Environmental and Occupational Medicine, Department of Family and Community Medicine, University of Texas Health Science Center at San Antonio, San Antonio, Texas 78229-3900, USA
In science, anomalies expose the limitations of existing paradigms
and drive the search for new ones. In the late 1800s, physicians
observed that certain illnesses spread from sick, feverish individuals
to those contacting them, paving the way for the germ theory
of disease. The germ theory served as a crude, but elegant formulation
that explained dozens of seemingly unrelated illnesses affecting
literally every organ system. Today, we are witnessing another
medical anomaly—a unique pattern of illness involving
chemically exposed groups in more than a dozen countries, who
subsequently report multisystem symptoms and new-onset chemical,
food, and drug intolerances. These intolerances may be the hallmark
for a new disease process or paradigm, just as fever is a hallmark
for infection. The fact that diverse demographic groups, sharing
little in common except some initial chemical exposure event,
develop these intolerances is a compelling anomaly pointing
to a possible new theory of disease, one that has been referred
to as "Toxicant-Induced Loss of Tolerance" ("TILT"). TILT has
the potential to explain certain cases of asthma, migraine headaches,
and depression, as well as chronic fatigue, fibromyalgia, and
"Gulf War syndrome". It appears to evolve in two stages: (1)
initiation, characterized by a profound breakdown in prior,
natural tolerance resulting from either acute or chronic exposure
to chemicals (pesticides, solvents, indoor air contaminants,
etc.), followed by (2)
triggering of symptoms by small quantities
of previously tolerated chemicals (traffic exhaust, fragrances,
gasoline), foods, drugs, and food/drug combinations (alcohol,
caffeine). While the underlying dynamic remains an enigma, observations
indicating that affected individuals respond to structurally
unrelated drugs and experience cravings and withdrawal-like
symptoms, paralleling drug addiction, suggest that multiple
neurotransmitter pathways may be involved.
