This is what film prop cigarettes are actually made of

For his iconic role in Peaky Blinders, it was reported that Murphy had smoked well over a thousand fake cigarettes while starring as chain-smoking gang leader, Thomas Shelby.

For his titular role in Oppenheimer, which sees Murphy play the father of the atomic bomb, Robert Oppenheimer, he was also forced to knock back many more fake cigarettes.

As many of you will well know, the real Robert Oppenheimer was a very heavy drinker and smoker, both of which eventually led to his death at the age of 62 from throat cancer.

In fact, Oppenheimer smoked so many cigarettes that one of his students, Edward Gerjuoy, recalled that the most distinctive feature of his lectures was his chain-smoking.

In a recent interview, Murphy's co-star in the epic biopic, Robert Downey Jr., commented that Murphy had made "the greatest sacrifice by a lead actor" he had ever seen and one of these sacrifices must surely have been Murphy's relentless chain smoking of prop cigarettes despite not being a real-life smoker.

But just what is in these prop cigarettes? Well, they're actually herbal and do not contain tobacco, nicotine, or other additives.

While they look identical to the real thing they are far less dangerous than the ones that Oppenheimer really inhaled time and time again.

The prop-cigarettes include ingredients such as rose petals, clover, and tea leaves.

While the fake cigs are much better for you than real ones, they still carry some health risks.

Following on from his role in Oppenheimer and Peaky Blinders, Murphy has said that he will not be accepting roles which require a restless inhalation of fake cigarettes in the future.

He explained: "I've smoked so many fake cigarettes for 'Peaky' and this. My next character will not be a smoker. They can't be good for you. Even herbal cigarettes have health warnings now."

Let's just be thankful Daniel Day Lewis didn't get the role of Oppenheimer otherwise the world could be a much darker place right now.