Multiple Chemical Sensitivity
Historical Timeline



Multiple Chemical Sensitivity (MCS) has been around for a long time.  Here is a brief overview of the history.


Keywords:    chemical sensitivity, MCS, history



1914-1918:  Soldiers in World War I are exposed to toxic gasses on the battlefields. Many who recover have long-term respiratory effects, such as asthma, but mainstream medicine refuse to accept it until sixty years later.


1925:  A biography is published about the French author Marcel Proust (1871-1922), revealing he probably had MCS.


1947(1):  The pesticide DDT is aggressively marketed. A full-page ad in TIME magazine features a homemaker, farm animals and vegetables singing “DDT is good for me.”


1947(2):  Dr. Theron Randolph, an allergist in Chicago, realizes one of his patients is unusually reactive to low levels of chemicals.


1952:  The infamous London smog became so bad it killed 2800 people in one week. The remedy had been known for more than a century: order the city's industries to clean up or move out, but the government resisted. Some insisted it was just a bad case of the flu.


1953:  Dr. Randolph sees a patient who gets sick when eating a commercial apple, but has no trouble with apples that are not treated with pesticides.


1961:  More than a hundred German workers and soldiers were studied 15-25 years after they were accidentally exposed to minute amounts of gasses from chemical weapons. Their symptoms were remarkably similar to MCS.


1962(1):  Dr. Randolph publishes the book Human Ecology and Susceptibility to the Chemical Environment.


1962(2):  Rachel Carson publishes her book Silent Spring, about the dangers from pesticides. TIME magazine calls it "emotional" and "hysterical".


1963:  Three patients reliably identify whether food and water was stored in food-grade plastic containers or glass. This is the first double-blinded MCS challenge test.


1965:  The Society of Clinical Ecology is formed as a medical society. It is later renamed American Academy of Environmental Medicine.


1967:  The Human Ecology Study Group is formed as a patient support group in Chicago.


1969:  The Cuyahoga River in Cleveland is so polluted it catches fire.


1970:  President Nixon creates the U.S. Environmental Protection Agency (EPA). The agency has been under attack by the polluters and their political supporters ever since.


1975:  Dr. William Rea opens the Environmental Health Center in Dallas, Texas.


1976(1):  Following the oil crisis and rising energy prices, new buildings are built to conserve energy with tighter construction, inoperable windows and centrally controlled ventilation systems. The result is “sick building syndrome,” which becomes a buzzword a decade later.


1976(2):  A factory near Seveso, Italy accidentally pollutes the area with dioxin. It results in a massive cleanup and evacuation. The European Community enacts industrial safety regulations as a direct response.


1977(1):  The Human Ecology Action League (HEAL) becomes the first national MCS patient organization in the United States. By 1985 there were 32 local chapters.


1977(2):  Arlene Blum a chemist at the University of California, finds that the flame retardant chlorinated tris causes cancer in children. The industry voluntarily removes it from children's sleepwear. However, thirty years later it was still widely used in nursing pillows, car seats, highchairs and diaper-changing pads.


1978(1):  Residents of the Love Canal neighborhood are evacuated. Their houses were built on top of a toxic waste dump. President Jimmy Carter declares a national emergency for the area.


1978(2):  A community for people with MCS is started near Wimberley, Texas.


1978(3):  Dr. William Rea is able to induce arrythmia in ten heart patients, by exposing them to foods, fumes or even tap water that they are sensitive to.


1979(1):  The U.S. National Institute for Occupational Safety and Health (NIOSH) sponsors a three-day symposium named “Mass Psychogenic Illness.” All but one presenter promotes the idea that MCS is psychosomatic.


1979(2):  The U.S. Surgeon General states: “There is virtually no major chronic disease to which environmental factors do not contribute, directly or indirectly.”


1981:  The California Medical Association adopts the position that clinical ecology (treatment of MCS) is not a valid medical discipline.


1982:  The first MCS rental housing opens near Seagoville, Texas. It mostly serves patients at Dr. Rea’s clinic in Dallas.


1983:  The Los Angeles Times comic Strip Hello Carol makes fun of people with MCS.


1984(1):  Law AB3587 is passed by both houses in the California legislature, but is vetoed by governor Deukmejian after a lobbying effort. It would have funded scientific research on MCS.


