Written by: Lirong Shi and Manaswini Sarangi
Editor: Sarah Kearns and Alyse Krausz
As a scientist working around scientists, we may not realize how much scientific waste we and our colleagues produce every day, just like everyone else who may not pay attention to how much household waste we produce in our kitchen. We are so used to the waste in the lab, and compared to the large garbage bin outside, we might think the small plastic bucket in the lab should be negligible. But that is not true. Accounting for only 0.1% of the population, scientists create approximately 5.5 million tons of plastic waste annually in life science alone, which accounts for approximately 2% of the plastic waste produced worldwide . The large amount of plastic waste wandering around the oceans can disrupt carbon balance, poison fish, and end up on humans’ tables. Through experiments, scientists are attempting to improve everyone’s life while also literally contributing to the detriment of the world.
By definition, waste can be either “substances or objects which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law” , or “materials that are not prime products for which the generator has no further use in terms of his/her own production, transformation or consumption and of which he/she wants to dispose” . Waste that is produced in a scientific lab is regarded as scientific waste. Even beyond scientific waste, efforts are being made to curb the amount of pollution, and as such it is very important to first understand the categories of scientific waste to know how to regulate them.
Types of scientific waste
The Occupational Safety and Health Administration (OSHA) Lab Standards have set a comprehensive set of rules that encompasses accountability, organization, safety consciousness, and education for people working in a laboratory setting. The Office of Environment, Health and Safety (EHS) takes care of implementing these standards to ensure safe practices are followed from the time chemicals and labwares enter research areas until they are disposed of. On any given day, science laboratories produce a range of scientific waste, the quantity of which varies across labs as well as across experiments within labs. This waste falls into two main categories: non-hazardous or hazardous to health.
A solvent is a substance that dissolves another substance (known as a solute), resulting in a solution. To most life science and chemistry researchers, this may seem familiar as solvents account for almost half of the total waste generated during any chemical process. Water is the most common solvent, as well as organic solvents such as methanol, ethanol, acetone, and toluene . Solvents can be used not only in a chemical synthesis, but also in all kinds of cleaning processes. Certain substances need to be treated by a particular kind of solvent. Therefore, it is not just that the solvents are in greater quantities, but a variety of them exist in relatively smaller quantities, creating complex mixtures.
What happens to these solvents next? The good news is many types of solvents are able to be isolated with minimal amounts of contaminants and that these recovered solvents may be used for cleaning reactors or sent for recycling. Because solvent mixtures can be complex, the isolation method for reuse or recycling differs depending on the property of its constituents . For instance, distillation (the action of purifying a liquid by a process of heating or cooling) can be used to separate solvents with distinct boiling points. It may result in complete or partial separation of compounds. For compounds that have similar boiling points, other methods of separation may apply.
Another non-hazardous but ubiquitous element in labs is glassware. Laboratory glassware like test-tubes, beakers, pasteur pipettes, and reagent bottles consists of a variety of borosilicate blends, which are composed of a different type of glass with more resistance to thermal shock than any other common glass. Though glass recycling follows a standard procedure that processes all household glassware, lab glassware needs to be treated differently depending on its condition. If uncontaminated with hazardous chemicals, broken lab glassware with either clear or brown glass, can be recycled  rather than getting buried (land-fill) or burnt (incinerated).
Apart from recycling, uncontaminated glassware can be reused. One of the most widely used glassware types is test-tubes: they are known to be sturdy in terms of susceptibility to breakage and durable with regard to heat resistance; however, they are mostly in an experimenter’s hand for a single use. Test-tubes are produced through a resource intensive process, and their characteristic feature of sturdiness makes them difficult to recycle. If test-tubes cannot be recycled, then they should be reused. Especially if uncontaminated and unbroken, test-tubes can easily be cleaned and reused at least once before disposal. For example, among its several initiatives for green processes, waste, and recycling, Pfizer has shown that a single reuse of test-tubes by washing them along with normal glassware saved the company > $40,000/year in production and disposal costs ! If such amounts could be saved, developing plans to capitalize on waste minimization should not only be done by companies like Pfizer but also be a part and parcel of small and large academic research laboratories.
Paper & Plastic
Research laboratories run on glass, plastic, and loads of packaging boxes of all shapes and sizes. Most institutions have a recycling program that collects and recycles uncontaminated packaging materials such as cardboard boxes, bubble wrap, foam, needle caps, bottle caps, bottles, and plastic covers. Even though many of these items may not have the traditional recycle symbol, they are certainly recyclable if not contaminated with hazardous materials, so we should deposit the appropriate ones in the nearest blue recycling bin.
