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Multiple Chemical Sensitivity


According to a 1995 random population study 16 percent of people report an "unusual sensitivity to chemicals used in manufactured products, including scented hair and body products.

According to a 1995 random population study 16 percent of people report an "unusual sensitivity" to chemicals used in manufactured products, including scented hair and body products. As much as six percent of the general population react with severe symptoms diagnosed as multiple chemical sensitivity, or MCS disorder.

Reactions vary from person to person, but all are brought on by the volatile organic chemicals used in product manufacture. Scented hair and body products, scented candles, and a wide range of other materials, including newsprint, building materials, fabrics, carpets and furnishings, pesticides, and diesel fuels contain chemical compounds that linger in the air and bring on symptoms. Problems can be compounded when people with MCS work in sealed buildings where fresh air comes from mechanical ventilation systems rather than open windows.

What is Multiple Chemical Sensitivity?

Multiple chemical sensitivity is an acquired disorder characterized by recurrent symptoms affecting multiple organ systems. Reactions can cause the limbic system and other parts of the brain to become sensitized and hyperactive to environmental triggers at increasingly lower levels of exposure.

MCS was first described in 1952 by Theron Randolph, MD, and first defined in a 1989 multidisciplinary survey of 89 clinicians and researchers who had extensive experience in, but widely differing views of, MCS. In June 1999, they redefined their top five consensus criteria, defining MCS as: (1) a chronic condition (2) with symptoms that recur reproducibly (3) in response to low levels of exposure (4) to multiple unrelated chemicals, and (5) improve or resolve when incitants are removed.

They also proposed a sixth criterion, requiring that symptoms occur in multiple organ systems, and encouraged physicians to support the 1994 consensus of the American Lung Association, American Medical Association, US Environmental Protection Agency, and the US Consumer Product Safety Commission that "complaints [of] should not be dismissed as psychogenic, and a thorough workup is essential."

Toxic Overload

MCS is caused by toxic overload. The "total load" theory compares our immune system to a barrel filled to its saturation point: at a particular level of total load, the individual loses adaptability and illness results.

Toxins in scented products include ethanol, formaldehyde, benzene derivatives, acetones, phenol, methylene chloride, and toluene to name a few. According to the Scented Products Education and Information Association of Canada (, these chemicals have been linked with cancer, birth defects, and damaged nervous systems. Yet Health Canada deems them safe under Cosmetic Regulations in the Foods and Drugs Act. Ten years ago second-hand cigarette smoke was considered safe, too.

Increasingly Recognized

With an increased general incidence of MCS, many people are aware of the negative effects of their perfume. They practise courtesy and consideration, choosing from the many scent-free products available.

Nevertheless, the social stigma of living with MCS is real. A recent study at the University of California in San Francisco surveyed the impact of the syndrome on family and relationships, finding that this hidden disability strongly impacts social relationships and daily life. Tense situations among friends, family, and colleagues can occur over the use of scented products. No matter how graciously it is explained that scents trigger serious health reactions, some people defend their freedom to use them. As a result, people with MCS are usually in constant conflict, feel misunderstood, and isolated. Others suffer in silence.

A 1997 New Mexico study found that 2.1 percent of participants had lost a job or a career because of their chemical sensitivities.

Good News

To date more than 490 scientific articles have been published in medical journals worldwide on the effects of MCS, and governments are beginning to respond with support for people disabled with MCS. In a November 2000 update to the International Classification of Diseases (ICD-10-SGBV, version 3.1), Germany added MCS as a disabling disease.

In Canada, RAINET, a research, advocacy, and information network that has represented Canadian workers with MCS since 1997, reported on MCS to the Canadian Ministry of Human Resources in October 2003.

Further, the Canadian Human Rights Commission has recognized MCS as a disability. In May 1990, Maxwell Yalden, former chair of the Commission stated, "We will investigate complaints from any person who believes that he has been discriminated against because of suffering from environmental sensitivity…I think we have a duty to try to help people to understand what is involved and to do something about it."

Others are following suit, becoming increasingly aware of MCS so that they understand and respect this disorder, which affects so many people.

Prevent and Treat MCS

  • Avoid exposure: If possible, avoid chemical triggers whenever possible by decreasing the total load of stressors: chemical, physical, biological, and psychological. Any and all contribute to, cause, or aggravate existing health problems.
  • Change jobs: If MCS is severe and there is little co-operation from your employer, change jobs or stop work temporarily. Educate your employer or school with the support of a knowledgeable family doctor.
  • Control your environment: At home and in the office, create an environmentally safe oasis. To ensure good air quality, provide adequate ventilation and humidity, get rid of any mold, and install an air purifier. Use safe paints and finishes. Avoid synthetic or off-gassing furnishings and carpeting (hard surface floors are best), gas stoves, and kerosene heaters. Do not use pesticides. Above all, use fragrance-free personal and household products.
  • Diet Considerations: Attention to diet is crucial. Check for food allergies or sensitivities. Consume a wide variety of fresh organic foods exclusively or whenever possible. Drink pure spring or filtered water. Take plenty of antioxidants, including tolerated vitamin and mineral supplements.
  • Detoxify: Exercise a minimum of one hour three times per week. Supervised sauna therapy and liver cleansing can also help. Check for dental mercury amalgams.
  • Fresh air: Breathe plenty of fresh air whenever possible but be careful if you have concomitant outdoor allergies. Get away from city pollution periodically. Oxygen therapy may be beneficial, particularly after exposure.
  • Immunotherapy: Desensitization or immunotherapy from a knowledgeable doctor may help in the long term and in coping with inadvertent and/or unavoidable exposures.
  • Coping tactics: Develop coping tactics such as rest, proper breathing, meditation, and psychological support.

Source: Jozef Krop, MD, author of Healing the Planet One Patient at a Time: A Primer in Environmental Medicine (Kos Publishing, 2002).

MCS Symptoms

Symptoms range from mild to severe:

  • heightened sense of smell
  • sleep disorders
  • rashes
  • eye irritation
  • respiratory problems
  • nausea
  • coughing
  • headaches
  • muscle, joint, and stomach pain
  • fatigue
  • dizziness
  • temporary memory loss
  • disorientation
  • concentration loss
  • anxiety
  • bowel problems


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Leah PayneLeah Payne