity
316L stainless steel contains nickel (typically 8-12%). Most users tolerate this; however, individuals with nickel contact dermatitis may experience reactions with prolonged skin contact, especially if the watch is worn tightly or in humid conditions that promote ion leaching.
What’s reassuring
Base material not linked to PFAS
The main material recorded for this product is not one associated with PFAS.
Sapphire crystal coatings
Withings has not disclosed whether the sapphire crystal has anti-reflective or oleophobic coatings. Some sapphire watches use Teflon-family coating or silicone-based treatments; if present, their safety profile is not disclosed. Natural sapphire itself poses no chemical hazard.
The full breakdown
What it's made of and why it matters
The Scanwatch HWA09 uses 316L stainless steel (watch body), sapphire crystal (screen), and elastomer (rubber/synthetic polymer band). Stainless steel is chemically stable and does not leach metals under normal skin contact. Sapphire crystal is inert and extremely durable. The elastomer band is the variable component, elastomers can degrade over time with sweat exposure, UV light, and repeated flexing, potentially releasing breakdown products or becoming sticky or brittle.
The brand's record and disclosure
Withings has not published detailed material safety data sheets, PFAS sourcing information, or third-party safety certifications for the Scanwatch line. The company does not publicly disclose chemical composition of the elastomer band or confirm absence of flame retardants, phthalates, or other synthetic additives common in elastomers. No major recalls affecting the Scanwatch HWA09 have been documented for chemical hazards, but transparency around waterproofing chemistry (which often relies on fluorinated compounds) remains absent.
How it compares in its category
Most hybrid smartwatches use identical material combinations (stainless steel, sapphire, elastomer). Few brands disclose elastomer composition; Garmin and Apple similarly lack detailed breakdowns. The Scanwatch's advantage is lower overall electronic complexity and battery life reduce need for frequent device replacement. However, absence of stated material certifications (e.g., FDA biocompatibility for elastomer, phthalate-free) is standard across the category, not a differentiator.
If you buy it
Rinse the elastomer band weekly with fresh water after sweating to reduce bacterial buildup and slow polymer degradation. Avoid extended direct sunlight exposure, which accelerates elastomer brittleness. Replace the band every 2-3 years or sooner if it becomes visibly cracked, sticky, or develops an odor (sign of microbial growth or polymer breakdown). Do not expose the watch to high heat (>60°C) or aggressive chemicals; the elastomer can soften or leach additives under thermal or chemical stress.
What we don’t know
- Basis
- Model estimate, 45% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Withings has made none
Formulations change between production runs, so check the current label. How we grade.
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.