What Is MCS? Multiple Chemical Sensitivity 'Affects Millions of Americans,' But It Isn't a Real Illness

Everyday products from cleaning supplies to perfumes trigger health problems in an estimated 55 million Americans, according to a new study into a disputed condition known as Multiple Chemical Sensitivities (MCS).

One in four Americans report being sensitive to household chemicals, research conducted by the University of Melbourne, Australia, found. Of those, almost half were diagnosed with MCS: an umbrella term used to describe patients who say their lives are hit by low-level exposure to chemicals.

First noted in 1952, MCS is also known as "idiopathic environmental intolerance," "environmental illness," and "sick building syndrome." MCS is not officially recognized by bodies such as the American Medical Association or the World Health Organization. There is, therefore, currently no treatment for those who claim to suffer from it.

According to the study, rates of chemical sensitivity have spiked by 200% among Americans in the past decade, while the prevalence of MCS has risen by 300%. That amounts to an estimated 55 million adults with either a sensitivity or MCS. In the past year, an estimated 22 million Americans called in sick to work after coming into contact with a fragranced consumer product in the workplace, the new figures indicate.

The range of non-specific symptoms that people report due to MCS make it difficult to pin down. These include migraines, dizziness and breathing difficulties, the study showed. Over three quarters of people with MCS said they were debilitated by their symptoms.

The author behind the study published in the Journal of Occupational and Environmental Medicine noted that products including insect spray, paint, cleaning supplies, perfumes, air fresheners, scented laundry products, fragranced candles, personal care products and petrochemical fumes can set off apparent symptoms.

The research also highlighted that 71% of people who reported having MCS were asthmatic.

Anne Steinemann, professor of civil engineering and chair of sustainable cities at the University of Melbourne School of Engineering, made her findings by analyzing an online survey with a national random sample of 1,137 people held by the Survey Sampling International.

"MCS is a serious and potentially disabling disease that is widespread and increasing in the US population," Professor Steinemann said in a statement.

"People with MCS are like human canaries. They react earlier and more severely to chemical pollutants, even at low levels," she argued.

A 2017 study by the West Virginia University School of Medicine published in the Journal of Occupational and Environmental Medicine was the latest to conclude there is no evidence to prove that MCS patients are different from anyone else.

Read more: Science Says Wi-fi Allergies Are Fake - but People Are Still Sick

"No consistent physical findings or laboratory abnormalities have yet been found to differentiate MCS patients from the remainder of the population," it read.

It mirrored the findings of a 2011 report by the Queensland Department of Health, Australia, which said that conditions such as fibromyalgia and chronic fatigue syndrome have comparable symptoms to MCS. Similarly, a 1998 review by the U.S. government concluded that although patients may be greatly affected by their symptoms, they cannot be given costly and potentially dangerous treatments that are not proven to work.

Further research is needed to determine whether MCS is a physical condition or a symptom of mental conditions such as depression and anxiety, according to WebMD.

That isn't much comfort for people like Josephine Wadley-Evans, a former sheep farmer living in Sydney, Australia, who was diagnosed with MCS almost three decades ago. She said household items including perfumes, deodorants and washing powders can cause her to go into anaphylaxis.

"The chemicals make me allergic to paramedics and allergic to hospitals," she told Australian news website ABC. She added: "I sort of remain as much as I can inside my house."

Wadley-Evans said she first became sick after coming into contact with chemicals such as fungicides, herbicides, pesticides, sheep dips and deodorants.