One of the potential factors affecting neurotransmitter
function is the consumption of toxic pesticide residues,
which are nearly ubiquitous in the modern food supply.
Pesticides work by causing swift and irreparable damage to
the nervous systems of insects, particularly affecting the
cholinergic system (important for learning and memory).
Although it would take massive, concentrated exposure to
have this effect in humans, it is not implausible that lifetime
exposure to low levels through contaminated food could
alter the function of our neurotransmitters—a scientific
unknown at this point.
There is also strong evidence linking pesticides and
herbicides to Parkinson’s disease, the most common
neurodegenerative disease after Alzheimer’s, where the
dopamine-producing cells of the substantia nigra die. In
human studies, people who have been exposed to large
amounts of these chemicals display dramatically increased
risk for Parkinson’s, with exposure to some fungicides
associated with twofold risk!^41 Parkinson’s disease etiology
—what causes it to develop—is not yet understood, but
toxic exposure is a leading suspect.^42
Pesticides can also cause harm in developing fetuses via
a similar lever. Studies in lab animals using model
compounds suggest that many pesticides currently in use
can cause adverse effects on brain development. Curiously,
current safety requirements for pesticide use do not include
testing for developmental neurotoxicity.
To be clear, the verdict on how this all affects humans is
not yet certain, and it could be years before science arrives
at concrete conclusions. Given the astonishing degree of