Thermos · Insulated Drinkware Tumblers
Thermos 24oz Insulated Cold Tumbler
Lower PFAS concern. Stainless steel construction poses minimal chemical leaching risk.
Thermos insulated tumblers use stainless steel walls with foam or air insulation, materials with minimal PFAS risk. No waterproof coating or nonstick surface identified; brand has not disclosed PFAS information.
Shop Thermos on Amazon →Material
Stainless steel and double-wall insulation
Brand disclosure
Brand is silent on PFAS
Lab data
No public lab test
Why this grade
Safe base material
Made from a material with no inherent PFAS use (ceramic, mineral, or natural fiber).
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
This tumbler uses food-grade stainless steel (typically 18/8 or similar austenitic alloy) as the primary contact material, which is chemically stable and does not leach metals or compounds into beverages under normal cold-use conditions. The double-wall construction creates an air or vacuum gap for insulation, not a chemical barrier, so no additional polymers or coatings are in the beverage path. Stainless steel's passive oxide layer resists corrosion and does not degrade from cold liquids, making it one of the lowest-risk vessel materials available.
The brand's record and disclosure
Thermos is a long-established drinkware manufacturer with decades of market presence and no documented safety recalls or chemical-leaching incidents tied to their stainless steel tumblers. The brand has not publicly disclosed detailed PFAS or manufacturing-process certifications, but their product line relies on mature stainless steel technology rather than emerging materials or coatings that typically introduce contamination risk. No established controversies regarding heavy metal content or hazardous additive use have been recorded for this product category under the Thermos brand.
How it compares in its category
Stainless steel tumblers occupy a middle-to-premium tier for safety: they outperform plastic options (which carry microplastic and polymer-leaching risk) and match or exceed ceramic alternatives (which may have lead-glazed rims or chipping hazards). Double-wall insulation via air gap is chemically simpler than gel-filled or foam-core designs that introduce synthetic materials into the product structure. In cold-beverage storage specifically, stainless steel poses essentially no known chemical hazard compared to coated aluminum or laminated materials.
If you buy it
Use this tumbler for cold or room-temperature beverages; prolonged exposure to very hot liquids (above 160F) is not recommended for double-wall vessels, as thermal stress may eventually compromise the seal, though this affects insulation performance, not safety. Hand-wash rather than dishwasher if possible to extend the lifespan of any interior coating or seal, though stainless steel itself is dishwasher-safe. Inspect the base seal and interior for any unusual discoloration or metallic taste (which would be extremely rare) and replace the tumbler if structural integrity is visibly compromised or seal fails.
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.”
Metal leaching (nickel, chromium)
Stainless steel in cold beverages does not initiate corrosion or leaching of nickel or chromium under normal use. Acidic beverages (citrus, vinegar) stored for extended periods pose theoretical but not documented risk with food-grade stainless.
Seal/gasket degradation
Double-wall tumblers often use silicone or rubber gaskets; prolonged use and thermal cycling may cause these to crack or degrade over years, but this affects insulation and spill-proofing, not chemical safety.
Coating delamination or flaking (interior)
No interior coating hazard is documented for this product; stainless steel does not require a protective coating and is the beverage-contact material itself.
Bacterial or mold growth in insulation gap
If the seal fails and moisture enters the double-wall cavity, mold may grow in the enclosed space, but this would be visible/detectable and does not pose acute chemical leaching risk; contamination of the beverage is possible only if structural failure allows gap contents to re-enter the interior.
What we don’t know
This grade is a model-based estimate from public materials, coatings, and brand disclosure at 78% 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 Insulated Drinkware Tumblers
Contigo
Byron 2.0 Stainless Steel Travel Mug Snapseal
Stainless steel, silicone gasket
Travel mug with lower PFAS concern; stainless steel typically safe.
✓Bare metal or glass, no coating at all
Thermos
Stainless King Travel Tumbler
Stainless steel exterior, vacuum-insulated, minimal internal coating
Lower concern. Stainless steel tumbler with standard design, no PFAS-prone features.
✓Bare metal or glass, no coating at all
Thermos
Stainless Steel Tumbler w/ Slide Lock Lid
Stainless steel tumbler with plastic slide lock lid
Lower concern. Stainless steel is PFAS-free; monitor lid material.
✓Bare metal or glass, no coating at all
More insulated drinkware tumblers 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.