4 ms·

Anyone know a simple method of testing for lead in food? Say a wet chemistry method? I live in California, and I've noticed that everything has a CA Propositi

Anyone know a simple method of testing for lead in food? Say a wet chemistry method? I live in California, and I've noticed that everything has a CA Proposition 65 warning label. When I look into it it's generally lead that has bioaccumulated in the plant. What I can't find is how much or how widespread it is in the food.

Cordiali 2y ago
There's test swabs for leaded paint, but I don't know if they'd be sensitive enough for food. At least where I live, they're pretty cheap, so it could be an interesting experiment. I remember seeing an article a while ago, where some local councils here specifically recommended building raised garden beds for veggie gardens. They apparently found, that in cities/towns older than about a hundred years, the risk of soil contamination can be pretty high, the main suspects being lead and arsenic. Raised garden beds is an easy way of eliminating that risk.
- throwup238 2y ago
  > I remember seeing an article a while ago, where some local councils here specifically recommended building raised garden beds for veggie gardens. They apparently found, that in cities/towns older than about a hundred years, the risk of soil contamination can be pretty high, the main suspects being lead and arsenic. Raised garden beds is an easy way of eliminating that risk. I'd recommend raised beds to anyone who lives in a suburb or city that's even a few decades old. The particulates and oils washing off the street and down roof shingles alone introduces plenty of contamination. Very rainy regions like the Pacific Northwest have to build rain gardens [1] everywhere to filter out baseline levels of suburban pollution, otherwise their water gets really bad. [1] https://en.wikipedia.org/wiki/Rain_garden https://en.wikipedia.org/wiki/Rain_garden
- nanomonkey 2y ago
  Yeah, City Slickers in Oakland stopped testing the soil and just told everyone that they should use raised beds. Problem is that there are so many fruit trees and self starting plants that I want to eat (I'm looking at you collards), but I'd like to know what I'm getting into. Also I've read that sunflowers are really good at pulling up heavy metals, and all of the bags that I purchase have warning labels on them. I'm curious if this is a real concern!
  - kombookcha 2y ago
    IIRC sunflowers store heavy metals in their fatty tissues, which means it's particularly concentrated in their seeds, so if you're using them to pull heavy metals out of your soil you should probably be sending the wilted plant away at the end of the season, seeds and all.
speed_spread 2y ago
Rice is good at sucking up heavy metals from the ground. American rice fields often occupy old cotton fields where lead products were used as insecticide.
pomian 2y ago
Those test swabs work quite well. They are designed to test ceramics, clay etc. You can find them in pottery supply stores. If trying on food,I would soak or boil that food to reduce water and thereby increase concentration if there is any. You could add lemon to the water, as acids (vinegar for example) help extract metals. The problem is you don't get an actual number, just over a certain limit. I think it might be 50 ppm. But it's been twenty years, so please check that number. Alternative is to send to a lab, ask for a 32 element icp. Should cost between 50-150$, especially if you state you don't need chain of custody proof. You will get 32 elements. Which is fun. (Can even look for gold, but that's extra $ testing.) Lead naturally occurs in the environment, depending where, in the world you are, from 2 to 20 even UpTo 50 ppm. Industrial/commercial sites are common to have up to 150ppm. Contaminated toxic sites way over that, over a thousand. We could go on. But the swabs work as a starting point.
nanomonkey 2y ago
To answer my own question: potassium rhodizonate mixed with glacial vinegar creates a visual test for lead. I assume that I could grind up the food, test the slurry and then maybe do a more in depth test involving putting the food in a kiln and testing the ash for lead (assuming you use temps low enough to not vaporize the lead, below 1750C).

Cordiali 2y ago

There's test swabs for leaded paint, but I don't know if they'd be sensitive enough for food. At least where I live, they're pretty cheap, so it could be an interesting experiment. I remember seeing an article a while ago, where some local councils here specifically recommended building raised garden beds for veggie gardens. They apparently found, that in cities/towns older than about a hundred years, the risk of soil contamination can be pretty high, the main suspects being lead and arsenic. Raised garden beds is an easy way of eliminating that risk.

throwup238 2y ago
> I remember seeing an article a while ago, where some local councils here specifically recommended building raised garden beds for veggie gardens. They apparently found, that in cities/towns older than about a hundred years, the risk of soil contamination can be pretty high, the main suspects being lead and arsenic. Raised garden beds is an easy way of eliminating that risk. I'd recommend raised beds to anyone who lives in a suburb or city that's even a few decades old. The particulates and oils washing off the street and down roof shingles alone introduces plenty of contamination. Very rainy regions like the Pacific Northwest have to build rain gardens [1] everywhere to filter out baseline levels of suburban pollution, otherwise their water gets really bad. [1] https://en.wikipedia.org/wiki/Rain_garden https://en.wikipedia.org/wiki/Rain_garden
nanomonkey 2y ago
Yeah, City Slickers in Oakland stopped testing the soil and just told everyone that they should use raised beds. Problem is that there are so many fruit trees and self starting plants that I want to eat (I'm looking at you collards), but I'd like to know what I'm getting into. Also I've read that sunflowers are really good at pulling up heavy metals, and all of the bags that I purchase have warning labels on them. I'm curious if this is a real concern!
- kombookcha 2y ago
  IIRC sunflowers store heavy metals in their fatty tissues, which means it's particularly concentrated in their seeds, so if you're using them to pull heavy metals out of your soil you should probably be sending the wilted plant away at the end of the season, seeds and all.

speed_spread 2y ago

Rice is good at sucking up heavy metals from the ground. American rice fields often occupy old cotton fields where lead products were used as insecticide.

pomian 2y ago

Those test swabs work quite well. They are designed to test ceramics, clay etc. You can find them in pottery supply stores. If trying on food,I would soak or boil that food to reduce water and thereby increase concentration if there is any. You could add lemon to the water, as acids (vinegar for example) help extract metals. The problem is you don't get an actual number, just over a certain limit. I think it might be 50 ppm. But it's been twenty years, so please check that number. Alternative is to send to a lab, ask for a 32 element icp. Should cost between 50-150$, especially if you state you don't need chain of custody proof. You will get 32 elements. Which is fun. (Can even look for gold, but that's extra $ testing.) Lead naturally occurs in the environment, depending where, in the world you are, from 2 to 20 even UpTo 50 ppm. Industrial/commercial sites are common to have up to 150ppm. Contaminated toxic sites way over that, over a thousand. We could go on. But the swabs work as a starting point.

nanomonkey 2y ago

To answer my own question: potassium rhodizonate mixed with glacial vinegar creates a visual test for lead. I assume that I could grind up the food, test the slurry and then maybe do a more in depth test involving putting the food in a kiln and testing the ash for lead (assuming you use temps low enough to not vaporize the lead, below 1750C).