A finding of probable cause under this subsection (3)(a) shall not be based solely upon a positive drug test of a newborn or parent for marijuana; however, a finding of probable cause may be based upon an evidence-based finding of harm to the child or a parent's inability to provide for the care and supervision of the child due to the parent's use of marijuana. Probable cause for unlawful use of any controlled substance, except as otherwise provided in this subsection (3)(a) for marijuana, may be based: 1. upon a parent's positive drug test for unlawful use of a controlled substance only if the child is endangered or the parent is unable to provide proper care or supervision of the child because of the unlawful use and there is no reasonable alternative to custody; and 2. upon a newborn's positive drug screen for a controlled substance that was used unlawfully only if the child is endangered or the parent is unable to provide proper care or supervision of the child because of the unlawful use and there is no reasonable alternative to custody.