While LCA characterizes emissions and waste over a product's life cycle, it does not allow for a complete assessment of a product's potential impacts, also sometimes referred to as its "safety profile" or its "risk assessment." This is because risk assessments evaluates the actual risk to the environment (or human) as the result of a specific exposure in a specific situation (such as the effects of the presence of a detergent residue in surface waters), whereas Life Cycle Assessments report and analyse the emissions from across all lifecycle phases, normalised on a chosen functional unit basis (i.e., amount of emissions per 1000 wash cycles or per 1 kg finished product).
In addition to risk assessments, LCA is one of the tools in our toolbox for assessing and improving P&G products, packaging and processes. An LCA does not consider exposure such as the concentration of a chemical in an environmental compartment (expressed in mg/l), which is critical for assessing risk. An LCA quantifies emissions as a mass (g or kg). The actual impacts of those emissions depend on when, where and how they are released into the environment, and these are elements of a risk assessment. The exposure and hazard assessments, required as input for the risk assessments, are then not part of the LCA. For each type of emission, the probability of adverse impacts can be quantified by risk assessment, taking into account all sources of exposure.
LCA was not designed to do that, but rather it was designed to understand the relative contribution of each stage of the life cycle to certain environmental impact categories. LCA also allows comparisons between equivalent stages of life cycles (i.e., the consumer stage of product A and the consumer stage of product B), provided that the Life Cycle Inventories (LCIs) rely on the same databases and the same assumptions.
Thus, even though LCA cannot tell us whether the use of a product is "safe," it does provide us with "indicators" concerning impact assessment scores of the relative contributions of entire or partial product life cycles to specified impact categories.
As such, it can be a powerful aid for the risk manager in business or in government, which is needed to decide which exposures should be managed first and to communicate this effectively to diverse audiences.
Depending on the goal of the study, the level of detail of an LCA may vary considerably. If it is for internal and screening purposes, the quality of the data may be less scrutinized (or less important) than if the work is going to be used for external claims. For external claims, P&G feels that full compliance with ISO guidelines is a must.