Fitbit · Waterproof Fitness Trackers & Cases
Fitbit Sense Advanced Health Smartwatch
No coating described, and no PFAS statement from the brand.
The product information we reviewed describes stainless steel case, glass screen, elastomer/silicone band, with no water-repellent coating named. Water resistance on products like this usually comes from the material and its seals rather than a surface treatment. The brand has published no PFAS statement for it.
We flunk more products than we pass. This one earned its grade. How we grade
Material
Stainless steel case, glass screen, elastomer/silicone 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.
Nickel in stainless steel (skin contact allergen)
Stainless steel case and any metal buckles or connectors contain nickel as part of the alloy. For most wearers, the concentration is too low to cause sensitization; however, individuals with existing nickel allergies may experience contact dermatitis, especially if sweat or moisture concentrates the exposure.
Skin irritation from moisture and bacteria trapping
Tight or prolonged band wear over damp skin can trap moisture and encourage bacterial or fungal growth, leading to localized irritation or folliculitis. This is a mechanical issue, not a chemical hazard, but common in all wearable bands and is reversible with air-drying and band rotation.
What’s reassuring
Base material not linked to PFAS
The main material recorded for this product is not one associated with PFAS.
Silicone band degradation and microparticle shedding
No reported cases of silicone degradation or microparticle release from the Sense band under normal use have been documented. Silicone is highly stable; however, cracks or surface wear over years of use could theoretically allow particles to contact skin, though ingestion is not a plausible route for a wrist-worn device.
Heavy metals
The glass screen and optical sensors are sealed behind the display and do not contact skin or food. No testing data or recalls indicate heavy metal contamination in the optical components of the Sense. This is a low-risk element because exposure is not plausible.
Source, FDA ↗Adhesives or inks in band printing or assembly
The band attachment and any printed graphics or branding on the elastomer involve adhesives and inks that are not specified by Fitbit. These are typically cured and inert after manufacture, but no third-party testing or disclosure is available. Contact risk is minimal if surfaces are not cracked or heavily worn.
The full breakdown
What it's made of and why it matters
The Fitbit Sense case is stainless steel, the screen is glass, and the band is elastomer or silicone. These are chemically stable materials with low leaching risk under normal wear. Stainless steel does not degrade into the skin under standard use. Silicone elastomer is widely used in wearables precisely because it resists breakdown and does not off-gas volatile compounds at body temperature.
The brand's record and disclosure
Fitbit (owned by Google since 2021) does not publish detailed material safety disclosures or third-party safety certifications for this model. No major recalls or hazard warnings related to the Sense have been publicly reported. The brand has not made public statements on heavy metals, allergens, or flame retardants in smartwatch materials, which is typical for the wearables category but limits transparency.
How it compares in its category
Smartwatch bands are a known allergen concern in the wearables category, often because of nickel in metal buckles or adhesives in rubber compounds. The Sense uses stainless steel (nickel-containing but stabilized in alloy form) and silicone; this is a standard, mid-range material choice. Competitors like Apple Watch and Garmin use similar constructions, so the Sense sits in the middle ground for material safety in its class.
If you buy it
Rotate the band regularly to reduce prolonged skin contact and let the wrist dry fully. Remove the watch before hot showers or extended water submersion beyond the rated 50 meters, as seams and the back sensor pod may be entry points over time. If you develop redness or itching under the band, wash with mild soap and air-dry the band and wrist separately. Replace the band if elastomer cracks or loses elasticity, as micro-degradation is unlikely but cracks can trap moisture.
What we don’t know
- Basis
- Model estimate, 42% confidence, not a lab result
- Lab test
- None on record for this exact product
- Brand statement
- Fitbit has made none
Formulations change between production runs, so check the current label. How we grade.
More waterproof fitness trackers & 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.