The text below was taken from the site of the ABA - Brazilian Association of Astrology (in Portuguese)
Should the wandering Planetoid or Comet Chiron not be used?
It is reckless to use a body in Astrology whose orbit is decidedly irregular and which to this day is not known with certainty to be an asteroid or a small comet that is progressively losing its nucleus.
Opportunistic astrologers (mainly in the United States) flooded the market with Ephemerides and books on the Interpretation of Chiron only months after its discovery in 1977.
The existing ephemerides of Chiron are not reliable, and until its true position can be determined with confidence, its interpretation will be, at the very least, doubtful and unsuitable for immediate use.