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Since September 11, 2001, concern about potential terrorist attacks has increased in the United States. To reduce morbidity and mortality from outbreaks of illness from the intentional release of chemical agents, we examine data from the Toxic Exposure Surveillance System (TESS). TESS, a national system for timely collection of reports from US poison control centers, can facilitate early recognition of outbreaks of illness from chemical exposures. TESS data can serve as proxy markers for a diagnosis and may provide early alerts to potential outbreaks of covert events. We use 3 categories of information from TESS to detect potential outbreaks, including call volume, clinical effect, and substance-specific data. Analysis of the data identifies aberrations by comparing the observed number of events with a threshold based on historical data. Using TESS, we have identified several events of potential public health significance, including an arsenic poisoning at a local church gathering in Maine, the TOPOFF 2 national preparedness exercise, and contaminated food and water during the northeastern US blackout. Integration of poison control centers into the public health network will enhance the detection and response to emerging chemical threats. Traditionally, emergency physicians and other health care providers have used poison control centers for management information; their reporting to these centers is crucial in poisoning surveillance efforts.

Toxic oil syndrome appeared in epidemic form in Spain in 1981. Epidemiologic studies have demonstrated that illness was caused by consumption of rapeseed oil that had been denatured with aniline. Chemical analyses of oil specimens conducted in conjunction with epidemiologic studies have established that consumption of specific oils containing fatty acid anilide contaminants was associated with increased risk for disease. New chemical analytic methods identified a family of compounds, the di-fatty acid esters of phenylamino propane-diol, and one of these compounds, the 1,2-di-oleyl ester of 3-(N-phenylamino)-1,2-propanediol (DPAP), has been found to be more strongly associated with disease status than the fatty acid anilides. We found the odds ratio for exposure to DPAP (OR = 26.4, 95% CI = 6.4-76.3) is much higher than the odds ratio for exposure to oleyl anilide (OR = 4.1, 95% CI = 2.2-7.8), implying that exposure to DPAP was a more relevant risk factor for development of toxic oil syndrome than exposure to oleyl anilide. In this paper, we review and present analyses of data from multiple studies of the possible etiologic role of DPAP in toxic oil syndrome. The presence of DPAP in oil collected from affected and unaffected households was a more specific correlate of case relatedness than was the presence of fatty acid anilides, and it was equally sensitive. Moreover, DPAP was found in oil from the only refinery whose oil was clearly associated with illness.

Rapeseed oil denatured with aniline was the vehicle of the causal agent of the toxic oil syndrome (TOS) epidemic that occurred in Spain in 1981. Although the precise aetiologic agent remains unknown, researchers established that increasing concentrations of oleyl anilide and other fatty acid anilides were associated with an increased risk for disease. To examine the hypothesis that 5-litre plastic containers of rapeseed oil associated with TOS, and which contained oleyl anilide had a characteristic shape, we measured fatty acid, sterol and fatty acid anilide levels in oil from containers of different shapes. We identified 1673 bottles of oil that had been collected during the Spanish Government's oil exchange programme and linked these bottles to people with TOS as reported in the official government census of patients with TOS. Although rapeseed oil (identified by the presence of brassicasterol) was found in 798 (47.7%) of the 1673 bottles examined, contamination with fatty acid anilide occurred in only 329 (19.6%) of the 1673 bottles and 319 (97%) of the 329 were oil containers of the shape sold by RAELCA, an oil company in Madrid. The first aniline-denatured oil that RAELCA had purchased to be refined specifically for distribution was refined at the ITH refinery of Seville, and this oil has been most directly associated with the epidemic. Previous work has shown that the only toxic oil linked to a specific refinery was that associated with rapeseed oil from the ITH refinery in Seville, and the epidemic began shortly after this oil was delivered to RAELCA for retail sale. On the basis of these findings, we conclude that oil refined by ITH and distributed by RAELCA was the principal, and probably the only, oil responsible for the TOS epidemic. Information about the history and treatment of this oil may yield important clues towards identifying the aetiologic agent of TOS.

In late October 1989, over 1,500 cases of an unusual illness involving severe myalgia and striking peripheral eosinophilia were reported in the United States and several other countries. Other clinical manifestations included pulmonary involvement (interstitial infiltrates and pleural effusions), skin rash and edema, axonal polyneuropathy, perimyositis, and possible adverse neurocognitive effects. Because of the primary manifestations of the illness, it was named "eosinophilia-myalgia syndrome" (EMS) by the Centers for Disease Control. Epidemiologic studies clearly linked illness to the ingestion of tryptophan produced by a single manufacturer in Japan, and the time course of the epidemic was most consistent with its being caused by a product contaminant. Epidemiologic analysis of plant operating conditions and data obtained from chemical analyses of case- and control-associated lots implicated 1,1'-ethylidene-bis(tryptophan) (EBT) as a candidate for the compound that causes EMS. However, the etiologic significance of EBT is still uncertain. Factors found to increase a person's risk for EMS included higher tryptophan dose and older age. Although cases occurred predominantly in women and patients had frequently been taking other medications concurrently with tryptophan, sex and use of several categories of other medications were not shown to influence the risk of illness. Few patients recovered rapidly and fully from the disease. Many were treated with glucocorticoid medications, and although they may have benefited from therapy in the short term, the development of chronic sequelae of EMS appears not to have been prevented. Public health practitioners currently depend on the reports of alert clinicians to detect this type of outbreak. In this case, state and federal government epidemiologists, once they were notified, were able to develop substantial basic information about the epidemic in a relatively short time. Control measures were introduced rapidly, effectively stopping the epidemic.

