After assuming the nova rate of the Galaxy to be a constant over a Hubble time, the above estimates of the masses of the nova shells, coupled with a galactic nova rate of 25 outbursts per year (Della Valle and Livio 1994, A&A, 286, 786), imply that are processed through the ejecta over the lifetime of the Galaxy. These figures have to be compared with the mass of interstellar/dust content of Milky Way, which is . It follows that only nuclei enriched by a factor in nova ejecta, such as 13C, 15N, 17O, can contribute significantly to the nucleosynthesis of galaxies. This fact could have some cosmological interest too, since novae are believed to be producers of 7Li with enrichments larger than a factor 100 (Norgaard and Arnould 1975, A&A, 40, 331; Starrfield et al. 1978, ApJ, 222, 600, Greggio & Matteucci 199, A&A, ), and therefore, at least in principle, they might be a source of contamination for the primordial Lithium.