A new IRIS review has been issued for public comment by the EPA, describing the scientific basis for the human health hazard and dose-response assessments of the explosive, RDX (systematically: hexahydro-1,3,5-trinitro-1,3,5-triazine), in connection with IRIS (the Integrated Risk Information System database, available via http://www.epa.gov/iris/index.html).

While oral exposure is possible from ingestion of contaminated water, or eating crops irrigated with contaminated groundwater, inhalation and dermal exposures are more likely in occupational setting. Considering effects other than cancer, EPA derived an oral reference dose (RfD) of 3 μg/kg bw/day based on nervous system effects.

RDX caused tumours in the liver and lungs of rats and mice following lifetime, dietary administration. EPA calculated the benchmark dose associated with a 10% extra risk of either tumour, from which an oral slope factor (OSF) of 0.04 per mg/kg bw/day was derived. This slope factor is equivalent to an excess cancer risk of 1 in 100,000 from a lifetime daily intake of 0.25 μg RDX/kg bw/day.

The available data on health effects of RDX did not support the derivation of an inhalation reference concentration (RfC) nor an inhalation unit risk (IUR) value, and the available information on toxicokinetics were not suitable to support route-to-route extrapolation from the oral RfD or OSF.

US Environmental Protection Agency (EPA) (2016). Toxicological review of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) (CASRN 121-82-4) in support of summary information on the Integrated Risk Information System (IRIS). March 2016. EPA/635/R-15/034a.

https://cfpub.epa.gov/ncea/iris_drafts/recordisplay.cfm?deid=274653

 

The above items were taken from the April 2016 issue of Toxicology and Regulatory News which is sent automatically to members of bibra (click here)

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