1984(2):  A study of forty houses in Tennessee by the U.S. Consumer Product Safety Commission found the indoor air up to ten times as polluted as outside. They found between 20 and 150 different chemicals in each home.


1984(3):  An explosion at a pesticide factory in Bhopal, India, releases a toxic cloud. Four thousand people are immediately killed and hundreds of thousands are injured by the gas.


1985(1):   California legislators make a second attempt on an MCS law. SB 1177 passes the Senate Health Committee, but never comes to a full vote.


1985(2):   Two small towns and one county in the United States pass ordinances requiring lawn care companies to plant warning flags after they've sprayed. The industry tried to fight it in court.


1985(3):  The first ban on smoking in workplaces is enacted in Tucson, Arizona, thanks to MCS activists.


1986(1):   The American Academy of Allergy and Immunology publishes a position paper opposing MCS.


1986(2):  California voters pass Proposition 65 (The Safe Drinking Water and Toxic Enforcement Act), which requires labeling of products that contain chemicals known to cause cancer, birth defects or reproductive harm.


1986(3):  Hundreds of workers in Silicon Valley chip factories become ill with MCS. The manufacture of semiconductors involves many highly toxic chemicals.


1986(4):  Half of the six hundred workers in a new building at the University of Florida, Gainesville, complain about poor air quality.


1986(5):  Scientists expose 62 volunteers to a mixture of 22 common indoor air pollutants. The volunteers had previously reported problems with indoor air. They all had acute reactions to the mixture, but not to the blanks (placebo).


1986(6):   The U. S. Environmental Protection Agency bans lead for soldering water pipes.


1987:  Professor Mark Cullen publishes the book Workers with Multiple Chemical Sensitivities, which provides the first definition of MCS.


1988(1):  More than a hundred employees at the Environmental Protection Agency’s headquarters in Washington, D.C. are sickened when new carpeting is installed in a poorly ventilated building. Indoor air quality problems are extensively covered by the press over the next five years.


1988(2):  The Environmental Protection Agency publishes a report on the air quality inside ten buildings, including four nursing homes, a hospital, a school and four office buildings. They found up to 500 different chemicals in the building air at concentrations up to a hundred times the outside air.


1988(3):  The EPA states in their guide to indoor air quality that ventilation guidelines are only “intended to satisfy 80 percent of a building’s occupants.”


1988(4):  The U.S. Social Security Administration adds a section about MCS to its manual for determining disability.


1988(5):  An MCS community is started near Snowflake, Arizona.


1988(6):  Major hospitals in the United States start restricting indoor smoking.


1988(7):  A smoking ban on domestic flights of two hours or less takes effect in the U.S. The ban is gradually expanded to cover all flights.


1988(8):  Hundreds of people in Germany get MCS after exposure to the wood preservative lindane (pentachlorophenol).


1989(1):  A patron of the Bloomingdale’s department store in New York is involuntarily sprayed with perfume by a salesperson and ends up in the hospital for 11 days.


1989(2):  The tanker Exxon Valdez creates a massive oil spill in Alaska. Several people hired to clean up the coast get sick with MCS from working with the harsh solvents.


1989(3):  A position statement from the America College of Physicians is dismissive of MCS.


1989(4):  Professors Nicholas Ashford and Claudia Miller produce a report on MCS for the New Jersey State Department of Health. It wins the World Health Organization’s Macedo Award for Public Health.


1989(5):  Marin General Hospital in Marin County, California, opens a new five-story wing which is made less-toxic with input from the local MCS community.


1989(6):  An employee of Kent State University is by an appeals court found to be disabled and discriminated against by her employer. She had trouble breathing when exposed to cosmetics, hair spray, pesticides and other petrochemicals in her office.


1989(7):  The popular syndicated column "Dear Abby" mentions MCS and provides the address of the HEAL support group. The group receives 3000 inquiries in the following two weeks.


1989(8)  The U.S. Environmental Protection Agency unveils its Toxics Release Inventory, a database detailing pollution sources across the country. The program was weakened by the Bush administration in 2006.


1989-1997:  American Broadcasting Corporation (ABC) airs seven TV programs that are directly or indirectly critical of MCS.


