Also known as chemical intolerance, environmental illness, and, misleadingly, total allergy syndrome, Multiple Chemical Sensitivity is a condition in which the patient experiences a reaction to various chemicals, fumes, and synthetic materials. Multiple Chemical Sensitivity seems to develop in two stages. In the initiation stage, hypersensitivity to one or more toxic chemicals occurs either from a major incident, like exposure to a chemical spill, or through chronic long-term exposure – working in a poorly ventilated office or hairdressing salon, for instance – or from a combination of the two. This event may simply overwhelm the body's ability to detoxify the chemical, particularly if the individual's detoxifying enzymes are less efficient than they should be. Then, in the triggering stage, symptoms appear on exposure to not just the initiating chemical but to a wider range of chemicals as well.

Although MCS sometimes shares some of the same symptoms of allergic
diseases, such as coughing or running eyes, it is not a true allergy. It
is a difficult condition to diagnose, treat, and manage, and is far
less well understood than asthma, eczema, or rhinitis.
Some doctors and organisations don't actually believe that Multiple
Chemical Sensitivity is a 'true' illness and a patient may be told it is
'all in the mind'. For some patients, psychological symptoms can,
indeed, be part of the picture in Multiple Chemical Sensitivity. We do
not know why some people are more sensitive to chemicals and react to
tiny amounts of chemicals that normally do not cause ill effects in
people not suffering with Multiple Chemical Sensitivity. One theory is
that the liver enzymes of patients with Multiple Chemical Sensitivity
are less efficient and take longer to detoxify and excrete any chemicals
taken into the body. Another theory is that the part of the brain
involved in processing odours may react differently to chemical
exposures in people suffering with Multiple Chemical Sensitivity. A
further theory is based upon abnormally high levels of nitric oxide, a
biochemical

Common triggers for MCS include:

• Tobacco smoke
• Perfume
• Petrol and traffic fumes
• Paint
• Photocopier chemicals
• Formaldehyde and other Volatile Organic Compounds (found in a wide range of products like DIY materials, glues, new carpet)
• Pesticides and other agrochemicals
• Chlorine in swimming pools
• Nail polish and nail polish remover
• Hair spray and other chemicals found in hairdressing and beauty salons
• Newsprint and glossy paper in magazines
• Household cleaners
• Dry cleaning fluid

Because some doctors do not recognise Multiple Chemical Sensitivity as a health problem, it may be either undiagnosed or diagnosed as something else. Therefore, there are no accurate figures on how common Multiple Chemical Sensitivity actually is, except for a study carried out in 2004 which suggests that 11.2% of the United States population is hypersensitive to one or more of the chemical triggers listed above. This study, which surveyed 1,054 people by telephone, found that only 2.5% had a formal diagnosis of Multiple Chemical Sensitivity.

Multiple Chemical Sensitivity is far more common among women than men, and most patients are in the 30-50 age group.

People with Multiple Chemical Sensitivity report a wide range of symptoms. Some people will suffer from many, others from only one or two. Symptoms include:

• Breathing problems
• Sneezing, blocked or runny nose
• Sore throat
• Headaches
• Muscle pain
• Fatigue
• Skin rash
• Memory problems
• Mood changes
• Confusion
• Difficulty concentrating

Symptoms vary in severity from mild to disabling. Often the person suffering with Multiple Chemical Sensitivity finds themselves in a real quandary. They may not be able to pinpoint their triggers and so continue to suffer their symptoms. Or they may know their triggers, decide to avoid them but find this has a huge negative impact on their work, social, and personal lives.

Taking a careful case history is the key to diagnosis in Multiple Chemical Sensitivity. In particular, the doctor should try to help the patient uncover any link between their routine and activities and symptoms which might reveal which chemical exposures are involved. The patient can help here, by keeping a precise diary. A thorough medical should also include any appropriate X-rays or blood tests to exclude other possible causes for the symptoms. A referral to an allergy or other specialists may form part of the investigation. It is important to find a GP who will not dismiss a patient's concerns if they feel they may have Multiple Chemical Sensitivity. Unfortunately, there is no specific diagnostic test for Multiple Chemical Sensitivity. It is therefore far harder to diagnose than other allergic diseases, such as asthma or rhinitis.

Try to achieve a balance between avoiding chemical triggers and leading a normal life. Avoid withdrawal from people and everyday life for fear of being exposed to a trigger as much as you can. Having said that, it is obviously crucial to do all you can to avoid exposure to your triggers. For instance, you could:

• Chose bedding, paint and other household products that are made specifically for those with Multiple Chemical Sensitivity.
• Improve the quality of your indoor air with an air purifier fitted with efficient absorbers made of activated charcoal, such as the IQAir GC MultiGas.
• Don't let anyone smoke around you, if smoke is your trigger.
• Make sure your home is well ventilated.

A survey of nearly 1,000 people with Multiple Chemical Sensitivity by researchers at James Madison University, Virginia, USA, revealed that achieving a chemical-free living space and avoidance of chemicals, were the most effective management techniques for the condition.

The doctor should reassure the patient that the symptoms of Multiple Chemical Sensitivity, while troublesome, will not cause any long-term damage. Any co-existing or underlying medical problems should be treated in the usual way. There are a number of unproven treatments around for Multiple Chemical Sensitivity but, at the present time, there are no treatments for the condition which have stood the test of rigorous clinical trials because such trials have not yet been carried out.

What research is being done into Multiple Chemical Sensitivity?

There is not as much research into Multiple Chemical Sensitivity as might be justified for a condition that seems to affect so many people. One leading figure is Martin Pall, a professor at Washington State University, who is developing a comprehensive biochemical theory of Multiple Chemical Sensitivity based upon damage caused by elevated levels of nitric oxide and peroxynitrite in tissue which also plays a role in other poorly understood conditions like fibromyalgia and chronic fatigue (it is called the NO/ONOO – pronounced "no, oh no" – theory, for short).

Meanwhile, the REACH project might help us make more sense of that ‘sea’ of everyday chemicals. REACH (Registration, Evaluation, Authorisation and Restriction of Chemical substances) is a massive European Community project which began in 2007. REACH was set up because information on the long-term health effects – including Multiple Chemical Sensitivity – of the thousands of synthetic chemicals we are exposed to every day is limited. Over the next few years, manufacturers will have to provide information about the chemicals they make and how they can be handled safely. There will also be a move to replace hazardous chemicals with safer alternatives. Information is freely available from a central database run by the European Chemicals Agency in Helsinki. The database will help consumers find hazard information on various chemicals and its very existence might even help raise awareness of Multiple Chemical Sensitivity.

Multiple Chemical Sensitivity is generally regarded as a chronic illness. Although there are various anecdotal accounts of recovery,
there really hasn't been enough scientific research into Multiple
Chemical Sensitivity to be able to describe the natural course of the
condition.