Safety/Risk Group Guide


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Risk Groups

Most countries use a four-level Risk Group system to classify microorganisms (bacteria, fungi, and viruses) according to how dangerous they are to humans. The World Health Organization, an agency of the United Nations, uses four Risk Groups: Risk Group 1 is for the most safe organisms, and Risk Group 4 is for the most dangerous organisms. Risk Groups 2 and 3 fall in between. Most countries in the world use a similar system, and iGEM uses this system as well.

Common iGEM Organisms
Species Risk Group
Escherichia coli K-12 (and derivatives: DH5alpha, TOP10, etc) RG 1
Bacillus subtilis RG 1
Yeast (Saccharomyces cerevisiae) RG 1
Lactobacillus spp. RG 1
  • RG 1: Low risk -- organisms generally do not cause disease in healthy adult humans.
  • RG 2: Moderate risk -- organisms cause disease in humans, but the disease is treatable, and it should not present a serious hazard to public health.
  • RG 3: High risk -- organisms cause serious disease in humans. Treatments and vaccines for the disease are usually available.
  • RG 4: Extreme risk -- organisms cause deadly disease in humans, and there are no effective treatments or vaccinations.

The four laboratory Safety Levels correspond with Risk Groups -- so if you are working with Risk Group 2 organisms, you should work in a Level 2 laboratory.

International Variation

Not every country uses the exact same system for Risk Groups and lab Safety Levels. Note these variations, and make sure you are working in accordance with your own country's system!
  • Reversed numbering: Some countries, especially those that were formerly part of the Soviet Union, use a system similar to that described above, but with the numbers reversed. In this system, Risk Group 1 contains the most dangerous pathogens, and Level 1 labs have the strongest safety measures. Make sure you know which system your country uses, and whether it is the reverse of what iGEM uses!
  • Special categories: Each country has its own laws that govern microbiology research, and its own rules for how to work with different organisms safely in the lab. In addition to the four basic Risk Groups, many countries also define special Risk Group / Safety Level categories for certain microorganisms. For example, there might be a category "2+" for organisms that are among the most dangerous of Risk Group 2, or a category "2-Agricultural" for organisms that cause disease in farm animals or crop plants.
  • Differences in Risk Group classification: Different countries may assign the same organism to different Risk Groups. Often, this is because the same organism is more dangerous in certain parts of the world. For example, a pathogen that is more deadly in hot climates might be rated Risk Group 3 by countries with hot weather, but the same organism might be rated Risk Group 2 in countries with very cold weather.

How can I find out the Risk Group of my organism?

To determine the Risk Group of an organism, we must consult reliable sources. There is no world-wide standard list of microorganisms and their Risk Groups. Some countries and some cell culture vendors have provided lists, but no single list includes all species, so you might need to check several sources. iGEM recommends three sources for Risk Group information: Canadian PSDS, NIH Guidelines, and DSMZ.

Canadian Pathogen Safety Data Sheets (PSDS)

The Public Health Agency of Canada has published safety data sheets for a wide variety of microorganisms.

To use the PSDS, begin by scrolling down and finding your species in the list. Click on the species name to bring up extensive safety information about that species. Scroll down to "SECTION VII". Some species have a "RISK GROUP" explicitly listed. Other species only have "CONTAINMENT REQUIREMENTS", which will recommend an appropriate laboratory Safety Level / Containment Level.

NIH Guidelines

The NIH Guidelines are a set of rules that govern research on recombinant/synthetic DNA in the United States. Appendix B of the guidelines gives a list of pathogens in Risk Groups 2, 3, and 4. It does not list Risk Group 1 organisms.

Click here to go directly to Appendix B.


"Always check your strain!"
A note about E. coli K-12

Escherichia coli is the most commonly used bacterium in molecular biology. E. coli bacteria naturally live inside the human digestive system. We scientists are used to thinking of E. coli as "safe", but many strains of E. coli cause terrible diseases! Famous strains such as E. coli O157:H7 have caused many deaths. Most disease-causing strains of E. coli are considered Risk Group 2.

