  A representative sample of unevolved early B-type stars in nearby OB
associations and the field is analysed to unprecedented precision using NLTE
techniques. The resulting chemical composition is found to be more metal-rich
and much more homogeneous than indicated by previous work. A rms scatter of
~10% in abundances is found for the six stars (and confirmed by six evolved
stars), the same as reported for ISM gas-phase abundances. A cosmic abundance
standard for the present-day solar neighbourhood is proposed, implying mass
fractions for hydrogen, helium and metals of X=0.715, Y=0.271 and Z=0.014. Good
agreement with solar photospheric abundances as reported from recent 3D
radiative-hydrodynamical simulations of the solar atmosphere is obtained. As a
first application we use the cosmic abundance standard as a proxy for the
determination of the local ISM dust-phase composition, putting tight
observational constraints on dust models.
