Is Tylenol — not improving air quality — to blame for the alleged asthma epidemic of the past 30 years?
The EPA and enviros have improbably claimed since the mid-1990s that the alleged epidemic of childhood asthma was caused by air pollution — despite steadily improving air quality since 1980.
A new study in Pediatrics reports,
The epidemiologic association between acetaminophen use and asthma prevalence and severity in children and adults is well established. A variety of observations suggest that acetaminophen use has contributed to the recent increase in asthma prevalence in children: (1) the strength of the association; (2) the consistency of the association across age, geography, and culture; (3) the dose-response relationship; (4) the timing of increased acetaminophen use and the asthma epidemic; (5) the relationship between per-capita sales of acetaminophen and asthma prevalence across countries; (6) the results of a double-blind trial of ibuprofen and acetaminophen for treatment of fever in asthmatic children; and (7) the biologically plausible mechanism of glutathione depletion in airway mucosa. Until future studies document the safety of this drug, children with asthma or at risk for asthma should avoid the use of acetaminophen…
Many observations suggest that the epidemiologic association between acetaminophen and asthma is causative: (1) the strength of the association; (2) the consistency of the association across geography, culture, and age; (3) the dose-response relationship between acetaminophen exposure and asthma; (4) the coincidence in the timing of increasing asthma prevalence and increasing acetaminophen use; (5) our inability to identify any other abrupt environmental change that could explain this increase in asthma morbidity; and (6) the relationship between per-capita sales of acetaminophen and asthma morbidity across countries. Furthermore, the metabolism of acetaminophen provides a biologically plausible explanation for causation: depletion in airway mucosal glutathione that could contribute to vulnerability to oxidant stress.[Emphasis added and footnotes omitted]
Specifically about the ‘epidemic of asthma,” the study says,
ACETAMINOPHEN AND THE ASTHMA EPIDEMIC
The possibility that acetaminophen causes asthma is of particular importance because of the coincidence of the asthma epidemic and the increased use of acetaminophen that followed recognition of the association of Reye syndrome with the use of aspirin. Between 1980 and 2003, the prevalence of pediatric asthma in the United States increased from 3.6% to 5.8%, and similar increases were observed throughout the world. Asthma prevalence leveled off in the 1990s at a time in which acetaminophen had already become the most commonly used analgesic/antipyretic for children. Although other changes in the environment have been suggested that might explain an increase in childhood asthma, including the “hygiene hypothesis,” none so easily explains the rapid increase in asthma in the 1980s and the subsequent leveling off of asthma prevalence over the last 15 years. Furthermore, the prevalence of childhood wheezing in 36 countries around the world is predicted by each country’s per-capita sales of acetaminophen. [Emphasis added and footnotes omitted]
If indeed the increase in asthma prevalence from 3.6% to 5.8% over 23 years is real and not due to increased reporting and diagnostic changes, then unless the fine particulate swirling in the air is Tylenol, the unlikely air quality-asthma epidemic link ought finally be ascribed to the ash heap of junk science history.