5.2 Waste production, impacts, and management

Among the UN Sustainable Development Goals, issues of waste are covered best by the goal for responsible consumption and production. But the impacts associated with waste are relevant to several other goals, including good health and well-being and sustainable cities and communities. Waste is not directly identified in any of the planetary boundaries, but plastics – synthetic materials – contribute importantly to waste and are considered a novel entity, which is a planetary boundary at high risk. A number of hazardous wastes are or contain synthetic chemicals and so are also novel entities.

Trends in waste production

During 1960-2018, the period for which data are available, US municipal solid waste increased more than three-fold (Fig 1). Some of this increase (from 2017-2018) was mainly due to a change in the way food waste was measured.

Globally, solid waste generation varies considerably among regions, both in total volume generated and in per capita generation (Fig 2). Wealthier countries tend to produce more waste per person.^[1][2] Overall, predicted waste generation continues to increase through 2050 and to the end of the 21st century.^[3][4]

Environmental impacts of waste

Life-cycle analysis or assessment is an approach to understanding the impacts of a product throughout its existence – the phrase “cradle-to-grave” is often used. Waste impacts and impacts related to processing can occur in the acquisition of raw materials, production, use, and disposal of a product. For consumers to understand the true impacts of their purchases, they need information not only on disposability and recycling options, but on the full suite of impacts that occur during the life of a product.

Waste that is not disposed of – what we would call “litter” or “leaks” – is a form of pollution. Depending on the nature of the waste, it may pollute air, soil, and/or water. It can harm people and wildlife, and can interfere with the proper functioning of ecosystems. If it fouls waterways, it may also result in economic impacts to businesses and utilities and reduce water availability.

Uncontrolled dumping and burning are usually associated with the greatest environmental harms from waste. Open dumps produce unpleasant odors and attract pests. As hazardous materials leach out or are dissolved out by rain, the leachate percolates through the soil, polluting soil, groundwater and surface water. Trash can be blown out or carried out by scavengers, spreading toxins and infectious material over the landscape. Open burning in dumps creates greenhouse gases and other air pollution, creating new toxins by burning plastics and other synthetic materials that can carry far from the burn site. Children and others seeking useful items in the dump suffer from physical injury and exposure to air-borne and water-borne toxins including carcinogens and other harmful materials.

In more controlled settings, even well-constructed landfills may leak, especially with age, causing soil and water pollution; if they are not well constructed, then the extent of soil and water pollution will obviously be worse. All landfills are sources of methane from the decomposition of organic material. Methane is a potent greenhouse gas, which may be captured for energy or heat, or may be released to the atmosphere. In the US, in 2022, landfills were the third largest contributor of methane emissions.^[5] Landfills take up valuable space, although, if well managed after they close, the space may become available again, for some uses.

Incinerators produce substantial greenhouse-gas emissions even when well-regulated. If they are used for energy and heating, some of the emissions may be offset, but even so, they are significant contributors to global warming. Incineration is sometimes listed as a “green” waste management approach, but its global warming impacts are close to those for fossil-fuel plants, even if energy recovery is in place.^[6]

Without careful monitoring and maintenance, pollution beyond GHGs can be released. Incinerator fly ash – the solid waste that is captured from the flue emissions of the incinerator – is hazardous waste that can cause environmental harm on its own, if not properly treated and disposed of. With best-available technology, most harmful particulates and non-GHG gases can be captured – in fact, incineration is a preferred technique for disposing of many hazardous wastes.

Environmental impacts and regulation of international (transboundary) movement of hazardous waste

Concern about transboundary movement of wastes dates back to the 1980s when perhaps 10% of hazardous wastes were estimated to be shipped internationally, often from developed countries with stricter environmental controls to less-developed countries with looser environmental regulations, such as countries of Eastern Europe, Africa, and Asia.^[7] Less regulated disposal of hazardous wastes, particularly dumping in open dumps or in streams or open-air burning leads to contamination of air, soil, and water, with attendant impacts to human health and ecosystems.^[8]

Even legal transboundary movements, accompanied by payments to the receiving countries, can lead to environmental impacts if the receiving countries lack the capacity for proper disposal. Illegal movements are even more likely to lead to environmental harm. Because nations and industries may seek to reduce costs for disposal of dangerous wastes, and because some wastes include valuable, recoverable substances, so-called waste trafficking is estimated to involve billions of dollars of illegal trade.^[9]

In response to concerns about international movement of wastes, 187 nations met and developed the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal, which was adopted in 1989 and came into force in 1992. The Convention requires that movements of hazardous wastes occur only where they are permitted by relevant national laws, only when appropriate disposal facilities are available to process the waste, and only when prior informed, written consent has been obtained for the transfer. The need for appropriate facilities and prior, informed consent set standards that allow for easier policing of waste shipments.

The Convention includes the establishment of training centers to improve national capacity for appropriate disposal of hazardous wastes, as well as support for nations entering into regional and bilateral agreements for transboundary movement of waste. Amendments have been added over time, including agreements to require that movement of mixed, contaminated or hard-to-recycle plastics meet the same standards as previously defined hazardous wastes (passed in 2019 and effective in 2021).^[10]

Waste management

There is wide agreement about the preferred options for waste management (Fig 3). It is easiest to manage waste that is not produced, so reducing waste generation through reduced consumption and increased reuse is the most preferred option. Frequently mentioned methods to reduce waste include reducing use of “single-use” plastics including much packaging material, avoiding “fast fashion” clothing in favor of longer-lasting items, and working to reduce food waste. We have seen in Figure 2 that, however much reduction and reuse may occur in the near future, it is not expected to halt the increase in waste generation.

