Here is the official NCHILB statement:
"Polybutylene plumbing supply lines (PB) are installed in the subject house. It has been used in this area for many years, but has had a higher than normal failure rate. Copper and brass fittings used in later years have reduced the failure rate. The subject house has ( circle one ) brass – copper – plastic – fittings. Polybutene plumbing pipe is an approved material in North Carolina. For further details contact 1-800-392-7591 or visit the Website Polybutylene Pipe Settlement Fund > Home"