Arsenic in our food, What is going on?!

Originally posted by jdmmade

Worst part is there are holistic food places that found out and have to fish out that crap. Buy local grown and nothing from mexico and china.

edit on 16-9-2011 by jdmmade because: (no reason given)

Exactly, by simply asking around and doing a little legwork you can weed this crap out. I agree buy local that way you can visit the farmers if you don't trust their labeling and see for yourself what it is they are up to.

Many farmers are very good folks and will be more than happy to talk about these things with someone genuinely interested and friendly.

Low levels of arsenic are ingested daily and easily detoxified by the body, arsenic is found in many plants and their edible parts. There's nothing to be alarmed about.

reply to post by muzzleflash

You're going through some unnecessary steps. Just to clarify a little, parts per billion (ppb) is typically being reported on a mass/mass basis when we're talking about water or food quality. So if the limit of arsenic in water is 10 ppb, you're talking about 10 g of arsenic for every 1B g of water. Or you can choose any other unit for mass, as long as you're expressing the solute and the solvent in the same units.

So let's say you have an 8 oz. glass of water that's at the 10 ppb limit. For argument's sake, let's say 250 mL is equivalent to 8 oz. So you have 250g of water, assuming it's relative pure and therefore has a specific gravity of about 1. Here's where the factor label method comes in handy:

250 g water x (10 g arsenic/1000000000 g of water) = 0.0000025 g (or 2.5 x 10^-6 g) of arsenic in an 8 oz. glass of water if there's 10 ppb of arsenic in the water.

The second part to be considered is the toxicology of arsenic. For simplicity's sake, let's just say it's metallic arsenic. The values for acute oral LD50 (the amount that would kill 50% of a population) for metallic arsenic varies widely from species to species -- it's 145mg of arsenic per kg of body weight for mice, but 763mg/kg for rats. Again, let's just say for humans it's in the middle, or about 450mg/kg. The average adult in the US weighs, ballpark, 80kg. So the average person would need to ingest 36000mg, or 36g of metallic arsenic to stand a fair chance at dying. So let's say your water has 10 ppb of arsenic, we can go back to the factor label method:

36 g arsenic x (1000000000 g of water/10 g arsenic) = 3600000000 g of water

What we're calculating here is how much water you'd have to drink in one sitting to stand a 50/50 chance of dying from metallic arsenic. This is just an example of the calculations you can use to move back and forth between ppb and masses when you're trying to figure out impurities or toxicological circumstances. Obviously the more looming concern are chronic health effects that can be experienced at much lower levels of ingestion and, in the case of arsenic, metallic arsenic is pretty harmless. Organoarsenic compounds are much more toxic.

Originally posted by WildWorld
reply to post by muzzleflash

 

There is also a form of cyanide in B12 supplements.....just wanted to add that for anyone who was interested. I didn't know that until I had to start taking B12.

The cobalt centre in B12 has a cyano ligand, but that is not the same as the supplements simply containing cyanide. A lot of compounds you eat contain cyanide groups (nitrile groups), but are not toxic. It is only when it a compound is metabolised to release cyanide that it becomes a problem.

Originally posted by Griffo
Many plants contain poisonous chemicals. The cassava root, for example, naturally contains a very high amount of cyanide and if it is not prepared correctly you may die.

Organic arsenic, like you would find in food, is less poisonous than inorganic arsenic (500 times less poisonous). According to wikipedia though, the minimal lethal dose of arsenic is estimated to be between 70 to 200 mg. (I don't know how that would equate to parts per billion - anyone care to do the maths?)

Arsenic poisoning

edit on 15/9/2011 by Griffo because: (no reason given)

ppm is measured in mg/litre (making ppb a fraction of that), so it would depend on the person.

Originally posted by Griffo
reply to post by jdmmade

 

Just because a molecule contains a poisonous element or functional group does not mean that the whole molecule will become poisonous. Salt, for example, contains sodium and fluorine - two very poisonous chemicals on their own, but when combined are no where near as deadly

Salt is a very broad description so I may be misinterpreting this, but I do hope that your table salt isn't composed of NaF.

Originally posted by muzzleflash



Anyone want to correct my math? Be my guest.

I think I finally got the right answer though.

7.492 ten quadrillionths of a gram. For 10 parts in one billion parts.

As above, ppm is simply a mass/mass fraction, which often converts to mg of solute per L of solvent or mg/kg. It's a somewhat confusing unit of concentration given it's name, I know.

To the OP. I went ahead and did my own research into the matter and I found that sea-food is in fact the major contributor to dietary intake of As as well as various other elements.

A survey of people in Catalonia, Spain, found arsenic present in a number of food types. It is best summarised by the following figures, which I copied from the paper (found here*):





Additionally, the above study, which was performed in 2003, noted a significant decrease from previous surveys completed in 1998 by the same group. Dietary habits were not found to have changed much, which makes it quite an interesting finding.

For shellfish, the levels of As are actually above the provisional tolerable weekly intake levels. However the authors go on to note that the As present in shellfish is primarily found in organic compounds, so its toxicity is somewhat attenuated compared to that of the inorganic variety. Given that only 0.02-11% of the As in shellfish is inorganic, the results they obtained are deemed acceptable for all age groups.

Another study (found here*) I read noted the following in regards to marine organisms:

Inorganic arsenic is not formed after ingestion of these compounds (Buchet et al., 1994, 1996), indicating little or no metabolism in humans to the most toxic forms of arsenic. The complex arsenic compounds that predominate in marine organisms are much less acutely toxic than soluble inorganic arsenic compounds, with arsenobetaine (the predo- minant compound in finfish) being virtually non- toxic (Shiomi, 1994; Yamauchi and Fowler, 1994). Monomethylarsonic (MMA) and dimethylarsenic (DMA) acids are also less acutely toxic than the inorganic forms, arsenite (As3+) and arsenate (As5+).

In regards to the comment about pasteurizing/cooking foodstuffs not decreasing As concentrations. In a lot of cases, cooking or heating food can decrease the concentration of certain compounds. Specifically in regards to As, however, I found a paper (here*) that actually found there to be an increase in concentration depending on cooking time and method. This is summarized by the following picture:




Regarding toxicity and expulsion from the body, I found this paper, which is very detailed and freely available. It's a very interesting read for anyone who's interesting and can handle the jargon.


* these papers are accessible only if you purchase them or have institutional access. If you have further queries regarding them, I do have access and can divulge further. The abstracts to all of them are freely available.

reply to post by hypervalentiodine


This is a good post thank you for doing all that research and leg work for us.

I find it very interesting that heating certain compounds can sometimes in fact increase the level of As within the substance under specific conditions. This is very interesting information.

It makes me wonder how much of this we don't know about. I can imagine there is quite a bit of stuff that is out there somewhere but it has been overlooked and it is up to us to go find it.

I really love it when people go out of their way to do some real research on topics and help educate people about various aspects of an issue. If I could give you 10 stars I would, tyvm.

Here's an update:

reply to post by jdmmade


I don't think arsenic works like that. In order for it to kill you slowly it would still have to be a high enough dose to make you constantly sick. You should research how long it stays in your body. I dont know that it is one of those build up over time things. I am no expert myself, but maybe look into that before scaring people.