The critical review of life cycle assessment studies according to ISO 14040 and 14044

The revision of the ISO LCA (life cycle assessment) standards in October 2006 brought some changes of the critical review process compared to the older series ISO 14040-43 (1997, 1998, 2000a, b). Furthermore, the importance of LCA has grown rapidly in recent years, but this growth was not accompanied by a corresponding increase of knowledge about the voluntary and obligatory review processes. It is the intention of this paper to analyse the relevant standards and to present some personal experiences in conducting critical reviews. A peer review for LCA studies was first proposed in the Society of Environmental Toxicology and Chemistry (SETAC) guidelines "A Code of Practice" (1993). The ISO standard 14040 (1997) took up this proposition and described three types of "Critical review" which are optional in general, but mandatory "for LCA studies used to make a comparative assertion that is disclosed to the public". This strong prescription was reinforced in the revised standards ISO 14040 and 14044 (2006a, b) and even stricter, unambiguous formulations were added to the text. In addition, the minimum number of experts in a "review by interested parties" is now three (including the chair). Large panels with more than four experts are rare, but do occur occasionally. Out of personal experience, I strongly support the interactive (accompanying) mode of conducting the critical review process (ISO also allows the "a posteriori" mode). I also suggest the removal of some inconsistencies during the next update of the standards. No major changes are recommended, however, since ISO 14040 + 14044 has become the reference standard for several other international standards based on the life cycle concept.