Cadmium and tomatoes

[The_simpsons]

So i did a laboration in my environmental sciences class, what i did was measure zinc and cadmium levels in ecologically and non-ecoligally grown spanish tomatoes. My problem is the conclusion of it all. There is more zinc in the ecological tomatoes, but with cadmium is the complete opposite. The ecological ones have 0.

 

And the cadmium in the non-ecological tomato is still low, it is very hard to know if it depends on merely the geographic location (natural soil variations) or is it because of the use of fertilizer?

 

Here are the numbers btw, in dry weight:

Zn in normal tomato: 0.00056 mg/kg

Zn in eco-tomato: 0.0001206 mg/kg (almost double)

Cd in normal tomato: 0.00001205 mg/kg

Cd in eco-tomato: 0 mg/kg

 

So, what do you guys make out of it all?

[John Cuthber]

Presumably the zero means "not detected". What's the detection limit and how good is the precision of measurement there (these are pretty low levels and I suspect the measurement's accuracy may suffer on that account). I really don'y believe you can distinguish between 0.00001205 and 0.00001206 so I think that's an outbreak of spurious accuracy.

 

In any event I don't think you will be able to answer the question becuse you don't know what the soil is like and also you don't know what it was like before people started growing crops there.

[The_simpsons]

That was pretty much the conclusion i finally wrote in the report. The levels of cadmium are far too low and inconclusive, could as far as we know come only from naturally ocurring cadmium in soils. They are far lower then the average cadmium content in vegetables (which was around 20 micrograms/kg, and the tomato contained ca 0.012 micrograms/kg).

But tomatoes on average contain 2 mg of zinc per 100 g, it's not so rich in cadmium and zinc of all vegetables.

So it's impossible to say if the tomato was anyhow contaminated by for example artificial fertilizer.

Btw the measuring appartus we used was a atomic absorption spectrometer, for measuring metals (iron, zinc, cadmium, lead, copper, and aluminium).

 

If i would redo this experiment i probably would have measured these metals in kidneys, livers, mushrooms or mussels.