Chemical safety of U.S. Navy Fleet soda lime.

Contamination was suspected of U.S. Navy Fleet soda lime (High Performance Sodasorb) when an ammonia-like odor was reported during its use in August 1992. This material contained indicator dye and was used for carbon dioxide absorption during diving. This incident had a major impact on the U.S Navy diving program when the Navy temporarily banned use of Sodasorb and authorized Sofnolime as an interim replacement. The Naval Medical Research Institute was assigned to investigate. Testing involved sampling from the headspace (gas space) inside closed buckets and from an apparatus simulating conditions during operational diving. Volatile organic compounds were analyzed by gas chromatography and mass spectrometry; ammonia and amines were measured by infrared spectroscopy. Significant amounts of ammonia (up to 30 ppm), ethyl and diethyl amines (up to several ppm), and various aliphatic hydrocarbons (up to 60 ppm) were detected during testing of both Sodasorb and Sofnolime. Contaminants were slowly removed by gas flow and did not return. The source(s) of the ammonia and amines are unknown, although they may result from the breakdown of the indicator dye. Hydrocarbon contamination seems to result from the materials of which the bucket is constructed. Unfortunately, evaluation of potential hazards associated with this contamination is difficult, due in part to the large number of variables of operational use and the absence of appropriate exposure limits. Based on these findings, the U.S. Navy has begun to phase in, for all diving, non-indicating soda lime that will be required to meet defined contaminant limits.