Coffee Mug vs Guardian Stainless Steel Mug: which is safer?
Corkcicle Coffee Mug edges it on pure PFAS risk, but Thermos Guardian Stainless Steel Mug wins overall once other hazards are counted.
Corkcicle
Coffee Mug
PFAS grade
A 100/100
Overall grade
B 88/100
Verdict
Buy
Hazard flags
⚑ 3
Material
Stainless steel interior, insulated walls with cork/polymer exterior
Confidence
75%
PossiblePolymer off-gassing from insulation layer
PossibleCork degradation and mold
PossibleDouble-wall seal failure
Our pick
Thermos
Guardian Stainless Steel Mug
PFAS grade
A 95/100
Overall grade
A 91/100
Verdict
Buy
Hazard flags
⚑ 1
Material
Stainless steel (uncoated)
Confidence
85%
PossibleBacterial growth in storage
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 travel mugs: see the full ranking