When I started medical school, the formaldehyde-based solutions used to embalm the cadavers in the human anatomy labs would cause my nose to burn and my eyes to well up – representing the mild, mundane end of a chemical sensitivity spectrum, writes writes Xi Chen in The Guardian.
The other extreme of the spectrum is an environmental intolerance of unknown cause (referred to as idiopathic by doctors) or, as it is commonly known, multiple chemical sensitivity (MCS). An official definition of MCS does not exist because the condition is not recognised as a distinct medical entity by the World Health Organisation or the American Medical Association, although it has been recognised as a disability in countries such as Germany and Canada.
Disagreement over the validity of the disease is partially due to the lack of a distinct set of signs and symptoms, or an accepted cause.
There are many different triggers for MCS, sometimes extending beyond chemicals to food and even electromagnetic fields. Consistent physical findings and reproducible lab results have not been found and, as a result, many people not only endure severe, chronic illness but also scrutiny over whether their condition is “real”.
The first reported case of MCS was published in the Journal of Laboratory and Clinical Medicine in 1952 by the American allergist Theron Randolph. Although he claimed to have previously encountered 40 cases, Randolph chose to focus on the story of one woman, Nora Barnes (41). She had arrived at Randolph’s office in Illinois with a diverse, bizarre array of symptoms. A former cosmetics salesperson, she represented an “extreme case”. She was always tired, her arms and legs were swollen, and headaches and intermittent blackouts ruined her ability to work.
A doctor had previously diagnosed her with hypochondria, but Barnes was desperate for a “real” diagnosis.
Randolph said the drive into Chicago from Michigan had worsened her symptoms, which spontaneously resolved when she checked into her room on the 23rd floor of a hotel where, she reasoned, she was far from the noxious motor exhaust filling the streets.
in his report, Randolph listed 30 substances to which Barnes reacted when touched (nylon, nail polish), ingested (aspirin, food dye), inhaled (perfume, the “burning of pine in fireplace”) and injected (the synthetic opiate meperidine, and Benadryl).
He posited that Barnes and his 40 other patients were sensitive to petroleum products in ways that defied the classic clinical picture of allergies. That is, rather than an adverse immune response, such as hives or a rash where the body is reacting to a particular antigen, patients with chemical sensitivities were displaying an intolerance.
Randolph theorised that, just as people who are lactose-intolerant experience abdominal pain, diarrhoea and gas because of undigested lactose creating excess fluid in their gastrointestinal tract, his patients were vulnerable to toxicity at relatively low concentrations of certain chemicals that they were unable to metabolise.
He even suggested that chemical sensitivity research was being suppressed by “the ubiquitous distribution of petroleum and wood products”. MCS, he believed, was not only a matter of scientific exploration, but also of deep-seated corporate interest. Randolph concluded his report with his recommended treatment: avoidance of exposure.
In that one-page abstract, Randolph cut the ribbon on the completely novel but controversial field of environmental medicine.
Nowadays, we hardly question the ties between the environment and well-being. The danger of secondhand smoke, the realities of climate change and the endemic nature of respiratory maladies like asthma are common knowledge. The issue was that Randolph’s patients lacked abnormal test results (specifically, diagnostic levels of immunoglobulin E, a blood marker elevated during an immune response). Whatever afflicted them were not conventional allergies, so conventional allergists resisted Randolph’s hypotheses.
Randolph asked another question: why did this seem to be a distinctly American phenomenon? After all, the only other mention of chemical sensitivities in medical literature was in the US neurologist George Miller Beard’s 1880 textbook A Practical Treatise on Nervous Exhaustion (Neurasthenia). Beard said sensitivity to foods containing alcohol or caffeine was associated with neurasthenia, a now-defunct term used to describe the exhaustion of the nervous system propagated by the US’ frenetic culture of productivity.
Like Beard, Randolph saw chemical sensitivities as a disease of modernity, and conceived the origin as wear-and-tear as opposed to overload.
Randolph proposed that Americans, propelled by the post-World War 2 boom, had increasingly encountered synthetic chemicals in their workplaces and homes, at concentrations considered acceptable for most people. Chronic exposure to these subtoxic dosages, in conjunction with genetic predispositions, strained the body and made patients vulnerable.
Consequently, he developed a new branch of medicine and, with colleagues, founded the Society for Clinical Ecology, now known as the American Academy of Environmental Medicine.
Despite this growth in interest, researchers never identified blood markers in MCS patients, and trials found that people with MCS couldn’t differentiate between triggers and placebos.
By 2001, a review in the Journal of Internal Medicine found MCS virtually non-existent outside western industrialised countries, despite the globalisation of chemical use, suggesting the phenomenon was culturally bound.