1990(1):  Two dozen employees are made permanently sick with MCS after extensive pesticide spraying at a casino by Lake Tahoe, Nevada.


1990(2):  Eleven-year-old Kevin Ryan testifies before a U.S. Senate committee about the lawn-care pesticides that gave him MCS.


1990(3):  The Indoor Air Quality Act passes the U.S. Senate, but never gets through the U.S. House of Representatives.


1990(4):  The Department of Housing and Urban Development (a United States federal agency) recognizes MCS as a disability requiring “reasonable accommodation.”


1990(5):  The Americans with Disabilities Act is enacted. It provides broad protection for disabled people against discrimination in employment and access to workplaces, public buildings, public places and public transportation. The law’s broad definition of who qualifies clearly includes people with MCS, but attempts to get the courts to enforce the law prove extremely difficult. Anti-disability forces spend the next decade convincing the courts to strongly limit who "deserves" to be protected.


Three people representing the MCS community were invited and able to attend the White House signing ceremony.


1990(6):  The Chemical Manufacturers Association produces a briefing document for its members, where the grim consequences of an acceptance of MCS is spelled out.


1990(7):  The American Petroleum Institute and the Chemical Manufacturers Association convene a conference to discuss MCS.


1990(8):  The American College of Allergy and Immunology hold their annual conference in San Francisco. One day is dedicated to discussing MCS, with all the scheduled speakers advancing the idea that MCS is purely psychological. The conference is disrupted by demonstrators.


1990(9):  A chemical detector alarm goes off in a part of the Seattle Children’s Hospital that stores hazardous chemicals. There was no leak, the installation of new carpeting triggered the alarm.


1990(10):  A U.S. House of Representatives committee finds that the Reagan White House and the Centers for Disease Control covered up the health effects of the Agent Orange herbicide used during the Vietnam war.


1990(11):  United Airlines refuse to let people with MCS board their planes on two different occasions. Both passengers sue and win in court.


1991(1):  About 700.000 American troops serve in the Persian Gulf War, where they got exposed to several toxic chemicals. At least a quarter of them develop Gulf War Syndrome, which appears similar to MCS. Many physicians write it off as purely psychological.


1991(2):  The two professors Nicholas Ashford and Claudia Miller publish the book Chemical Exposures: Low Levels and High Stakes. (A second edition came out in 1998.)


1992(1):  Dr. Iris Bell proposes her Time-Dependent Sensitization hypothesis for MCS.


1992(2):  The city of Oakland, California drafts a policy to request people attending public meetings arrive fragrance free. They gave up after being “hammered” by industry lobbyists.


1992(3):  California enacts a law protecting magazine subscribers against scented ads.


1992(4):  Major American magazines, including New Yorker, People and Harper’s Bazaar, stop perfumed ads or offer perfume-free versions.


1992(5):  The sixth season of the TV series L.A. Law features a character with MCS in one episode.


1992(6):  The fourth season of the TV series Northern Exposure features a character with MCS.


1992(7):  The United States Housing and Urban Development officially accepts that MCS can be a disability.


1993(1):  A clinic catering to people with MCS, AIDS, CFS and other controversial illnesses opens in Queretaro, Mexico. It is operated by physicians who moved from the United States to avoid trouble with the medical boards.


1993(2):  The U.S. Supreme Court issues the Daubert rule which makes it harder to prove “toxic tort,” including MCS.


1993(3):  As airlines recycle more and more of the cabin air in order to save fuel, passengers and flight crews start to complain.


1993(4):  A passenger was denied the use of a respirator on flights from Tel Aviv to Atlanta, via Zurich.


1993(5):  Indoor air quality problems of Brigham and Women's Hospital in Boston sickens staff. 18 out of 80 nurses from one floor go on disability.


1994(1):  More than a hundred workers at Boeing in Seattle become sick with MCS when working with toxic chemicals. It is brushed off as mass hysteria.


1994(2):  A Washington State Medical Association official says MCS is “a belief, not a disease. It’s a culturally acquired anxiety disorder, without known cause.”


1994(3):  Ten scientific articles published in the previous decade suggested MCS was purely psychological. Several of them were frequently mentioned in the press. A review by Davidoff and Fogarty concluded that “only one study reviewed . . . was judged to have fewer than eight methodologic problems . . .”