Recovery of materials or nutrients through recycling and composting is the second most preferred option, followed by energy recovery through incineration combined with heat or electricity generation and gas generation through anaerobic digestion (usually in landfills) with recovery of methane. Regulated landfills and incineration without energy capture would be less preferred. Finally, open dumping and open-air burning, such as still occur in many developing nations, are the most harmful and least preferred methods of disposal.

The Environmental Performance Index, housed in Yale’s Center for Environmental Law and Policy in the US creates an annual product that includes a Waste Management subcategory (Fig 4). The Waste Management index is computed for each nation based on volume of municipal waste generated per person (40%), recovery of energy and materials from waste (40%), and proportion of waste that treated through recycling, regulated landfill, and regulated incineration (20%). Although few countries are in the top performance category, few are in the bottom category, as well.

The maps of Figure 5 show the anticipated change in per capita solid waste generation between 2015 and 2050 – positive for almost all countries. In addition, the left-hand bars show types of waste and the right-hand bars waste treatment, for 7 countries around the world, for both years. We see high variability in reliance on uncontrolled dumps for waste management in 2015; this approach diminishes in 2050 as a proportion of waste management, although use of landfills tends to grow more than use of recycling and composting. The palette of waste management approaches is most stable over time in the US and in Europe. The anticipated proportion of organic material (from food waste and other “green” sources such as yard waste, site clearing, and landscaping) drops over time, with other wastes increasing, particularly paper. ^[11] Plastics increase as a proportion of municipal waste in all the countries shown.

Different kinds of waste are predicted to increase in quantity differently over the 21st century (Fig 6), and the methods of treating them are predicted to change over time. Production of organic wastes, which usually include a large component of food waste, is predicted to flatten out by the end of the century, as population flattens and food demand plateaus. The share of organic waste going to dumps declines, and incineration and composting increase somewhat. Paper, plastic, glass, and metal wastes are all predicted to increase throughout the 21st century, with increasing amounts of recycling. However, recycling is not predicted to become the primary means of treatment for any of these wastes, and only clearly rises above 30% for metal. Overall, landfills remain the primary means of treatment throughout the century.

Note that Chen et al. (2020) did not quantify waste treated by open burning.

Plastic waste

Plastic wastes are of particular concern in the waste stream because they do not decompose, they produce toxic chemicals when burned, they leach toxic chemicals when they are repeatedly wetted in uncontrolled dumps. As they degrade over time, they produce microplastics, which are everywhere in the environment and in all kinds of organisms – able to cross the placental barrier, the blood-brain barrier, and enter circulatory systems through gas-exchange systems (e.g., in the lungs, in humans) and through food intake (e.g., in plankton). Discarded plastic items clog waterways, are plowed into fields, harm wildlife, and eventually degrade to microplastics that cause additional harm. UN member states agreed, in 2022, to create an international agreement to reduce plastic waste. However, efforts to do so have failed. The most recent attempt, in the summer of 2025 failed due to the insistence of nations with large fossil-fuel and plastics industries (fossil fuels are feedstocks for plastic production) that there be no specific goals to reduce production of plastics.^[12]

For information on the oceanic “garbage patches” composed primarily of plastic pollution, but probably not the plastics you thought, visit [click] here.

For the United Nations’ Environment Programme site for plastic pollution, visit [click] here.

Plastic recycling is covered in section 5.4.

E-waste

E-wastes are electronic wastes – cell phones, monitors, computers, televisions, refrigerators, etc. The UN’s 2024 Global E-waste Monitor reported that in 2022, 62 million tonnes of e-waste was produced – the equivalent of 7.8 kg (about 17 pounds) per person for the world – and predicted that figure would rise to 82 million tonnes by 2030.^[13]

E-wastes are difficult wastes because they are mixtures of dangerous and valuable components, and they are seldom constructed to allow easy separation or recycling of those components. In the past, the developed world tended to dump e-wastes on the less-developed world, where low labor costs often made recovery of valuable components worthwhile. However, as the potential harm from uncontrolled dumping of e-wastes has become more apparent, many nations have closed their borders to e-waste. E-wastes often include toxic components such as lead and mercury, and also often include plastics. Leaching of these materials in open dumps pollutes soil, groundwater and surface water. Open burning of e-wastes creates toxins from the plastics and other components and releases lead and mercury into the atmosphere. Informal processing of e-waste with acids to recover valuable components such as gold results in soil and water pollution. Where informal recovery of valuable components is conducted in the developing world, child labor is often involved. However, so little recycling of any kind is undertaken that the Global E-waste Monitor report indicates that recycling meets only 1% of the demand for critical minerals, leading to ongoing mining and its attendant environmental harms. The report estimates that unrecovered resources in e-waste are worth US$ 62 billion.

For the World Health Organization site on e-wastes and other links, visit [click] here.

Landfills

Read here to understand how US regulated landfills are constructed and operated to minimize environmental impacts. Landfills receive many kinds of waste, including hazardous waste, and appropriate monitoring and maintenance are needed to ensure their safe use.

Incineration

Watch here to learn about the pros and cons of incineration and its place in waste management, overall. Like landfills, incinerators receive many kinds of waste, including hazardous waste, and appropriate monitoring and maintenance are needed to ensure their safe use.

Composting

Read here to understand the pros and cons of and alternatives to using composting to deal with food waste

Recycling

Recycling is discussed in section 5.4.

Knowledge Check

Take a moment to complete the short quiz below to assess your understanding of this section. Read each question carefully and refer to the section content as needed. This quiz is not graded – it’s simply an opportunity for you to reflect on what you’ve learned and reinforce key concepts.