Another chemical group present in tobacco leaves is
coumarins. Gasparotto Jr et al. (2005) showed that
coumarins have significant molluscicidal activity against
Biomphalaria glabrata. Our results confirmed the presence
of coumarins and we believe that this chemical group accounts
for the toxicity in H. aspersa after 72 h, when 50%
of the snails exposed to tobacco leaves died (data not
shown). Overall, coumarins are not genotoxic, and both
negative and positive responses have been reported for
these compounds in the Ames test, sister chromatid exchange
(SCE), MN and chromosome aberration tests in
mammalian cells (Lake, 1999).