If you knew someone who was a recreational drug user and around their young child? The young girl (22) who does the drug taking does not have sole charge of the child but child adores them and it's possible they could be alone with them at some time.
My friend said I would be starting a witch hunt and could be done for slander.
The parent I might be alerting is not aware of this girl as she is separated from her ex and so doesn't know who her kid is really spending time with