Originally posted by Blue That was the FA 43 and it was allegedly changed before the 77 or 31 were released. It was either lead in the coating or the glass but the details have been sketchy. I am guessing someone like Hirakawa Jun would be the only one that could definitively answer that question regarding the 43.
The EU ROHS (Restriction of Hazardous Substances) directive prohibiting use of lead in camera lenses (among other goods) only took effect in 2006. The FA31 commenced production in 2001. It would be fair to say that all Lens manufacturers including Pentax used lens blanks that had lead before 2006, or atleast sometime between 2003 when the ROHS was agreed to in the EU and 2006, when it came into effect.
The copy of the FA31 MIJ I have was purchased in 2005, I believe there's a fair chance that my copy has leaded glass, the fact that it was bought in a non EU country, gives me more reason to believe so.