Section 105.20 - Guidance and interpretations(a)Hazardous materials regulations . You can obtain information and answers to your questions on compliance with the hazardous materials regulations ( 49 CFR parts 171 through 180 ) and interpretations of those regulations by contacting PHMSA's Office of Hazardous Materials Safety as follows:(1) Call the Hazardous Materials Information Center at 1-800-467-4922 (in Washington, DC, call (202) 366-4488). The Center is staffed from 9 a.m. through 5 p.m. Eastern time, Monday through Friday except Federal holidays. After hours, you can leave a recorded message and your call will be returned by the next business day.(2) E-mail the Hazardous Materials Information Center at infocntr@dot.gov .(4) Send a letter, with your return address and a daytime telephone number, to: Standards and Rulemaking Division, Pipeline and Hazardous Materials Safety Administration, Attn: PHH-10, U.S. Department of Transportation, East Building, 1200 New Jersey Avenue, SE., Washington, DC 20590-0001.(b)Federal hazardous materials transportation law and preemption . You can obtain information and answers to your questions on Federal hazardous materials transportation law, 49 U.S.C. 5101 et seq. , and Federal preemption of State, local, and Indian tribe hazardous material transportation requirements, by contacting PHMSA's Office of the Chief Counsel as follows: (1) Call the office of the Chief Counsel at (202) 366-4400 from 9 a.m. to 5 p.m. Eastern time, Monday through Friday except Federal holidays.(3) Send a letter, with your return address and a daytime telephone number, to: Office of the Chief Counsel, Pipeline and Hazardous Materials Safety Administration, Attn: PHC-10, U.S. Department of Transportation, East Building, 1200 New Jersey Avenue, SE., Washington, DC 20590-0001.(4) Contact the Office of the Chief Counsel for a copy of applications for preemption determinations, waiver of preemption determinations, and inconsistency rulings received by PHMSA before February 1, 1997.70 FR 56087, 9/23/2005, as amended at 72 FR 55682, 10/1/2007; 76 FR 56310, 9/13/2011