Therefore, the Postal Service needs the assistance of those 
agencies. The Postal Service in turn can provide those agencies 
information on any hazardous materials discovered in its system 
through packaging failures. 
Any mailability rules and preparation requirements must take into 
account the way mail is accepted, handled and processed. Except 
for tagging of mail sacks containing hazardous material, or when 
tendered to an airline, mail pieces containing hazardous 
materials are not handled separately from other mail. Mail is 
processed together in batches manually and on automated equipment 
so that pieces containing hazardous materials receive no 
treatment different from that accorded the other categories of 
mail. As a result, parcels of hazardous materials are merged 
into the mailstream and tend to be invisible within it even when 
the Etiologic Agents/Biomedical Material label is attached. 
Mail handling takes place in thousands of sites, many of them too 
small to be prepared for other than very basic identification, 
handling and leakage containment procedures for hazardous 
materials. There is a need, therefore, to exclude materials from 
the mailstream that become deadly or very dangerous in the event 
of a package failure, and to restrict the quantities of hazardous 
materials shipped in accordance with rules established by CDC and 
DOT and postal experience. 
Recombinant DNA Research, Volume 13 
[395] 
