The University of Manchester has since 1999 been preparing Sustainability Impact Assessments (SIA).
Frequently Asked Questions are available, http://europa.eu.int/comm/trade/issues/global/sia/faqs.htm
IISD has described the process, http://www.iisd.org/trade/handbook/6_2.htm

The latest SIA is on the Doha Development Agenda (DDA), http://www.sia-trade.org/wto/final%20report%20page.shtml

A 68-page handbook on the SIA process is almost ready for wider publication, but now is only in MS doc format, trade-info.cec.eu.int/doclib/docs/2005/april/tradoc_122363.doc