Fitbit · Waterproof Smartwatches & Fitness Trackers
Fitbit Sense Smartwatch
Unknown waterproof coating composition; no PFAS disclosure from brand.
Fitbit does not publicly disclose PFAS status or coating materials for the Sense. Smartwatch waterproofing typically uses water-repellent coating treatments of unknown PFAS content. Limited transparency prevents confident assessment.
The safe swap
Swatch
Swatch Chrono 42 Quartz Watch
85/100 safety
Same rubric that flunked this product. The swap earned its B.
Still want this one anyway? Check the price on Amazon. We’d swap it.
Material
Aluminum, stainless steel, rubber, unspecified coatings
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
The Fitbit Sense uses aluminum casing, stainless steel components, and elastomer rubber for the band. Aluminum is lightweight and corrosion-resistant but can leach in acidic conditions (sweat, acidic lotions). The stainless steel is inert under normal wear. The critical unknown is the waterproof coating layer: Fitbit has not disclosed its composition, and waterproofing electronics typically requires fluorinated compounds (PFAS) or newer alternatives, neither confirmed here.
The brand's record and disclosure
Fitbit (owned by Google since 2021) has not published material transparency reports or PFAS disclosure statements for wearables. The company offers standard warranty coverage but does not highlight chemical safety certifications or third-party testing for coatings. No public recalls or health complaints specific to material leaching have been documented for Sense models, though absence of reporting does not confirm safety.
How it compares in its category
Smartwatches generally pose lower chemical exposure risk than cookware or apparel because contact is external and brief. However, the Sense's permanent rubber band and sealed aluminum housing create potential for prolonged skin contact and sweat interaction. Competitors (Garmin, Apple Watch) similarly avoid disclosure of waterproof coatings, making this a category-wide gap rather than a Fitbit-specific failure.
If you buy it
Rinse the watch and band with fresh water after swimming or heavy sweating to prevent salt and sweat salts from degrading the coating and accelerating any potential metal leaching. Replace the rubber band every 1-2 years or if visible cracking appears, as degraded elastomer may off-gas or shed particles. Avoid leaving the watch in direct sunlight for extended periods, as UV can degrade coatings. Remove before using harsh soaps, perfumes, or hand sanitizers, which may weaken adhesion of the waterproof layer.
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.”
Aluminum leaching from casing
Aluminum is generally safe on skin, but acidic sweat or acidic skincare products can slowly dissolve the surface. The risk is low for short-term wear but cumulative exposure over years is not established in literature for this device specifically.
Unknown waterproof coating composition
Fitbit does not specify whether the waterproof layer uses PFAS, siloxanes, or other fluorine-free polymers. No safety data sheet is available. This opacity prevents full hazard assessment and is the primary reason PFAS grade is 40/100.
Rubber band degradation and off-gassing
Elastomer bands can degrade under UV, heat, and sweat exposure, potentially releasing volatile compounds. Fitbit does not certify the band material as phthalate-free or heavy-metal-free, though no complaints are on public record.
Nickel in stainless steel components (contact dermatitis risk)
Stainless steel contains small amounts of nickel (typically 8-12%). People with nickel sensitivity may develop localized rash from prolonged wrist contact, especially if skin is wet or irritated. Fitbit does not offer a nickel-free variant.
Battery leakage or ingestion hazard (design, not material)
The Sense has a sealed battery; no documented cases of leakage. Risk is low unless the device is damaged, in which case lithium compounds could pose burn hazard to skin or eyes.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 35% 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 Smartwatches & Fitness Trackers
Swatch
Chrono 42 Quartz Watch
Stainless steel case, mineral/plastic crystal, standard watch components
Lower concern. Standard watch materials pose minimal PFAS risk.
⚠Brand says nothing about PFAS
Swatch
SEA WASP
Plastic/resin watch case and strap
Typical consumer watch, no known PFAS risk signal identified
⚠Brand says nothing about PFAS
Swatch
Neon Seppia Big Bold Chrono Quartz Watch
Stainless steel case, plastic/resin band, mineral or acrylic crystal
Lower concern. Standard watch materials typically lack intentional PFAS use.
⚠Brand says nothing about PFAS
More waterproof smartwatches & fitness trackers 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.