Epidemiologic Notes and Reports Ethylene Glycol Intoxication Due to Contamination of Water Systems
Within the past 2 years, two instances of ethylene glycol intoxication due to contamination of water systems have been reported to CDC. The first occurred in New York in 1985; the second, in North Dakota in 1987. Details of the two investigations follow.
New York. In March 1985, a 52-year-old hospitalized woman died 1 day after being exposed to ethylene glycol during a session of hemodialysis for chronic renal failure. Review of the events preceding the accident revealed that the hospital's potable water system, which was the source of water used to prepare dialysis fluid, had been inadvertently contaminated when the air-conditioning system was flushed with a commercial solution that is 95% ethylene glycol and contains a marker dye.
Contrary to the municipal building code, there was a direct line connection between the potable water system and the chilled water circuit of the air-conditioning system. This connecting line was open for flushing of the chilled water circuit when the chilled water pump was activated. A check valve in the line failed to prevent backflow from the pressurized circuit into the potable water system. Despite its being detected elsewhere in the hospital, contamination of the potable water went unrecognized in the dialysis unit.
The patient was noted to be somnolent after her final dialysis session, but ethylene glycol intoxication was not suspected until coma, metabolic acidosis, and irreversible shock developed 12 hours later. One other patient had been dialyzed earlier on the same day as the injured patient but showed no evidence of ethylene glycol exposure. One hospital worker had taken a sip of contaminated water but had not swallowed it because of its taste and obvious discoloration. No other exposures were reported.
North Dakota. On the evening of April 12, 1987, two children, 4 and 7 years of age, were admitted to a rural North Dakota hospital because of the acute onset of marked somnolence, vomiting, and ataxia. After developing hematuria, the children were transferred to the pediatric intensive care unit of a Fargo hospital. They were given fluids intravenously and recovered fully within 2 days. Urinalysis for each child revealed calcium oxalate crystals, and toxicologic studies of their urine samples revealed the presence of ethylene glycol.
On the day they became ill, both children had been at a picnic attended by approximately 400 persons at a firehall in rural North Dakota. Three hundred and fifty-four (91%) of the 391 attendees identified were interviewed by telephone about symptoms related to ethylene glycol toxicity and the foods and beverages they consumed at the picnic. Those persons who reported marked fatigue * or ataxia on the evening of the picnic and who had not drunk beer were considered as having met the case definition of acute illness. Reports for children under 12 years of age were made by an accompanying adult.
Twenty-nine (8%) of the 354 persons interviewed met the case definition. Nineteen (66%) of the cases were among children younger than 10 years of age. The symptoms most frequently reported were excessive fatigue (90%), excessive sleepiness (76%), unsteadiness when walking (62%), and dizziness (55%). Only the two children mentioned above were hospitalized, and there were no fatalities. One food item, a noncarbonated soft drink, was strongly associated with illness (relative risk, 31.0). Among those who consumed the soft drink, 18% (28/159) became ill, while among nonconsumers, 0.6% (1/176) became ill.
There was a marked dose effect among children under 10 years of age. No cases occurred among those who did not consume the beverage; two cases (10%) occurred among those consuming less than or equal to 1/2 cup; five cases (42%), among those consuming greater than 1/2 to 1-1/2 cups; and 12 cases (80%), among those consuming greater than 1-1/2 cups.
The water used to prepare the powdered beverage had been drawn from the spigot nearest the firehall's heating system. The heating system used a mixture of water and antifreeze and was cross-connected to the potable water supply. The cross-connection was regulated by a single valve. It was uncertain whether the valve had been closed during preparation of the beverage. All other food items and beverages were prepared at a kitchen sink approximately 30 feet from the spigot nearest the heating system. A water sample taken at the spigot the evening of the picnic had an ethylene glycol concentration of 9%.
Because the firehall was not licensed as a public dining facility, it had not been inspected by food service sanitarians. Recommendations were made to redesign the heating system to separate it permanently from the potable water supply. Reported by: S Schultz, MD, New York City Dept of Health. M Kinde, MPH, D Johnson, MS, S Holmes, JL Pearson, DrPH, State Epidemiologist, North Dakota Dept of Health. Div of Nutrition, Center for Health Promotion and Education; Div of Field Svcs, Epidemiology Program Office, CDC.
Editorial Note: Ethylene glycol is a solvent with a sweetish, acrid taste, best known for its use in antifreeze solution. Because of its thermal properties, an ethylene glycol and water solution is sometimes used in the heating and cooling systems of buildings. Acute poisoning from ingestion can result in central nervous system depression, vomiting, hypotension, respiratory failure, coma, convulsions, and renal damage. The fatal dose for ingestion by adults is approximately 100 g (1).
It is estimated that as many as 60 deaths occur annually in the United States from ethylene glycol poisoning; most of these are due to renal failure (1,2). There have been numerous reports of ethylene glycol intoxication among persons drinking it during a suicide attempt, as a substitute for ethanol, or by mistake (2-5). These reports cite the ingestion, often by adults or older adolescents, of large amounts of concentrated solutions of antifreeze, resulting in severe illness and a high fatality rate.
The North Dakota outbreak is unusual in three respects: the toxic illness was relatively mild, the patients were mostly younger children, and the source of ethylene glycol was the water supply. Ethylene-glycol-based heating systems, which have become increasingly popular in North Dakota in the last few years, are usually designed to circulate a heated mixture of ethylene glycol and water through pipes embedded in concrete floors. These systems are most often found in farmers' workshops and auto repair shops. The most effective public health measure for preventing such exposure is ensuring that ethylene-glycol-based heating and cooling systems are not connected to the potable water supply. Systems that are currently connected to the potable water supply should be disconnected, and other methods should be used to mix water with ethylene glycol in these systems.
The only significant exposure in the New York incident occurred in the dialysis setting. It is unlikely that there was significant ingestion of the contaminated water because of the vivid green color imparted by the marker dye. Moreover, the maximum level of contamination was likely less than 0.5% because this concentration at equilibration with the dialyzed patient's blood would have been immediately fatal (oral ingestion of even 1 liter of 0.5% ethylene glycol would impart a dose of only 5 g). Neither color, odor, nor relatively low concentration of a toxin can protect a patient during dialysis. Only stringent protection of the quality of the water used in dialysis can prevent similar injury to this vulnerable population.
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