Question: When was it discovered that asbestos was dangerous?
Disambiguated questions and answers: question: When was it thought to have been first reported that asbestos may be dangerous?
When was it though to have been first reported that asbestos had negative health effects?
When was the death with a cause related to asbestos?
answer: 1898
1899
1906
Natural Questions answer: 1899 (from the Wikipedia article "Asbestos")