During October 2014 PHMSA attempted to contact numerous explosive approval holders via letters delivered by certified mail. Each letter informed the approval holder that they were to submit their intentions regarding the approvals to PHMSA within 30 days. Each policy holder was informed that they could either provide evidence of UN 6(d) testing, request a reassignment of the EX number to a higher group, or request a termination. PHMSA has published the explosive approval numbers that they have not received any response from.
