Tonka beans...delicious but toxic

“The problem is it’s not like you’re going to realise when you’ve got to the level where you’re eating too much – the effects build up over years,” says Dirk Lachenmeier from the Chemical and Veterinary Investigation Laboratory (CVUA) of Karlsruhe, Germany, who has developed a new way of detecting coumarin in foods.

The easy way to find out is obvious; alas, it turns out feeding people toxic chemicals isn’t allowed. Instead, the safe limits in humans are based on studies in animals, from baboons to dogs. To account for an any differences in our biology, the highest amount which hasn’t caused any harm in animals is multiplied by 100.

For most people, the current limit is probably ultra conservative   

For an average-sized person, this works out at a measly one quarter of a tonka bean or a quarter of a cinnamon bun per day – though if you remove the safety factor, your allowance shoots up to more like 25 tonka beans or 20 cinnamon buns (5680 calories, a challenge for even the most hardened binge eaters).

http://www.bbc.com/future/story/20170620-the-delicious-flavour-with-a-toxic-secret