40oz Stainless Steel Tumbler vs Stainless Mug: which is safer?
These two grade almost identically. Pick on price and preference; neither has a PFAS edge.
Calpak
40oz Stainless Steel Tumbler
PFAS grade
Overall grade
Verdict
Hazard flags
Material
Confidence
PossibleNickel leaching (stainless steel alloy)
PossibleLid gasket and seal degradation
PossibleBacterial or mold growth in insulation gap
Zojirushi
Stainless Mug
PFAS grade
Overall grade
Verdict
Hazard flags
Material
Confidence
PossibleNickel leaching (from stainless steel alloy)
PossibleBacterial growth in trapped water (between walls)
PossibleThermal stress from extreme temperature swings
Both products run through the same public rubric: materials, coatings, brand disclosure, lab findings, and recalls, plus a beyond-PFAS hazard analysis. Grades are model-based estimates, not lab tests. How grades work →
More insulated drinkware tumblers: see the full ranking