Food loss and waste
Food loss and waste is food that is not eaten. The causes of food waste or loss are numerous and occur throughout the food system, during production, processing, distribution, retail and food service sales, and consumption. Overall, about one-third of the world's food is thrown away. A 2021 metaanalysis that did not include food lost during production, by the United Nations Environment Programme found that food waste was a challenge in all countries at all levels of economic development. The analysis estimated that global food waste was 931 million tonnes of food waste (about  121 kg per capita) across three sectors: 61 per cent from households, 26 per cent from food service and 13 per cent from retail. Food loss and waste is a major part of the impact of agriculture on climate change (it amounts to 3.3 billion tons of CO emissions annually) and other environmental issues. Moreover, food waste that is not handled or reclaimed properly, i.e. through composting, can have many negative environmental consequences. For example, landfill gas from anaerobic digestion of organic matter is a major source of the greenhouse gas methane, and unreclaimed phosphorus in food waste, leads to  further phosphate mining. Moreover, reducing food waste in all parts of the food system is an important part of reducing the environmental impact of agriculture, by reducing the total amount of water, land, and other resources used. The UN's Sustainable Development Goal Target 12.3 seeks to "halve global per capita food waste at the retail and consumer levels and reduce food losses along production and supply chains, including post-harvest losses" by 2030. Climate change mitigation strategies prominently feature reducing food waste. Definition. Food loss and waste occurs at all stages of the food supply chain – production, processing, sales , and consumption. Definitions of what constitutes food loss versus food waste or what parts of foods (i.e., inedible parts) exit the food supply chain are considered lost or wasted vary. Terms are often defined on a situational basis (as is the case more generally with definitions of waste). Professional bodies, including international organizations, state governments, and secretariats may use their own definitions. United Nations. The Food and Agriculture Organization (FAO) of the United Nations defines food loss and waste as the decrease in quantity or quality of food along the food supply chain. Within this framework, UN Agencies distinguish loss  and waste at two different stages in the process: Important components of this definition include: Under Sustainable Development Goal 12, the Food and Agriculture Organization is responsible for measuring food loss, while the UN Environmental Program measures food waste. European Union. In the European Union (EU), food waste was defined as "any food substance, raw or cooked, which is discarded, or intended or required to be discarded" since 1975 until 2000 when the old directive was repealed by Directive 2008/98/EC, which has no specific definition of food waste. The directive, 75/442/EEC, containing this definition was amended in 1991  (91/156) with the addition of "categories of waste" (Annex I) and the omission of any reference to national law. United States. The United States Environmental Protection Agency defines food waste for the United States, such as "uneaten food and food preparation wastes from residences and commercial establishments such as grocery stores, restaurants, produce stands, institutional cafeterias and kitchens, and industrial sources like employee lunchrooms". The states remain free to define food waste differently for their purposes, though many choose not to. According to the Natural Resources Defense Council, Americans throw away up to 40% of food that is safe to  eat. Other definitions. The inclusion of food that goes to nonfood productive use in definitions of food waste, such as that of the EU an earlier definition from the Food and Agriculture Organization (before its 2019 revision), come under criticism. According to the authors of one study, this is flawed for two reasons: "First, if recovered food is used as an input, such as animal feed, fertilizer, or biomass to produce output, then by definition it is not wasted. However, there might be economic losses if the cost of recovered food is higher than the average cost of inputs in  the alternative, nonfood use. Second, the definition creates practical problems for measuring food waste because the measurement requires tracking food loss in every stage of the supply chain and its proportion that flows to nonfood uses." The authors of the study argue that only food that ends up in landfills should be counted as food waste. Sources. Production. In the US, food loss can occur at most stages of the food industry and in significant amounts. In subsistence agriculture, the amounts of food loss are unknown, but are likely to be insignificant by comparison, due to the limited stages at  which loss can occur, and given that food is grown for projected need as opposed to a global marketplace