Bronwyn King knows the lethal power of tobacco better than most.

As a young doctor, some of the first patients she cared for at Peter MacCallum Cancer Centre were cursed by lung cancer.

Radiation oncologist Dr Bronwyn King. Credit:Photo: Eddie Jim

But while doing her best to help these people – fathers, mothers, grandparents she considered victims of the tobacco industry – the radiation oncologist had no idea she was also funding the global production of cigarettes.

It was only during a meeting with a representative of her superannuation fund in 2010 that she learnt some of her money was flowing to tobacco companies through the "default" option, rather than the "greenie" option that screened out tobacco, alcohol and mining company investments.