What is Chemical Sensitivity?

People who are sensitive to a chemical get symptoms from exposure to low levels of that chemical - levels that do not cause symptoms in most people. For example, being near cigarette smoke or perfume or car exhaust may give someone sensitive to chemicals asthma or a headache. It is like an allergy, in that people react to things that don't bother other people, but the biological mechanisms are different.

How common is it?

In the New South Wales Adult Health Survey 2002, 2.9% of respondents reported having been diagnosed with chemical sensitivity and 24.6% of respondents reported sensitivity to chemical odours.

Multiple Chemical Sensitivity (MCS) explained

People with Multiple Chemical Sensitivity (MCS) are sensitive to many chemicals and have symptoms in more than one organ system. MCS ranges in severity from mild to extreme.

The 1999 Consensus Statement criteria for Multiple Chemical Sensitivity (MCS) are:

  • 1. The symptoms are reproducible with (repeated chemical) exposure.
  • 2. The condition is chronic.
  • 3. Low levels of exposure (lower than previously or commonly tolerated) result in manifestations of the syndrome.
  • 4. The symptoms improve or resolve when the incitants are removed.
  • 5. Responses occur to multiple chemically unrelated substances.
  • 6. Symptoms involve multiple organ systems.
What are the symptoms of chemical sensitivity?

Chemical sensitivity can cause many symptoms. These include fatigue, asthma, shortness of breath, rhinitis, blocked nose, sinus pain, sore throat, earaches, dry or sore eyes, nausea, bloating, diarrhea, constipation, headaches, confusion, memory problems, depression, anxiety, hyperactivity, sleep disturbance, joint pain, muscle pain, rashes and palpitations.

What are people with MCS sensitive to?

Car exhaust, diesel fumes, perfume, aftershave, air freshener, fragrances, washing powders, chlorine, polyester, formaldehyde, foam, plastics, rubber, pesticides, insecticides, herbicides, mothballs, disinfectants, paints, solvents, gas, newsprint, cigarette smoke, wood smoke, artificial colourings, flavourings, preservatives and other food additives.

Eighty percent of people with MCS also have food allergies/sensitivities. Allergies to moulds, dust mite and pollen are common. Some people with MCS are also sensitive to sunlight and/or electro-magnetic radiation.

What causes chemical sensitivity?

People can become sensitive to chemicals after a major chemical exposure or after long-term, low-level exposure to chemicals, e.g. pesticides. Chemical sensitivity can also occur after a virus or other illness, or with hormonal disturbances, e.g. during or after pregnancy. Some people are genetically susceptible. People with allergic illnesses such as hay fever or asthma appear to be more likely to be sensitive to chemicals.

How is chemical sensitivity diagnosed?

Doctors test for chemical sensitivity with sublingual drops, intradermal injections and/or exposure in a booth. Immune tests often show abnormalities. Food sensitivities are usually tested for with an elimination diet and food challenges.

How is chemical sensitivity treated?

The main treatment is to avoid the chemicals or other substances that cause symptoms.

Depending on how severe the problem is, this may involve:

  • 1. Changing to more natural and non-toxic personal care products, cleaning products, clothing, bedding and furniture.
  • 2. Removing toxic products from the home.
  • 3. Using non-toxic methods to control pests.
  • 4. Using non-toxic or less toxic building materials when building or renovating.
  • 5. Moving to a less polluted area.
  • 6. Eating organic food.
  • 7. Using a good air purifier and/or water filter.

Workplaces, schools and other places can be made safer for people with chemical sensitivities. Chemical sensitivity is considered a disability for the purposes of the Disability Discrimination Act.

Some nutritional supplements and other treatments can be helpful to people with chemical sensitivities, but they are not a substitute for avoiding toxic chemicals. 

What is the prognosis?

Many people can become free of symptoms by avoiding chemicals they are sensitive to. A few people make a full recovery and are no longer affected by low levels of chemicals. MCS is worsened by continued exposure to toxic chemicals. Occasionally MCS is fatal.

Centre for Epidemiology and Research, NSW Department of Health. 'New South Wales Adult Health Survey 2002', NSW Public Health Bulletin 2003; 14(S-4). 

'Multiple chemical sensitivity: a 1999 consensus' 1999 Archives of Environmental Health Vol. 54(3):147-9.