Nutritional, Economic, and Environmental Costs of Milk Waste in a Classroom School Breakfast Program

Abstract

Objectives. To measure fluid milk waste in a US School Breakfast in the Classroom Program and estimate its nutritional, economic, and environmental effects.

Methods. Fluid milk waste was directly measured on 60 elementary school classroom days in a medium-sized, urban district. The US Department of Agriculture nutrition database, district cost data, and carbon dioxide equivalent (CO₂e) emissions and water footprint estimates for fluid milk were used to calculate the associated nutritional, economic, and environmental costs.

Results. Of the total milk offered to School Breakfast Program participants, 45% was wasted. A considerably smaller portion of served milk was wasted (26%). The amount of milk wasted translated into 27% of vitamin D and 41% of calcium required of School Breakfast Program meals. The economic and environmental costs amounted to an estimated $274 782 (16% of the district’s total annual School Breakfast Program food expenditures), 644 893 kilograms of CO₂e, and 192 260 155 liters of water over the school year in the district.

Conclusions. These substantial effects of milk waste undermine the School Breakfast Program’s capacity to ensure short- and long-term food security and federal food waste reduction targets. Interventions that reduce waste are urgently needed.

Public health professionals and the US federal government have increasingly recognized the importance of considering sustainability effects of dietary recommendations and nutrition programs.¹ To this end, the United States committed to halving food waste over the next 15 years and specified school meal program food waste as 1 of 6 Food Waste Challenge priorities, designating research on the amount of plate waste in schools as 1 of 4 primary goals. To date, only 2 studies have quantitatively investigated food waste in the School Breakfast Program, both in universal-free Breakfast in the Classroom programs initiated prior to the Healthy Hunger-Free Kids Act.^2,3 Although both suggested that food waste in the School Breakfast Program is substantial, the observational and simulated experimental methodology used restricts the validity and generalizability of their findings.

Qualitative research in a large, urban School Breakfast in the Classroom Program identified fluid milk as a particularly troublesome source of food waste.^4,5 Because milk is nutrient-dense, resource-intensive to produce, and susceptible to spoilage and must be offered at every meal, its wastage in the School Breakfast Program has potential short- and long-term effects on food security. The objective of this study was to measure fluid milk waste in a School Breakfast in the Classroom Program and quantify its nutritional, economic, and environmental effects.

METHODS

We recruited 6 elementary schools on a first-response basis from a medium-sized, urban school district (approximately 20 schools) in the United States implementing an offer-versus-serve, universal-free School Breakfast in the Classroom Program. We recruited third and fourth grade classrooms from within consenting schools, and teachers who agreed to participate received a $50 gift card.

Data Collection

We collected data on 3 days in each classroom, May to June 2014. Research assistants counted and recorded the number of milk cartons delivered to each classroom and collected all breakfast trash on rolling carts. Milk cartons were counted and emptied into buckets, which were weighed to the nearest gram using Smart Weigh (China) digital glass food scales (5-unit modes, liquid measurement technology).

The district provided School Breakfast Program food purchasing and waste management cost data.

Data Analysis

We used the Research Electronic Data Capture program hosted at Tufts University to double-enter the data and Stata version 14 (StataCorp LP, College Station, TX) to analyze the data. The nutritional effect of milk waste was estimated as the mean absolute value for essential shortfall nutrients identified by the 2015 Dietary Guidelines for Americans (calcium, vitamin D, magnesium, potassium).¹ We calculated the economic cost of milk waste as an absolute value and proportion of the district’s total annual food- and milk-specific School Breakfast Program purchasing costs ($1 696 246 and $474 949, respectively). We calculated waste management costs attributable to milk waste on the basis of district landfill fees ($32/ton). We quantified the environmental cost of milk waste as climate change effect (carbon footprint) and natural resource investment (water footprint). Table 1 contains calculation details.

TABLE 1—

Mean Nutritional and Sustainability Effects of Fluid Milk Waste in a US School Breakfast in the Classroom Program in 6 Urban Elementary Schools: May–June 2014

	Nutritional Effecta				Sustainability Effectb,c,d
	Vitamin D, IU	Calcium, mg	Magnesium, mg	Potassium, mg	Cost, $	Greenhouse Gas Emissions, kg CO2e	Water, L
Participant per day	41.6	133.2	14.6	168.6	0.11	0.28	83
Classroom per day					2.03	4.93	1 469
District per day					1 479	3 583	1 068 112
District per year					274 782	644 893	192 260 155

Note. CO₂e = carbon dioxide equivalent. All calculations were based on observed mean daily classroom participation rates and the mean daily and annual participation rate (12 897 students per day) across a 180-day school year.

Source. Thoma et al.⁶; Mekonnen and Hoekstra 2010.⁷

^aThe nutritional effect of milk waste was quantified by multiplying the nutrient content per gram of milk by the average gram weight wasted per student.

