The Earthsure program primarily uses the US EPA’s LCIA model called TRACI.
Effective 2 July 2014 here are the relevant files
Documentation can be found at the following locations:
Bare, J. C.; Norris, G. A.; Pennington, D. W.; McKone, T., TRACI – The Tool for the Reduction and Assessment of Chemical and other environmental Impacts. Journal of Industrial Ecology 2003, 6, (3), 49-78.
Bare, J., TRACI 2.0: the tool for the reduction and assessment of chemical and other environmental impacts 2.0. Clean Technologies and Environmental Policy 2011, 13, (5).
Bare, J. C. Tool for the Reduction and Assessment of Chemical and other Environmental Impacts (TRACI), Software Name and Version Number: TRACI Version 2.1 – User’s Manual; 2012.