Cases of poisoning with dry ice occur worldwide, and have been reported in countries such as Germany, Japan, Thailand, Switzerland and the United States. Accidents involving the handling of dry ice also include cases of frostbite or damage caused by the explosion of freight containers. This BfR Opinion focuses on the risk of poisoning.
The term 'dry ice' refers to solid carbon dioxide (CO2) cooled to at least ?78.5 °C. At room temperature, dry ice turns into gaseous CO2 by sublimation. This is accompanied by a strong increase in pressure with a risk of explosion in airtight containers. The gaseous CO2 released by dry ice can cause suffocation. This is because the CO2 displaces the oxygen in the air, such as in rooms with inadequate ventilation or during transport in vehicles. As a result, the oxygen content of inhaled air is reduced. At the same time, the uptake of oxygen into red blood cells is also reduced in the lungs. High concentrations of CO2 in inhaled air can lead to an insufficient supply of oxygen in the brain or bodily tissue. From simple headaches, symptoms at levels exceeding about 2 percent CO2 can include perspiration, shortness of breath, palpitations, respiratory distress, fainting, visual disturbances, tremors and impaired consciousness. At concentrations above 5 percent in inhaled air, CO2 has a narcotic effect. Once the level of CO2 exceeds about 8-10 percent, unconsciousness and death by suffocation can occur in a matter of minutes.
The risk of dry ice poisoning increases in proportion to the quantity of dry ice used, the size of the room and ventilation. As a general rule, dry ice should be stored and transported only in appropriate, well-insulated containers. These containers must not be airtight (danger of explosion). In enclosed spaces and vehicles, adequate ventilation must always be ensured during transportation, storage and use.
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