Chemical Food Safety A Scientist`s Perspective Jim Riviere

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er resides in the immune system. For MCS, the detector is our sense of smell
and the amplifier is our brain and nervous system along with the rest of the
body it controls. Susceptible individuals may have underlying psychological
problems such as depression or stress, hormonal imbalances, compulsive
behavior syndrome, genetic predispositions, or an inappropriate belief that
chemicals cause harm. Whatever the cause, this syndrome produces a true
and potentially debilitating disease.
In some cases relevant to food, our sense of taste may serve as the detector.
Conversely, the patient may not be conscious of detection except by exhibit-
ing the response. Early in our evolutionary history, this reflex probably served
a very useful function since food which previously caused problems could be
eliminated before absorption occurred. Since taste and smell are our body s
most sensitive detectors, this reflex prevented unwanted intake of poisons.
Our olfactory systems can detect chemicals at concentrations far below those
necessary to induce a biological response. Today the mind is inappropriately
associating certain distinctive organic smells with harm.
Patients with MCS believe that their symptoms result from low-level chem-
ical exposure. Many patients respond to signs by avoiding situations of per-
104 CHAPTER 7
ceived exposure. This action reinforces the belief that the signs will abate
when the individual believes there is no exposure. To some psychiatrists
progressive withdrawal and the resulting disability associated with this iso-
lation are the label of severe chemical sensitivity. The media has covered
severe cases, such as people living in remote environments or sterilized and
chemical-free quarantined homes. Even popular television shows, such as
Northern Exposure, publicize the subject. The reader should differentiate this
from individuals with nonfunctional immune systems who were once treated
by living in sterile environments due to their inability to combat any infec-
tious disease. Individuals with this type of MCS may be treated by psychiatric
intervention, and some antipsychotic drugs have also been effective in break-
ing this vicious cycle. The association of psychological factors with MCS does
not diminish the medical reality of the disease!
As the reader can appreciate, the above description of this syndrome is, by
necessity, incomplete and simplifies the complex presentation of this disease.
There has been some overlap with the signs of Chronic Fatigue Syndrome,
which might have an infectious disease trigger. Both have psychological man-
ifestations. What is curious is that some researchers have even reported evi-
dence of this hypersensitivity syndrome being discussed in the seventeenth
century. This obviously was not due to the products of twentieth-century
chemistry.
To me, the frightening aspect of this psychological hypothesis is that weak
associations could easily be reinforced by higher cognitive areas of the brain
if the individual truly believes, based on media accounts, that low-level chem-
icals are uniformly harmful to us. In these individuals, perception of potential
harm is the important factor, as opposed to toxicological activity of the chem-
ical itself. This perception is translated into serious physical disease. The
reader should recall our discussion of the placebo effect in Chapter 1 since
many aspects of this phenomenon are pertinent. Continued media exposure
of these issues reinforces this perception and actually creates a definable
syndrome.
Most readers can appreciate that our sense of smell is extremely sensitive
and is capable of detecting truly minute concentrations of volatile aromatic
substances. It is no surprise that most perfumes are made from the same class
of compounds. The scenario presented above is capable of explaining indi-
vidual reactions to very low concentrations of chemicals in our environment.
Some recent studies have even suggested that there may be a unique anatom-
ical pathway in our nose that allows chemicals to directly enter the nerves
responsible for smell. These olfactory nerves, with receptors in the nose, then
connect to the limbic system of the brain (see below for a definition of the
limbic system). This pathway has been clearly demonstrated with manganese
transport after inhalational exposure. Note, however, that oral exposure of
SOME REAL ISSUES IN CHEMICAL TOXICOLOGY 105
this metal does not result in access to a similar pathway to the brain. This
olfactory nerve pathway provides a direct link between the outside environ-
ment and the nervous system. In some sensitive individuals, this provides a
biological mechanism for the wide variety of symptoms associated with MCS
and the allergic-like amplification process seen where minute exposure results
in an exaggerated response. However, exposure to chemicals in food would
not function by this mechanism.
In these cases, the amplification would be mediated through physiological
rather than psychological actions of the brain. There are even specific mecha-
nisms in the brain for chemical sensitization (termed kindling) to produce [ Pobierz całość w formacie PDF ]

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