Idiopathic environmental intolerances (IEI) are medical

syndromes A syndrome is a set of medical signs and symptoms which are correlated with each other and often associated with a particular disease or disorder. The word derives from the Greek σύνδρομον, meaning "concurrence". When a syndrome is paire ...

with no proven cause, but which the affected people attribute to various environmental situations. The most common forms are

multiple chemical sensitivity Multiple chemical sensitivity (MCS) is an unrecognized and controversial diagnosis characterized by chronic symptoms attributed to exposure to low levels of commonly used chemicals. Symptoms are typically vagueness, vague and non-specific sympt ...

, electromagnetic hypersensitivity (electricity), and wind turbine syndrome (noise).

Commonalities

Although the identified

environmental factor An environmental factor, ecological factor or eco factor is any factor, abiotic or biotic, that influences living organisms. Abiotic factors include ambient temperature, amount of sunlight, air, soil, water and pH of the water soil in which an ...

differs, there are several qualities shared by all of these conditions. All of them are controversial, and none of them result from a scientifically proven

pathogenesis In pathology, pathogenesis is the process by which a disease or disorder develops. It can include factors which contribute not only to the onset of the disease or disorder, but also to its progression and maintenance. The word comes . Descript ...

and

pathophysiology Pathophysiology (or physiopathology) is a branch of study, at the intersection of pathology and physiology, concerning disordered physiological processes that cause, result from, or are otherwise associated with a disease or injury. Pathology is ...

. There is a wide variety of symptoms, with no pattern associating particular exposures with particular symptoms. Symptoms do not appear consistently after exposure in blinded experiments. However, the expectancy-induced

nocebo effect A nocebo effect is said to occur when a patient's expectations for a treatment cause the treatment to have a worse effect than it otherwise would have. For example, when a patient anticipates a side effect of a medication, they can experience that ...

seems to produce symptoms when they believe they have been exposed, even if they have not been exposed to it. That is, people generally do not feel bad when they believe they are safe, but they may learn to fear exposure to a particular substance or situation, if something unrelated but unpleasant happens at the same time. Evidence indicates that at least part of the distress has a psychological or behavioral component. For example, people with IEIs are often hypervigilant about how their bodies feel. One medical challenge relates to the

mind–body problem The mind–body problem is a List_of_philosophical_problems#Mind–body_problem, philosophical problem concerning the relationship between thought and consciousness in the human mind and Human body, body. It addresses the nature of consciousness ...

, with people's experiences being dismissed as "all in their heads" and debates about whether it is a "real" or "physical" condition. It can be difficult to distinguish IEIs from other

somatic symptom disorders Somatic may refer to: * Somatic (biology), referring to the cells of the body in contrast to the germ line cells ** Somatic cell, a non-gametic cell in a multicellular organism * Somatic nervous system, the portion of the vertebrate nervous syst ...

and from poorly understood syndromes, such as

myalgic encephalomyelitis/chronic fatigue syndrome Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a disabling Chronic condition, chronic illness. People with ME/CFS experience profound fatigue that does not go away with rest, as well as sleep issues and problems with memory ...

and

fibromyalgia Fibromyalgia (FM) is a functional somatic syndrome with symptoms of widespread chronic pain, accompanied by fatigue, sleep disturbance including awakening unrefreshed, and Cognitive deficit, cognitive symptoms. Other symptoms can include he ...

Attributed causes

Chemicals

Multiple chemical sensitivity (MCS) is a

chronic condition A chronic condition (also known as chronic disease or chronic illness) is a health condition or disease that is persistent or otherwise long-lasting in its effects or a disease that comes with time. The term ''chronic'' is often applied when the ...

involving non-specific physical and psychological symptoms that appear when the affected person has been exposed to "chemicals", or at least believes they have been exposed to. Typical triggers include substances with strong or bad odors, such as vehicle exhaust,

smoke Smoke is an aerosol (a suspension of airborne particulates and gases) emitted when a material undergoes combustion or pyrolysis, together with the quantity of air that is entrained or otherwise mixed into the mass. It is commonly an unwante ...

, or

cleaning products Cleaning is the process of removing unwanted substances, such as dirt, infectious agents, and other impurities, from an object or environment. Cleaning is often performed for beauty, aesthetic, hygiene, hygienic, Function (engineering), function ...

. Symptoms often relate to the

central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain, spinal cord and retina. The CNS is so named because the brain integrates the received information and coordinates and influences the activity o ...

(e.g., difficulty concentrating, feeling lightheaded),

musculoskeletal system The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their Muscular system, muscular and Human skeleton, skeletal systems. ...

(e.g., pain),

gastrointestinal system The gastrointestinal tract (GI tract, digestive tract, alimentary canal) is the tract or passageway of the digestive system that leads from the mouth to the anus. The tract is the largest of the body's systems, after the cardiovascular system. T ...

(e.g., indigestion), and

skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other animal coverings, such as the arthropod exoskeleton, have different ...

