Odor Aversion or Multiple Chemical Sensitivities: Recommendation for a Name Change and Description of Successful Behavioral Medicine Treatment

REGULATORY TOXICOLOGY AND PHARMACOLOGY ARTICLE NO.

24, S116–S118 (1996)

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Odor Aversion or Multiple Chemical Sensitivities: Recommendation for a Name Change and Description of Successful Behavioral Medicine Treatment MELVIN A. AMUNDSEN, M.D.,* NORMAN P. HANSON, M.D.,† BARBARA K. BRUCE, PH.D.,† TIMOTHY D. LANTZ, M.A.,† MARK S. SCHWARTZ, PH.D.,†,1 AND BRIAN M. LUKACH, PH.D.†,2 *Division of Preventive Medicine and Internal Medicine and †Department of Psychiatry and Psychology, Mayo Clinic Rochester, Rochester, Minnesota 55903 Received May 17, 1996

Patients with odor-triggered symptoms, meeting the case definition of multiple chemical sensitivities (MCS), continue to be seen in our institution and other health science centers [Amundsen, Mayo Clinic Dept. Intern. Med. Newslett. 9(1) (1986)]. The term MCS, unfortunately, feeds the thesis that symptoms are allergic–immune system in origin, a theory that has not withstood scientific scrutiny [American College of Physicians, Ann. Intern. Med. 111, 168–178 (1989); Terr, Ann. Intern. Med. 119, 163–164 (1993)]. It has been proposed that some of these cases may be examples of classical (Pavlovian) conditioning: many MCS patients meet diagnostic criteria for psychiatric illnesses, especially mood, anxiety, and somatoform disorders. Attention is turning to the complex relationship between olfactory stimulation, memory, and mood (psyche) in an attempt to understand why some individuals develop odor aversion symptoms and how to best manage these, frequently, severely disabled patients. Two subjects with typical odor-triggered symptoms have been treated, using behavioral medicine techniques, with marked improvement in both cases. The term ‘‘odor aversion’’ is proposed rather than MCS to describe patients with these symptoms. q 1996 Academic Press, Inc.

Patients with odor-triggered symptoms, meeting the case definition for multiple chemical sensitivities (MCS), continue to be recognized in our institution and other health science centers and by other clinicians. Cullen’s definition contains seven main diagnostic features (Cullen, 1987, 1994): 1. The syndrome is acquired, usually after the occur1 Current address: 3527 Lakeshore Road, Sheboygan, Wisconsin 53083. 2 Current address: Mayo Clinic Jacksonville.

0273-2300/96 $18.00 Copyright q 1996 by Academic Press, Inc. All rights of reproduction in any form reserved.

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rence of a more clearly evident (although not necessarily serious) health event caused by environmental exposure, such as solvent intoxication, respiratory tract irritation, pesticide poisoning, or sick building syndrome. 2. The patient experiences multiple symptoms referable to several organ systems, almost always including the central nervous system. 3. Although there may be persistent complaints between exposures, the symptoms are characteristically and predictably precipitated by a perceived environmental exposure. 4. The agents that may precipitate the symptoms are multiple and chemically diverse. 5. The doses of these agents that may precipitate the symptoms are at least two orders of magnitude lower than the established thresholds for acute health effects. 6. No test of physiologic function can explain the symptoms. Although there may be clinical abnormalities, such as mild bronchospasm or neuropsychologic dysfunction, these are insufficient to explain the illness pattern. 7. No other organic disorder is present that can explain the pattern of symptoms. Because we believe the term ‘‘sensitivities’’ can feed the thesis of an immune system disorder or other organic cause for the syndrome, something which has not withstood scientific scrutiny to date, we have avoided its use. Instead, we conclude that ‘‘odor aversion’’ better describes this clinical picture (Amundsen et al., 1986). This conclusion is strengthened by review of a sample of 374 patients out of all referrals to Mayo’s Division of Preventive and Internal Medicine for occupational– environmental medicine consultation since 1980, 34 of whom described odor-triggered symptoms for which no organic explanation could be identified. Four theories of the etiology of MCS were thoroughly

