Multiple chemical sensitivity (MCS) is a chronic medical condition with symptoms that affected individuals attribute to low level chemical exposure. Some believe that MCS which is an environmental illness exists and should be treated while others believe that MCS is a psychological illness. However, it is important to address the issues of MCS as it plays an important role in environmental politics and in compensation courts.

Symptoms of MCS include fatigue, headaches, bowel disorders and muscle aches. These symptoms are similar to ailments such as chronic fatigue and Gulf War syndromes. Hence, a group of activists consisting of doctors and patients theorise that since the symptoms are similar there must be connection between these ailments and toxic in the environment which causes MCS. They believe that a Gulf War veteran who believes that he has been exposed to biological weapons, a sheepshearer who has developed chemical sensitivity and an office worker with chronic fatigue are all victims of toxic environment.

On the other hand, a group of doctors and psychiatrists point out that symptoms such as nausea, headaches and muscle aches occur in people who are suffering from psychological disorders such as depression. Studies show that people who claim that they are suffering from MCS already suffer from depression and anxiety. Furthermore, MCS is not recognised by medical associations due to the lack of scientific evidence supporting a cause-and-effect relationship between very low level exposure to chemicals and the symptoms of MCS. Clinical trials have shown that MCS patients often react in a similar manner to placebos as they do when chemical stimuli are present. This could be due to the perception that a chemical stimulus is present when placebos are used. It is also challenging to conduct trials using stimuli to test for sensitivity as many substances used in the trials have an odour. The presence of an odour can cause a psychosomatic response from patients. In addition, there are no changes in heart rate, blood pressure or severity when MCS patients are exposed to clean air and to air with chemicals that are in concentrations extremely low to smell.

People come in contact with chemicals more often now at work and at home. As the environment gets more and more loaded with chemicals, more people believe that they are affected by these chemicals which cause many ailments. There are many lawsuits filed by workers who claim that they have been exposed to chemicals at work such as asbestos, pesticides and hazardous waste materials. Exposure to such chemicals are usually in high concentrations. However, MCS involves low chemical exposure. In fact, the Gulf War syndrome sufferers who were not exposed to high chemicals and used personal pesticides were more likely to display MCS. It is also difficult to prove whether a person is affected by certain chemicals. Hence, it is nearly impossible for a person to file lawsuits against low chemical exposure. To make matters more difficult activists of MCS promote MCS through publications, talk shows, support groups and political manoeuvring. They create a false impression that individuals affected by MCS have the right to sue relevant companies and authorities responsible for the toxic in the environment.

Hence, it is important to conduct proper clinical and epidemiological studies to identify whether MCS really exists or it is psychosomatic. These studies need to provide scientific evidence supporting a cause-and-effect relationship between very low level exposure to chemicals and the symptoms of MCS in order to have MCS accepted as a medical condition by medical associations. Meanwhile, it is important not to treat MCS as a disease as this not only wrongly spreads the perception that such a condition exists but it can also be useless.