To link environmental impacts to the 332 commodity foods in FCID, we followed a four-step
process (see table1 ). First, we used data from
original research on specific foods inventoried in the literature review, as described above.
The mean, standard deviation, minimum and maximum values for CED and GHGE at farm gate and at
processor gate were calculated for each specific food, and then matched to the FCID. Studies of
heated greenhouse vegetable production or those of beef from dairy herds were not included in
our averages because information on market share of these production methods is unavailable or
unreliable. Second, if we did not have an original research report on an FCID food, we turned
to reports with previously-compiled food LCA data to supply environmental impacts [23 –29 (link)]. These resources contained data not captured in the literature review, perhaps due
to non-English language reports or proprietary sources. Overall, for stage 1 and 2 of the
linkage process, CED matches were made for 35% of the food commodities, and GHGE matches for
47%. Third, remaining FCID foods were populated with values from similar foods as proxies.
Specifically, we took an average of either CED or GHGE values from existing entries within a
specific food grouping (e.g. berries, brassicas, brassica greens, citrus, fresh herbs, grains,
other greens, nuts, roots, dried spices, other tree fruit, tropical fruit) to proxy for a
specific food item in that same grouping that was lacking data. Failing this approach, other
proxies of foods with similar form were then assigned. These assignments were based on
similarities of specific crops in their botany and, most importantly, production methods, as
determined by the expertise of our research team. Values that were assigned from other foods in
the database in this third stage accounted for 50% of CED values and 39% of GHGE values.
Fourth, the FCID dataset includes minimally processed forms of fruits and vegetables (e.g.
strawberry juice, dried apples). Where direct LCA matches were not available for these forms,
we applied a mass conversion factor, gathered from nutritional databases [30 , 31 ], to the
base fruit or vegetable in order to approximate the agricultural production burdens of these
processed forms. This stage accounted for the remaining 15% of CED and 15% of GHGE values for
FCID foods. For juices, vinegar and maple syrup, additional sources were used to develop valid
estimates. These additions are detailed in supporting information.
Because of the inconsistency in full life cycle boundary conditions across the literature
review entries, cradle-to-farm gate impact factors were chosen for the vast majority of foods.
This choice is further supported by the fact that these commodity foods, in many cases, become
ingredients in processed, as-consumed foods, and inclusion of life cycle stages downstream from
the farm gate would not necessarily reflect impacts of the actual foods consumed. The
exceptions to this farm gate boundary condition are foods within the FCID listing that require
processing: flours, refined sugars, vegetable oils, etc supporting information contains
additional details on these boundary condition choices, as well as an environmentally extended
input-output based estimate of the cumulative food processing impacts excluded in this
analysis.
process (see table
original research on specific foods inventoried in the literature review, as described above.
The mean, standard deviation, minimum and maximum values for CED and GHGE at farm gate and at
processor gate were calculated for each specific food, and then matched to the FCID. Studies of
heated greenhouse vegetable production or those of beef from dairy herds were not included in
our averages because information on market share of these production methods is unavailable or
unreliable. Second, if we did not have an original research report on an FCID food, we turned
to reports with previously-compiled food LCA data to supply environmental impacts [23 –29 (link)]. These resources contained data not captured in the literature review, perhaps due
to non-English language reports or proprietary sources. Overall, for stage 1 and 2 of the
linkage process, CED matches were made for 35% of the food commodities, and GHGE matches for
47%. Third, remaining FCID foods were populated with values from similar foods as proxies.
Specifically, we took an average of either CED or GHGE values from existing entries within a
specific food grouping (e.g. berries, brassicas, brassica greens, citrus, fresh herbs, grains,
other greens, nuts, roots, dried spices, other tree fruit, tropical fruit) to proxy for a
specific food item in that same grouping that was lacking data. Failing this approach, other
proxies of foods with similar form were then assigned. These assignments were based on
similarities of specific crops in their botany and, most importantly, production methods, as
determined by the expertise of our research team. Values that were assigned from other foods in
the database in this third stage accounted for 50% of CED values and 39% of GHGE values.
Fourth, the FCID dataset includes minimally processed forms of fruits and vegetables (e.g.
strawberry juice, dried apples). Where direct LCA matches were not available for these forms,
we applied a mass conversion factor, gathered from nutritional databases [30 , 31 ], to the
base fruit or vegetable in order to approximate the agricultural production burdens of these
processed forms. This stage accounted for the remaining 15% of CED and 15% of GHGE values for
FCID foods. For juices, vinegar and maple syrup, additional sources were used to develop valid
estimates. These additions are detailed in supporting information.
Because of the inconsistency in full life cycle boundary conditions across the literature
review entries, cradle-to-farm gate impact factors were chosen for the vast majority of foods.
This choice is further supported by the fact that these commodity foods, in many cases, become
ingredients in processed, as-consumed foods, and inclusion of life cycle stages downstream from
the farm gate would not necessarily reflect impacts of the actual foods consumed. The
exceptions to this farm gate boundary condition are foods within the FCID listing that require
processing: flours, refined sugars, vegetable oils, etc supporting information contains
additional details on these boundary condition choices, as well as an environmentally extended
input-output based estimate of the cumulative food processing impacts excluded in this
analysis.
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