demand. Nevertheless, on-farm losses in storage in developing countries, particularly in African countries, can be high although the exact nature of such losses is much debated. In the food industry of the United States, the food supply of which is the most diverse and abundant of any country in the world, loss occurs from the beginning of food production chain. From planting, crops can be subjected to pest infestations and severe weather, which cause losses before harvest. Since natural forces  (e.g. temperature and precipitation) remain the primary drivers of crop growth, losses from these can be experienced by all forms of outdoor agriculture. On average, farms in the United States lose up to six billion pounds of crops every year because of these unpredictable conditions. According to the IPCC sixth assessment report, encouraging the development of technologies that address issues in food harvesting and post-harvesting could have a significant impact on decreasing food waste in the supply chain early-on. The use of machinery in harvesting can cause loss, as harvesters may be unable to discern between ripe and  immature crops, or collect only part of a crop. Economic factors, such as regulations and standards for quality and appearance, also cause food waste; farmers often harvest selectively, preferring to leave crops not to standard in the field (where they can be used as fertilizer or animal feed), since they would otherwise be discarded later. This method of removing undesirable produce from harvest collection, distribution sites and grocery stores is called culling. However, usually when culling occurs at the production, food processing, retail and consumption stages, it is to remove or dispose of produce with a strange or imperfect appearance  rather than produce that is spoiled or unsafe to eat. In urban areas, fruit and nut trees often go unharvested because people either do not realize that the fruit is edible or they fear that it is contaminated, despite research which shows that urban fruit is safe to consume. Food processing. Food loss continues in the post-harvest stage, but the amounts of post-harvest loss involved are relatively unknown and difficult to estimate. Regardless, the variety of factors that contribute to food loss, both biological/environmental and socio-economical, would limit the usefulness and reliability of general figures. In  storage, considerable quantitative losses can be attributed to pests and micro-organisms. This is a particular problem for countries that experience a combination of heat (around 30 °C) and ambient humidity (between 70 and 90 per cent), as such conditions encourage the reproduction of insect pests and micro-organisms. Losses in the nutritional value, caloric value and edibility of crops, by extremes of temperature, humidity or the action of micro-organisms, also account for food waste. Further losses are generated in the handling of food and by shrinkage in weight or volume. Some of the food loss produced by  processing can be difficult to reduce without affecting the quality of the finished product. Food safety regulations are able to claim foods that contradict standards before they reach markets. Although this can conflict with efforts to reuse food loss (such as in animal feed), safety regulations are in place to ensure the health of the consumer; they are vitally important, especially in the processing of foodstuffs of animal origin (e.g. meat and dairy products), as contaminated products from these sources can lead to and are associated with microbiological and chemical hazards. Retail. Packaging protects food from damage during its transportation  from farms and factories via warehouses to retailing, as well as preserving its freshness upon arrival. Although it avoids considerable food waste, packaging can compromise efforts to reduce food waste in other ways, such as by contaminating waste that could be used for animal feedstocks with plastics. In 2013, the nonprofit Natural Resources Defense Council (NRDC) performed research that suggests that the leading cause of food waste in America is due to uncertainty over food expiration dates, such as confusion in deciphering best-before, sell-by, or use-by dates. Joined by Harvard's Food Law and Policy Clinic, the  NRDC produced a study called "The Dating Game: How Confusing Food Date Labels Leads to Food Waste in America". This United States-based study looked at the intertwining laws which lead labeling to end up unclear and erratic. This uncertainty leads to consumers to toss food, most often because they think the food may be unsafe or misunderstand the labeling on the food completely. Lack of regulation on labeling can result in large quantities of food being removed from the market overall. Retail stores throw away large quantities of food. Usually, this consists of items that have reached either their  best-before, sell-by, or use-by dates. Food that has passed the best -before, and sell-by date, and even some food that passed the use-by date is still edible at the time of disposal, but stores have widely varying policies to