trees have a magical power to tell each person what they need to hear. they speak to each human being as well as the whole of humankind across the world. tomoko watanabe from the project green legacy hiroshima. remember, you can watch witness history every month on the bbc news channel or you can catch up on all our films along with over 1000 radio programmes on our online archive. now let's head post warjapan and a shocking example of the environmental damage that can be caused by lax regulations on big business. in the 19505, thousands of people in the town of minamata were poisoned by industrial waste. a factory was pumping heavy metals into a river that led to the sea.