Key findings Higher combined PFAS exposure, largely driven by the chemical PFHxS, was associated with roughly 50% greater odds of MS overall and about 60% greater odds among women. PFHxS, used in stain-resistant fabrics, food packaging, and firefighting foams, showed the strongest and most consistent association with MS. For each increase in PFHxS levels, the odds of MS rose by about 53% overall and 56% in women.