handle the excess food. Some stores put effort into preventing access to poor or homeless people, while others work with charitable organization to distribute food. Retailers also contribute to waste as a result of their contractual arrangements with suppliers. Failure to supply agreed quantities renders farmers or processors liable to have their contracts cancelled. As a  consequence, they plan to produce more than actually required to meet the contract, to have a margin of error. Surplus production is often simply disposed of. Retailers usually have strict cosmetic standards for produce, and if fruits or vegetables are misshapen or superficially bruised, they are often not put on the shelf. In the United States, an estimated six billion pounds of produce are wasted each year because of its appearance. The USDA publishes guidelines used as a baseline assessment by produce distributors, grocery stores, restaurants and other consumers in order to rate the quality of food. These guidelines and  how they rate are readily available on their website. For example, apples get graded by their size, color, wax residue, firmness, and skin appearance. If apples rank highly in these categories and show close to no superficial defects, they are rated as "U.S. Extra Fancy" or "U.S. Fancy", these are the typical ratings sought out by grocery stores when purchasing their produce. Any apples with suboptimal levels of appearance are ranked as either "U.S. Number 1" or "Utility" and are not normally purchased for retail, as recommended by produce marketing sources, despite being safe and edible. A number of regional  programs and organizations have been established by the EPA and USDA in an attempt to reduce such produce waste. Organizations in other countries, such as Good & Fugly in Australia and No Food Waste in India, are making similar efforts worldwide. The fishing industry wastes substantial amounts of food: about 40–60% of fish caught in Europe is discarded as the wrong size or wrong species. This comes to about 2.3 million tonnes per annum in the North Atlantic and the North Sea. Consumption. Consumers are directly and indirectly responsible for wasting a lot of food, which could for a large part  be avoided if they were willing to accept suboptimal food (SOF) that deviates in sensory characteristics (odd shapes, discolorations) or has a best-before date that is approaching or has passed, but is still perfectly fine to eat. Extent. Global extent. Efforts are underway by the Food and Agriculture Organization (FAO) and the United Nations Environment Programme (UNEP) to measure progress towards SDG Target 12.3 through two separate indices: the Food Loss Index (FLI) and the Food Waste Index (FWI). According to FAO's "The State of Food and Agriculture 2019", globally, in 2016, around 14 percent of the world 's food is lost from production before reaching the retail level. Generally, levels of loss are higher for fruits and vegetables than for cereals and pulses. However, even for the latter, significant levels are found in sub-Saharan Africa and Eastern and South-Eastern Asia, while they are limited in Central and Southern Asia. Estimates from UN Environment's Food Waste Index suggest that about 931 million tonnes of food, or 17 percent of total food available to consumers in 2019, went into the waste bins of households, retailers, restaurants and other food services. Earlier estimates. In 2011, an FAO  publication based on studies carried out by The Swedish Institute for Food and Biotechnology (SIK) found that the total of global amount of food loss and waste was around one third of the edible parts of food produced for human consumption, amounting to about per year. As the following table shows, industrialized and developing countries differ substantially. In developing countries, it is estimated that 400–500 calories per day per person are wasted, while in developed countries 1,500 calories per day per person are wasted. In the former, more than 40% of losses occur at the post-harvest and processing stages , while in the latter, more than 40% of losses occur at the retail and consumer levels. The total food waste by consumers in industrialized countries () is almost equal to the entire food production in sub-Saharan Africa (). A 2013 report from the British Institution of Mechanical Engineers (IME) likewise estimated that 30–50% (or ) of all food produced remains uneaten. Individual countries. Australia. Each year in New South Wales, more than 25 million meals are delivered by charity OzHarvest from food that would otherwise be wasted. Each year, the Australian economy loses $20 billion in food waste. This has a  crucial environmental impact through the waste of resources used to produce, manufacture, package, and distribute that food. In addition, it is estimated that 7.6 million tonnes of CO is generated by the disposed food in landfills. It is also the cause of odour, leaching, and potential generation for diseases. In March 2019, the Australian ministry of the environment shared the key findings of Australia's National food waste baseline, which will