Many vintage books have lead in both the covers (in the dyes of the fabric or leather, the printing/ink and in any decorative paints used) and pages (in the ink). While the distinction of the word “vintage” changes as the years pass (“vintage” vs. “new”, vs. “antique”) please remember that 1981 (while it seems like it was just yesterday to me at least) was already 37 years ago!
This book was positive for a very low level of lead (Pb), coming in at just 49 ppm in the pages. This is considered safe by all modern standards.
For context, modern (newly manufactured) products intended for use by children are required to be below 90 ppm lead in the paint or coating and below 100 ppm in the substrate.
As always, please let me know if you have any questions!