Never change a running system.

What is a sustainable method, and how can it be assessed?

Never change a running system. I am sure everybody knows this phrase. And isn't it true? Methods are established, and your whole experimental design is working, so why change anything or even think about it? But – have you ever checked if your method is sustainable? Moreover, what is a sustainable method, and how can it be assessed? 

My name is Kerstin Hermuth-Kleinschmidt; I am an independent sustainability consultant focusing strongly on labs and life sciences companies. This article discusses what defines a sustainable method and provides some ideas and hints for your daily lab work.

 

Why you should rethink your methods and experimental routines?

Every lab has established methods – that's fine because everyone is sure that the methods are working and the experiments are reliable as well as reproducible. So why change them? Besides, changing methods is time-consuming, complex and costly, and if we change one thing in our experimental routine, perhaps we have to change other things as well. On the other hand, each method also impacts the environment and other aspects, such as ethical issues, should be considered.

 

The impact of your methods.

Experiments use various reagents, consumables and further resources like energy or water. Reagents in the lab are, to a greater or lesser extent, hazardous. Consumables and single-use devices are, in most cases, made of plastic which is produced from non-renewable resources and at the end of your experiment, you must dispose of everything as waste. Thereby, laboratory waste has to be disposed of in a specific way; in most cases, it is incinerated, adding further CO2 to the atmosphere.

But even before the different ingredients you need to run your experiment enter the lab, there may be an environmental impact. Take the production of agarose gels as an example. It begins with the collection of red algae that grow on the shores of Chile, Morocco and other countries. Overharvesting of these algae, not only but also due to their use in the life sciences industry, nearly led to the extinction of these organisms. For some years, the collection has been limited, and efforts to grow these algae in aquaculture are underway. 

Horseshoe crabs, which produce a specific protein for detecting endotoxins, have the same fate. They are under threat. But there is a recombinant version of this protein, and you can help save these animals by using it. The most prominent example, FBS, is widely known for its ethical implications, and scientists working with cell cultures should do their best to switch to FBS-free media. These are just some examples, and there are many more. But for people working in the lab, the question remains – what are the criteria of a sustainable method, and how can you opt for the best one? 

 

The principles of green analytical chemistry as a guidance.

In 1998, Paul Anastas and John C. Warner published the twelve principles of green chemistry. These principles guide chemists to conduct experiments that use less energy and other resources, produce less waste, use safe and environmentally benign substances made of renewable resources, and design safe and biodegradable chemicals so that they do not accumulate in the environment. Only some years later, the analytical chemistry community took over these principles and adapted them to their needs. They published the 12 principles of analytical chemistry, which can serve as guidance also for people working in biochemistry, genomics or cell culture. 

• Principle 1: Prefer direct analytical methods and avoid sample treatment
• Principle 2: Minimize sample size and the number of samples
• Principle 3: Prefer in-situ measurements
• Principle 4: Integrate analytical processes and operations in your workflow
• Principle 5: Choose automated and miniaturized methods
• Principle 6: Avoid derivatization
• Principle 7: Avoid the generation of large volumes of analytical waste and take care of proper waste disposal
• Principle 8: Prefer multi-analyte and multi-parameter methods
• Principle 9: Reduce your energy consumption
• Principle 10: Use reagents from renewable resources
• Principle 11: Use non-toxic alternatives
• Principle 12: The operator's safety should be increased  
• Instead of remembering all the 12 principles, let's condense the most important facts to help you better decide on a more sustainable method. 

 

1.    Focus on saving and leave out the unnecessary 

First of all, start with the design of your experiment. What are the steps from the sample preparation to your desired result? Do you need a specific sample preparation method that already requires a lot of reagents and consumables, like DNA preparation? Or could you use a paper-based extraction method that saves reagents, consumables, time and money? With this protocol, you only need to lyse the bacterial cells to release the genomic DNA, which is then immobilized on a membrane and can be used directly, for example, in a PCR reaction.

How do you store your samples – at room temperature or in a freezer? A freezer is not essential as there are other ways to store DNA at room temperature. DNA can be bound to a membrane or preserved with a protective layer miming tardigrade anhydrobiosis. Trehalose and polyvinyl alcohol are the main components and help stabilize DNA during room temperature storage. Other saving tips include minor changes such as using pipette tips for the same solution, opting for master mixes or adjusting vessel sizes to your sample sizes. 

 

2.    Focus on miniaturization and reduction 

Less is better. Rethink your experimental design and see if you can minimize your sample size, the volume of your experiments and the number of samples necessary. Microextraction techniques such as liquid-liquid microextraction (LLME) or solid-phase microextraction (SPME) are good examples of miniaturization. Microextraction works in the µl range and allows substances to be specifically extracted and enriched for subsequent identification by HPLC or other detection methods. On the other hand, classical extraction techniques such as SPE, work in the ml range and require more reagents and sample material. Both ways give you reliable and reproducible results – but one with a lower environmental impact and smaller sample volumes. Another, simpler example is the dilution series for bacteria. You can use a new agar plate for each dilution or you can use a track or drop technique to make a dilution series on just one agar plate. This again saves you time, resources and money. 

 

3.    Focus on substitution and non-toxic alternatives 

Check the solvents and reagents and rely on green solvent guides. These guides sort solvents according to their environmental, health and safety (EHS) impact and help you choose the ecological and safe option. The GHS symbols on the packaging or safety data sheet give you specific information about the hazard.

A typical solvent like methanol often used to decolour Western Blottings or protein gels, can be substituted by the less hazardous ethanol. And a reagent like beta-mercaptoethanol can be replaced by the less toxic Dithiothreitol (DTT). Formamide is a typical reagent for in situ hybridization techniques. But it is also toxic and suspected to cause cancer. Ethylene carbonate is a suitable non-toxic substitution that even reduces hybridization time in some experimental designs.  

 

4.    Opt for renewable resources

Renewable resources include not only green energy. Meanwhile, solvents are being produced from renewable resources, such as ethanol, which can be used for laboratory experiments. And even some laboratory materials are at least partially made from renewable resources.

 

5.    Focus on automation

Yes, also automation is part of a sustainable methods strategy. Why? Often, automated experiments are done in a smaller volume and monitored; therefore, the risk of failure and repetition is minimized. It also increases the operator’s safety as contact with reagents and solvents during the experiment is minimal. 

 

6.    What else? 

Do your planning well, and if you search for a new method, include keywords like miniaturization, resource-efficient, green analytical chemistry or other sustainability- related aspects in your search. Be creative and test different keywords out. And next time, you use a method, ask yourself: is this environmentally friendly, does it have negative ethical implications and might there be an alternative?

Scientists need to be aware that their research has consequences – by contributing to new knowledge and innovation, but also in terms of sustainability. Therefore, it is important to keep both aspects in mind and to show that sustainable science is possible.