What are Biotoxins?
Biotoxins are substances which are both toxic and have a biological origin. They come in many forms and can be produced by nearly every type of living organism: there are mycotoxins (made by fungi), zootoxins (made by animals) and phytotoxins (made by plants). Whilst some appear to have no advantage for the organism making them (they might be a waste product, for example), most are produced to help in two main activities – predation and defence against predation by other species, and so have very important roles in the life cycle of the organism. As we can see, biotoxins are varied in both function/mechanism and form: they can be used for a variety of activities or even none at all and can be anything from large complex molecules right down to fairly simple proteins. They can also be administered in lots of ways, including orally ingesting them, being injected as venom or being released into the environment via a type of pore.
Many biotoxins can be further classified into what kind of effects they have on the body. Some of these groups include the following:
necrotoxins, substances that cause tissue destruction via cell death and are carried in the bloodstream.- neurotoxins, substances that affect the nervous system.
- haemotoxins, substances that are carried in the bloodstream and target red blood cells.
- cyanotoxins, produced by cyanobacteria.
- cytotoxins, substances toxic at the level of the cell (kills individual cells).
- mycotoxins, produced by fungi.
- apitoxin, honey bee venom, injected via the sting.
Biotoxins that are a threat to human health (and often animals too) are classified as biological hazards. These hazards are often labelled with the well know 'Biohazard' symbol, so that those who might handle the substance, or come into contact with it, will know that it poses a threat and that the correct precautions must be taken. This symbol was developed by the Dow Chemical Company in 1966 and was later adopted by the Centers for Disease Control, the Occupational Safety and Health Administration and the National Institutes of Health in the USA after it was publicised in Science, before it spread around the world. There are four levels of biohazard (the Biosafety Levels), which can be seen most clearly by looking at the categorisation of the CDC (the Centers for Disease Control and Prevention, USA):
Minimum risk, which involves the least amount of protection – such as the wearing of gloves and a mask. Decontamination procedures for this level are similar to normal hygiene routines: washing hands with soap, disinfect surfaces and autoclave cultures not needed anymore. This level includes bacteria and viruses such as the chicken pox virus (varicella) and Escherichia coli.- Microorganisms that will cause mild disease only, or cannot be contracted easily via the air. For some organisms, special facilities and procedures must be used to make sure that there is not a public outbreak of disease. This includes diseases such as salmonella, influenza and HIV.
- Microorganisms that can cause severe and possibly fatal disease. However, these organisms don't make the top level as there will be vaccines in existence to protect against them. Diseases in this level include tuberculosis, Plasmodium falciparum (causes malaria) and anthrax.
- These microorganisms can, again, cause severe or fatal diseases – but in this case, treatments or vaccines are not available. These must be dealt with with extreme care: the lab must be protected by special entrance and exit procedures including showers, vacuum rooms and UV rooms to make sure that no traces of biohazardous chemicals leave the area, Hazmat suits must be worn at all times and an oxygen supply into the designated lab area must be maintained. Diseases included in this final level include smallpox and Ebola.