MCS subsequently became a diagnosis of exclusion, a leftover label used after every other possibility was eliminated. The empirical uncertainty came to a head in 2021, when Quebec’s public health agency, the INSPQ, published an 840-page report that reviewed more than 4 000 articles in the scientific literature, concluding that MCS is an anxiety disorder. In medicine, psychiatric disorders are not intrinsically inferior; serious mental illness is, after all, the product of neurological dysfunction. But many MCS patients found the language offensive and irresponsible. Reducing what they felt in their eyes, throats, lungs and guts to anxiety was not acceptable at all.
In fact, because MCS is so stigmatising, such patients may never receive the level of specialised care they need. After her “treatment”, one patient was frequently bedbound from crushing fatigue, and no one took her MCS seriously. “I think doctors fail to understand we are intelligent,” she said. “Many of us with chemical sensitivities spend lots of our time researching and reading scientific articles and papers.”
When she was younger, she had developed irritable bowel syndrome and doctors said she was stressed.
Later, a new paint job at her home gave her fatigue and diarrhoea. She used to browse the local art museum weekly, but even fumes from the paintings irritated her symptoms. She visited every primary care doctor in her city, as well as gastroenterologists, cardiologists, neurologists, endocrinologists and even geneticists. Most reacted the same way: with an antidepressant prescription.
“Not one allopathic doctor has been able to help me,” she said.
Morton Teich is one of the few physicians who diagnoses and treats patients with MCS in New York. Although several of his patients were chemically sensitive, MCS was rarely the central focus of visits.
When he introduced me to his first patient of the day, a petrol-intolerant woman whose appointment was over the phone because she was house-bound, she admitted to never having heard of the condition MCS. “You must remember,” Teich said, “that MCS is a symptom. It’s just one aspect of my patients’ problems. My goal is to get a good history and find the underlying cause.” Later, when I asked him whether he had observed any patterns suggesting an organic cause of MCS, he responded: “Mould. Almost always.”
Many people with MCS I encountered also cited mould as a probable cause. One patient had her first episode in 1998: chest pain after discovering black mould in her family’s trailer home. A cardiac examination had produced no remarkable results, and her primary care physician said she was having a panic attack related to the stress of a recent miscarriage. She recognised that this contributed to her sudden health decline, but also found the symptoms resolved only once she began sleeping away from home.
“Mould is everywhere,” Teich said. “Not just indoors. Mould grows on leaves. That’s why people without seasonal allergies can become chemically sensitive during autumn.” When trees shed their leaves, he told me, mould spores fly into the air. He suspected that American mould is not American at all, but an invasive species that rode wind currents over the Pacific from China.
In fact, Teich commonly treats patients with nystatin, an antifungal medication used to treat candida yeast infections, which often infect the mouth, skin and vagina.
He believes the recombinant MMR vaccine could trigger “acute autism” – traditionally an anti-science point of view. When one of his patients exhibited severe, purple swelling up to his knees and a clear case of stasis dermatitis (irritation of the skin caused by varicose veins), Teich blamed mould and wrote a prescription for nystatin instead of urging Mark to see a cardiologist.
He said: “We have candida everywhere, and its toxins are released into the blood and travel to every part of the body. The thing is, most people don’t notice until it’s too late.”
Moulds and fungi are easy scapegoats for inexplicable illnesses because they are so ubiquitous in our indoor and outdoor environments. A great deal of concern over mould toxicity (or, to use the technical term, mycotoxicosis) stems from the concept of “sick-building syndrome”, in which visible black mould is thought to increase sensitivity and make people ill.
Yet in mainstream medicine, diseases caused by moulds are restricted to allergies, hypersensitivity pneumonitis (an immunologic reaction to an inhaled agent, usually organic, within the lungs) and infection. Disseminated fungal infections occur almost exclusively in patients who are immunocompromised, hospitalised or have an invasive foreign body such as a catheter.
Furthermore, if “clinical ecologists” like Teich are correct that moulds such as candida can damage multiple organs, then it must be spreading through the bloodstream. But I have yet to encounter a patient with MCS who reported fever or other symptoms of sepsis (the traumatic, whole-body reaction to infection) as part of their experience.
Teich himself did not use blood cultures to verify his claims of “systemic candidiasis”, and instead looked to chronic fungal infection of the nails, common in the general population, as sufficient proof.
“I don’t need tests or blood work,” he said. “I can see with my eyes that he has mould, and that’s enough.” It was Teich’s common practice to ask his patients to remove their socks to reveal the inevitable ridges and splits on their big toenails, and that’s all he needed.
Donald Black, associate chief of staff for mental health at the Iowa City Veterans Administration Health Care, co-authored a recent article on idiopathic environmental intolerance that took a uniform stance on MCS as a psychosomatic disorder. In 1988, as a new faculty member at the University of Iowa, he interviewed a patient entering a drug trial for obsessive-compulsive disorder. He asked the woman to list her medications, and watched as she started unloading strange supplements and a book about environmental illness from her bag.
