Can herbs absorb harmful substances leached in water supply?

Question

I have small herb garden (parsley, coriander mint and basil) that is watered from below by a hydrophilic filter using capillary action from a reservoir. This filter allows water soluble nutrients to be fed to the herbs. The manufacturer of the filter use a special propitiatory additive in the filter that allows for excellent water flow. I need to know the the harmful implications of the material as they have stated the unknown "additive in the filter is not FDA approved". They will not tell us what additive is to protect their intellectual property. My question is that will the herbs absorb the additive regardless assuming the additive is leaching into the water. Say that 1 ppm (parts per million) of substance X is in the water. Will the herbs absorb that and propagate it to their leaves. If so how much of the substance? (very rough estimate will do) TIA, Dave

Answer 1

Hello Dave!

I'm going to try to answer your question to the best of my knowledge and according to the information that you have given me. Now you stated something very important I want to reemphasize: without knowing what compounds the additive is made up of, we can't say for sure exactly what is being absorbed. As you said, they have intellectual property over what they've created, and it's pretty common among a lot of companies in the natural science field. It'll also depend on a lot of other variables: soil nutrients, the type of herb (as some herbs can absorb nutrients more readily than others), and overall health of the seedling. So taking these factors into consideration, I'm going to give my best hypothesis about what this filter is doing.

Now I'm going to take an extreme example, not because it's what I believe the filter is made of, but it gives me a basis to have some type of reference for harmful compounds plants can absorb. I took data based on arsenic, which as I'm sure you're aware is a highly toxic substance to humans, and how much arsenic is absorbed by plants. Data has shown anywhere from 0.03 to 0.5 ppm of arsenic can be absorbed by plants, much lower than 1 ppm. However, the same type of data also suggests that plants can actually neutralize arsenic even in the lowest amounts and won't harm the plants or even show the compounds in the leaves.

So assuming what they have isn't as toxic as arsenic, it is safe to hypothesize that the materials they are using won't harm the herbs you have and that they can be filtered out through the soil, the roots, away from the leaves.

I will attach the data I have used in my example so you can read through where I made my ideas and it is from a very credible site about biology and chemistry related research (a site to find multiple papers and research topics). If you have any more questions please let us know!

-Caitlin

https://www.ncbi.nlm.nih.gov/books/NBK231010/