Thursday, April 15, 2010

How much lead are you eating?

Many foods contain lead and other heavy metals. There is pretty much nothing you can do about this, these metals are ubiquitous in our culture. After decades of leaded petrol, consumer electronics and other pollution it is not surprising that heavy metals would be in our food chain.

One has to be careful that you don't fall into the trap of saying "we can measure it, so it must be bad". I remember stories in my university studies about people who change reference methods. The old equipment never detected any of the bad stuff. However the new equipment was 100 times better at measuring, thus over night the factory went from having no problem to everyone panicking as they now had contaminates that never used to be there.

So whole bread from Madrid has 59.2 micro grams per kg of lead. So I didn't want to fall into the trap of being hysterical about this level, where the body can easily cope with this low level. So I wondered what is an ok level of lead? A quick wikipedia check we get:
No safe threshold for lead exposure has been discovered—that is, there is no known amount of lead that is too small to cause the body harm.
So if I read this right the lead intake from bread / cereals even at low levels is bad for us. And yet our cereals (flour, rice, etc ) contain lead and we know that. The only disclaimer is that zero lead blood level is what is acceptable. The body might have ways to excrete lead as fast as it is consumed at this low level.

If I ran a "organic" business or other business selling "health" foods I would get the heavy metal concentration measured. Thus if it was high, I could find ways to rectify this. One way is to use lime, hence I always give a sprinkling of dolomite  lime (it doesn't alter the pH to much) when I plant anything to bind up any bad metals, so they are not up-taken by the plant.

If my heavy metals were low - I would use this as an advertising point. Low heavy metal food!

Reference: Cuadrado et al Cereals contribution to the total dietary intake of heavy metals in Madrid Spain, Jounral of food composition and analysis vol 13 g 495 2000. : 

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