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ODOR AVERSION OR MULTIPLE CHEMICAL SENSITIVITIES

TABLE 1 Case 1: Odor Categories and Representative Noxious Smelling Substances Listed in Order of Presentation Odor category

Representative substances

Hexane

Waste oil Tar Paint Cleaning solutions Fertilizers Pesticides Hog barn Sulfur dioxide Spoiled food Industrial chemicals Engine exhaust Shaving cream Cologne Air fresheners Cigarette smoke Welding smoke Gravel dust Burnt wood

Methyl ethyl ketone Ethyl acetate Carbon disulfide Pyridine

Diesel fuel Perfume

Other aversive odors not represented during exposure

Hot asphalt Industrial solvents Antifreeze Weed killers Insect repellent Cow barn Cut grass Dead fish

Gasoline vapor Shaving lotion Hair spray Bathing soaps Burnt rubber Leather Saw dust

explored by Sparks et al. in a comprehensive review (Sparks et al., 1994a,b): 1. MCS is a purely biological/physical or psychophysiologic reaction to low-level chemical exposures (for example, immunologic, neurotoxic, behavioral conditioning, limbic kindling, etc.); 2. MCS symptoms may be elicited by low-level environmental chemical exposures, but the sensitivity is initiated by psychologic stress (for example, cacosmia);

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3. MCS is a misdiagnosis and chemical exposure is not the cause. The symptoms may be due to a misdiagnosed physical or psychologic illness (for example, depression, anxiety, somatization, etc.); and 4. MCS is an illness belief system manifested by culturally shaped illness behavior (for example, clinical ecology, chronic fatigue syndrome, etc.). It is clear that many MCS patients meet diagnostic criteria for mental illnesses, especially mood, anxiety, and somatoform disorders. Not all individuals have premorbid psychiatric conditions, however, although such conditions probably play an important role in predisposing many or most of these patients to develop odor aversion symptoms (Black et al., 1990; Feidler et al., 1992; Buchwald et al., 1994). However, there are other patients without preexposure mental problems who may be examples of either (1) a stress response syndrome such as a specific adjustment disorder or posttraumatic stress disorder or (2) a classical conditioned response, with stimulus generalization, of phobic-anxiety and avoidance (Shusterman et al., 1988; Bolla-Wilson et al., 1988) (Tables 1 and 2). Because of the crucial role that odor perception plays in producing symptoms in these patients, it seems clear that the olfactory system and how it works deserve more than our passing attention (Hirsch, 1990; Gibbons, 1986). The olfactory nerves have a more intimate or direct connection to the brain than any of the other senses, specifically with the hippocampus, amygdala, and other components of the limbic system. It is because of these connections that associations are formed between odor and other events, including their emo-

TABLE 2 Case 2: Hierarchy of Self-Reported Substance Odors and Symptom Descriptions Subject’s rating Highly offensive

Moderately offensive

Least offensive

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Odors

Symptoms

Contact cement Solvents/petroleum distillates Methyl ethyl ketone Alcohols Oil-based paints Vehicle exhaust Nail polish Latex Glues Paints Silicone caulking Roofing tar Some petroleum distillates Cedar wood Mink oil Perfume Bleach Odor of floor cleaner in stores

‘‘Confused, difficult to concentrate, stupid, forgetful, head pressure like my head is full of water, almost pressure behind the eyes, cannot read, intense anxiety lingers for days.’’

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Generally the same as above but with more facial tension and headaches than other symptoms. Intensity 15–20% less than above.

Same symptoms but the intensity approximately 10% less than with moderately offensive odors.