1994(4):   The American Lung Association, the Environmental Protection Agency, the U.S. Consumer Product Safety Commission and the American Medical Association jointly issue the document Indoor Air Pollution: An Introduction for Health Professionals, which recommends people outgas new carpets safely and speaks mildly supportive of MCS and Sick Building Syndrome.


1994(5):  The world’s first publicly funded MCS housing project, Ecology House, opens in San Rafael, California.


1994(6):  Ecology House is mocked on both television and in printed media.


1994(7):  The Canadian Mortgage and Housing Corporation builds a prototype MCS mobile home with in-floor heating.


1995(1):  Film director Todd Haynes produces the movie Safe, which uses MCS to comment on the ongoing AIDS crisis and suburban dystopia. Most reviewers interpret MCS as a psychological illness.


1995(2):  A survey of MCS patients and health providers is conducted across nine European countries.


1995(3):  The Environmental Sensitivities Research Institute (ESRI) is created to “support sound scientific and medical research into environmental intolerance issues, and to compile and disseminate information on those issues.” It was widely considered an industry front created to discredit MCS. Membership fees ranged from $5000 to $10,000 a year. It closed around 2008.


1995(4):  ESRI hires a public relations firm to place advertorials in newspapers across the United States. They state that MCS “exists only because a patient believes it does and because a doctor validates that belief.”


1995(5):  The comic strip Dilbert makes fun of people who wear too much perfume. The Dogbert character wears a gasmask.


1995(6):  Terrorists release sarin poison gas in Tokyo subway. 13 people die, more than 6000 are sickened. Even 15 years later, many survivors struggle with symptoms.


1996(1):  American Broadcasting Corporation attempts to entrap Dr. Grace Ziem with fake patients posing as having MCS, but the attempt backfires.


1996(2):  The World Health Organization sponsors an invitation-only MCS conference in Berlin. Anti-MCS forces strongly promote a new name, idiopathic environmental intolerance (IEI), to distance the illness from chemical causes.


1996(3):  A government-funded MCS and EHS apartment building is finished in Uppsala, Sweden. It was poorly designed and never became a success.


1996(4):  Scientists at DePaul University asked 305 MCS patients about treatments they’ve tried. Avoiding chemicals was rated best by far. Psychiatric drugs, such as Prozac, Zoloft and Wellbutrin were rated the most harmful.


1996(5):  Dr. William Meggs and colleagues conduct a large MCS prevalence study on 1,027 people in North Carolina.


1996(6):  The license is revoked for a Colorado dentist who campaigned to stop the use of mercury in dental fillings.


1996(7):  Professor William Morton proposes that MCS is linked to the illness porphyria.


1997(1):  Cindy Duehring is awarded the Right Livelihood Award for her MCS advocacy work. She dies two years later from a pesticide exposure at the age of 35.


1997(2):  Professor Claudia Miller names her proposed explanation for MCS Toxicant-induced Loss of Tolerance (TILT).


1997(3):  The documentary Final Insult is produced in Australia, featuring four people with MCS. The movie is shown to the MCS community but the public release is mysteriously delayed for eight months. It is then displayed on Australian Broadcasting Corporation TV followed by a studio debate between three physicians and a “moderator,” whose bias against MCS is well known. Only one person in the studio has sympathy for people with MCS.


1997(4):  Wall-mounted battery-powered fragrance emitters become the norm for public restrooms in the U.S. Previously, milder fragrancing or none at all were common.


1998(1):  A group of workers were exposed to high levels of gasoline fumes while digging a tunnel through soil beneath a gas station. A quarter of the workers became chemically sensitive.


1998(2):  The San Francisco Police Department adds a page about MCS to its Disability Awareness Guide.


1998(3):  The Governors of five American states issue proclamations in support of people with MCS. More join in following years.


1998(4):  The professors Nicholas Ashford and Claudia Miller states that scientific studies of MCS are "stymied by scientists and physicians with financial conflicts of interest [which] generally remain undisclosed".


1998(5):  The United States Environmental Protection Agency bans the carcinogen chloroform from drinking water. It is caused by chlorination and is inhaled while showering. The chemical industry gets the ban overturned.


1998(6):  Scientists find that about 100,000 Americans die every year from the use of prescription drugs, while in a hospital.