facilitate the tracking of the progress towards their goal to halve Australian food waste by 2030. Many initiatives were taken by the Australian government in order to help achieve  this goal. In fact, they financed $1.2 million in organization that invest in renewable energies systems to store and transport food. They also funded more than $10 million for research on food waste reduction. Local governments have also implemented programs such as information sessions on storing food and composting, diversion of waste from restaurants and cafes from landfills to shared recycling facilities and donation of food to organization that would otherwise be wasted. Canada. In Canada, 58% of all food is wasted, amounting to 35.5 million tonnes of food per annuum. The value of this lost food is  equivalent to CA$21 billion. Such quantities of food would be enough to feed all Canadians for five months. It is estimated that about one third of this waste could be spared and sent to those in need. There are many factors that contribute to such large-scale waste. Manufacturing and processing food alone incur costs of CA$21 billion, or 4.82 million tons. Per household, it is estimated that $1,766 is lost in food loss and waste. The Government of Canada identifies three main factors contributing to household waste: (1) buying too much food and not eating it before it  spoils, (2) malfunctioning or poorly-designed packaging that does not deter spoilage rates or contamination, and (3) improper disposing of food – using garbage bins instead of those intended for organic waste. Canada, Mexico, and the United States are working together under the Commission for Environmental Cooperation in order to address the severe problem of food waste in North America. Canada specifically is working in the following ways to reduce food waste: China. In 2015 the Chinese Academy of Sciences reported that in big cities there was 17 to 18 million tons of food waste, enough to feed over 30 million  people. About 25% of the waste was staple foods and about 18% meat. In August 2020 the Chinese Communist Party general secretary Xi Jinping said the amount of food waste was shocking and distressing. A local authority campaign "Operation empty plate" () was started to reduce waste, including encouraging food outlets to limit orders to one fewer main dish than the number of customers. As of December 2020, a draft law is under consideration to penalise food outlets if they encourage or mislead customers to order excessive meals causing obvious waste, first with a warning and then fines of up to  10,000 yuan. It would allow restaurants to charge customers who leave excessive leftovers. Broadcasters who promote overeating or food waste could also be fined up to 100,000 yuan. Denmark. According to Ministry of Environment (Denmark), over 700,000 tonnes per year of food is wasted every year in Denmark in the entire food value chain from farm to fork. Due to the work of activist Selina Juul's Stop Wasting Food movement, Denmark has achieved a national reduction in food waste by 25% in 5 years (2010–2015). France. In France, approximately 1.3–1.9 million tonnes of food waste is produced every year , or between 20 and 30 kilograms per person per year. Out of the 10 million tonnes of food that is either lost or wasted in the country, 7.1 million tonnes of food wasted in the country, only 11% comes from supermarkets. Not only does this cost the French €16 billion per year, but also the negative impact on the environment is also shocking. In France, food waste emits 15.3 million tonnes of CO, which represents 3% of the country's total CO emission. In response to this issue, in 2016, France became the first country in the world to  pass a unanimous legislation that bans supermarkets from throwing away or destroying unsold food. Instead, supermarkets are expected to donate such food to charities and food banks. In addition to donating food, many businesses claim to prevent food waste by selling soon-to-be wasted products at discounted prices. The National Pact Against Food Waste in France has outlined eleven measures to achieve a food waste reduction by half by 2025. Hungary. According to the research of National Food Chain Safety Office in 2019 based on the official EU methodological framework, an average Hungarian consumer generates 68 kg food waste  annually. 