In the spring and summer of 1981, an epidemic of a new illness now referred to as the toxic oil syndrome occurred in central and northwestern Spain, resulting in some 20,000 cases, 12,000 hospital admissions and greater than 300 deaths in the 1st year of the epidemic. The initial onset of illness was usually acute, and patients presented primarily with a respiratory syndrome involving cough, fever, dyspnea, hypoxemia, pulmonary infiltrates and pleural effusions. While approximately 50% of patients recovered from this acute phase of the illness without apparent sequelae, the remaining patients developed an intermediate or chronic phase, or both, of illness involving severe myalgia, eosinophilia, peripheral nerve damage, sclerodermiform skin lesions, sicca syndrome, alopecia and joint contractures, among other findings. Epidemiologic and analytic chemical studies have clearly linked the toxic oil syndrome to the ingestion of oil mixtures containing rapeseed oil denatured with aniline. However, the precise identity of the etiologic agent within this oil has never been determined. Aniline itself did not cause the illness, but the causal agent may be a reaction product of aniline with some oil component. Although many aspects of disease activity in the involved patients have lessened with time, the ultimate consequences of their disease are not clear and are the subject of ongoing study. The recently described eosinophilia-myalgia syndrome in the United States clinically resembles the toxic oil syndrome.

On Oct 30, 1989, the New Mexico Health and Environment Department learned of 3 patients with eosinophilia and severe myalgia who had been taking L-tryptophan. Further review of these and similar cases led to the initial recognition of the eosinophilia-myalgia syndrome (EMS) epidemic. To elucidate the apparent association between L-tryptophan-containing products (LTCPs) and EMS a case-control study was done. The case definition was unexplained peripheral eosinophilia (2000/microliters or more) and incapacitating myalgia. Cases were found through review of white blood cell counts from May 1 to Oct 31, 1989, in nine medical laboratories in New Mexico. 11 cases and 22 matched controls were interviewed for information on symptoms and other clinical findings, on the use of LTCPs, and on potential confounding factors. All 11 cases (100%) used LTCPs compared with only 2 controls. These findings led to a ban on the sale of LTCPs in New Mexico, followed by a nationwide recall of such preparations in the United States.

An outbreak of paralytic shellfish poisoning occurred in Champerico, on the Pacific coast of Guatemala, July-August 1987. Of 187 people affected with characteristic neurologic symptoms, 26 died. A case study implicated a species of clam, Amphichaena kindermani, harvested from local beaches as the vehicle of the neurotoxins (saxitoxins). Children less than 6 years old had a higher fatality rate (50%) than people greater than 18 years of age (7%). The minimum lethal dose for 1 child was estimated to have been 140 mouse units of toxin/kg body weight; thus children may be more sensitive to the saxitoxins than are adults. This is the first large outbreak of paralytic shellfish poisoning recognized in Guatemala.

The authors studied the pattern of occurrence of toxic oil syndrome, a previously undescribed disease that occurred in Spain in epidemic form in 1981, in two convents in Madrid. In one convent, the disease affected 66% of 35 novices and nuns who ingested oil from a suspect source, but none of 56 laywomen who ate the same meals but used a different type of oil. In the second convent, in which nuns were also exposed but laywomen were not, 98% of 43 nuns developed toxic oil syndrome compared with none of 70 laywomen. These findings support the hypothesis that a food oil transmitted the etiologic agent of toxic oil syndrome.

In a cluster of illness reported among students at an elementary school parents mentioned many signs and symptoms including headache, pallor, dark circles under the eyes, nausea, and vomiting--which they attributed to exposure to recurrent leaks of natural gas at the school. It is likely that the parents spread among themselves the notion of toxic exposure at the school. A questionnaire revealed no spatial clustering, but increased reports of symptoms were related to intense media coverage. A thorough environmental and epidemiological investigation was negative, there being no evidence of a continuing gas leak or other potential causes. At a strictly biological level, the complaints in this reported "cluster" apparently represented the sporadic occurrence of common childhood illnesses. The possibility of an epidemic from toxic exposure at the school caused intense parental concern and led to a major public health problem. The established term "mass sociogenic illness" seems inapplicable here because complaints did not come principally from the students and the apparent epidemic illness was not transmitted among them. The term "mass sociogenic illness by proxy" is proposed to describe this incident, in which transmission in one group (the parents) resulted in reports of an epidemic in another group (students).

The identity of the etiologic agent that caused the 1981 epidemic of toxic oil syndrome in Spain has not been established, and toxicologic study of oil specimens from the outbreak has been hampered by uncertainty about which oils were actually capable of causing illness. To identify chemical characteristics associated with pathogenicity, the authors compared specimens collected during the Spanish government's oil recall program in June and July 1981 from affected and unaffected households in the two contiguous towns of Alcorcón and Leganés (Madrid Province). Oils were blind-coded for laboratory analysis, and personnel with no knowledge of the laboratory results determined whether illness was present in a family. Contamination with free aniline and oleyl, linoleyl, and palmityl anilides was strikingly more frequent and extensive in oils collected from the case (affected) families. There was a clear-cut dose-response effect, with increasing concentrations of aniline and anilides associated with increasing risk of illness. Differences in fatty acid and sterol compositions among oils indicated more rapeseed oil admixture in the case group, but these indicators of rapeseed oil admixture did not contribute significantly to risk after the degree of aniline/anilide contamination had been taken into account. The authors conclude that the presence of relatively high levels of aniline and fatty acid anilides in oil specimens collected during the epidemic in the two towns studied indicates a high probability of the current or prior presence of the etiologic agent of toxic oil syndrome. Although these data do not necessarily indicate that any of the compounds measured actually caused the illness, further toxicologic work should concentrate on oils with substantial concentrations of the marker compounds.