The why
OtterBox Defender. Multi-layer rugged case with a polycarbonate hard shell, TPU rubber bumper, and a synthetic foam interior. The Defender's value proposition is impact protection, not material profile. Daily 10 plus hour skin contact with polycarbonate carries documented BPA residual migration: NSF measured ~0.53 micrograms per day from polycarbonate eyewear (the closest published analog to phone cases), below California MADL of 3 micrograms per day but above zero. TPU is generally inert when cured, but Bessa 2023 ES&T showed brominated flame retardants in plastics cross the skin barrier via dermal contact and sweat increases bioavailability; phone case flame retardant chemistry is not publicly disclosed. The 2022 Liu et al. ScienceDirect paper on protective mobile phone cases as microplastic sources documents wear and abrasion releasing microplastic fragments during normal use. OtterBox publishes a Global Restricted Substances Policy referencing TSCA and PFAS regulations but no independent PFAS-free testing. Roughly 50% of the plastic in OtterBox's most popular designs is recycled per their UL Environmental Claim Validation. No B Corp or Climate Neutral certifications. Score 4-5 reflects the petrochemical dermal exposure pathways plus microplastic shedding holding the floor at 4, with the recycled content credit preventing the ceiling from rising above 5. Ingredients verified 05 2026.