Abstract

On October 31, 1988, three men who were plugging leaks in and waterproofing an underground water tank at a building in Salcedo Village, Makati, Republic of the Philippines, were overcome by paint fumes and died in the tank. The incident was investigated by the Philippines Department of Health Field Epidemiology Training Program. The underground water storage tank measured 20 meters (66 feet) long by 6 meters (19.8 feet) wide by 3 meters (9.9 feet) high and was divided into three communicating compartments; entry and exit were through one access hole. Because of typhoon rains on the evening of October 30, the tank contained approximately 60 centimeters (2 feet) of water when the five-person crew began work at 8 a.m., although company procedures required that such tanks be dry before any waterproofing materials were applied. By 9 p.m., when the crew started to apply an epoxeal waterproofing paint, the water was 10.2 centimeters (4 inches) deep. Two 60-centimeter (2-foot) diameter electrically powered exhaust fans were provided to ventilate the tank, but the workers did not use them because of concern for a possible electrocution hazard from the standing water. At approximately 10 p.m., one worker left the tank because he had become drowsy and nauseated and was vomiting. At 10:30 p.m., a second worker left the tank to obtain coffee. When these two workers returned to the tank at approximately 11:30 p.m., they found the three other crewmembers dead. Autopsy reports attributed the cause of death to asphyxia. A toxicology report from the Philippines National Bureau of Investigation indicated that blood specimens from the three men who died were negative for alcohol, sulfur, cyanide, and phosphorus. Analysis of samples of the paint by the Philippines Department of Science and Technology confirmed the presence of an epoxy resin. Reported by: RR Gavino, MD, ES Salva, MD, SP Gregorio, MD, NB Bautista, MD, MM Dayrit, MD, Field Epidemiology Training Program, CN Reodica, MD, National Capital Region, Philippines Dept of Health; E Luis, MD, V Diaz, MD, Dept of Science and Technology; B Vitasa, MD, Coll of Public Health, Univ of the Philippines; R Garcia, MD, Philippines National Bureau of Investigation. Global EIS Program, Div of Field Svcs, Epidemiology Program Office; Div of Safety Research, National Institute for Occupational Safety and Health, CDC.

Editorial Note
Editorial Note: Epoxy-based waterproofing paints contain several types of toxic chemicals, and precautionary measures are required when these paints are used in a confined space. Constituents of epoxy resins will displace oxygen in a confined space and may have an independent narcotic effect on exposed workers. In this episode, the epoxy paint contained glycidyl ether, a reactive dilutent used to decrease viscosity (1). Uncured glycidyl ether vapors are more dense than air and will settle to the bottom of a confined space, such as the water storage tank, thereby displacing oxygen. For this reason, in the United States, CDC's National Institute for Occupational Safety and Health (NIOSH) recommends use of appropriate personal protective equipment (i.e., a positive pressure-supplied air respirator and clothing) and adequate ventilation when persons work with (or assess the presence of) glycidyl ether in confined spaces. In the United States, acute traumatic occupational deaths are monitored by NIOSH through the National Traumatic Occupational Fatalities (NTOF) data file (2). The NTOF data file uses death certificates as the source of information for work-related fatalities resulting from external causes of injury and poisoning (International Classification of Diseases, Ninth Revision (ICD-9), rubrics E800-E899). From 1980 through 1985, the NTOF data file included 286 deaths (an average of 48 work-related deaths per year) that involved workers in confined spaces with cause of death directly attributable to asphyxiation, explosion, or drowning. This figure probably underestimates the number of such confined-space-related fatalities in the United States because of misclassification and the lack of a specific ICD-9 code for "confined spaces" on the death certificate. NIOSH defines a confined space as one that "by design has limited openings for entry and exit, unfavorable natural ventilation which could contain or produce dangerous air contaminants, and which is not intended for continuous employee occupancy" (3). The water storage tank in the incident reported here not only met these criteria, but also contained dangerous air contaminants introduced by the workers through the use of epoxeal waterproofing paint. Companies, municipalities, and other organizations who assign workers to perform tasks within confined spaces should develop and implement a comprehensive program for working in confined spaces (3,4). Important considerations for such recommendations are whether 1) entry is necessary or the assigned task can be completed from the outside; 2) a confined space safe entry permit has been issued by the company; 3) warning signs are posted where they will be noticed by employees; 4) air quality in the confined space has been tested for safety according to basic criteria*; 5) employees and supervisors have been trained in the proper selection and use of appropriate respiratory protection (6,7), protective clothing, lifelines, and emergency rescue equipment; 6) employees have been trained to work in confined spaces and in confined space rescue procedures; and 7) ventilation equipment is available and/or used and air quality is tested when the ventilation system is operating. In addition, confined space procedures for work performed inside tanks should specifically incorporate use of explosion-proof lighting and fixtures in and near flammable atmospheres** and use of nonflammable paints (when possible) for coating the interior of tanks.

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