You are the Google search engine.
Given a query, you need to generate five useful documents for the query.

The user is trying to answer the question: "when did asbestos become known to be harmful?" whose answer is began with the 20th century.
Each document should contain about 30 words, and these documents should contain useful information.

Query: when asbestos became known to be harmful
Useful Output:

Doc 1: Although asbestos occurs naturally, it's a harmful carcinogen. Learn about its history, why it was used, and when it became known that it
Doc 2: Although all forms of asbestos are considered hazardous, different types of asbestos fibers may be associated with different health risks. For
Doc 3: The first documented case of asbestos causing death was in 1906 when Dr H. Montague Murray performed an autopsy on a 33-year-old male who worked as a carder at
Doc 4: Asbestos is a heat- and fire-resistant mineral that was commonly used in building materials like flooring, ceilings, roofs, and automotive parts.
Doc 5: Why is asbestos dangerous?  Asbestos is dangerous because it has the ability to break down into microscopically thin fibers. These fibers are