Now over the last several decades, these chemicals have been developed at this breakneck pace with now more than a 9,000 PFAS related chemicals to date.

过去几十年来，这些化学物质以惊人的速度发展，到目前为止，已经有超过9,000种与PFAS相关的化学物质。

The first PFAS were invented in the mid-20th century and they were initially used in a wide range of industrial and commercial applications.

第一个 PFAS 发明于 20 世纪中叶，最初用于广泛的工业和商业应用。