The woman had been seeing a psychiatrist who had diagnosed her with systemic candidiasis. Black was flummoxed. If that diagnosis was true, then the woman would be very ill, not sitting calmly before him. Besides, it was not up to a psychiatrist to treat a fungal infection. How did he make the diagnosis? Did he do a physical or run blood tests? No, the patient told him, the psychiatrist just said her symptoms were compatible with candidiasis. These included chemical sensitivities. After advising the patient to discard her supplements and find a new psychiatrist, Black made some calls and discovered that, indeed, his colleague had fallen in with the clinical ecologists.
Black was intrigued by this condition that had garnered an endless number of names: environmentally induced illness, toxicant-induced loss of tolerance, chemical hypersensitivity disease, immune dysregulation syndrome, cerebral allergy, 20th-century disease, and mould toxicity.
In 1990, with the aid of a medical student, he found 26 subjects diagnosed by clinical ecologists with chemical sensitivities and conducted an “emotional profile”. Every participant filled out questions that determined whether they satisfied any of the criteria for psychiatric disorders. Compared with the controls, the chemically sensitive subjects had 6.3 times higher lifetime prevalence of major depression, and 6.8 times higher lifetime prevalence of panic disorder or agoraphobia; 17% of the cases met the criteria for somatisation disorder (an extreme focus on physical symptoms – such as pain or fatigue – that causes major emotional distress and problems functioning).
In reviewing the literature, it is clear the most compelling evidence for MCS came from case studies of large-scale “initiating events” such as the Gulf war (where soldiers were exposed to pesticides and pyridostigmine bromide pills to protect against nerve agents) or the terrorist attacks on the US of 11 September 2001 (when toxins from the falling towers caused cancers and respiratory ailments for years).
In both instances, significant numbers of victims developed chemical intolerances compared with populations who were not exposed. From a national survey of veterans deployed in the Gulf war, researchers found that up to a third reported multi-symptom illnesses, including sensitivity to pesticides – twice the rate of veterans who had not deployed.
Black has no current clinical experience with MCS patients. (Apart from the papers he wrote more than 20 years ago, he had seen only a handful of MCS patients over his career.) Despite this, he had not only written the article about MCS, but also a guide in a major online medical manual on how to approach MCS treatment as a psychiatric disease. When I asked him if there was a way for physicians to regain the trust of patients who have been bruised by the medical system, he simply replied: “No.”
For him, there would always be a subset of patients who are searching for answers or treatments that traditional medicine could not satisfy. Those were the people who saw clinical ecologists, or who left society altogether. In a time of limited resources, these were not the patients on whom Black thought psychiatry needed to focus.
In his 1990 paper, Black – then a young doctor – rightly observed that “traditional medical practitioners are probably insensitive to patients with vague complaints, and need to develop new approaches to keep them within the medical fold. The study subjects clearly believed that their clinical ecologists had something to offer them that others did not: sympathy, recognition of pain and suffering, a physical explanation for their suffering, and active participation in medical care.”
I wondered if Black had given up on these “new approaches” because few MCS patients wanted to see a psychiatrist in the first place.
Physicians on either side of the debate agreed that mental illness is a crucial part of treating MCS, with one I spoke to believing that stress causes MCS, and another believing that MCS causes stress. Another physician, Christine Oliver, a doctor of occupational medicine in Toronto, who has served on the Ontario Task Force on Environmental Health, believes that both stances are probably valid and true. “No matter what side you’re on,” she said, “there’s a growing consensus that this is a public health problem.”
Oliver represents a useful third position, which takes the MCS illness experience seriously while sticking closely to medical science. She believes in a physiological cause for MCS that we cannot know and therefore cannot treat directly due to lack of research.
She agrees with Randolph’s original suggestion of avoiding exposures, although she understands this approach has resulted in traumatising changes in patients’ abilities to function. For her, the priority for MCS patients is a practical one: finding appropriate housing. Often unable to work and with a limited income, many of her patients occupy public housing or multi-family dwellings.
The physician of an MCS patient must act like a social worker. Facilities like hospitals, she feels, should be made more accessible by reducing scented cleaning products and soaps. Ultimately, finding a non-threatening space with digital access to healthcare providers and social support is the best way to allow the illness to run its course.
Whether organic or psychosomatic or something in between, MCS is a chronic illness.
In chronic pain, analgesics can deaden a patient’s suffering. The same cannot be said for MCS symptoms, which are disorienting in their chaotic variety, inescapability and inexpressibility. There are few established avenues for patients to completely avoid triggering their MCS, and so they learn to orient their lives around mitigating symptoms instead, whether that is a change in diet or moving house. MCS comes to define their existence.
People within the online MCS community call themselves “canaries”, after the birds historically used as sentinels in coalmines to detect toxic levels of carbon monoxide. With a higher metabolism and respiratory rate, the small birds would theoretically perish before the less-sensitive human miners, providing a signal to escape. The question for people with MCS is: will anyone listen?
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