^bThe cost of milk waste was calculated by multiplying the 2014–2015 carton price ($0.27) by the number of carton-equivalents wasted. The annual landfill cost attributable to milk waste was calculated by multiplying the total annual estimated weight of milk waste by the district’s landfill fee ($32/ton).

^cThe carbon footprint (kg CO₂e greenhouse gas emissions) associated with milk waste was calculated by multiplying the cradle-to-grave life cycle assessment estimate derived by Thoma et al.⁶ for US fluid milk consumption–adjusted School Breakfast Program functional unit and system boundaries (2.67 kg CO₂e per kg milk wasted) by the observed milk waste estimates.

^dThe water footprint was calculated by applying the combined green (precipitation), blue (surface and groundwater), and gray (required for pollutant assimilation) water resource investment estimate for US fluid milk production (796 L/kg of water) to our waste estimates.

RESULTS

Participating schools were sociodemographically representative of the district, which serves a racially/ethnically diverse, low-income student body (65% Hispanic; 90% free or reduced meal price eligible). Per US Department of Agriculture standards, milk was offered daily. Under offer-versus-serve policy, participants were not required to select milk, and unserved cartons were discarded in adherence with food safety regulations. The number of cartons offered was determined by anticipated participation and selection rates. Flavored milk was offered at the school’s discretion (2 schools).

On average, 81.5% of the students present each day were offered milk; 75% of the offered cartons were served (SD = 24; range = 0–84), 97.9% of which were opened. On average, 44.7% (SD = 19.4) of the milk offered and 25.8% (SD = 12.8) of the milk served to students was wasted, equating to an average of 7.5 carton-equivalents per classroom day.

Table 1 displays the mean absolute value of nutrients wasted and carbon and water footprints of milk waste at the individual, classroom, and district level. As a proportion of the one-quarter age-specific recommended daily allowance required to be provided by the School Breakfast Program, 41% of this value of calcium and vitamin A, 27% of vitamin D, and 24% of magnesium were diverted as waste.

The calculated cost of milk waste per participant was $0.11, or approximately $2 per classroom per day ($1.20 attributable to unserved milk). This amounted to nearly $1500 daily and $266 270 annually across the district, representing 16% of total annual School Breakfast Program food expenditures. The additional $8512 in landfill fees brought the total estimated cost of milk waste to $274 782 annually. The environmental footprint of milk waste was 0.28 kilograms of carbon dioxide equivalent (CO₂e) and 83 liters of water resources per participant per day. Milk waste per participant accounted for more than one third (41%) of a theoretical per-meal maximum sustainable CO₂e (0.68 kg CO₂e/meal)⁸ emission limit and more than one quarter (29%) of the maximum water resource limit (83 L/meal).⁹

DISCUSSION

In this study, nearly half of the fluid milk offered and approximately one quarter of the fluid milk served to students was not consumed. This district was already taking action to reduce milk waste by calibrating the number of cartons offered with expected selection. Our estimates are considerably higher than the national estimates of consumer or retail waste (32%).¹⁰ Our findings suggest that a substantial portion of milk wasted was a result of milk that was offered but not served. Possible waste mitigation strategies include preserving milk once it reaches the classroom (e.g., shelf-stable packaging, refrigeration) and aligning supply with demand (e.g., preordering, cafeteria pickup).

Milk is an excellent source of shortfall nutrients not found in other foods commonly consumed by children in the United States.¹¹ However, as studies suggested, merely offering milk, or even requiring participants to select it, does not necessarily affect consumption. Moreover, declining overall trends in fluid milk consumption in the United States and across adolescence suggest that school consumption patterns may reflect secular and home trends.¹² Exploring other food sources of nutrients provided by milk may offer an alternative means of ensuring adequate nutrient intake.

In addition to the apparent nutritional effects of milk waste found in this study, its direct economic effect warrants attention. The more than one-quarter million dollars spent on unconsumed milk in this district represents a substantial portion (almost one fifth) of School Breakfast Program spending. If School Breakfast Programs nationwide were to generate an equivalent amount of waste, this would equate to approximately $256 million in unconsumed milk nationally per year. Finally, the public health implications of the environmental effects of food waste’s avoidable contributions to greenhouse gas emissions and resource use are recognizable. On a national scale, this would equate to 489 million kilograms of CO₂e and 247 billion liters of water per year on average assuming comparable wastage rates.

Strengths of this study include direct measurement of fluid milk waste across multiple observation days in the School Breakfast in the Classroom Program operating in situ post–Healthy Hunger-Free Kids Act and comprehensive evaluation of its effect. Although mitigated to the extent possible, limitations include generalizability of findings beyond the district and grades studied and the possible influences of researcher presence and season.

PUBLIC HEALTH IMPLICATIONS

Optimizing the short-term nutritional and economic effects and long-term sustainability of the School Breakfast Program, especially among the most resource-poor districts more likely to deliver breakfast in the classroom, is important in ensuring food security for current and future generations. To this end, strategies to reduce milk waste in the Program while promoting adequate nutrient intake should be actively pursued.