(e.g., rash), but any

organ system An organ system is a biological system consisting of a group of organ (biology), organs that work together to perform one or more bodily functions. Each organ has a specialized role in an organism body, and is made up of distinct Tissue (biolog ...

can be affected. Emotional and mood-related symptoms are common (e.g., feeling anxious after a perceived exposure). They are less likely to attribute their symptoms to psychological factors than healthier people. For example, a healthier person might say that a headache was probably caused by stress, but a person with MCS is more likely to blame an external factor, such as chemicals. People with MCS frequently have other medical conditions, including

somatic symptom disorder Somatic symptom disorder, also known as somatoform disorder or somatization disorder, is chronic somatization. One or more chronic physical symptoms coincide with excessive and maladaptive thoughts, emotions, and behaviors connected to those symp ...

, affective disorder,

anxiety disorder Anxiety disorders are a group of mental disorders characterized by significant and uncontrollable feelings of anxiety and fear such that a person's social, occupational, and personal functions are significantly impaired. Anxiety may cause phys ...

, and

psychotic disorders In psychopathology, psychosis is a condition in which a person is unable to distinguish, in their experience of life, between what is and is not real. Examples of psychotic symptoms are delusions, hallucinations, and disorganized or incoh ...

. They are often neurotic, have high

negative affectivity In psychology, negative affectivity (NA), or negative affect, is a personality variable that involves the experience of negative emotions and poor self-concept. Negative affectivity subsumes a variety of negative emotions, including anger, contem ...

(e.g., feeling anxious), and tend to be absorbed by perceived exposures. They also tend to have very strong concerns about chemicals and pollution.

Electromagnetic fields

Electromagnetic hypersensitivity (EHS or IEI-EMF) is a chronic condition very similar to MCS, except that the affected person blames

electromagnetic fields In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

for their symptoms, rather than chemicals. Typical claims for triggers involve mobile phones and cell sites, cordless telephones, and power lines. Symptoms produced involve

sleep disorders A sleep disorder, or somnipathy, is a medical disorder affecting an individual's sleep patterns, sometimes impacting physical, mental, social, and emotional functioning. Polysomnography and actigraphy are tests commonly ordered for diagnosing sle ...

headaches A headache, also known as cephalalgia, is the symptom of pain in the face, head, or neck. It can occur as a migraine, tension-type headache, or cluster headache. There is an increased risk of depression in those with severe headaches. Head ...

nervousness Anxiety is an emotion characterised by an unpleasant state of inner turmoil and includes feelings of dread over anticipated events. Anxiety is different from fear in that fear is defined as the emotional response to a present threat, where ...

fatigue Fatigue is a state of tiredness (which is not sleepiness), exhaustion or loss of energy. It is a signs and symptoms, symptom of any of various diseases; it is not a disease in itself. Fatigue (in the medical sense) is sometimes associated wit ...

, and difficulty with concentrating. People with EHS frequently have other mental disorders, such as

major depressive disorder Major depressive disorder (MDD), also known as clinical depression, is a mental disorder characterized by at least two weeks of pervasive depression (mood), low mood, low self-esteem, and anhedonia, loss of interest or pleasure in normally ...

generalized anxiety disorder Generalized anxiety disorder (GAD) is an anxiety disorder characterized by excessive, uncontrollable and often irrational worry about events or activities. Worry often interferes with daily functioning. Individuals with GAD are often overly con ...

, and

Sounds

Infrasound hypersensitivity (IHS) is a collection of symptoms that appears when the person has been exposed to low-frequency or

infrasound Infrasound, sometimes referred to as low frequency sound or incorrectly subsonic (subsonic being a descriptor for "less than the speed of sound"), describes sound waves with a Audio frequency, frequency below the lower limit of human audibility ...

noise, usually from machinery such as a

wind turbine A wind turbine is a device that wind power, converts the kinetic energy of wind into electrical energy. , hundreds of thousands of list of most powerful wind turbines, large turbines, in installations known as wind farms, were generating over ...

. It is sometimes called ''wind turbine syndrome'' or ''vibroacoustic syndrome.'' The trigger for this is the noise produced, and not, e.g., disliking the visual appearance of wind turbines. Symptoms include ear-related symptoms (e.g.,

tinnitus Tinnitus is a condition when a person hears a ringing sound or a different variety of sound when no corresponding external sound is present and other people cannot hear it. Nearly everyone experiences faint "normal tinnitus" in a completely ...

), balance problems (e.g.,

dizziness Dizziness is an imprecise term that can refer to a sense of disorientation in space, vertigo, or lightheadedness. It can also refer to Balance disorder, disequilibrium or a non-specific feeling, such as giddiness or foolishness. Dizziness is a ...

), problems with concentration and memory, heart palpitations, fatigue, and sleep problems. The psychological symptoms, which can be significant, include feelings of frustration, anger, depression, and anxiety. Feeling annoyed by the presence of wind turbines is correlated with poor sleep. IHS is not the same as

hyperacusis Hyperacusis is an increased Hearing, sensitivity to sound and a low tolerance for environmental noise. Definitions of hyperacusis can vary significantly; it often revolves around damage to or dysfunction of the Stapes, ''stapes'' bone, stapedius ...

Others

Other IEIs include

sick building syndrome Sick building syndrome (SBS) is a condition in which people develop symptoms of illness or become infected with chronic disease from the building in which they work or reside. In scientific literature, SBS is also known as building-related illn ...

and some types of food intolerance.

References

{{reflist Ailments of unknown cause Sensitivities