High risk materials

Reduce the hazard of the materials used - avoid the use of materials that are persistent, bio-accumulative, or are named on any list of high-risk materials published by a safety regulator. 

The US DOT is responsible for shipment regulation in general, and for packaging standards for low-risk materials. Packaging standards for high-risk materials are established by the U.S. Nuclear Regulatory Commission (US NRC). 

Carbon dioxide is useful where the minimum damage should be eaused to the materials at risk, on fires in liquid, solids or eleetrieal fires but not where there is a high risk of reignition. It is likely to be ineffeetive outdoors due to rapid dispersal. It is unsuitable for reaetive metals, metal hydrides or materials with their own oxygen supply, e.g. eellulose nitrate. 

High hazard material - selection of lower hazard material recommended if I substitution is not feasible perform health risk assessment and adopt exposure control strategy to reduce health risks... 

The dry material is readily ignited, bums very rapidly and is moderately sensitive to heat, shock, friction or contact with combustible materials. When heated above its m.p. (103-105°C), instantaneous and explosive decomposition occurs without flame, but the decomposition products are flammable. If under confinement (or in large bulk), decomposition may be violently explosive [1], An explosion which occurred when a screw-capped bottle of the peroxide was opened was attributed to friction initiating a mixture of peroxide and organic dust in the cap threads [2], Waxed paper tubs are recommended to store this and other sensitive solids [3], Crystallisation of the peroxide from hot chloroform solution involves a high risk of explosion. Precipitation from cold chloroform solution by methanol is safer [4], Water- or plasticiser-containing pastes of dibenzoyl peroxide are much safer for industrial use. 

High-risk procedures include implantation of prosthetic materials and other procedures in which surgical-site infection is associated with high morbidity. 

Inorganic and organic materials can be dissolved rapidly in Parr acid digestion bombs with Teflon liners and using strong mineral acids, usually nitric and/or aqua regia and, occasionally, hydrofluoric acid. Perchloric acid must not be used in these bombs due to the high risk of explosion. 

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