Multiple chemical sensitivity—is the environment really to blame?

The American Academy of Allergy, Asthma and Immunologyl has reaffirmed its doubts about the scientific status of what is known as multiple chemical sensitivity (MCS). Yet despite a long line of such authoritative rejections2-4 MCS continues to gain in popularity, political support and media attention. The emergence of MCS followed reports of a multitude of symptoms triggered by exposure to substances in the environment5-9. These substances include synthetic fabrics, food additives, paints and pesticides. Other labels for multiple chemical sensitivity are listed in Box 1. The characteristic feature of multiple chemical sensitivity is that the reported symptoms are unaccompanied by physical signs or biomedical test abnormalitiesl1. Nevertheless the symptoms (Box 2) are usually attributed to immunological or neurological dysfunction caused by environmental toxins. The status of this illness is viewed with scepticism by many physicians11 12 but a report commissioned by the UK Health and Safety Executive13 is less dismissive. Although the authors note the paucity of objective evidence, they comment that 'the available evidence seems most strongly to support a physical mechanism involving sensitization of part of the midbrain known as the limbic system.' In addition, an increasing number of doctors known as clinical ecologists or environmental physicians have based their practice on MCS, particularly in the USA. Indeed, the controversy has reached the political arena with interested parties attempting to stifle research findings inconsistent with their aims14. Research in chemical sensitivity has focused on the development of immunological or neurophysiological theories offering a pathophysiological basis for the syndrome or on a quest for psychological morbidity amongst these patients. What was missing until lately was a perspective taking account of the historical and cultural context of the condition. This deficiency was remedied by Shorter, who in an elegant review15 traced the development of clinical ecology in the USA. The principal advocate was a Chicago-based allergist, Randolph, who diagnosed MCS in his wife and in several colleagues. He Box 1 Other labels for multiple chemical sensitivity