49% of this amount would be avoidable. The research team (Wasteless project) replicated the study in 2019 involving 165 households. According to the data, food waste generated by the Hungarian households was estimated to be 65.5 kg per capita annually. Between the two periods, a 4% decrease was observed, despite significant economic expansion. Italy. According to REDUCE project, which produced the first baseline dataset for Italy based on official EU methodological framework, food waste is 530 g per person per week at household stage (only edible fraction); food waste in school canteens corresponds to 586 g per pupil per  week; retail food waste per capita, per year corresponds to 2.9 kg. See https://www.sprecozero.it/wp-content/uploads/2019/07/REDUCE-FINAL_SDG-12.3-ITALY_FOOD-WASTE-1.pdf Netherlands. According to a publication of Wageningen University and Research report it is estimated that in the Netherlands, between 30% and 50% of all food produced is lost or thrown away. In total, people in the Netherlands waste at least 9.5m tonnes of food per year, worth at least €4.4bn. New Zealand. Research done on household food waste in New Zealand found that larger households and households with more young people created more food waste. The average household in this case study put 40 % of food waste into the rubbish. Singapore. In Singapore, of food was wasted in 2014. Of that, were recycled. Since Singapore has limited agriculture ability, the country spent about S$14.8 billion (US$10.6 billion) on importing food in 2014. US$1.4 billion of it ends up being wasted, or 13 percent. On January 1, 2020, Singapore implemented the Zero Waste Masterplan which aims to reduce Singapore's daily waste production by 30 percent. The project also aims to extend the lifespan of the Semaku Landfill, Singapore's only landfill, beyond 2025. As a direct result of the project, food waste  dropped to 665,000 tonnes, showing a significant decrease from 2017's all-time high of 810,000 tonnes. United Kingdom. In the UK, per year of wasted food (purchased and edible food which is discarded) amounts to a cost of £10.2 billion each year. This represents costs of £250 to £400 a year per household. United States. Estimates of food waste in the United States range from 35 million tons to 103 million tons. In a study done by National Geographic in 2014, Elizabeth Royte indicated more than 30 percent of food in the United States, valued at  $162 billion annually, isn't eaten. The University of Arizona conducted a study in 2004, which indicated that 14 to 15% of United States edible food is untouched or unopened, amounting to $43 billion worth of discarded, but edible, food. In 2010, the United States Department of Agriculture has come forth with estimations from the Economic Research Service that approximates food waste in the United States to be equivalent to 141 trillion calories. USDA data from 2010 shows that 26% of fish, meat, poultry were thrown away at the retail and consumer level. Since then meat production has  increased by more than 10%. Data scientist Harish Sethu says this means that billions of animals are raised and slaughtered only to end up in a landfill. Impact on the environment. Empirical evidence at the global level on the environmental footprints for major commodity groups suggests that, if the aim is to reduce land use, the primary focus should be on meat and animal products, which account for 60 percent of the land footprint associated with food loss and waste. If the aim is to target water scarcity, cereals and pulses make the largest contribution (more than 70 percent), followed  by fruits and vegetables. In terms of greenhouse gas (GHG) emissions associated with food loss and waste, the biggest contribution is again from cereals and pulses (more than 60 percent), followed by roots, tubers and oil-bearing crops. However, the environmental footprint for different commodities also varies across regions and countries, due, among other things, to differences in crop yields and production techniques. According to the IPCC 6th Assessment Report, the reduction of food waste would be beneficial for improving availability of resources such as "water, land-use, energy consumption" and the overall reduction of greenhouse gas emissions into the  atmosphere. Reduction. According to FAO's The State of Food and Agriculture 2019, the case for reducing food loss and waste includes gains that society can reap but which individual actors may not take into account, namely: (i) increased productivity and economic growth; (ii) improved food security and nutrition; and (iii) mitigation of environmental impacts of losing and wasting food, in particular terms of reducing greenhouse gas (GHG emissions as well as lowering pressure on land and water resources. The last two societal gains, in particular, are typically seen as externalities of reducing food loss and waste. Response to the  problem of food waste at all social levels has varied hugely, including campaigns from advisory and environmental groups, and concentrated media attention on the subject. Consumer marketing. One way of dealing with food waste is to reduce its creation. Consumers can reduce spoilage by planning their food shopping, avoiding potentially wasteful spontaneous purchases, and storing foods properly (and also preventing a too large buildup of perishable stock). Widespread educational campaigns have been shown to be an effective way to reduce food waste. A British campaign called "Love Food, Hate Waste" has raised awareness about preventative measures to address food waste  for consumers. Through advertisements, information on food storage and preparation and in-store education, the UK observed a 21% decrease in avoidable household food waste over the course of 5 years. Another potential solution is for "smart packaging" which would indicate