Acute illness from dry ice exposure during hurricane Ivan—Alabama, 2004

Morbidity and Mortality Weekly Report, Dec 24, 2004 by M. Tucker, B. Eichold, II, K. Micher, J.P. Lofgren, J. Schier, M. Belson, M.Rubin Patel, C.

Natural disasters such as hurricanes often impair delivery of essential services, including electricity. When normal refrigeration methods are unavailable, affected populations seek alternative means of protecting perishable foodstuffs. One alternative is to use frozen carbon dioxide (C[O.sub.2]) (i.e., dry ice).

In September 2004, in anticipation of a power outage during the aftermath of Hurricane Ivan, a man aged 34 years in Mobile, Alabama, purchased a 100-lb block of dry ice from a local ice house. The block of dry ice was divided into four equal parts and packaged in brown paper bags, which were placed in the front seat of the man's pickup truck. The windows were closed, and the air conditioner was set to recirculate air inside the cab of the truck. After driving approximately one quarter mile from the ice house, the man had shortness of breath; his breathing difficulty increased as he drove the next mile. The man telephoned his wife and asked her to call 911. He then pulled his truck into a parking lot, parked, and lost consciousness. His wife drove to the parking lot and located her husband's truck; immediately after she opened the door to the vehicle, her husband began to awaken.

Emergency medical services personnel arrived soon afterward. They determined that the man's vital signs were normal and he required no further medical evaluation. Although the man complained of a headache for the next 24 hours, he recovered completely.

Dry ice has a temperature of -109.3[degrees]F (-78.5[degrees]C) and can be used to keep perishable foods cold (1). As dry ice melts, it undergoes sublimation (i.e., direct conversion from a solid into gaseous C[O.sub.2], bypassing the liquid state). Improper ventilation during use, transport, or storage of dry ice can lead to inhalation of large concentrations of C[O.sub.2] with subsequent harmful effects, including death (1,2). Previous reports have described illness and death caused by occupational exposures and unintentional nonoccupational exposures to dry ice in enclosed spaces such as automobiles and submarines (1,2).

Under normal conditions at ambient temperature, C[O.sub.2] is a colorless, odorless gas and a simple asphyxiant that displaces oxygen when inhaled. As the inhaled concentration of C[O.sub.2] increases, more oxygen is displaced from the lung alveoli, where gas exchange takes place. The central nervous system (CNS) tightly regulates dissolved C[O.sub.2] in the blood; changes in the partial pressure of C[O.sub.2] cause changes in the respiratory rate. An increase in C[O.sub.2] concentrations triggers an increase in respiratory rate, causing further uptake of C[O.sub.2], which can ultimately lead to signs and symptoms of hypoxia and hypoxemia, including headache, confusion, disorientation, and death. Respiratory and CNS changes can occur within seconds of exposure to high levels of C[O.sub.2], suggesting that the toxicity of C[O.sub.2] might be related to systemic effects that are not fully understood.

Because C[O.sub.2] is colorless and odorless, persons who transport, use, and store dry ice must be educated about its potential dangers. Dry ice should be kept in small quantities in an insulated "cold box" or similar transport medium that is maintained at (-94.0[degrees]F (-70.0[degrees]C) or in an open, well-ventilated space (3). Persons with signs or symptoms of illness while exposed to dry ice should be moved to an area with fresh air and provided with supplemental oxygen. Usually, the long-term outcome for patients with mild-to-moderate C[O.sub.2] poisoning is excellent.

In the case described in this report, the man did not receive any warnings from the ice house regarding the potential danger of C[O.sub.2] exposure from dry ice. If the air conditioner had not been set to recirculate air inside the cab of the truck, the C[O.sub.2] poisoning symptoms might not have occurred. In addition, placing the ice in the bed of the man's truck would have reduced exposure.

* Blood carboxyhemoglobin levels of smokers might be higher than those of nonsmokers. 1,3 smokers, levels commonly reach 10% and can exceed 15%, compared with 1%-3% in nonsmokers.

References

(1.) Goldfrank LR, Flomenbaum NE, Lewin NA, Howland MA, Hoffman RS, Nelson LS, eds. Goldfrank's toxicologic emergencies. 7th ed. New York, NY: McGraw-Hill; 2002.

(2.) Gill JR, Ely SF, Hua Z. Environmental gas displacement: three accidental deaths in the workplace. Am J Forensic Med Pathol 2002;23:26-30.

(3.) Baxter PJ, Kapila M, Mfonfu D. Lake Nyos disaster, Cameroon, 1986: the medical effects of large scale emission of carbon dioxide? BMJ 1989;298:1437-41.

Reported by: M Tucker, B Eichold II, MD, DrPH, K Micher, MS, Mobile County Health Dept; JP Lofgren, MD, Alabama Dept of Public Health. J Schier MD, M Belson, MD, M. Patel, MD, C Rubin, Div of Environmental Hazards and Health Effects, National Center for Environmental Health, CDC.