1999(1):  Dr. Richard Kreutzer and colleagues finds that 6.3 percent of Californians have been diagnosed with MCS by a physician and 15.9 percent report they are "unusually sensitive to everyday chemicals."


1999(2):  A consensus criteria for diagnosing MCS is published by 34 physicians. There are six criteria, based on symptoms.


2000(1):  Brigham and Women’s Hospital, a part of Harvard University in Boston, institutes a fragrance policy to improve their indoor air quality.


2000(2):  An issue of the Jehovah’s Witness magazine Awake! is dedicated to MCS. The faith starts modifying some of their churches to accommodate people with MCS.


2000(3):  Halifax, Canada, becomes the first major city to restrict fragrances in public places.


2000(4):  The U. S. Centers for Disease Control and Prevention (CDC) issues a fact-sheet that states: “Virtually all human diseases result from the interaction of genetic susceptibility factors and modifiable environmental factors...”


2000(5):  California passes The Healthy Schools Act, which encourages the use of non-toxic methods to combat bugs. When pesticides have to be used parents and staff must be notified in advance and warning signs posted.


2000(6):  The chemical manufacturer 3M stops producing the chemicals PFOS and PFOA because of health concerns. For decades they were the main ingredient in 3M’s Scotchguard product that makes carpets, clothing and other fabrics stain repellent.


2000(7):  The U.S. Access Board is tasked with setting rules so disabled people can access public places. Years of requests for help from the MCS community finally produces a small token: they ask people attending their public meetings to arrive fragrance free.


2001(1):  The World Trade Center in New York is destroyed by terrorists. The toxic smoke from the burning buildings makes several people sick with MCS.


2001(2):  An assistant at a medical clinic comments on a patient’s powerful fragrance odor. The patient assaults the assistant with her fragrance spray so the assistant collapses with anaphylactic shock and must be hospitalized.


2003(1):  British researchers find that use of household products with volatile chemicals is associated with infant earaches, diarrhea and vomiting.


2003(2):  A woman in Florida assaults her husband with fragrances and cleaning agents during a heated marital conflict. Her husband has severe MCS. The police charge her with aggravated battery.


2003(3):  The U.S. Environmental Protection Agency declares a new flame retardant chemical as safe and unlikely to accumulate in people or wildlife. This was based on limited information provided by the manufacturer. Independent scientists were not able to check, since the chemical was secret, until it was discovered showing up in dust samples and sewage sludge. Later it was found in wildlife, including polar bears.


2005(1):  A woman with MCS wore a respirator while visiting a shopping center in Queensland, Australia. Someone thought she was a terrorist and called the police. She had some difficulty convincing the police she was harmless.


2005(2):  Hurricane Katrina leaves thousands of families homeless. They are housed in brand new “FEMA trailers” with high levels of formaldehyde. Forty-two percent of the children in a study have respiratory problems.


2006(1):  Chemical manufacturer 3M agrees to pay a $1.5 million penalty for 244 violations of the Toxics Substances Control Act in the United States.


2006(2):  The European Union adopts the REACH law, where no new chemical may be marketed without testing it for human health effects.


2006(3):  The Danish government creates The Danish Research Centre for Chemical Sensitivities. It was funded for eight years.


2007(1):  Professor Martin Pall proposes the NO/ONOO theory to explain both MCS and electrical sensitivities.


2007(2):  Anonymous special interests attempt to revoke the licenses of Dr. William Rea and other environmental physicians, but have limited success.


2008(1):  The United States Congress passes the ADA Amendments Act that strengthens the Americans with Disabilities Act from 1990.


2008(2):  A woman in Australia is forcefully committed to a mental hospital because of “Fixed belief that she is sensitive to chemicals and electromagnetic forces,” according to the paperwork.


2008(3):  The Canadian province of Ontario enacts a comprehensive ban on the cosmetic use of lawn and garden pesticides.


2009(1):  Researchers from the U.S. Environmental Protection Agency tested the floors of 500 random homes. They found residue of the pesticides chlordane (74%), DDT (42%) and heptachlor (13%) despite they have not been available for at least two decades, demonstrating how long-lived they are. They do not say if they found any home without pesticides, but it seems unlikely, since just one pesticide, permethrin, was found in 89% of the homes.


