27 April 2001
Study allays heavy metal concerns

By FWi staff

MOST UK grain falls well within newly imposed EU limits on heavy metal content, according to new research.

Where it does not, the choice of different varieties could help growers reduce levels, the Home Grown Cereals Authority funded research reveals.

Heavy metals occur naturally in soils and are also found in farmyard manures, phosphate fertilisers and some sewage sludges.

They are taken up by plants and can be found in small amounts in plant tissue and grain.

The study shows that levels of cadmium and lead in UK grain samples fall well within the new EU limits in the vast majority of cases.

Martin Adams of IACR-Rothamsted who conducted the research, said cadmium should be watched more than lead, as UK levels are closer to EU limits

The project showed big differences between varieties in uptake levels. Some wheat and barley cultivars took three times more metal in glasshouse experiments.

“It may be that areas with naturally higher levels of lead and cadmium can be planted with varieties which have lower uptakes,” said Dr Adams.

Growers should be aware that levels in soil alone should not be used as an indication of likely grain content, he adds.

“Our studies have shown that soils containing similar levels of cadmium can give very different grain concentrations. Soil and grain content may not agree.”

The project is also determining the factors that affect metal uptake, such as soil pH and fertiliser form, including sewage sludge.

Knowing the effects of previous sewage sludge applications on grain cadmium and lead will help growers manage land in future.

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