MCS is a controversial illness. Patients complain of fatigue, memory problems, mood changes and many other health problems. To those who accept it, MCS is a new diagnosis in medicine that is in a transitional stage of acceptance. They cite lupus and multiple sclerosis as examples where doctors detected a disorder, but could not immediately understand it.
How do people become chemically sensitive?
A two-step process seems to lead to chemical sensitivity: + Sensitization. "In many MCS patients, the illness appears to develop following a major exposure to any of a wide range of environmental chemicals. The sensitizing event may be either an acute high-level exposure, such as a chemical spill, or it may be a repeated or continuous exposure occurring at much lower levels such as in a sick building," said Claudia S. Miller, MD, an authority on chemical sensitivity. + Triggering. "Following sensitization, patients report that extremely low levels of common chemicals tolerated by the majority of the population -- for example, tobacco smoke, perfume and traffic exhaust -- trigger severe symptoms. Commonly, they report that their symptoms are triggered not only by the chemicals involved in the original exposure, but also everyday, low- level exposures to other chemicals that are structurally different from the original exposure," she said.
What things can make people sick?
Patients say a wide range of products trigger symptoms. These include nail polish remover, new carpet, insecticides, a fresh newspaper, perfume, tobacco smoke, hair spray, fresh paint and even the detergent aisle at the supermarket.
Why is MCS so controversial?
Chemically sensitive patients do not react the same way as people with allergies. The body produces IgE, an antibody, when it encounters a known allergen such as ragweed or bee venom. With MCS, no such "biological marker" has been discovered; therefore, there is skepticism that the syndrome exists.
How do chemicals get into the human system?
Dr. Miller and Iris Bell, MD, PhD, a leading researcher on the subject, theorize that airborne chemicals may sensitize the brain's limbic region, which controls mood and helps record new memories, making it more vulnerable to subsequent exposures. Nerves in the nose that allow us to smell connect directly to the olfactory bulb, which is within the brain and offers the most direct pathway between the brain and the outside chemical environment. The limbic system is a primitive region of the brain associated with instinctual responses and behavior. For example, it records the pleasant value most people assign to the smell of new-mowed grass or bread baking. The limbic region's role, if any, in chemical sensitivity is unknown, but is becoming the subject of research.
How many people have MCS?
No one knows. One theory is that many people suffer from chemical sensitivity but may not recognize it. Humans have an enormous capacity to adapt to many substances. Examples are nicotine and alcohol. "MCS patients refer to adaptation as 'masking.' Many report that their illness began with flu-like symptoms. If they avoided exposures, either intentionally or unintentionally, they noticed their symptoms improved. With re-exposure, they observed that their symptoms recurred," Dr. Miller said.
Who is susceptible to chemical sensitivity?
No one knows. Dr. Miller said there are many theories. Nutrition or stress may play a part. Genetics also is a possible factor because many chemically sensitive patients report having relatives with similar problems.