  We have conducted the first dedicated spectroscopic survey of long-duration
gamma-ray burst (LGRB) host galaxies at z < 1, and use these observations along
with data from the literature to determine a wide range of ISM properties and a
statistically robust mass-metallicity relation. LGRBs have been proposed as
possible tracers of star formation at high redshift; however, such an
association is dependent on a thorough understanding of the relationship
between LGRB progenitors and their host environments. In particular, the
metallicity of LGRB host galaxies has become a matter of hot debate in recent
years. We conclude that LGRBs do exhibit a general trend toward
lower-metallicity host galaxies, but also detect several high-metallicity hosts
in our sample. We have also compared the energetic and environmental properties
of the LGRBs in our sample, and find no statistically significant correlation
between host metallicity and isotropic or beaming-corrected gamma-ray energy
release. This is at odds with previous theoretical and observational
predictions of an inverse correlation between gamma-ray energy release and host
metallicity, and demonstrates that the complex role of metallicity in LGRB
progenitor formation still remains unclear.
