which has proved difficult and time consuming. This paper attempts to outline some of the difficulties and uncertainties that still exist.

Several fields contribute data relevant to LCA in the pulp and paper industry. These include forestry (e.g., carbon studies of balance and sustainability), pulp and paper, and recycling (e.g., studies of fiber balance and energy-carbon dioxide); and economics (e.g., supply-demand and import-export studies). In preparing this brief review, several publications in these fields and on LCA were consulted in forestry (Adger et al., 1992; Alban and Perala, 1992; Dewar, 1990; Harmon et al., 1990; Nilsson, 1992; Sedjo, 1989; Squire et al., 1991; and Sullivan, 1992), economics ( Australian Industry Commission, 1991; James and O'Neill, 1992; Pease, 1992; Wiseman, 1993; and Westernbarger et al., 1991), and in life cycle analysis (Assies, 1991; Boustead, 1990; Boustead and Hancock, 1981; Fecker, 1992; Grant, 1992; Kirkpatrick, 1992; and Lübkert et al., 1991).

One factor governing the acceptability of LCAs is how much the individual industry market sectors are detailed in the study. Too much detail tends to obscure the major issues, whereas too much aggregation will produce a meaningless result. For instance, an overall model of the paper industry, such as that used by Hamm and Göttsching in their German study (1993), is unlikely to satisfy many of the specific environmental questions. Similarly, Wiseman's (1993) model of recycling in the United States fails to distinguish sufficient market sectors for it to be anything more than a crude economic tool.

Different sectoral recycling scenarios and major cross-sectoral flows in the recycling streams define minimum levels of disaggregation. The pulp and paper industry is realizing that sectoral LCA differences allow sectors to be isolated and targeted by its opponents. Hence for technical, commercial, and political reasons, there is an urgent need to ensure that the level of disaggregation is just sufficient to answer the potential queries. Studies from the international literature have varied from treating paper as a single product (Figure 1) (Hamm and Göttsching, 1993; Wiseman, 1993) to having 34 product classifications (Table 1) (Clifford et al., 1978). In Australia, there is some basic information on intersectoral fiber flows based on a five-product model that includes packaging and industrial papers, newsprint, printing and writing paper (mechanical pulp base), printing and writing paper (chemical pulp base), and tissues (B. La Fontaine, personal communication, 1992).

Some CO₂-energy studies have also been carried out on a four-product sector basis (B. La Fontaine, personal communication, 1992). Individual companies may have developed predictive models for commercial purposes that analyze