when food is spoiled more precisely than expiration dates currently do, for example with temperature-sensitive ink, plastic that changes color when exposed to oxygen, or gels that change color with time. An initiative in Curitiba, Brazil called Cambio Verde allows farmers to provide surplus produce (produce they would otherwise discard due to too low prices) to people that  bring glass and metal to recycling facilities (to encourage further waste reduction). In Europe, the Food Surplus Entrepreneurs Network (FSE Network), coordinates a network of social businesses and nonprofit initiatives with the goal to spread best practices to increase the use of surplus food and reduction of food waste. An overarching consensus exists on the substantial environmental benefits of food waste reduction. On the other hand, one study looking at food waste reduction measures in the United Kingdom found that rebound effect may cause substitutive consumption as a result of economic savings made from food waste prevention. They estimated that  a reduction of one tonne of food waste could lead to substantial reductions in GHG emissions, in the order of 706–896 kg CO2-eq. Rebound effect may however reduce such GHG savings by up to 60%. Collection. In areas where the waste collection is a public function, food waste is usually managed by the same governmental organization as other waste collection. Most food waste is combined with general waste at the source. Separate collections, also known as source-separated organics, have the advantage that food waste can be disposed of in ways not applicable to other wastes. In the United  States, companies find higher and better uses for large commercial generators of food and beverage waste. From the end of the 19th century through the middle of the 20th century, many municipalities collected food waste (called "garbage" as opposed to "trash") separately. This was typically disinfected by steaming and fed to pigs, either on private farms or in municipal piggeries. Separate curbside collection of food waste is now being revived in some areas. To keep collection costs down and raise the rate of food waste segregation, some local authorities, especially in Europe, have introduced "alternate weekly collections" of biodegradable waste  (including, e.g., garden waste), which enable a wider range of recyclable materials to be collected at reasonable cost, and improve their collection rates. However, they result in a two-week wait before the waste will be collected. The criticism is that particularly during hot weather, food waste rots and stinks, and attracts vermin. Waste container design is therefore essential to making such operations feasible. Curbside collection of food waste is also done in the U.S., some ways by combining food scraps and yard waste together. Several states in the U.S. have introduced a yard waste ban, not accepting leaves, brush , trimmings, etc. in landfills. Collection of food scraps and yard waste combined is then recycled and composted for reuse. Disposal. As alternatives to landfill, food waste can be composted to produce soil and fertilizer, fed to animals or insects, or used to produce energy or fuel. Some wasted fruit parts, can also be biorefined to extract useful substances for the industry (i.e. succinic acid from orange peels, lycopene from tomato peels). Landfills and greenhouse gases. Dumping food waste in a landfill causes odour as it decomposes, attracts flies and vermin, and has the potential to add biological oxygen demand (BOD ) to the leachate. The European Union Landfill Directive and Waste Regulations, like regulations in other countries, enjoin diverting organic wastes away from landfill disposal for these reasons. Starting in 2015, organic waste from New York City restaurants will be banned from landfills. In countries such as the United States and the United Kingdom, food scraps constitute around 19% of the waste buried in landfills, where it biodegrades very easily and produces methane, a powerful greenhouse gas. Methane, or CH, is the second most prevalent greenhouse gas that is released into the air, also produced by landfills in the U.S. Although  methane spends less time in the atmosphere (12 years) than CO, it's more efficient at trapping radiation. It is 25 times greater to impact climate change than CO in a 100-year period. Humans accounts over 60% of methane emissions globally. Fodder and insect feed. Large quantities of fish, meat, dairy and grain are discarded at a global scale annually, when they can be used for things other than human consumption. The feeding of food scraps or slop to domesticated animals such as pigs or chickens is, historically, the most common way of dealing with household food waste. The  animals turn roughly two thirds of their ingested food into gas or fecal waste, while the last third is digested and repurposed as meat or dairy products. There are also different ways of growing produce and feeding livestock that could ultimately reduce waste. Bread and other cereal products discarded from the human food chain could be used to feed chickens. Chickens