A study of more than 300 French wines has found that only 10% of those tested were clean of any traces of chemicals used during vine treatments.

Pascal Chatonnet and the EXCELL laboratory in Bordeaux tested wines from the 2009 and 2010 vintages of Bordeaux, the Rhone, and the widerAquitaine region, including appellations such as Madiran and Gaillac.

Wines were tested for 50 different molecules found in a range of vine treatments, such as pesticides and fungicides.

Some wines contained up to nine separate molecules, with ‘anti-rot’ fungicides the most commonly found. These are often applied late in the growing season.

‘Even though the individual molecules were below threshold levels of toxicity,’ Chatonnet told Decanter.com, ‘there is a worrying lack of research into the accumulation effect, and how the molecules interact with each other. 
‘It is possible that the presence of several molecules combined is more harmful than a higher level of a single molecule,’ he said.

Vineyards represent just 3% of agricultural land in France, but the wine industry accounts for 20% of phytosanitary product volumes, and 80% of fungicide use specifically.

Since 2008, France’s Ecophyto national plan (involving the study of the ways in which organisms are adapted to their environment) has sought to cut pesticide use by 50% by 2018.

‘By 2012, there had been no reduction at all, even a small rise of 2.7% between 2010 and 2011,’ said Stéphane Boutou, also of EXCELL.

While EU rules limit pesticide residues on grapes to 250 molecules, there are no limits set for wine.

‘Some molecules will break down during the process of fermentation, and we need more research into what they synthesise into, and more traceability in place,’ Chatonnet said.

‘But we should not forget that it is not the consumers who are most impacted by this, it is the vineyard workers who are applying the treatments.’

In May 2012, the French government officially recognised a link between pesticides and Parkinson’s disease in agricultural workers.