Abstract
Cyclonite (RDX) is an explosive material that is commonly compounded with 2,4,6-trinitrotoluene. The current American Conference of Governmental Industrial Hygienists 8-hour, time-weighted average threshold limit value (TLV) for cyclonite is 1.5 mg/m3 and it contains a “skin” notation. The present study has reviewed the human and animal toxicity literature available for RDX for the purpose of assessing the relative safety of the current RDX standard. Although the only available health study of occupational exposure to RDX finds no evidence of chronic toxicity in areas where the current TLV level was achieved, the evidence for the reported effectiveness of this TLV is of a very limited nature. The animal data are more extensive, and several chronic studies have been completed. When no observed adverse effect levels identified from the chronic animal studies are used to derive a TLV for RDX, and these derivations adopt relatively standard safety factors for this type of animal-to-human dosage extrapolation, the calculations suggest permissible air exposure levels for RDX between 0.03 and 0.3 mg/m3. Given these findings we suggest the TLV for RDX be reconsidered. Also, support from the literature for a “skin” notation for RDX is at best equivocal, and the inclusion of this notation should also be reevaluated.