have traditionally been given mixtures of waste grains and milling by-products in a mixture called chicken scratch. As well, giving table scraps to backyard chickens is a large part of that movement's claim to sustainability, though not  all backyard chicken growers recommend it. Ruminants and pigs have also been fed bakery waste for a long time. Certain food waste (such as flesh) can also be used as feed in maggot farming. The maggots can then be fed to other animals. In China, some food waste is being processed by feeding it to cockroaches. Also, black soldier fly larvae can be grown on food waste. Composting. Food waste can be biodegraded by composting, and reused to fertilize soil. Composting is the aerobic process completed by microorganisms in which the bacteria break down the food waste into simpler organic  materials that can then be used in soil. By redistributing nutrients and high microbial populations, compost reduces water runoff and soil erosion by enhancing rainfall penetration, which has been shown to reduce the loss of sediment, nutrients, and pesticide losses to streams by 75–95%. Composting food waste leads to a decrease in the quantity of greenhouse gases released into the atmosphere. In landfills, organic food waste decomposes anaerobically, producing methane gas that is emitted into the atmosphere. When this biodegradable waste is composted, it decomposes aerobically and does not produce methane, but instead produces organic compost that can then be  utilized in agriculture. Recently, the city of New York has begun to require that restaurants and food-producing companies begin to compost their leftover food. Another instance of composting progress is a Wisconsin-based company called WasteCap, who is dedicated towards aiding local communities create composting plans. Municipal Food Waste (MFW) can be composted to create this product of organic fertilizer, and many municipalities choose to do this citing environmental protection and economic efficiency as reasoning. Transporting and dumping waste in landfills requires both money and room in the landfills that have very limited available space. One municipality who chose  to regulate MFW is San Francisco, who requires citizens to separate compost from trash on their own, instituting fines for non-compliance at $100 for individual homes and $500 for businesses. The city's economic reasoning for this controversial mandate is supported by their estimate that one business can save up to $30000 annually on garbage disposal costs with the implementation of the required composting. Home composting. Composting is an economical and environmentally conscious step many homeowners could take to reduce their impact on landfill waste. Instead of food scraps and spoiled food taking up space in  trashcans or stinking up the kitchen before the bag is full, it could be put outside and broken down by worms and added to garden beds. Anaerobic digestion. Anaerobic digestion produces both useful gaseous products and a solid fibrous "compostable" material. Anaerobic digestion plants can provide energy from waste by burning the methane created from food and other organic wastes to generate electricity, defraying the plants' costs and reducing greenhouse gas emissions. The United States Environmental Protection Agency states that the use of anaerobic composting allows for large amounts of food waste to avoid the landfills. Instead of producing these  greenhouse gasses into the environment from being in a landfill, the gasses can alternatively be harnessed in these facilities for reuse. Since this process of composting produces high volumes of biogas, there are potential safety issues such as explosion and poisoning. These interactions require proper maintenance and personal protective equipment is utilized. Certain U.S. states, such as Oregon, have implemented the requirement for permits on such facilities, based on the potential danger to the population and surrounding environment. Food waste coming through the sanitary sewers from garbage disposal units is treated along with other sewage and contributes to sludge. Commercial  liquid food waste. Commercially, food waste in the form of wastewater coming from commercial kitchens' sinks, dishwashers and floor drains is collected in holding tanks called grease interceptors to minimize flow to the sewer system. This often foul-smelling waste contains both organic and inorganic waste (chemical cleaners, etc.) and may also contain hazardous hydrogen sulfide gases. It is referred to as fats, oils, and grease (FOG) waste or more commonly "brown grease" (versus "yellow grease", which is fryer oil that is easily collected and processed into biodiesel) and is an overwhelming problem, especially in the US, for the aging  sewer systems. Per the US EPA, sanitary sewer overflows also occur due to the improper discharge of FOGs to the collection system. Overflows discharge – of untreated wastewater annually into local waterways, and up to 3,700 illnesses annually are due to exposure to contamination from sanitary sewer overflows into recreational waters.