Coffee Mug vs Stainless Steel Mug: which is safer?

Corkcicle Coffee Mug is our pick: better on PFAS and on the overall hazard picture.

Our pick

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

Why this gradeBuy

Thermos

Stainless Steel Mug

PFAS grade

A 95/100

Overall grade

B 87/100

Verdict

Buy

Hazard flags

⚑ 2

Material

stainless steel, no stated coating

Confidence

85%

PossibleSeam or lid leachables

PossibleBacterial growth in valve/seal areas

Why this gradeBuy

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