Posts Tagged ‘cadmium’

Information and knowledge

January 30, 2013

Agressive information based on insufficient knowledge or limited perspectives is worse than weeds in a garden. Two actual examples  in Sweden:

“There are poisonous heavy metals in child food”.  How terrible and whose fault is it?

The truth is that all basic elements are present in almost everything. Cadmium, mercury and arsenic are found also in the most virgin and pure of vegetable products. It is all about content.

“Heavy metals in sludge are not taken up by the crop, according to 30 years experiments”. Consequently sludge can safely be used.

This is not untrue, but a very limited truth. Small additions during a limited time (decades) may drown in the variation of analytical values and no significant differences are found. But it does not mean that the practice is sustainable and should continue. Of course, a question is: shall we care about our grandchildren. It is their fault to be born so late. We have no problems (but we have some slight economic advantages).

My view is that the conditions we used in Hydro/Yara during the 1990s still is a good model:

1. Is the element or substance harmful for health och soil life?

2. Is it accumulated in the soil so that the soil content continually will increase?

3. Is the applied amount high enough to increase the soil content by more than 10% in 100 years?

If the answer is “yes” for all 3 points we have a problem to solve.

30 years is not enough for general propaganda. Those results say that during this time not much happens. But for grandchildren and sustainability we need to consider the mechanisms and widen the time perspectives and make conclusions from that base.

 

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Cadmium and health

November 12, 2012

Headlines in the press:  Cadmium in food gives health problems.

This is true according to research. Maybe it should be called potential problems. First, decades ago, kidney function was the issue. As work continues more adverse effects of cadmium are found.  Weaker skeleton, more fractures. Cadmium can be involved also in cancer.

The daily intake of cadmium is no direct problem, but for some groups the margin is close.  So – it seems important to reduce the cadmium in our food system. And quite a lot has been done. The fertilizers in the Swedish market are almost cadmium free, there are hard limits and reduction programmes for cadmium in sewage  sludge

Cadmium is a natural element present in all soils and in products from soils. What we can do is to reduce the cadmium flows in our environment. Personally I hope our low cadmium policy in fertilizers can continue and also that pure phosphorus can be extracted in the sewage works. The cadmium in our environment and the balance in the soil is a longterm issue.

But outside Scandinavia the cadmium problem has not the same  priority.  I asked English collegues about it: “Cadmium – is that a problem??”

It seems, however, that the cadmium issue in the world is going somewhat in the Swedish direction.

Country differences.

January 30, 2009

At the conference in December arranged by The International Fertiliser Society (see tag Recycling) phosphate was an issue. We have to economize with this limited resource. Some figures for UK (minus N Ireland) were mentioned, meaning that the agriculture (and river banks) looses about 0.8 kg P per hectare agricultural land (incl pastures) to surrounding seas. We in Sweden are struggling to reduce a loss of 0.4 even further.

 

In England the Cd content in sewage sludge now is reduced to 70-120 mg Cd/kg P (“not much different from mineral fertiliser”). The Swedish figures are about 40 and 10 respectively.

The regulations for sewage sludge in England say that the content 3 g Cd/kg soil shall not be exceeded and the additions of Cd are maximized to 150 g in a ten year period. The average Cd content in Swedish soils is about 0.5 g/kg and we do not want any increase at all. The goal is balance, but a problem is that about 0.5 g/hectare is deposited from the atmosphere.

 

For phosphorus it might be a question of stage. We started to adapt the nutrient management a couple of decades ago and are leading in Europe.

The base for the differences in cadmium is unclear. Different interpretation of scientific reports?

But this favourable situation for Swedish agriculture gives no advantages for the farmer, only costs. And more pressure.That is the problem with products influenced by commodity pricing in a global scale.