Leakproof Ultra Thin High Rise Brief vs Rubylove First Period Kit +teen Period Underwear: which is safer?

Rubylove First Period Kit +teen Period Underwear is the clear pick. Knix Leakproof Ultra Thin High Rise Brief carries a failing PFAS grade, and we never recommend buying a failing product.

Knix Leakproof Ultra Thin High Rise Brief

Knix

Leakproof Ultra Thin High Rise Brief

PFAS grade

Poor 25/100

Overall grade

Bad 0/100

Verdict

Skip

Hazard flags

⚑ 4

Material

Fabric with waterproof/leak-resistant coating, unspecified

Confidence

35%

LikelyFluorinated coating chemistry (PFAS status unknown)

PossibleCoating degradation and microparticle release

PossibleSkin sensitization from coating or textile dyes

Our pick

Rubylove First Period Kit +teen Period Underwear

Ruby Love

Rubylove First Period Kit +teen Period Underwear

PFAS grade

Excellent 100/100

Overall grade

Excellent 92/100

Verdict

Buy

Hazard flags

⚑ 2

Material

organic cotton, waterproof backing layer

Confidence

82%

PossibleCoating degradation and microparticle shedding

PossibleBacterial or fungal growth if improperly stored

Where these two actually differ

  • We flag Fluorinated coating chemistry (PFAS status unknown), Coating degradation and microparticle release, Skin sensitization from coating or textile dyes and Volatile organic compound (VOC) off-gassing from synthetic coating on the Knix and not on the Ruby Love.
  • We flag Coating degradation and microparticle shedding and Bacterial or fungal growth if improperly stored on the Ruby Love and not on the Knix.
  • The Knix is Fabric with waterproof/leak-resistant coating, unspecified where the Ruby Love is organic cotton, waterproof backing layer, which is most of the difference in these two grades.
  • The gap is 75 points, wide enough that this is not a close call, and the Ruby Love is the one to buy.
  • We are less certain about the Knix grade, at 35% confidence against 82%, because it discloses less.

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 period underwear: see the full ranking