A few drops of blood taken within days of birth are now adding to one of the most troubling questions in environmental health: what happens when exposure to “forever chemicals” begins before a child even leaves the hospital? Researchers at the University of California, Irvine found that newborns with higher levels of certain PFAS compounds in dried blood spots had higher odds of later developing acute lymphoblastic leukemia, or ALL, the most common childhood cancer. The link was strongest for two of the best-known PFAS chemicals, PFOA and PFOS, and it appeared to grow when both were elevated together. The work, published in the Journal of Exposure Science & Environmental Epidemiology, does not prove that PFAS cause leukemia. Still, it pushes the evidence a step closer to the earliest window of life by measuring chemicals present at birth rather than estimating exposure from drinking water or other outside sources. PFAS, short for per- and polyfluoroalkyl substances, have been used since the 1950s in products built to resist heat, grease, stains, and water. They have turned …