2009(2):  The United States Centers for Disease Control and Prevention (CDC) issues a no-fragrance staff policy. It deems fragrances “not appropriate for a professional work environment.”


2010(1):  Susan McBride wins lawsuit against the City of Detroit, which didn’t accommodate her inability to breathe in a fragranced office.


2010(2):  The Deepwater Horizon oil rig explodes in the Gulf of Mexico. Oil gushes into the ocean for 87 days and pollutes nearby shores. Sixty percent of the children in a hard-hit area are sickened.


2011(1):  Copenhagen Airport creates a route so fragrance-sensitive passengers can bypass the perfume counters in the duty-free shopping area. Vancouver and Helsinki follow a few years later.


2011(2):  A Danish study with 3460 people found that people with severe MCS also tend to have non-allergic skin reactions to chemicals.


2012:  An article by researchers at the King’s College Psychiatry Department claims that people with MCS just want to retreat from society and live like hermits.


2013(1):   Filmmaker Susan Abod releases the documentary movie Homesick.


2013(2):  An apartment building, specifically built for people with MCS and EHS, opens in Zurich, Switzerland. It is organized as a cooperative with public and private donations.


2013(3):  The American College of Obstetricians and Gynecologists, together with the American Society of Reproductive Medicine, issue a statement suggesting that women who are pregnant, try to become pregnant or nurses a child, should eat healthy organic foods and limit their exposure to pesticides and other toxic chemicals.


2014(1):  The Danish supermarket chain Irma stops selling products containing fabric softener, chlorine or triclosan (Microban) because they are “unnecessary and damaging to the environment.”


2014(2):  The Canadian Community Health Survey finds that 2.7% of Canadians have MCS.


2014(3):  The Canadian Human Rights Commission issues Policy on Environmental Sensitivities in support of accommodating people with MCS.


2015(1):  A study from the University of Texas find that mothers with MCS are two to three times as likely to have a child with autism or attention deficit hyperactivity (ADHD).


2015(2):  German automaker Volkswagen is fined billions of dollars for an elaborate emissions test swindle.


2015(3):  Scientists of the University of Virginia discover a link between the immune system and the brain. This may be a breakthrough in the understanding of neurological diseases.


2016(1):  The American retailer Target publishes a list of hundreds of toxic chemicals it encourages vendors to eliminate from their products.


2016(2):  Walmart, the world’s largest retailer, follows Target’s lead by asking its vendors to remove eight chemicals from their products. The list includes formaldehyde, triclosan and toluene.


2017(1):  The documentary movie The Sensitives, directed by Drew Xanthopoulos, premieres at the Tribeca Film Festival.


2017(2):  A jury awards a California office worker $3 million because his supervisor refused to accommodate his MCS disability, and he was subjected to hostile acts such as finding his things soaked in perfume. An appeals court upholds the verdict two years later.


2018(1):  A population study by professor Anne Steinemann shows the prevalence of MCS has doubled in a decade and it is easier for men to get a diagnosis than for women.


2018(2):  The streaming video service Netflix airs the seven-part “docuseries” Afflicted, about people with chronic and controversial illnesses, such as MCS. It paints them as psychosomatic. Several of the people filmed say they were deceived by the film people and demand Netflix removes the series.


2018(3):  The U.S. Food and Drug Administration bans lead in hair dyes.


2018(4):  Australian scientists analyze 24 commercial essential oils and find toxic chemicals in all of them, even those labeled “natural” or “organic.” The most common chemicals are acetaldehyde and acetone, found in all, or nearly all, products.


2018(5):  Wisconsin becomes the first American state to ban fragrances from all their rest areas.


2019(1):  Researchers of McGill university finds a genetic explanation why some people have a "heightened somatic awareness," which is often falsely thought to be purely psychological.


2019(2):  A survey of 295 restaurant staff finds that 42% believed that patrons with food allergies were not believable. 19% would prefer not to serve people with food allergies.



The references are available at


Illustration credit

The illustration at the top of this document is the front page of the booklet Multiple Chemical Sensitivity at Work, which was published by The Labor Institute (New York) in 1993. The illustration is made by Howard Saunders. Used with permission.


More MCS history




2017 (updated 2021)