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AMUNDSEN ET AL.

tional context, and are subsequently retrievable. It is normal for odors to evoke, frighten, and arouse us. REFERENCES American College of Physicians (1989). Clinical ecology. Ann. Intern. Med. 111, 168–178. Amundsen, M. A. (1986). Environmental aversion phenomena. Mayo Clinic Dept. Intern. Med. Newslett. 9(1). Amundsen, M. A., Hodgson, C. J., Hanson, N. P., Bruce, B. K., and Lantz, T. D. (1986). Environmental aversion following chemical exposure. Presented at the Central States Occupational Medicine Association and North Central Occupational Medicine Joint Fall Conference, September 26–27, Rochester, NY. Bell, I. R. (1994). Neuropsychiatric aspects of sensitivity to low level chemicals: A neural sensitization model. Toxicol. Ind. Health 10(4/ 5), 277–312. Bell, I. R., Miller, C. S., and Schwartz, G. E. (1992). An olfactory– limbic model of multiple chemical sensitivity syndrome: Possible relationships to kindling and affective spectrum disorders. Biol. Psychiatry 32, 218–242. Black, D. W., Rathe, A., and Goldstein, R. B. (1990). Environmental illness. A controlled study of 26 subjects with ‘‘20th century disease.’’ JAMA 264, 3166–3170. Bolla-Wilson, K., Wilson, R. J., and Bleecker, M. L. (1988). Conditioning of physical symptoms after neurotoxic exposure. J. Occup. Med. 30, 684–686. Buchwald, D., et al. (1994). Comparison of patients with chronic fatigue syndrome, fibromyalgia, and multiple chemical sensitivities. Arch. Int. Med. 154. Cullen, M. R. (Ed.) (1987). The worker with multiple chemical sensitivities: An overview. Occup. Med. State Art Rev. 2(1), 655–662. Cullen, M. R. (1994). Textbook of Clinical Occupational Medicine

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(Rosenstock and Cullen, Eds.), Chap. 25, p. 670. Saunders, Philadelphia. Engen, T. (1991). Odor, Sensation and Memory. Praeger, NY. Fiedler, N., Maccia, C., and Kipen, H. (1992). Evaluation of chemically sensitive patients. J. Occup. Med. 34, 529–538. Gibbons, B. (1986). The intimate sense of smell. Natl. Geograph. 170, 324–360. Haller, E. (1993). Successful management of patients with ‘‘multiple chemical sensitivities’’ on an in-patient psychiatric unit. J. Clin. Psychiatry 54. Hirsch, A. (1990). The nose knows: How does the olfactory nerve relate to hallucinations, depression and emotions? Chicago Med. 93(14). Rosenberg, S. J., Freedman, M. R., Schmaling, K. B., and Rose, C. (1990). Personality styles of patients asserting environmental illness. J. Occup. Med. 32, 678–681. Shusterman, D., Balmes, J., and Cone, J. (1988). Behavioral sensitization to irritants/odorants after acute overexposures. J. Occup. Med. 30, 565–567. Simon, G. E. (1992). Psychiatric treatments in multiple chemical sensitivity. Toxicol. Ind. Health 8, 67–72. Simon, G. E., Daniell, W., Stockbridge, H., Claypoole, K., and Rosenstock, L. (1993). Immunologic, psychological, and neuropsychological factors in multiple chemical sensitivity: A controlled study. Ann. Intern. Med. 119, 97–103. Sparks, P. J., Daniell, W., Black, D. W., Kipen, H. M., Altman, L. C., Simon, G. E., and Terr, A. I. (1994a). Multiple chemical sensitivity syndrome: A clinical perspective. I. Case definition, theories of pathogenesis, and research needs. J. Occup. Med. 36, 718– 730. Sparks, P. J., Daniell, W., Black, D. W., Kipen, H. M., Altman, L. C., Simon, G. E., and Terr, A. I. (1994b). Multiple chemical sensitivity syndrome: A clinical perspective. II. Evaluation, diagnostic testing, treatment, and social considerations. J. Occup. Med. 36, 731–737. Terr, A. I. (1993). Multiple chemical sensitivities. Ann. Intern. Med. 119, 163–164.

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