Comment from Anonymous

This comment is submitted in support of the request for a precautionary neurodevelopmental warning regarding acetaminophen use in infants and young children, including acetaminophen exposure beginning on the first day of life. Attached is a PDF copy of Tylenol and Autism: Evidence, Scientific Blunders, and Medicine Gone Wrong by William Parker, PhD. The book is highly relevant because it collects and organizes evidence concerning acetaminophen exposure during early brain development, including neonatal exposure, immature infant metabolism, oxidative stress, susceptibility, laboratory animal evidence, human epidemiologic evidence, and the absence of adequate long-term neurodevelopmental safety testing for pediatric use. This comment is not intended to ask FDA to rely on the book itself as dispositive evidence. Rather, the attached volume serves as a source guide, index, and synthesis of the underlying scientific literature, with citations to original studies provided in the notes section beginning on page 225. Several sections are particularly relevant. Chapter 5, beginning on page 81, addresses the timing of acetaminophen-associated neurodevelopmental risk and explains why the period immediately after birth and the first years of life may be especially important. Pediatric acetaminophen exposure can begin in the hospital, during the immediate postnatal period, when drug metabolism, detoxification capacity, and brain vulnerability may differ materially from older children and adults. Pages 85-90 are especially relevant to immature neonatal metabolism. Parker discusses evidence that newborns and young infants may not metabolize acetaminophen in the same way as older children and adults, and that the ability to process acetaminophen safely may change substantially during early life. This is central because long-standing assumptions about pediatric acetaminophen safety have often been based on liver injury endpoints, not long-term neurodevelopmental outcomes. Pages 91-95 discuss case histories and the Schultz findings concerning regression into autism following early-childhood acetaminophen exposure. These sections address pediatric exposure after birth, including repeated dosing during illness, vaccination-related fever or pain, and other common childhood circumstances in which acetaminophen may be administered. Chapter 6, beginning on page 97, summarizes laboratory animal evidence relevant to developmental neurotoxicity, including multiple studies reporting persistent behavioral, cognitive, social, auditory, or neurodevelopmental effects following early-life acetaminophen exposure. Pages 139-142 are especially important because they discuss recent work concerning N-acetyl-p-benzoquinone imine (NAPQI), the toxic metabolite of acetaminophen, and preliminary evidence of acetaminophen-related adduct formation in neonatal brain tissue. This evidence is directly relevant to biological plausibility and to whether the developing brain has been adequately protected by current pediatric labeling. Chapter 7, beginning on page 113, addresses additional evidence bearing on pediatric safety, including the history of assumptions that acetaminophen was safe for babies and children, the weakness of the evidence base supporting that assumption, and the difference between evidence of safety and the absence of adequate neurodevelopmental safety testing. Appendix B, pages 189-194, provides concise evidence summary tables organizing pharmacologic, epidemiologic, laboratory animal, and other lines of evidence. These tables may be useful to FDA as a roadmap for reviewing the underlying literature cited throughout the book. The central regulatory issue is not whether every mechanism has been fully resolved, but whether current labeling adequately communicates the uncertainty and potential neurodevelopmental risk during the most vulnerable periods of pediatric brain development. For these reasons, the attached book should be included in the administrative record and considered as a source guide and synthesis relevant to the requested pediatric neurodevelopmental warning for acetaminophen use in infants and young children.