It is not Multiple Sensitivity to Pollution, it is not Multiple Chemical Sensitivity, it is Multiple Chemical Element Sensitivity !!!
You have to understand the difference between sensitivity and toxicity. For example: If you are sensitive to mercury (most common), your body reacts to the exposure of each single molecule of mercury from inhalation, ingestion or transdermally and disturbs the order of your system, especially to the predisposed weak spots of your system (skin, immune system, joint fluid, etc.). If you are not disturbed by this vibration (or frequency) of mercury by exposure, your body is able to take care of all other toxins (Arsenic, Aluminum, Meds, Alcohol, Pesticides, etc., not in a toxicological doses), you are getting exposed to and is able to use compensatory pathways to make up weaknesses (genetic) of your body.
If the order of the system is disturbed, your body is not able to do this and will even react uncontrolled , irrational, dysautonomic ( see my Note: Dysautonomia)
Other patients are sensitive to Aluminum, Fluoride, Palladium, Iridium, Indium, Gold, Titan, Silicium, Formaldehyde and react to the vibration of this particular element and not to mercury. The word ‘chemical sensitivity’ should be individually narrowed down to the one or seldom two chemical elements.
The patient is sensitive to a product (fragrance, food, cosmetics, etc.), because it contains in trace amounts the chemical element, he or she is sensitive to, and this can vary from charge to charge of each product.
Calling it a sensitivity to fragrances turns sensitives into Pavlov dogs in being trained to react to anything they smell.