E. coli K-12 is a "lab strain". The K-12 strain cannot survive in the human digestive system, and does not produce toxins. K-12 is Risk Group 1, and it may be used in Level 1 laboratories with the most basic safety precautions, such as rubber gloves. Similarly, the strains derived from K-12 (such as DH5alpha, TOP10, etc.) are also Risk Group 1.

Always check your strain!

DSMZ (Deutsche Sammlung von Mikroorganismen und Zellkulturen / German Collection of Microorganisms and Cell Cultures) is a large collection that includes Risk Group information for thousands of different species, strains, and cell lines. It is more difficult to use, but it includes the most species of any source we have found.

  • Catalogue Microorganisms -- search bacteria. Enter your genus, species, and/or strain information in the "Search term" box, and click Search. You will receive a long list of results, which may include many different strains and species. Examine the list to find the correct strain, and click on its DSM number to view its catalogue page. The Risk Group is listed in the table.
  • Catalogue Human and Animal Cell Lines -- search this catalogue by the same method as for Catalogue Microorganisms.
  • Prokaryotic Nomenclature Up to Date is an alphabetical list of all bacterial and archaeal species names with standing in the literature. Find your species in the list, and click on its name to view details. In the table row "Type strain", look for a blue DSM link. If one is present, it will bring you to a DSMZ catalogue page where you can find details about that species. The Risk Group is listed in the table. (If there is no blue DSM link, it means that the DSMZ does not offer that species.) Note: Prokaryotic Nomenclature Up to Date concerns wild organisms, not lab strains. Therefore, it will tell you that E. coli is Risk Group 2. E. coli K-12, or "lab strain" E. coli, is not the same as "wild" E. coli! (For more information, read the orange box on the right.)

Other sources

If you cannot find your species in any of the recommended sources, you must find another reliable source. There may be a paper in the peer-reviewed scientific literature that describes your species. Your country's government might have a list of microorganisms and their Risk Groups.

For help finding a reliable source, you can consult your advisor, or speak to the biosafety authorities of your university. You can also contact for help.

What about animals and plants?

The four Risk Groups only apply to microorganisms (bacteria, fungi, and viruses), with very few exceptions. For animals, plants, and other multicellular organisms, there are different safety guidelines. Your country and your university have their own guidelines governing experiments on animals and plants. You should consult your advisor, your lab manager, or the authorities at your university.

If you are using a part from an animal or plant, you should consider the function of the part, and consider whether it might be dangerous to humans. For example, the gene that codes for Green Fluorescent Protein comes from the jellyfish Aequorea victoria. Therefore, in the strictest interpretation, GFP does not have any associated Risk Group. However, GFP is only a fluorescent protein, absorbing and emitting light, so it is safe for humans and you can use it in a Level 1 laboratory. If you consider a different gene from A. victoria, such as the gene that produces the toxin in its stinging tentacles, you might get a very different answer!

Laboratory Safety Levels

Quick Lesson on U.S. BioSafety Levels

This "Quick Learn Lesson" will give you a general idea of what the four BioSafety Levels look like. It should take about 15 minutes to complete. It is prepared by the U.S. Government, so it uses U.S. definitions for each Level. Most countries use similar systems, but some details may vary.

Most countries divide biological laboratories into four levels, based on how strictly they contain microorganisms.

The World Health Organization defines Level 1 as the least strict level (used for the least dangerous microorganisms), and Level 4 as the most strict (used for the most dangerous microorganisms). Most countries in the world follow this system, and iGEM follows this system as well.

iGEM participants usually use Level 1 labs, because the most common chassis organisms are Risk Group 1. Some iGEM projects use Level 2 labs. Level 3 and Level 4 labs are not used in iGEM.

Note: A smaller number of countries, mostly those that were formerly part of the Soviet Union, use a different system where the numbers are reversed (with Level 1 being the most strict laboratory, for the most dangerous pathogens). Make sure you know which system your country uses!

This section is under construction.

To learn more about BioSafety Levels, speak to your faculty advisor or lab manager, or consult the WHO Biosafety Manual.

Biosafety Level 1

Biosafety Level 2

Biosafety Level 3

Biosafety Level 4