The ubiquity of plastics seems to be justified due to their excellent properties for use in life sciences, such as resistance to solvents and chemicals, the (usually) lower manufacturing costs, low weight, and the almost infinite range of ways in which they can be adapted to the desired application area . However, given the aforementioned large amount of plastic waste disposed every year, which includes items like pipette tips, nitrile gloves, and cell culture flasks, it is urgent for us to think about improvements. Individuals can make a difference by reducing or recycling several pieces of plastics. The US Environmental Protection Agency (EPA) created an interactive model, iWARM, for people to “estimate how much energy you save by recycling aluminum cans, glass or plastic bottles, magazines or plastic grocery bags”, and to “also see how long those savings could power different electrical appliances”. Tools like the iWARM may inspire scientists to recycle more research materials.
Beyond paper and plastic, scientists also generate other more hazardous types of waste. We will briefly discuss here how they are categorized as described in the book Prudent Practices in the Laboratory . Here are some ground rules and awareness when it comes to dealing with hazardous wastes and how they ought to be treated differently from non-hazardous waste:
What is hazardous? According to federal law, the following properties pose hazards:
Combustible Materials – those with a liquid flash point of < 60°C, meaning that they carry the potential to cause fire. These include oxidizers or anything that can cause fire due to friction or moisture absorption under standard temperature and pressure conditions.
Corrosive materials – liquids that have a pH ≤ 2 (very acidic) or ≥ 12.5 (very basic) and/or those that can corrode steel.
Toxic materials – as per Toxicity Characteristic Leaching Procedure a leachate concentration is established above which the material is considered toxic. For example, the median lethal dose, LD50 (abbreviation for “lethal dose, 50%”), is a measure of the lethal dose of a toxin . The value of LD50 for a substance is the dose required to kill half the members of a mouse or rat population after a specified test duration. When materials exhibit an LD50 < 50 mg/kg, they are categorized as Acutely Hazardous .
Hazardous waste can be chemical, biological, radioactive or any combination of those three characteristics. Corrosive solvents like concentrated sulfuric acid, biohazardous waste like cell cultures of infectious agents, and radioactive nuclear waste are all hazardous waste.
How to determine regulatory status? The determination of whether a waste is regulated as hazardous is usually made either by the institution’s EHS staff or by employees of an institution’s waste disposal firm. The EPA has established environmentally sound management of hazardous waste from generator and identification to transportation, storage, and disposal . Usually, identification of the source or raw materials, in-lab test procedures, and analysis by EHS are required for waste characterization. Lab personnel also have the responsibility for identifying any newly synthesized hazardous substances. For off-site management, analytical methods are established by the EPA in certified or accredited environmental labs. The waste will be characterized wherever it is shipped to avoid redundant analysis, and waste disposal firms or off-site facilities often establish a waste stream profile.
What about collection containers and storage? Hazardous and/or flammable waste should always be collected in appropriate containers approved by the EHS at your respective institutions, along with proper labelling and ensuring the containers are sealed except while using it. Mixing of incompatible waste should be avoided at all times. With regards to the containers themselves, they are considered “empty” only when no more than 1 inch of waste residue is left, which can then be followed by triple rinsing that renders it free from federal regulation . Alternatively, some take a more convenient approach by treating such containers as hazardous and disposing of them accordingly.
If there are unknown chemicals in your lab that need to be categorized for appropriate waste disposal, the book Prudent Practices in the Laboratory is an excellent resource; refer to Fig 8.1 in Chapter 8  for a detailed flowchart!
How are hazardous wastes treated? Depending on the category of hazardous waste they are treated and/or recycled via various methods such as neutralization, oxidation-reduction, distillation, digestion, encapsulation, and thermal treatment . Incineration is one of the most common ways of disposing of harmful waste and is carried out in rotary kilns at 1200-1400°F . This method can be used to treat multi-hazardous waste types and results in the complete destruction of most organic materials with significantly reduced volumes of residual materials. However, due to the large volumes of fuel required for burning, incineration remains an expensive process for small scale waste disposal. Institutes can work with local waste disposal firms or other labs to avoid batch waste disposal and reduce cost.
The harm of scientific waste and how to reduce it
The large accumulation of scientific waste can cause harm to our environment and our health. Plastic waste in particular, which is designed to be long-lasting and stable, is floating in the ocean, with seabirds and whales dying after ingesting copious amounts of plastic in their habitats . And scientists have yet to map out the longer-term effects of tiny particles of plastic waste, or microplastics, that pollute terrestrial and aquatic environments and now pervade the human food supply—with unknown effects on human health . Hazardous waste, like nuclear waste, takes a tremendous toll on human health and the environment once released.
Given the potential for harm, individuals and institutions have the responsibility to take actions that will reduce the generation of scientific waste.
