In the Lensli Academy we regularly inform you about practical situations that we encounter in the sector, we talk about insights gained in practice, we give you cultivation tips and we share our knowledge about other interesting substrate-related matters.
Academy – Human Pathogens
Human pathogens in potting soil and substrate
Human pathogens are microorganisms (e.g. bacteria) that can cause disease in humans if they come into direct contact with them. Can human pathogens be present in potting soil or substrates and what are the risks?
RHP has written an extensive factsheet about this, and we are happy to include this article in our own knowledge base. (Source: RHP)
Human pathogens
There are different types of human pathogens. Often people think of bacteria, but they can also be fungi. However, people usually talk about bacteria, such as Salmonella and Listeria. Another well-known family of bacteria is Escherichia coli (E. coli).
This family includes mostly harmless species and some species that can pose a risk. People, for example those with poor health, can under certain circumstances become ill from human pathogens when they come into direct contact with them.
Hygiene measures, such as those recommended when preparing food, can further minimize the risk.
Human pathogens in substrate?
Potting soils and substrates often consist of organic products. Human pathogens can sometimes be present in these. The presence of human pathogens is usually the result of an external contamination that has occurred. These contaminations cannot always be prevented in the production chain. Packaged potting soils are generally slightly less sensitive than unpacked. Under specific circumstances, human pathogens can multiply in the packaged product during storage and transport.
What are the guidelines of the RHP quality mark?
All quality requirements of the RHP quality mark are described in the RHP product certification scheme. This concerns both process and product requirements. The requirements of the RHP quality mark are continuously updated, based on the latest developments. The process requirements for hygiene at the production locations are important. This greatly reduces the risk of pathogens. These requirements are checked during control audits. In addition to process requirements, product guidelines have also been included for human pathogens that are important in relation to food safety. The following are tested: Salmonella, Listeria, Campylobacter and E. coli. The RHP guidelines for all products are as follows:
RHP-certified companies must be able to demonstrate with analysis results from a recognized laboratory that their RHP-certified products comply with the RHP guidelines. For this purpose, random product samples are taken immediately after production. This provides the most realistic picture of any presence of human pathogens. After that, there is a chance that potting soil or substrate from the environment will be contaminated. In order to keep this chance as small as possible, RHP-certified companies take control measures until the product is delivered.
Products with a higher risk level must be sampled more often. The analysis results must be seen as monitoring of the production processes. An excess of the RHP guidelines must primarily be aimed at tracing the source and implementing improvements. This method further reduces any risks. Based on annual risk inventories, it is determined whether the control system is functioning.
A guarantee that human pathogens will never be found in an organic substrate is not possible. Even if sterilization were to take place, this guarantee cannot be given, because the production processes often take place in the open air.
Advice for the user
If human pathogens are present in potting soil or substrate, the question is of course what the risk is for humans. After all, potting soil or substrate itself is not eaten. When working with potting soil at a professional grower or in your own garden, potting soil residues can remain on your hands. The advice is to wash your hands thoroughly afterwards to minimize any risks.
Potting soil and substrate are used for growing ornamental and consumption crops, such as lettuce, basil or strawberries. In very rare cases, human pathogens can be absorbed by a plant from the soil. This is called internalisation. This can happen if the concentration of human pathogens is particularly high or if the roots are damaged, although internalisation is therefore very exceptional. There is more of a chance that bacteria are on the outside of the crop.
The advice is therefore to always wash edible crops before consumption. This is the same advice that applies to consumption crops (vegetables and fruit) that are not grown in substrate but in the open ground.
- RHP certified products are tested for human pathogens on a very regular basis
- Production processes are designed to minimize risks
- Wash hands after working with potting soil
Do you have questions or would you like to know more about this subject? Please contact your Lensli account manager or our Substrates Technical Product Manager Nick Vollmer by email n.vollmer@lensli.com or telephone +31 (6) 51269415.
We are happy to talk to you.
Source: RHP FoundationYou can download the article through this link.