Patrick, the packet loss could be genuine and could be because of multiple factors as line quality, CPE issues or your side termination/aggregation device issues. You need to troubleshoot further to get to the root cause of the problem. Probably your last mile/local loop engineers should be able to help you with some integrity testing of the lines. As generally packet loss wont be there without a problem.
Although here are a few links on ICMP providing some information.
http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f22.shtml
http://www.faqs.org/rfcs/rfc792.html
HTH-Cheers,
Swaroop