For the government and regulators, they should amend the existing regulations to lay more emphasis on reducing scientific waste along with recycling and recovery. The EPA regulates all household, industrial, and manufacturing solid and hazardous wastes under the Resource Conservation and Recovery Act (RCRA). RCRA’s goal is to protect us from the hazards of waste disposal and reducing both hazardous and non-hazardous waste is essential to achieving this goal. However, there are not many policies and guidance specifically about reducing scientific waste. Most documents deal with the waste aftermath, treatment, recycling, and recovery. We must have a clear goal of how much waste reduction we should achieve before we can amend the regulation appropriately.
For universities, sustainability is always the best practice. While focusing on campus sustainable acts on a day-to-day basis, we can add a specific goal for lab waste reduction particularly and set a quantitative number we want to achieve in the next decade. Safety always comes first when it comes to lab waste management, and pollution prevention and source reduction are often listed as the first principle in laboratory practices . Clearly, the best approach to laboratory waste is preventing its generation: a waste not, want not approach. Examples include “reducing the scale of laboratory operations, reducing the formation of waste during laboratory operations, and substituting non-hazardous or less hazardous chemicals in chemical procedures” . University labs should follow this kind of guidance and make improvements for a resourceful present and a better future.
For researchers, each individual who works in the lab has the responsibility to reduce the environmental impact of scientific waste. For example, we can reduce the use of single-use plastics by using more glassware repeatedly. When it is necessary to use materials made of plastics, we can still reduce the amount by carefully designing our experiments, for example, using a smaller size tube as long as it meets the need . People in charge of ordering should be mindful and make bulk orders to avoid extra packaging. To increase awareness, scientists shared pictures of themselves with all the plastic waste they generated during one day of lab work on a global Lab Waste Day on Twitter on 17 September 2019. As referred to in the #LabWasteDay results, keeping a logbook measuring how much waste we produce can help motivate us and set targets for reducing plastic waste . A chart in a C&EN article provides a perfect framework for us to decrease plastic waste in the lab . In addition to the three Rs, more ideas are brought up including “Rethink: Are biodegradable plastics a solution?” and “Replace: alternatives that use natural pulps or agricultural waste such as straw as the insulation material and more” . Those are all reminders that as scientists, it is our obligation and expertise to be creative when it comes to this waste problem!
Universities can build on researchers’ desires to reduce plastic waste by setting up sharing programs for reagents and consumables. For instance, the University of Michigan has a program through which researchers can donate extra chemicals, equipment, and other materials to other researchers at the University who may find a use for them . Research institutes and Universities could also significantly elevate their promotion levels of recycling and reuse of various categories of lab waste by rewarding researchers who actively and consciously take efforts towards mindful usage and disposal of wastes. For instance, a small step of providing recognition of such activities could potentially change the way lab researchers view waste reduction, and such encouragement could lead to many others who want to create a healthy planet through science.
Last but not least, manufacturers and producers could switch to less wasteful packaging and integrate more green science into their design process. In addition, they could also offer discounts for bulk orders and encourage reuse and recycling of the packaging materials.
Realizing the sheer amount of scientific waste we and others generate on a daily basis is eye-opening and taking actions to reduce it is a process. We have to push harder not only to reduce our own waste, but also to change the mentality of people around us and the institutions we work for. Scientists are responsible for planning their experiments thoroughly and minimizing the potential waste impact. Institutions and regulators should cooperate in this effort and highlight the importance of waste reduction along with recycling and recovery. One step at a time, we hope science can make the world a better place with less scientific waste.
Lirong Shi is a graduate student in Chemistry at University of Michigan. She is pursuing a PhD degree and a graduate certificate in Science, Technology and Public Policy (STPP). Besides lab work, Lirong has a variety of research interests, especially in science communication and diplomacy. She joined ESPA as a Public Engagement Committee member early this year and helped organize several virtual events. In her free time, Lirong likes music, piano, reading, and running around with her dog!
Manaswini is a postdoc in the Department of Molecular, Cellular and Developmental Biology at the University of Michigan. Outside research, she finds herself occupied in outreach, science communication, and visual arts. She coordinates communications across ESPA’s different initiatives, memberships, meetings, and events. She also co-chairs Postdoctoral Affairs for UMPDA where she is involved in different award initiatives for the postdoc community at the University of Michigan.
Engaging Scientists in Policy and Advocacy (ESPA) is a student organization founded in the fall of 2017, as a Rackham Interdisciplinary Workshop and a member of NSPN and UCS Allied Groups. We aim to promote the participation of scientists, engineers, and other STEM professionals in policy and advocacy. We are an interdisciplinary group of undergraduates, graduate students, postdocs, faculty, and staff at the University of Michigan, ranging from biomedical science to environmental science to health and public policy.
To join us, use this google form!
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