We are advised, for obvious reasons, to wash or peel fruit and vegetables before eating them. But fruit and vegetables consist largely of water, which the plants have sucked up through their roots. I’m guessing that the water used to irrigate those plants in many parts of the world is unlikely to be clean drinking water. It might well be raw sewage water, for all I know, or water contaminated with heavy metals or toxic chemicals.
So, when you bite into a juicy piece of fruit, can that juice itself be contaminated with pathogens or toxins that were in the water that the roots sucked up, and present a health risk? Or are plant roots an effective enough filter that the plant is basically just sucking up pure water?
And does the answer differ for, say, root vegetables, where you are eating the part that is sucking up that dirty water, compared to apples or something which are supplied with that water from a distance?
The plant cannot absorb pathogens like bacteria or viruses; so if it’s washed well, you can’t get local diseases from eating it. And that’s the main concern from vegetables grown with sewage or what-not.
Some ‘toxins’, such as heavy metals (lead,and suchlike) are taken up by plants, but there aren’t that many places with dangerous levels of metals, and you’re not going to have a problem from eating one or two vegetables from there. If you look at the whole range of potential soil contaminants, no doubt some can be absorbed by plants and some are not.
Again, the thing to worry about is pathogens from sewage-contaminated water, and washing/peeling will definitely get rid of them.
Confusing reply, Quercus, at least to easily-confused me. You begin with “cannot absorb pathogens”, so wash well, and finish with “the thing to worry about is pathogens from sewage-contaminated water”, so wash and peel.
Are you assuming that the crop is spray/irrigated with sewage, and all will be removed with washing/peeling? Surface-applied junk won’t creep in through fissures, cracks, blemishes?
And that’s just for garden-variety (heh) sewage. What about those teensy-weensy bacteria and viruses in solution being taken up by the roots and being installed in the mostly-water plant cells?
Lemme try this again: heavy metals and agricultural chems CAN get into vegetables and fruits, you don’t know about other chemicals and pharmaceuticals (chemicals, no?), and you maintain that water-borne bacteria and viruses can’t enter a plant, while they sure as heck can get into our mostly water-based bodies?
I’m hoping that someone who has actual knowledge of plant physiology will weigh in here; no more speculators, please.
Heavy metal contamination is an issue, but it’s greens that are most known for it. Plants like spinach have been used for heavy metal decontamination of soil (obviously, not a good idea to eat such spinach! And it can take multiple crops/years.) and after accidents like Chernobyl or Fukushima can be used to determine contamination levels in an area.
Fortunately, most of use don’t live downwind of a nuclear accident or over a former lead smelter (unless you live in East Chicago, Indiana where backyard gardens are discouraged).
So the toxins known as “heavy metals” are a concern.
Thanks Frankenstein Monster. Yeah, that’s a good addition but it is not necessarily due to accidents. There is a lot of contaminated land in the US due to radioactive tanks etc leak like in Savannah GA, Hanford WA…
Phytoremediation (Phytoremediation - Wikipedia) is a technique applied where plants are specifically selected for absorbing soil contaminants like Radioactive wastes, PCBs, etc.