THE CONCENTRATION OF THUJONE IN ABSINTHE FROM VALENTIN MAGNAN’S TIME

Abstract

The recent paper on absinthe, epileptic seizures and Valentin Magnan (Eadie MJ. Absinthe, epileptic seizures and Valentin Magnan. J R Coll Physicians Edinb 2009; 39:73-8) addresses an interesting question: can science from the 1870s be of any validity for today's view on the alcoholic beverage absinthe?

In an attempt to defend Magnan's conclusions on the responsibility of absinthe to cause epileptic seizures in humans, Eadie argues that the presence of thujone at convulsant concentrations in some of the available absinthes of Magnan's time cannot be known. We have demonstrated, however, that it can be known: not only from theoretical calculations,1 but also from chemical analyses of surviving products.2,3 The total thujone content in 21 analysed pre-ban absinthe samples ranged between 0.5 and 48.3 mg/l, whereas the average thujone content of 27.8 ± 17.1 mg/l fell within the modern Codex Alimentarius/ EU limit of 35 mg/l (derived from no-effect levels in animal experiments with an additional safety factor). We also provided evidence that thujone in bottled absinthe remains stable; therefore, our analyses of 100-year-old spirits were not confounded by significant thujone deterioration over time.3 We concluded that the scientific literature contains no proof that historic absinthe contained thujone in concentrations able to produce any of the effects experienced in the Magnan experiments conducted with pure wormwood oil. Our historical survey4 also showed that Magnan was swayed by specific anecdotal reports from which he inferred a general principle. Magnan attributed the epileptic seizures and general delirium observed in long-term absinthe drinkers to wormwood essence in absinthe in particular, rather than to alcohol in general, which is the more plausible explanation.

Another of Eadie's claims, which seems highly speculative, is that some of Magnan's patients might have had a genetic predisposition to juvenile myoclonic epilepsy (not described at the time) and thus may have been unusually vulnerable to thujone's convulsant effect. The relationship Magnan drew between absinthe and epilepsy was not restricted to a small number of drinkers, but to all of them.

In conclusion, we want to stress that while Magnan's conclusion on absinthe cannot uphold to today's standards, he is still rightly regarded as one of the fathers of French psychiatry.